Cooked by fire: As early as 780,000 years ago, early humans cooked their food by fire, as findings from Israel now prove. They are the earliest clear evidence of cooking among our ancestors. These are fossil fish teeth that show changes in their structure typical of controlled heating. This suggests that the early humans living in this area caught and cooked these fish in the nearby lake – presumably in some kind of earth oven, as the archaeologists report.
For the development of our ancestors and their increasingly large brains, nutrition and the use of fire played a crucial role. This is because cooked food is easier to digest, and the body can better tap into the nutrients. Early humans were therefore able to get more energy from cooked or roasted meat, fish, and plant foods. They thus needed less time to obtain food and had free resources for cultural development.
However, it is unclear since when early humans specifically cooked their food. It is true that there are one million-year-old traces of fireplaces of Homo erectus. However, it is disputed whether the bones and plant remains found in them were only burned or cooked in a controlled manner. Clear evidence of cooking was around 170,000 years old at the earliest and comes from Neanderthals and Homo sapiens.
Relics of thousands of fish
Carp skull similar to those caught by early humans.
But now, for the first time, archaeologists have found clear traces of cooking as early as the time of Homo erectus. The fossil evidence for this was discovered by Irit Zohar of Tel Aviv University and her team at the Gesher Benot Ya’aqov site in northern Israel. Stone tools, traces of fire, and food remains from hunter-gatherers from around 780,000 years ago have been found there. In addition to animal bones, the remains of thousands of fish that were caught in nearby Lake Hula and then consumed are found there.
What is striking is that the more than 40,000 fish remains come primarily from only two fish species – the two large, particularly nutritious barbel species, Luciobarbus longiceps and Carasobarbus canis. Curiously, however, the research team found hardly any bones of these fish species, although they would normally be preserved, but almost exclusively the pharyngeal teeth of these barbels.
Traces of moderate heat
In search of an explanation, Zohar and her team examined the fish teeth more closely using X-ray diffraction analysis. The crystal structure of the enamel thus made visible can reveal, among other things, whether the teeth were once heated and to what extent. In fact, it showed that a large proportion of the fish teeth found near the fireplaces had been exposed to temperatures of 570 to 930 degrees Fahrenheit (300 to 500 degrees Celsius).
“The enlargement of the apatite crystals in the enamel of the fish teeth shows us that the fish were only exposed to moderate heat and were not burned,” explains co-author Jens Najorka of the Natural History Museum in London. This suggests that early humans cooked the lake-caught fish in a controlled way in the fire. “We can refute an alternative explanation that people consumed the fish fresh or dried and then only burned the remains, because then the enamel would have been more altered,” the researchers said.
Cooking the fish could also explain why hardly any fish bones were preserved. Cooking softened the bones, which caused them to disintegrate more quickly over time.
First evidence of controlled cooking
According to the researchers, their findings suggest that early humans on the shores of Lake Hula ate cooked or steamed fish as early as 780,000 years ago. It’s the earliest evidence that our ancestors cooked their food in some way. Fish prepared in this way were not only nutritious and filling, but they were also available year-round, unlike many wild foods.
The hominids of Gesher Benot Ya’aqov thus had an abundant source of food, even in winter. The ability to cook their food, marked an important milestone in evolutionary development, because it enabled the optimal use of available food resources. It’s quite possible that early humans at that time cooked not only fish, but also various animal and plant foods.
Cooked in an earth oven
Because no fossil remains of the early humans of Gesher Benot Ya’aqov have been found so far, it is still unclear whether they were representatives of Homo erectus or another species. Also, still puzzling is the cooking method they used. No traces of cooking utensils have survived, either at this site or elsewhere, from this period. However, archaeologists suspect that the people at that time cooked their fish in a kind of earth oven, as is still common today among some primitive peoples. (Nature Ecology & Evolution, 2022; doi: 10.1038/s41559-022-01910-z)
Islands are home to unique flora, fauna, and people. They often differ greatly in size from their mainland relatives. In the same way that there used to be baby mammoths on Crete (Greece), there also used to be enormous birds in New Zealand. The existence of cases of island dwarfism and island gigantism continues to this day. Whence do they then emerge, though? Dwarfism has been studied on islands for generations. But why do so many island creatures seem to be abnormally small? Is it possible that this phenomenon may happen to people as well? Perhaps it has happened before. And what about the inverse phenomenon—island gigantism?
Island Dwarfism: The Lands Where Only Dwarfs Live
Homo floresiensis and some of the strangely sized animals that lived in their habitat (Image: National Museum of Nature and Science, Tokyo).
Any number of animals in the wild may become isolated from the rest of their species. Several of a colony of mice, for instance, may hitch a ride on a piece of wood and end up on a deserted island. When people go to uncharted territory, they experience different weather and other environmental factors. They now face new difficulties in their altered environment. To assure their continued existence, they will need to make some adjustments.
This may cause the island to be colonized by a new population that, over time, evolves into something radically different from the original inhabitants. This may cause remarkable growth or shrinkage of the body, particularly in island settings which are called insular gigantism and insular dwarfism.
The World’s Tiniest Mammoth
Fossils from the Ice Age are only one source that exemplifies this phenomenon of insular dwarfing. As such, they provide evidence that many extinct dwarf elephant species previously called the islands of the Mediterranean home, including Sicily and Malta. Some islands even have smaller, dwarf mammoths. The Cretan mammoth Mammuthus creticus, at just 1.13 meters in height, was the smallest of its kind anywhere on the globe. Dwarf mammoth bones have been found in Sardinia.
Approximately 1,500 years ago, Madagascar was home to three dwarf species of hippopotamuses (Hippopotamus madagascariensis) that are now extinct. The biggest specimens were 6.5 ft (2 m) in length and 2.5 ft (0.7 m) in height instead of 16.5 ft (5 m) in length and 5.3 ft (1.6 m) in height of today’s species. The Honshu wolf of Japan, like many extinct wolf species, was much smaller than modern wolves. They were the smallest subspecies of the grey wolf in the world, 30 cm in height and 88 cm in length.
Dwarfing Still Exists Today
However, island dwarfism, also known as insular dwarfism, is not a thing of the past. Raccoons, rabbits, pigs, and even deer all display this trait even now. With a few notable exceptions, even snakes tend to be smaller on islands. Even the so-called Svalbard reindeer of Norway’s Spitsbergen are noticeably smaller than their mainland counterparts. They stand at a meager 65 centimeters at the shoulders, compared to the 110 cm that mainland reindeer do.
A shrunken subspecies of elephant still exists in the modern world. There are only approximately a thousand of these Borneo dwarf elephants left in the wild, and they can only be found in the far northeast of the Indonesian island of Borneo. Male Asian elephants may grow to be as tall as three meters at the shoulders, whereas this species only reaches a height of two.
DNA samples from these elephants have lately been analyzed by scientists looking into their lineage. According to genetic studies, it has been around 300,000 years since Bornean elephants interacted with any other species or subspecies of elephants. The elephants probably traveled to Borneo through an existing overland route.
For whatever reason, animals that grow quite large on the mainland prefer to colonize islands, where dwarfism is the norm from one generation to the next.
Possible Causes of Dwarfing
But why do island animals tend to be smaller in size? When observing animals, a tiny size in a single specimen usually indicates a genetic flaw or starvation. However, additional variables are at play in the instance of island dwarfism, causing whole population to be of smaller stature.
Food accessibility is a main factor in insular dwarfism. Competition for scarce resources like food and shelter is certain to flare up the island’s animal population. Predators are just as guilty of this as herbivores. Because of their reliance on prey, they are often the first to become extinct when that resource becomes rare. Those who learn to make do with less have a leg up. As a result, island predators tend to be smaller than their mainland counterparts.
The same is true, for the most part, on islands for herbivores. Since there are no longer any predators to worry about, it turns out that having a large body size for defense is no longer evolutionary beneficial since it requires too much energy. However, because of the scarce food and water, being tiny becomes an evolutionary adaptation. A smaller body needs fewer calories to keep its metabolism steady. These reproductive benefits for survival are most prominent on the islands.
Survival of the Fittest
Selection pressure describes this environmental bias toward certain features in evolutionary theory. By living and reproducing at a higher rate than their conspecifics, people with advantageous qualities increase the likelihood that those traits will be passed on to future generations. Species of huge animals that need a lot of energy are especially vulnerable to the selective pressure that leads to island dwarfism.
An elephant that develops dwarfism as a result of a mutation may do well in an isolated environment. Elephants that can get by on less food or food with a lower energy density may have a better chance of survival if the island only has poor soil and few plant foods instead of extensive grassy fields like on the mainland. This elephant has the ability to have additional children and pass on the mutation to them.
Dwarfism’s genetic information is more likely to spread since islands are often home to just a few members of a given species. So, the unique environment and, most importantly, the scarcity of food on the island encourage the development of dwarfism among the local individuals.
Island Gigantism: The Advantage of Just Sheer Size
Two giant Komodo dragons fighting on Rinca Island, Indonesia.
Scientists have seen both the phenomenon of insular gigantism and insular dwarfism as a survival strategy on islands. But what are the reasons for wanting to bulk up? If so, what kind of creatures are impacted by this gigantism phenomenon?
When isolated from the mainland, certain rodents, especially those that are generally rather small, may grow to unusually huge sizes. Iguanas, geckos, and monitor lizards, like the Komodo dragon, also tend to grow to enormous sizes. This phenomenon, however, is not a new occurrence.
Giant Fossils
Humans wiped off the gigantic birds of Moa by overhunting them to extinction. Heinrich Harder (1858-1935)
The history of giants who lived on islands is extensive. The Moa, a flightless bird that formerly measured over 2.5 meters in length but is now extinct, is an excellent example for gigantism. The earliest people arrived in New Zealand in 1280 B.C. and started hunting the huge, flightless moas, driving them to extinction.
Researchers in New Zealand have uncovered further giant examples of these birds in 2019. The fossil of a penguin that was the size of a tiny person has been found among Moas. This ancient bird is among the world’s biggest and most ancient penguins. At 1.60 meters in length, it was at least 40 cm longer than the tallest penguins alive today.
The fossil of the one and only enormous parrot that ever lived is another. The one-meter-tall bird, which lived about 16–19 million years ago, was almost twice as heavy as the biggest surviving parrot. The enormous parrot probably killed and consumed other birds because of its formidable beak.
The Largest of Their Genus
Studies of island-based gigantism continue to this day, and sometimes with good reason: on Gough Island in the South Atlantic, mice have grown so huge that they assault the albatross chicks that live there. Seabirds on Gough have no natural defenses against animals or even quadrupeds, according to Chris Jones of the British bird conservation group RSPB.
The causes of the gigantic mouse size were investigated by biologists. It has been discovered that the genomes of big mice and mainland mice vary on 67 gene loci. This means that in small populations, the size increase is passed on quickly. However, why do individuals of such a large stature tend to prevail so well?
Small rodents, like mice, often fare better when they have many possible points of egress in the event of an attack. However, scientist Lawrence Heaney previously articulated in 1978 that the urge to maintain small body sizes reduces for many species in the absence of specialist predators, which is typically the situation on islands.
The Advantage of Getting Bigger
There may be a number of causes for gigantism. To begin with, the creatures can’t grow without favorable environmental conditions, enough water, and enough food. It’s also possible that the existence of predators of comparable size plays a role in insular gigantism. Those that wish to be successful in their region versus predators of the same size will profit from increasing their body size. Females may want to mate with the largest available male since it increases the likelihood of producing healthy, strong offspring. Biologists call this “sexual selection,” or the process of choosing mates via sexual encounters.
Another proposed cause of gigantism is selection, as shown in the Anaho Island iguana population. According to studies conducted by the University of Nevada, male iguanas engage in territorial competition similar to that of predatory cats. A male’s ability to successfully protect his territory depends on his size and aggression. Iguanas cannot freely distribute on islands, so huge lizards have an advantage in this environment.
As a result of these and other considerations, it is clear that the species best suited to the unique habitat of islands are those who exhibit either dwarfism or gigantism.
Can Humans Also Be Affected by Insular Dwarfism?
During excavations in the cave, skeletal parts of the dwarf humans were found. (Image: Rosino, CC-BY-SA 3.0)
“Hobbit Man”
In the animal world, dwarfism has an evolutionary benefit due to the limited food supply on islands. Because, you know, being little helps you save resources. But is human adaptability like this possible? Our ancestors lived on little islands, as shown by fossils discovered here. They have been called into question as to whether or not they should be considered their own species.
During excavations in the Liang Bua cave on the Indonesian island of Flores in 2003, fossils dating back around 18,000 years were found, suggesting the presence of a very small-bodied early dwarf human. The discovery concerned a female roughly a meter tall with a chimpanzee’s-sized brain. The newly discovered small-statured human species was named Homo floresiensis after the Indonesian island where she was discovered.
Mystery of Dwarfism
Researchers have now discovered the remains of nine other “hobbit men,” all of whom were equally short, in the same cave. Stone implements were also discovered.
Scientists have been debating where Homo floresiensis should be placed in the human evolutionary tree ever since the first fossils were discovered. Are they just deformed examples of our own species, Homo sapiens? Alternatively, did the “hobbit men” really reflect a prehistoric human species that has since gone the way of the dodo bird?
Is It a Sickness or a Flaw in the Genes?
One of the earliest hypotheses put forth was to explain the surprising discovery of a relatively tiny human brain. In 2005, researchers compared Homo floresiensis’s brain size to that of contemporary individuals with microcephaly. People with this condition have abnormally tiny heads and never grow beyond a certain height.
Great parallels were found between the two, suggesting that Flores’ small lady may have had microcephaly. It is puzzling, however, to speculate on the origin of the stone implements that were discovered. Due to the fact that anyone with microcephaly would be unable to construct or utilize such implements.
This was always suspected, but anatomical studies conducted by Robert Martin of the Field Museum in Chicago and his colleagues proved it. There are more than 400 distinct types of microcephaly in contemporary humans, and their research indicates that many of these characteristics are present in the bones. In a small population, this genetic flaw is handed down quickly through the generations. There is not enough evidence at this time to attribute the most extreme cases of low height to a particular condition. So, this theory is still only a guess at this point. There is no scientific proof since no DNA samples have been collected.
It wasn’t until 2008 that a brand-new theory emerged: Dwarfism on Flores may have been caused by a genetic mutation. Small stature and fragile bones were the results of this genetic flaw.
A Small Caveman
Researchers from all around the globe tried to figure out why Homo floresiensis was so short. New human fossils discovered in Mata Menge, roughly 70 kilometers east of the location where the “hobbit men” were unearthed, have shed some light on the mystery. Some six teeth and a piece of a lower jaw were discovered by paleontologists in a limestone cave, all of which belonged to an early human.
These fossils are undeniably hominin and remarkably similar to those of Homo floresiensis. Although the artifacts share many characteristics with Homo erectus, a modern human predecessor, and Homo floresiensis, they are up to 20% smaller than the hobbit men.
People that populated Flores about 700,000 years ago may be responsible for the recent discoveries. They had the same dwarf stature as Homo floresiensis and, at least in terms of dental features, also resembled the much bigger Homo erectus. Therefore, they could be an intermediate step in the development of the mysterious “hobbit men.” However, further skull and skeletal components of this human form would need to be discovered to provide conclusive evidence.
Ancestral Mystery
But the new fossils may lend credence to the idea that Homo floresiensis originally evolved from Homo erectus. This notion is supported by similarities with Homo erectus artifacts discovered in the area. Although other characteristics also point to the specimen possibly being a tiny example of an early human species, the small brain of Homo floresiensis stands out. Since Homo erectus only had a short period of time in which to develop their brain. It was about the same size as a chimpanzee today.
What’s more, we know that Homo erectus persisted in Indonesia for at least another 30,000 years. Homo erectus artifacts discovered on the Indonesian island date back 1.2 million years. Speculations suggest that the existence of these pre-humans in the cave may be traced back to the discovery of stone implements. It is estimated that the tools are 1 million years old.
This suggests a potential branching pattern for the human family tree that might accommodate the Hobbit men. It’s possible that some Homo erectus survivors washed up in Flores and made a new home there. Their gradual diminution over time reflects an observed adaptation in evolutionary biology. In this way, Homo erectus evolved into Homo floresiensis. However, it’s not clear whether this data is adequate to establish where this species originated. No examples of such fast growth in size in primates have been found.
Lineage of the Dwarf Humans: Who Was Homo Floresiensis?
Where did the Flores “hobbit people” originate from? This topic has yielded conflicting findings so far. For instance, the year 2017 saw the introduction of a novel theory. That would imply that Homo floresiensis didn’t necessarily come from Homo erectus. The “Hobbit” bones have been studied by scientists from the Australian National University, who have compared the remains to those of other early and prehuman species.
It seems unlikely that Homo erectus was the progenitor of Homo floresiensis. This is due to the fact that Homo erectus had a much more sophisticated jaw structure than Homo floresiensis. This theory posits an African origin for the first humans, who were notably shorter than modern humans. Comparisons indicate that Homo floresiensis is closely linked to Homo habilis.
Nearly 2 million years ago, Homo habilis appeared in Africa, predating even Homo erectus by a small margin. Based on the data, it seems that Homo floresiensis and Homo habilis are closely related. The two species shared a common ancestor 1.75 million years ago. The “hobbit” lineage could have diverged from this evolutionary tree long before Homo habilis existed.
An Evolutionary Phenomenon
Contrary to this theory, however, it seems that neither the ancestors of Homo habilis nor Homo habilis itself ever left Africa. As fossils show, only Homo erectus and his contemporaries made it to Asia.
It is, therefore, more than a mystery how Homo floresiensis or its predecessors arrived in Indonesia. Homo floresiensis may have originated in Africa and then spread over the world. However, it’s also possible that the hobbit ancestor didn’t become a race until after they departed Africa. The second hypothesis proposes that Homo floresiensis’ diminutive size was associated with the spartan conditions of their island home.
Human Dwarfs
This “island life” idea has additional supporting evidence. The evolutionary history of organisms in a closed and isolating environment, such as an island, can be significantly altered. As is still common in the animal realm today, scientists wondered whether the discovery may be a deformed human. The modern-day inhabitants of the area are still notably small.
The Flores pygmies are a group of individuals who are still alive and well today and whose genome has been studied. Comparing the genomes of Flores pygmies with those of people living on bigger islands like New Guinea or the Asian mainland revealed that there are differences in some locations. These genes, which are involved in regulating short stature among other things, have seen greater variation through time than the rest of the human population.
This provides genetic proof for the island theory. The Flores Hobbit was apparently distinct from its family due to the island’s climate, yet it was likely not an entirely new species. The origins of the hobbit people continue to be shrouded in obscurity, since it is unclear when or whether the island of Flores was ever colonized or if it was ever linked to the mainland.
We all know the old saying that men already have their hands full just trying to make bottles for their infants. If they also had to nurse, they wouldn’t have a chance. Thankfully, nature has saved them the trouble by just giving them two little pink bumps on their chest to serve as nipples. When considering the function of every part of the human body, the nipples on men may stand out as the most pointless. But why did nature retain them if they didn’t provide any milk? Just a matter of style, then?
Why do males need nipples? Except for maybe looking good on their chests, they have no practical use. And even then, this is only for the most muscular of them. Male nipples could have been lost to evolution since they are incapable of producing even a trace of milk. However, mother nature disagreed and insisted on keeping them where they belong. But to what end did this occur?
Nipples have to be traced all the way back to their beginnings so they can be properly understood. The point of this starts even before a baby is born.
During the earliest stages of development, embryos of both sexes contain basic structures that may eventually become either male or female reproductive organs (or rarely both). Whether a newborn is born male or female is determined by a combination of genes. An important master gene is located on the Y chromosome’s short arm and is known as SRY (sex-determining region Y).
About seven weeks during embryonic development, SRY is switched on. When turned on, it causes the female reproductive system to disappear while also causing the male reproductive system to develop.
However, breast and nipple development start between weeks four and six, far before the SRY gene is turned on. When this happens, there are two bumps (mammary ridges) between primitive axilla and groin. Thus, even when the mammary ridge fades later in male development, the cells that produce the primitive nipples and the nipple smooth muscle still persist in that area. The remaining cells develop into the complete breasts and nipples.
According to other scientists, nipples exist on men because the area is very sensitive for certain people. And our bodies’ erogenous zones seem crucial for reproduction.
An Early Stage of Development
In the initial few hours following fertilization, the embryo undergoes rapid and dramatic changes. Nipples are a part of normal male and female development up to a particular age. Paleoanthropologist Ian Tattersall from the American Museum of Natural History in New York, USA, says, “To put it simply, men and women are all built from the same genetic blueprint.”
However, distinctions start to become visible during the sixth and seventh weeks of pregnancy. This is because of Y chromosomal genes, which are only found in males. These predisposed male genes eventually promote testicular growth, leading to the production of the hormone testosterone. Multiple effects on the developing embryo are brought about by the chemical.
Its masculine traits mature and its genitalia fully form, but any potential for a future feminine identity is hindered. And the nipples still persist after this abrupt halt. There is no way to remove them after they have been set. The emerging male will wear them like badges of honor for the rest of his life.
Infant males and females have identical nipples and breasts. Only in puberty, when hormones are at work, do they start to alter. Both sexes experience a growth in the size of their nipples, albeit the female nipple expands more. As the female breasts enlarge and change form, the male ducts contract. The mature male nipple is smaller and more uniform in shape than the female counterpart.
What Accounts for the Evolutionary Survival of Human Nipples?
In humans, a child receives one copy of each gene from each parent at birth. Thus, a boy’s inherited characteristics should be a blend of his parents’ characteristics. From a genetic perspective, we must then ask backwards: how can men and women differ if genes are acquired from both parents?
Common examples of sexual dimorphism are the different plumage colors seen in birds and the varying sizes of male and female insects. Unless the same feature (color, for example) in men and females has been genetically dissociated, it is impossible for such disparities to arise.
This occurs when a characteristic is controlled by a distinct set of genes in males and females, when the relevant genes are situated on separate chromosomes, or when the genes’ expression has become conditional on environmental factors (if the genes are in a male or female genome). Evolutionary geneticists often assess a statistic known as genetic correlation, which represents the assumption that two qualities (here, in men and females) have a common genetic base. As a matter of course, evolution works on the assumption that sexes are genetically similar.
If the attribute is vital to the reproductive success of both men and women, yet the better or ideal trait is different for a male and a female, then we have a case of decoupling between male and female features. If the trait is essential in both sexes and has a comparable “optimal” value in both, then decoupling is unlikely to develop; conversely, decoupling is likely to occur if the attribute is important in one sex but not the other.
This is especially true for nipples. If you look at their reproductive success rates, it’s obvious that they have a distinct edge when it comes to females. The occurrence of nipples in men is likely best described as a genetic connection that survives owing to a lack of selection against them, rather than selection for them, given that the genetic “default” is that males and females share features. What this means is that evolution has not eliminated the male nipple for any reasonable cause.
Don’t Fix Something That Isn’t Broken
For what reason did mother nature make this choice? Men’s nipples aren’t very attractive, but they’re not exactly a waste of time either. Because having nipples doesn’t have much of an effect on your metabolism. Then, why get rid of something that has no purpose, does no harm, and provides no benefit? Perhaps they provide a touch of sexiness to otherwise macho physiques.
Sadly, this seems like a bit of a delusion that may end up costing a lot for some men. Because males may also have breast tumors, the disease is not limited to females. But male breast cancer accounts for fewer than 1% of all instances, and the chances are much lower for men who live healthy lifestyles.
Two of the most significant contributors to breast cancer are excess weight and alcohol intake. The key to maintaining toned nipples is a healthy diet and limited alcohol use. Those are literal “nipple-breakers.”
The written version of our genetic instruction manual, which has 3 billion letters, would take up many volumes’ worth of space in real life. However, it is only contained inside the tiny cellular structure of our body. From our gender to our physical characteristics to our susceptibility to disease, practically every aspect of our lives is determined by the choices our ancestors made. However, for a very long time, no one knew what this genetic code looked like and what it contained. Scientists eventually uncovered the shape, language, and exact function of our DNA, with some unexpected findings along the way.
The genetic specifications for all known creatures and many viruses are stored in a deoxyribonucleic acid or DNA, a polymer made up of two polynucleotide chains that coil around each other to create a double helix. DNA governs development, functioning, growth and reproduction.
Two men did change the world of science
In a statement made 70 years ago, according to James Watson, only a few discoveries have been of such exquisite beauty as DNA. Watson was referring to the double helix, a structure that is 2.5 nanometers in diameter, looks like a helically twisted rope ladder, and stands 7,2 feet (2,2 meters) in length if fully unfolded.
On April 25, 1953, James Watson and Francis Crick published a single page in Nature proposing a model for the three-dimensional structure of deoxyribonucleic acid (DNA), the molecule that encodes human genes.
It seemed that the two researchers were confident in the long-term relevance of their model since they cited “novel features of considerable biological interest” at the start of their paper.
Zero interest in chemistry
Although at first glance, it did not seem likely that two “scientific clowns,” as scientist Erwin Chargaff dubbed them, would produce such a groundbreaking discovery. James Watson, who was very talented, began studying biology at the University of Chicago when he was only 15 years old. Birds were his major focus at the time, thus he was able to avoid taking any science classes.
The zoologist’s understanding of chemistry and physics was quite limited when he first arrived at the Cavendish Laboratory in Cambridge, England, in the autumn of 1951, at the tender age of 23. In England, he met British scientist Francis Crick, who was 13 years older and whose loud laughing was the bane of his colleagues’ existence. Francis Crick’s prior life as a researcher was summed up by the institute’s director, Sir Lawrence Bragg. According to him, Francis was talking ceaselessly and had come up with next to nothing of decisive importance.
A scientific footrace
In 1949, Erwin Chargaff discovered that the DNA bases adenine, thymine, cytosine, and guanine always occur in DNA at a 1:1 ratio, or most likely in pairs. The next step was to figure out the structural integrity of the bases and how they fit together. Watson, who was originally uninterested, attended a presentation by neighboring King’s College London scientist Rosalind Franklin in November 1951, during which she shared recent X-ray diffraction photographs of DNA.
Waston found intriguing her speculation that DNA could exist in a twisty helical shape with two, three, or four twists. As soon as Watson and Crick got back to Cambridge, they set out to try to replicate this structure. They hypothesized, based on chemical calculations, that the structure would consist of three chains joined in a helix by magnesium ions, with the molecular arms pointing in all directions.
Success through failure
Watson, however, was not paying close attention, and the team’s model of the chemical reaction turned out to be incorrect. They made a disappointing appearance in front of Rosalind Franklin and London-based biophysicist Maurice Wilkins.
Colleagues were quite harsh in their criticism. Previous X-ray images produced by these two scientists had demonstrated conclusively that the supporting chains could not lay within, refuting the premise of Watson and Crick, and that magnesium ions were scarcely capable of maintaining this structure.
In July of 1952, Erwin Chargaff visited Watson and Crick in the lab and delivered a similarly damning assessment of their scientific prowess: “enormous ambition and aggressiveness, coupled with an almost complete ignorance of, and a contempt for, chemistry…”
When it became public that famous scientist Linus Pauling, on the other side of the Atlantic, shared a fascination with the structure of genetic information and suggested a model for it, the scientific reaction intensified. Urgency necessitated swift action.
Then, towards the end of 1952, Maurice Wilkins offered Watson and Crick an X-ray structural study of his colleague, Rosalind Franklin, which proved to be a pivotal event that ultimately led to triumph. It was, in fact, a picture of a recently discovered DNA structure. But this was all without Franklin’s consent.
By the end of the study, the two scientists had reached a consensus: DNA is made up of two strands that intertwine with each other like rungs on a rope ladder. Hydrogen bonds hold their molecular appendages, the complementary bases, together. Finally, Watson and Crick assembled their metal double helix structure like pieces of a jigsaw. This variation won over even the most skeptical people.
Recognition and respect
Many scientists date the beginning of molecular genetics to the publication of the “Watson-Crick Model” of the structure of DNA. James Watson, Francis Crick, and Maurice Wilkins all split the 1962 Nobel Prize in Medicine and Physiology equally. In contrast, Rosalind Franklin, whose research offered the last vital piece of the puzzle, came up empty. Sadly, she passed away from uterine cancer in 1958, when she was only 37 years old, without seeing the fruits of her labor. It’s safe to say that most people nowadays have forgotten who Franklin and Wilkins were. But the names Watson and Crick will forever be linked to the double helix model of DNA.
The exchange of information
Translation of genetic code
Since 1953, scientists have understood the fundamental nature of our DNA and that it includes the blueprints for every aspect of our identities, from physical appearance to health. It was quickly understood that each base pair represented a different letter in the manual. The question is how to give form to these inscrutable directives and create a live, breathing, and authentic human being.
In every human cell, two sets of 23 chromosomes are created when an egg from the mother and a sperm from the father fuse. The maternal contribution to these roughly X-shaped structures is half, whereas the paternal contribution is half.
We store and carry our DNA, or genetic information, in a compact form called chromosomes. All of our DNA, together with its protective envelope structures, is stored in a very condensed form on the many chromosomes in our bodies.
The sequence of bases as the alphabet of life
The typical RNA codon table is structured in the form of a wheel.
Adenine (A), Guanine (G), Thymine (T), and Cytosine (C) are the four bases that make up DNA. The two strands of DNA’s framework are held together by the pairs A-T and C-G. They serve as the rungs on this hereditary ladder. When you align the ladder segments of a single DNA strand, you’ll see a lengthy string of base letters.
And it is in them where the genetic code is found. Three of these letters are put together to spell out a word that specifies where in the process the production of protein should include a certain amino acid. A string of these letters forms a phrase, which in turn becomes the blueprint for a protein. And these molecules, in turn, play the role of a biochemical housekeeper who makes sure everything from cell and tissue formation to signal transduction and metabolic processes go smoothly.
Transcription and translation of DNA
Genes and proteins
How, however, does the blueprint for a structure end up as a protein? The process of making proteins from scratch is called biosynthesis. At this phase, the genome must be unpacked so that the information for a protein can be read from DNA. Generally found as a double strand, DNA separates into two single strands. Thus, the free arms of the rope ladder become accessible.
Enzymes have now made it possible to make carbon copies of this segment of the strand by simply joining a complementary base to each of the free arms. This time around, though, the base uracil bonds to the adenine instead of the thymine. In this case, however, the ribonucleic acid (RNA) serves as the scaffolding for these newly joined bases. After the copy is complete, enzymes cut the RNA strand and its accompanying DNA bases away, creating a copy of this region of the genome that can be moved throughout the cell, the messenger RNA (mRNA). Transcription refers to this process of making a copy of the genetic material and rewriting it.
Translation into protein building blocks
A ribosome’s translation of mRNA and protein synthesis is shown in this diagram.
However, this is just the beginning. mRNA now transports the genetic information copy from the nucleus into the cell plasma, where it will be read by the ribosomes and used to make proteins.
The mRNA is sandwiched between the two subunits, one larger than the other; this creates a reading unit similar to the needle on a tape recorder. It decodes the genetic code by identifying which of the three bases (and hence which genetic code word) is present in each instance.
Simultaneously, many of the amino acids that will make up the future protein accumulate on the ribosomes, each of which has a tiny piece of RNA consisting of precisely three base letters connected to it. These letters and numbers serve as a label, identifying the specific amino acid bound to this transport RNA (tRNA). It is the job of the ribosome to dock and connect the component of the amino acid that corresponds to the coding of the next amino acid in the read-out mRNA.
Polypeptides, or chains of amino acids, are produced in this fashion and are the building blocks from which proteins are assembled. DNA can only perform its job via translation, the process by which the genetic information is converted into a chain of amino acids.
Junk DNA
Discarded material transformed into a control center
A gene is a set of instructions for making a particular protein; it consists of a specific sequence of the base pairs cytosine, adenine, guanine, and thymine. It’s the blueprint for these critical messengers of our body’s processes.
It was quickly discovered, however, that significant portions of human DNA lacked any recognizable construction instructions. Sequences in an organism’s DNA that do not code for proteins are known as noncoding DNA (ncDNA). They looked to be made up of illogical and repeated DNA sequences that had no discernible purpose. Therefore, scientists called these pieces of DNA “junk DNA.”
Only 2% of your genes are real
However, scientists were baffled when they looked more closely at the breakdown of our genetic material and saw that around 44% of it is “junk” in the form of several copies of genes and gene fragments (repeats).
In addition, 52% seems to be useless as well and does not code for proteins. However, only around 2%–4% of human DNA is made up of genuine protein-coding genes.
It has long been a puzzle as to why evolution has preserved so much irrelevant DNA in addition to these gene sequences. But this issue was first answered by research in 2004. Scientists in the United States revealed a startling discovery about this “living genome deserts” that many regions of DNA that do not code for proteins were far from inactive. They include sequences that may activate or silence other genes, even if they are located far away.
A regulator made of “junk”?
This suggests that the genome’s so-called “junk” is playing a significant role in regulating gene activity, helping to shed light on the basic differences across species even though their genes are, on average, just a few percent different.
Also, scientists from LLNL and JGI found that different parts of junk DNA have experienced different degrees of modification during evolution. There are several non-coding regulatory elements in the “desert areas” that are resistant to rearrangement and defend themselves via repeating junk DNA patterns. It appears that genomic regions known as stable genome deserts are essentially hidden gene regulatory components that preserve the intricate function of neighboring genes.
About two-thirds of the genome deserts and about 20% of the overall genome could be gene segments that are completely useless for biology, indicating that most of the genome is redundant. At least, 75 percent or more of our genetic material is really just junk and only around 8–14% of our DNA is functional in some way.
Our genome is governed by junk DNA
Junk DNA and genome desert.
The term “junk DNA” refers to the 98% of the human genome that does not code for proteins but the truth is actually more complicated.
Because this notion of mostly useless junk DNA kind of shattered in 2011. The international ENCODE project discovered something astounding: almost all of our junk DNA functions as a massive control panel for our genome, containing millions of molecular switches that can activate and deactivate our genes as needed, including in regions where only an “unstable desert” had been suspected.
The “junk” has millions of switches
Scientists created a detailed map of the locations and distributions of control elements, which revealed that the control switches are often located in inconveniently distant genomic regions from the genes they regulate. However, due to the complex three-dimensional shape of the DNA strands, they can still come close and exert their regulatory effects.
That means, our genome is only functional because of switches: millions of buttons that control which genes are active.
Genes derived from junk DNA
But junk DNA has other, non-regulatory functions too; scientists from Europe identified a gene on mouse chromosome 10 that appeared out of nowhere but originated between 2.5 and 3.5 million years ago via genome-wide comparisons. The gene was the only one positioned in the center of a lengthy non-coding chromosomal part. This area is present in all other mammalian genomes as well. However, the gene is only found in mice.
There was some speculation that a gene may emerge at a place in the genome that had never been used before, but no evidence for this had ever been found. Yet it was discovered that the mutations that only occur in mice could be responsible for the new formation of the gene.
This demonstrates that the regions of DNA that do not code for proteins are an essential component of our genome and that they have long played a significant role in a variety of modern genetic analyses.
DNA and forensic science
It was all solved via a DNA analysis
You can identify a criminal by his genetic fingerprint from as little as a drop of saliva on a Coke bottle or cigarette filter, a few skin cells beneath the victim’s fingernails, or blood on his clothes.
Most of our bodily fluids also contain cells from our body, and with them our genetic information. Skin cells are always left behind when a hand is dragged along a rough surface or is scratched, and these cells carry our DNA.
However, there is a catch: there is far too little genetic material in the crime scene that remains for analysis, and this is precisely the reason why DNA analyses from such relics were unattainable for a long time. These genetic material remains can tell investigators whether or not their suspect was the perpetrator.
The polymerase chain reaction for DNA testing
But in 1983, US scientist Kary B. Mullis came up with a plan to multiply the few amounts of DNA that obtained and, in the process, devised one of the most pivotal techniques in genetics and biotechnology: the polymerase chain reaction (PCR).
A DNA fragment of up to 3,000 base pairs in length is heated to 201 to 205 degrees Fahrenheit (94 to 96 degrees Celsius), which breaks the hydrogen bonds between the bases of the double strand, resulting in the separation of the helix into two single strands. Two primers are then added to the DNA solution.
They bind to certain places on the DNA segments (based on their structures) and signal the beginning of the copying process, which is carried out by a heat-stable enzyme called polymerase.
At a temperature of 140–160 degrees Fahrenheit (60–70 degrees Celsius), it joins DNA-building components floating in solution to produce a perfect replica of the sequence designated by the primers, leading to another double strand and doubling the original amount of sequences.
Once the PCR is finished, the few remnants from the murder scene become a solution containing millions of copies of the perpetrator’s DNA, thanks to the process of repeated cycles in which the double strands are split from one another and then supplied with new halves by the polymerase.
A unique repeat pattern
The testing phase can now begin, with researchers comparing only small fragments of the DNA rather than the full sequence (which would take too long and be too laborious).
These fragments are found in the genome’s non-coding regions and are made up of several repeating base sequences termed “short tandem repeats” (STRs), which provide a unique genetic fingerprint since their numbers vary from person to person.
In many countries, a standard DNA analysis at a criminal lab includes testing for eight STR systems over several chromosomes and one sex-differentiating characteristic, which should be more than enough to rule out the possibility of a chance match.
Estimates suggest that the number of people with whom our unique STR pattern is shared is less than one in a billion, with the exception of identical twins. If a suspect’s genetic fingerprint matches that found at the crime scene, then it’s likely that s/he committed the crime in question; her/his own DNA has in fact convicted him.
Probing the paternity of a child
The mother’s identity is generally evident since she gives birth to the kid (barring surrogate moms), but the identity of the father is not always so clear.
It’s possible that the question of paternity won’t come up until the child is an adult if the woman has cheated on her partner in secret or if she gets pregnant shortly before breaking up with her partner and keeps the baby from him.
Numerous laboratories around the world have long offered such gene-based paternity tests online, and the process for those willing to take the test is very simple: just send in a saliva sample, a few hairs with a hair root, a baby’s pacifier covered with spit, or a piece of chewing gum that has been well chewed.
First, the DNA is extracted from the samples and amplified by polymerase chain reaction (PCR) in the lab; next, the DNA is compared to samples of the same genetic material from the child’s father or, ideally, the mother.
Short tandem repeats (STRs) are also used in forensic DNA analysis, and the frequency with which a given base sequence is repeated within an STR marker varies from person to person but is passed down from parents to offspring. Each person carries two STR marker variants at each gene locus, one inherited from mother and one from father.
In contrast, if the genetic material of the parent and child differs at three or more STR markers, paternity or maternity is considered to be ruled out. The probability that two unrelated people will have the exact same pattern of repeats at these markers is just one in 100 billion, according to current estimates.
The Human Genome Project (1990-2003)
Human Genome Project. Image credit: Encyclopædia Britannica, Inc.
Learning by reading life’s book
In the year 2000 in the United States, Bill Clinton and his British counterpart, Tony Blair, arranged for an unusual news conference in Washington. Nothing less than the human DNA itself was at stake here. The decoding of our genetic composition has been publicly announced by Clinton and, following him, by representatives of two rival research organizations, one government and one private.
And in 2022, scientists finally announced that they finished decoding the entire human genome. According to that, about 30,000 human genes are housed in the nucleus of each human cell, where they are contained in 23 chromosomal groups.
Humanity’s next big thing
An early version of the “Book of Life” has been deciphered by both the worldwide Human Genome Project (HGP) scientists and genetic engineering pioneer Craig Venter and his business Celera. About 3.1 billion letters make up our genome, which is composed entirely of apparently random sequences of the four nucleotide bases (adenine, cytosine, guanine, and thymine).
From the neurons that carry impulses throughout the brain to the immune cells that help protect us from external attack, each of the trillions of cells that make up our bodies has the same 3.1 billion DNA base pairs that make up the human genome.
It’s still not fully known what words and sentences may be constructed from these letters, as well as where certain functional units of genetic material are buried.
The decipherment of the human genome paved the way for novel approaches to illness prevention, diagnosis, and treatment. But these 3.1 billion letters of sequence in one human DNA were only the beginning of the long road to deciphering the human genome.
Interesting, but impossible
Things looked very different 25 years ago. In 1985, a group of genetics experts at the University of California, Santa Cruz, were approached by biologist Robert Sinsheimer with an unusual proposal: Why not try to sequence the human genome? The response was as unanimous as it was unequivocal: bold, exciting, but simply not feasible. Decoding even small sections of DNA was still too laborious at this time.
However, one of the researchers involved, Walter Gilbert of Harvard University, did not give up on the idea. About 20 years ago, he and a colleague were the first to develop a method for reading out the genetic code or genetic sequencing.
However, potential backers were still cautious, asking, “What if it turns out that the entire thing is not worth the massive effort?” and “Shouldn’t we possibly start with the genome of a small, less sophisticated creature, such as a bacterium?”
Genome arms race
Finally, in 1988, the U.S. National Institutes of Health (NIH) was convinced to organize a project to decode the human genome, led by none other than James Watson, one of the two discoverers of the double helix structure of DNA.
Understanding of the disease genes
However, progress has been sluggish since researchers were always debating whether or not it would be more efficient to begin by searching for illness genes rather than meticulously sequencing everything.
Craig Venter, a geneticist at the National Institute of Neurological Disorders and Stroke (NINDS), stood out because he and his colleagues had created a novel approach to discover gene fragments at an unparalleled rate, but without understanding their function.
Watson opposed and publicly complained about the sellout of genetic material which was met with early enthusiasm by NIH leaders since, if patented, these genes could be converted into cash. The fallout was seen when Watson was replaced as project head by Francis Collins in April 1992.
Not fast enough
Collins made a dismal prediction in 1993 that human genome sequencing wouldn’t be finished until 2005 at the earliest if things kept moving at their current rate. Part of the reason for this was the lack of resources that have so far prevented the development and widespread use of state-of-the-art DNA sequencers, which would greatly facilitate the automation of the genome decoding process.
On the other side, achieving a success rate of 99.99 percent was a need. After all, international research institutes were joining the effort at an increasing rate.
Upon meeting Craig Venter in 1995, the HGP researchers and management were rudely roused. As part of his new job at a commercial corporation, Venter released the first genome of a fully developed organism, that of the Haemophilus influenzae bacteria. He had accomplished it in a year because of the cutting-edge computing power available at the time. While progress was being made by Collins and the HGP researchers, it was slower than some would like.
Head to head
At the 1998 annual gathering of genetic experts, Venter pulled off his next move by announcing that his new firm would be able to decode the human genome in three years for a quarter of the cost of the HGP. He would be assisted by an automated sequencing system currently under development.
At this point, Collins and his group must take action. Six months later, they announced that instead of waiting until 2005, full genome sequencing was now expected to be completed in 2003 thanks to increased efforts. They wanted to provide the first functional version of the human genome that is around 90% valid by spring 2001.
It seemed like Craig Venter and his business, Celera, were in for a close finish. In reality, though, efforts to establish a mutually agreeable human genome resolution had already begun behind the scenes.
The HGP suggested holding a combined press conference to announce the initial versions of both projects at the same time on July 26, 2000. While the HGP had been publishing their sequencing in the British journal “Nature,” Venter and his colleagues had been contributing to the rival American journal “Science.” The unveiling of the virtually entire human genome was announced two years ahead of schedule, on April 14, 2003.
Thus, in April 2003, the Human Genome Project (HGP) was announced as completed but only around 85% of the genome was actually included. 15% of the remaining human genome was sequenced only by January 2022.
Dictionary of genetics
Amino acids
20 amino acids are the fundamental building blocks of proteins, and the genes determine the order in which these amino acids are put together to create a chain.
Bases
The nucleotides adenine (A) and thymine (T) and cytosine (C) and guanine (G) are paired with one another in double-stranded DNA through the complementary base pairing concept. Thymine (T) is switched out for uracil (U) in the ssRNA (single-stranded RNA).
Chromosomes
Chromosomes, which contain an organism’s genetic information, number 46 in humans thanks to the duplication of the 23 chromosomes found in each of our cells.
Codon
An amino acid’s genetic code is encoded in a sequence of three bases.
DNA
Deoxyribonucleic acid is a double-stranded molecule composed of a sugar backbone (deoxyribose) and a phosphate group, and a linear series of base pairs. The two single strands are complementary to each other, run in an antiparallel direction, and are kept together by base pairs.
DNA sequence
An order of the DNA molecule’s construction order.
Dolly
A well-known cloned sheep that was cloned in 1996 from an adult sheep’s single cell.
Gene
Genes are sections of DNA. In eukaryotes, genes are often made up of coding sections (exons) and noncoding sections (introns). Coding portions (exons) carry the genetic information for creating proteins or functional RNA (e.g., tRNA).
Genetics
Molecular genetics investigates the fundamental laws of heredity at the molecular level, whereas classical genetics focuses on the inheritance of characteristics, especially in higher species. Applied genetics focuses on the breeding of economically highly productive crops and animals.
Genetic code
The genetic code is a kind of encryption used to store information on DNA, and it is represented by a set of three-base pairs in all known forms of life.
Genetic fingerprint
Genetic fingerprints are unique to each person and are generated by using so-called restriction enzymes and undergoing further analytical processes.
Genome
A genome refers to the whole set of genetic instructions for a certain organism.
Human Genome Project
An international effort funded by many agencies to investigate the DNA sequence, protein function, and regulatory mechanisms of the human genome.
Gamete
Gametes are sexually reproducing cells (eggs, sperm) that contain just one copy of each of the 23 genes found in the human genome, which is called haploid (in humans).
Cloning
Producing offspring with the same genetic material by cell division or nuclear transplantation.
Mutation
Mutations, which may be caused by anything from exposure to ultraviolet light or naturally occurring radioactivity to the simple passage of time, are the fundamental mechanism by which new species are created and evolve.
Nucleic acids
Both DNA and/or RNA
Nucleotides
A phosphate group, a sugar, and a base make up the three components of the DNA-building block.
Nucleus
The nucleus is the membrane-bound organelle that houses the cell’s chromosomes.
Peptides
Peptides are compounds made up of two or more amino acids, which can be the same or different. Peptides are classified according to their length, with dipeptides consisting of two amino acids, tripeptides of three, oligopeptides of two to nine or ten amino acids, polypeptides of ten to ninety-nine or one hundred amino acids, and macropeptides of one hundred amino acids or more being considered proteins.
Polypeptide
Chain of ten or more amino acids held together by peptide bonds.
Polymerase
The protein-making enzyme uses DNA as its template.
PCR (Polymerase Chain Reaction)
In 1985, Kary Mullis devised a method of enzymatically amplifying tiny amounts of DNA to provide enough material for genetic analysis of nucleic acid sequences.
Protein biosynthesis
Translation and transcription are two steps in the protein production process, which takes place on ribosomes inside a cell. Enzymes, hormones, and antibodies are all examples of proteins. Protein is a class of molecules that is predominantly made up of 20 distinct amino acids.
Proteome
Complete set of proteins in a cell, organ, or tissue fluid.
Purine bases
Adenine and guanine are two examples of purine bases.
Pyrimidine bases
DNA and RNA both use the pyrimidine nucleotide uracil, however, RNA uses cytosine and DNA uses mostly thymine.
Restriction enzymes
DNA scissor enzymes are enzymes that detect a particular sequence of letters on DNA and cut the DNA at that sequence.
Ribonucleic acid (RNA)
Ribonucleic acid (RNA) is the “little sister” of deoxyribonucleic acid (DNA), a single-stranded nucleic acid molecule involved in protein production in which the nucleotide uracil (U) replaces thymine.
Ribosome
The ribosome is the cell’s “protein factory,” where proteins are made by reading a copy of a gene.
Telomeres
Normal cells may undergo around 2,000 cell divisions before showing signs of wear and tear, during which time DNA ends (telomeres) that do not carry genetic information shrink.
Transcription
The overwriting of a gene’s DNA into messenger RNA (mRNA).
Translation
The method carried out by ribosomes whereby a protein is synthesized from its constituent amino acids.
Virus
Pathogenic biological structure made up of proteins and nucleic acids that may infect, replicate, and kill host cells.
Viruses are dangerous because they rely on a “host” organism for their metabolism.
Cell
DNA is packed into chromosomes in the cell nucleus, making the cell the smallest reproducing unit in higher animals.
Many people have a negative impression of Neanderthals and see them as dumb cavemen who were too undeveloped and rigid to survive. The many discoveries made in the last several years, however, have painted a quite different image of our ancient relative. The Neanderthals had been in Europe for nearly 100,000 years when the first modern humans arrived. Early Homo sapiens fossils have been found in Africa dating back 300,000 years. Neanderthals evidently did not fall short of the newcomers in any way, whether it was technology, hunting prowess, or social customs. Our forebears not only lived in the same region as the Neanderthals, but we can also trace their genetic lineage down to modern populations. It turns out that we share more characteristics with Neanderthals than was previously believed. Nonetheless, it remains unclear what caused our ancient Stone Age ancestors to disappear from the face of the earth.
Where Did the Neanderthals Come From?
How did early humans reach Europe?
According to skeletal evidence, the range of the Neanderthals in Europe (blue), Southwest Asia (orange), Uzbekistan (green), and the Altai Mountains (violet). (Credit: Nilenbert, Nicolas Perrault III, CC BY-SA 3.0)
In the Schmerling Caves, Belgium, a Dutch scientist named Philippe-Charles Schmerling made the first discovery of Neanderthal bones, a skull known as “Engis 2,” in 1829. However, Schmerling mistook it for a fossilized modern human skull.
After that, miners in the Neandertal Valley near Düsseldorf, Germany, uncovered one of the first components of modern Neanderthal skeletal anatomy in 1856. These included a skullcap, numerous arm and leg bones, a hip pelvis, and remnants of a shoulder blade and ribs. The bones were odd to German scientist Johann Carl Fuhlrott; the cranium was excessively protruding, and the bones were unusually stocky.
Fuhlrott assumed that the fossils belonged to an ancient person. A debate erupted among academics about whether or not this skull shape was the result of a clinical abnormality, or whether or not it really represented a previously undiscovered ancestor of modern man.
Leaving the continent of Africa
Today, we know that it was none of them. Instead, Neanderthals represented a distinct branch of the human family tree. The term “Homo neanderthalensis” was officially used to describe this group of extinct humans. Being our distant relative, it is estimated that Neanderthals first existed in Europe and western Asia some 300,000 years ago during the Pleistocene Epoch. However, this time period is very contentious. Neanderthals became extinct about 35,000 years ago.
However, unlike Homo sapiens, Neanderthals did not make the trip to Europe. Instead, they likely diverged from Homo heidelbergensis, an even more ancient early human species, during their time in Europe. A lower jaw dating back 600,000 years was discovered in the town of Mauer, close to Heidelberg, Germany, providing more proof of their existence in Europe. Homo sapiens, however, originated in Africa and spread to Europe and Asia no more than 100,000 years ago.
It seems that the first Neanderthals followed certain natural migratory pathways as they migrated over Europe. Bones and ancient artifacts unearthed along these paths provide a map of their travels. Particularly well-liked were the valleys of rivers; the Danube is now thought to have been one of the principal ways in which prehistoric humans traveled to the heart of Europe. The renowned Neandertal Valley site was likely accessed by Neanderthals following the path of the Rhine River.
Heading toward Europe
Conversely, Neanderthals looked for ways to avoid the severely glaciated mountains. The Ice Age’s northern ice was just a bit further north during the period of greatest glaciation. The Neanderthals’ habitat in Europe was likely similar to modern northern Scandinavia, with a combination of sparse woodland and tundra covered with buckthorn, willows, and birches, as well as a wide variety of plants, grasses, and mosses. This means that during the summer, at least, Neanderthals might have made the journey to the area now known as Lower Lusatia in Central Europe. Winter’s heavy snowfall and icy conditions likely rendered the region uninhabitable, forcing the Ice Age inhabitants to seek warmer climes farther south.
First Neanderthals more than 400,000 years ago
Anthropologists have used artifacts discovered at the Sima de los Huesos “bone pit” in northern Spain to reconstruct the path of Neanderthals, or the transition from an earlier human ancestor to the Neanderthals. Reminiscent of Neanderthals, the skeletons unearthed there date back roughly 430,000 years.
The best-preserved remnants of Neanderthal dwellings may now be found in Spain. However, several fossils, particularly those from France and Italy, also provide light on their daily activities and methods of production. While the majority of Neanderthal findings come from Europe and Asia, there have been discoveries made in the Near East, the Caucasus, and the Russian Altai Mountains, suggesting that the Neanderthals’ range of residence was considerably wider than previously thought.
Stone Age tools
Tools from flint
For a long time, the stereotype of Neanderthals was that of the irrational caveman, who was thought to be nothing more than an animal. But the idea that Neanderthal man was so far behind in thought and technology compared to Homo sapiens is mistaken. The many tools that Neanderthals and prehistoric people utilized and made with such dexterity are proof enough of this.
Innovate technology from 300,000 years ago
These tools, which gave rise to the term “Stone Age,” were mostly made of flint or flintstone. Early Europeans utilized hand axes at least 600,000 years ago. However, a stone with the right form was required for this instrument, and it required very little alteration.
Yet, some 300,000 years ago, the Levallois style of stone cutting appeared, which was essentially revolutionary. The procedure begins with the first shape being carved into a stone that is chosen at random. Blades, spear points, fur scrapers, and other implements could be honed from this central core. Scientists had previously thought that this method had spread from Africa through migratory populations and word of mouth.
Nor Geghi 1 stone tools (above) in Armenia, however, demonstrate that Neanderthals living in the region about 325,000 years ago already had an advanced command of the Levallois method. Because of the great distances between the many early human groups, it seems unlikely that they would have gained this skill from any of the others. Therefore, scientists believe that Neanderthals were creative in their own right.
Neither dimwitted nor less developed
An ancient Neanderthal hand axe was discovered in Spain. Credit: National Museum Cardiff.
This is shown by contrasting the wide, primitive Neanderthal stone blades with the small, technologically superior contemporary human blades. Both forms of equipment were found to be equally effective, which came as a surprise. In other words, there were no evident benefits of one tool over the other. Even the most basic Neanderthal blades were a technological leap ahead of their modern Homo sapiens counterparts. This supports the idea that Neanderthals were not less intelligent than our forebears.
Neanderthals made the first bone tools in Europe
A breakthrough over sharp stones
Neanderthals probably competed with Homo sapiens in producing more than just flint. They also had access to another raw material in abundance: bones, which were more difficult to work with but were nonetheless readily accessible. Bone was preferable over stone because it was lighter and more malleable.
The ancestors of H. sapiens themselves were the first to realize this. Since the oldest bone tools appeared 1.5 million years ago in Africa. However, only more than 40,000 years ago Neanderthals crushed the bones’ ends into circular scrapers, so-called lissoirs, and utilized them in place of heavier stones to make tools with sharp edges and points. They used these convenient, easy-to-grip instruments to rub over animal skins until the leather was supple, smooth, and more water-resistant.
Excavations at two Neanderthal campsites near the Dordogne River in southern France uncovered a total of four shards of such bone scrapers, dating back to about 50,000 years ago. These tools had previously been ascribed solely to Homo sapiens. There is no indication that Homo sapiens ever visited either site, just Neanderthals.
The lissoirs carved from red deer ribs by Neanderthals were formerly used to improve the quality of animal skins by making them smoother and more resilient to water. Credit: Abri Peyrony and Pech-de-l’Azé I Projects.
Lissoirs fashioned from deer ribs were formerly used to soften, polish, and waterproof animal hides. Ribs are able to exert a steady pressure on the animal’s skin without ripping it due to their inherent flexibility. You can see how the downward pressure causes the fragmentation into little pieces in the bottom of the picture, just like the three pieces that were discovered together.
Exchange of cultures
Microscopic analysis of the tools showed typical evidence of usage, indicating that Neanderthals likely used these bone scrapers for the same purpose that modern people would use them for in the future, namely, to smooth and soften the leather. But the bone tool discovered at Pech-de-l’Azé I in France predates even the oldest evidence of Homo sapiens in Western Europe and predates other specialized bone toolmaking capabilities by a significant margin.
This suggests that Neanderthals, not Homo sapiens, were responsible for the development of this sort of bone implement. This is the first evidence that Neanderthals and our immediate ancestors may have shared certain cultural practices. After arriving in Europe, our forefathers may have brought this method with them.
What did Neanderthals eat?
Many theories have been proposed as to how Neanderthals obtained their food. There’s no doubt they lived as hunter-gatherers. The “Stone Age diet” is said to have its origins in the diets of individuals who lived between 50,000 and 100,000 years ago and subsisted mostly on meat. This, however, is a very unbalanced viewpoint.
Meat galore, but also some greens
View of the El Salt dig site where Neanderthal feces were discovered. Credit: University of Bologna.
Animal bones discovered at Neanderthal sites inspired the concept of these people being “carnivores.” Since no other dietary remnants were discovered, it was concluded that the Neanderthals subsisted only on meat. Conversely, bones last a lot longer than plant fossils do in the ground. Scientists worried that our ideas about what Neanderthals ate were skewed heavily toward meat.
The discovery of small stone pellets that turned out to be fossilized Neanderthal poop was made in the Spanish city of Alicante. Groups of Neanderthals camped there often between 60,000 and 45,000 years ago, as shown by the presence of bones and stone tools.
Cholesterol and the breakdown products of plant lipids were evident in the feces of the Stone Age. Researchers were able to extrapolate an estimated percentage of meat consumption among Neanderthals from this finding. This suggests that although meat was the mainstay of their diet, vegetation also played a significant role.
The diet of the Stone Age man was not low in carbohydrate
Neanderthal tooth. Credit: Natural History Museum, London/Blinkhorn, et al., 2021.
In addition to showing that early humans were not “pure” carnivores, plant remains on Neanderthal teeth discovered in Iraq’s Shanidar Cave demonstrate that they ate a wide variety of foods. In those days before toothbrushes, the tartar on people’s teeth was full of the remnants of the food they had eaten.
Scientists discovered starch granules on the teeths, suggesting that it likely came from a variety of plants such as wild grasses, roots, tubers, and vegetables. This disproves the hypothesis that Neanderthals had a “low carb” diet that mostly avoided carbohydrates. Heat treatment signals were also present on several of the granules, suggesting that the Neanderthals boiled or grilled their plant-based foods.
Medicinal plant residues were also found in Neanderthal tartars, suggesting that prehistoric humans already had knowledge on medicinal plants. But it is possible that Neanderthals used these plants merely as food and were unaware of the healing effects. The pleasant taste of many medicinally effective plants also speaks against this.
Adaptive hunting when supplies are low
Mammoth hunters go for a fishing
Meanwhile, scientists has debunked another myth about Neanderthals: that they were mostly “mammoth hunters.” Scientific evidence does not support depictions of mammoth hunts in which whole herds are pushed down a cliff by torches and spears. Bones from mammoths are surprisingly uncommon in excavations of places inhabited by Neanderthals contrary to popular belief.
Not only the mammoths
One notable exception is the Jersey Channel Islands, where a large number of mammoth skeletons were discovered at the La Cotte de St. Brelade site. Processing signs on the bones suggest that Neanderthals at this site often hunted down mammoths and cannibalized them.
Yet more evidence suggests that Neanderthals weren’t mammoth specialists. The skeletons discovered next to Neanderthals include those of woolly rhinoceroses, cattle, deer, and horses as well. Those animal remains demonstrate the Neanderthals’ adaptability and resourcefulness.
Meat alongside fish
Whole piles of fish bones, dating back to roughly 45,000 years, were discovered in Neanderthal caves in the Caucasus, demonstrating the extent to which they adapted to the local food supply. However, the salmon from which the bones originated might be eaten by cave bears or cave lions, which also lived in the area.
A comparative isotopic study of all the bones, however, revealed that the bears were vegetarians and the lions hunted herbivores, leaving just one contender as a salmon eater: the Neanderthals of this area, who were evidently excellent fishermen.
Neanderthals were very adaptable, since they subsisted on the foods that were naturally available to them in their environment. They ate a diet that was remarkably similar to that of modern humans.
How did the Neanderthals live?
Neanderthals had an easier time of it than was previously believed in their daily lives (Reconstruction from the Neanderthal Museum Mettmann). Credit: Sunhosch/Flickr (CC BY-SA 2.0)
The harsh Ice Age climate was already too different from our climate, let alone technological advances, for us to be able to imagine what life was like for the Neanderthals on a daily basis. The “Stone Age conditions” describe almost hopelessly backward situations, and it is assume that the Neanderthals’ entire existence must have been a single, hard fight for survival just before starvation.
Constantly challenging, but not insurmountable
Studies of Neanderthal teeth show that periods of starvation lasting up to three months were not uncommon. However, such traces of occasional malnutrition can be found in the teeth of Inuit skulls from Alaska that are around 2,500 years old.
It’s incredible that Neanderthals apparently weren’t as malnourished as we assumed. The findings demonstrate that Neanderthals fared no worse than the Inuit people in identical environments, despite the Inuit’s superior technology.
Nursery in Neanderthals
Therefore, experts think that despite the Neanderthals’ more secluded family groupings, they nonetheless maintained intimate emotional bonds that were at least as strong as in modern families, if not stronger.
Scientists found that Neanderthal children were an integral part of daily life, even if they were not yet hunting or gathering and were instead engaged in play and exercise. This suggests that children might have played a particularly significant role in Neanderthal society.
Ornate Neanderthal burials
Credit: Karen Carr.
Other fossils demonstrate that Neanderthals ritually buried their deceased, with the most ornate burials being those of children who died at a young age, suggesting that parents must have cared for them tenderly and attentively, often for months or even years.
The make up of their teeth, for example, suggests that Neanderthal moms nursed their infants for roughly the same amount of time as is still usual for kids today. Neanderthal children had their first solid meal at about seven months of age and were weaned at around 14 months of age.
Children of contemporary humans, on the other hand, have comparably slow development processes. Neanderthals reached full maturity at the age of 15. The evolutionary benefit of this extended maturation period might be that it allows humans more time for learning.
Neanderthals were cultural pioneers
Paintings, jewelry, and cosmetics
Every fictional or nonfictional account of prehistoric humans includes references to cave paintings. The murals in the Chauvet Cave in France, which have become renowned, are undeniably the work of Homo sapiens. However, the possibility that Neanderthals also created such pieces of art is up for debate.
Neanderthal handprints
Handprints on the wall of El Castillo Cave in northern Spain have been radiocarbon dated by scientists to be at least 37,300 years old. Credit: Pedro Saura, Wikipedia.
El Castillo Cave, located in northern Spain, has some of the world’s earliest known cave paintings. The minimum age of these objects is 40,800 years. Given this, they predate the Chauvet paintings by around 4,000 years. There are some potential causes for this extraordinary epoch. One possible explanation is that this cultural practice was transmitted to Europe by Homo sapiens from Africa.
However, it is not impossible that the earliest, most basic cave drawings date back to Neanderthal times. This would indicate that the handprints on the cave walls are really the traces of Neanderthal hands.
Red color derived from iron
At least at that time, Neanderthals had access to the essential dyes; they were producing red dye about 250,000 years ago. The red iron mineral hematite was used to create colors. They also moved the rock from its original location to other places where it does not exist naturally such as the site in Maastricht-Belvédère, the Netherlands.
However, the purpose of this bright red color is uncertain. It had several possible uses for the Neanderthals, including ceremonial painting, repelling insects, tanning skins, and perhaps medicinal purposes. Newer discoveries in Spain, however, suggest that Neanderthals used cosmetics for ceremonies as well.
Creativity and abstract thinking in Neanderthals
A fossil pair of white-tailed eagle claws were discovered at the Neanderthal site of Krapina in Croatia, and they show signs of having been processed, which makes them a good candidate for adornment. Credit: A. Luka Mjeda, Zagreb.
Whether or not they were fake, findings of painted and pierced shells in southern Spain indicate that Neanderthals were familiar with and wore different forms of jewelry. Such beads might be strung together and used as necklaces, for instance. The fact that Neanderthals used jewelry and ceremonial symbols suggests they were already capable of abstract thought. This ability to abstract was also seen in the form of prehistoric line drawings on the rock.
It’s widely accepted that Homo sapiens have this skill; after all, our forebears often wore ornaments and cosmetics. For a long time, people thought Neanderthals didn’t invent or even wear jewelry, and they lacked the essential level of sophistication to come up with something novel. The shell necklaces, however, are the first clear evidence of symbolic Neanderthal activity, dating back some 50,000 years, or some 10,000 years before Homo sapiens arrived in Europe.
Jewelry from the Neanderthal site of Krapina in what is now Croatia may be much older. The sea eagle’s claws with notches, incisions, and polished surfaces date back almost 130,000 years. Scientists believe the claws were previously made into a choker or bracelet based on the processing markings. The finding was impressive because this jewelry would have been created some 80,000 years before the first Homo sapiens appeared in the area.
A common heritage in Neanderthals and Homo sapiens
A contemporary human skeleton (right) and a Neanderthal skeleton (left).
Several areas in Europe have shown signs of interaction between native Neanderthals and the newly arrived humans, as seen by cultural commonalities such as shared toolmaking practices and an appreciation for similar ornamental styles. Comparing the modern human genome to the sequenced Neanderthal genome revealed how genetically similar the two human species were.
As it turns out, we have the Neanderthals to thank for a lot of our DNA; those of us who aren’t from Africa have anything from one to four percent of Neanderthal DNA. Because, the beneficial genes were protected to ensure their continued use in the evolutionary process.
I am a Neanderthal
In frigid Europe, for instance, the Neanderthals’ superior fat metabolism was a significant advantage. An extra immune receptor was helpful since it aided in the fight against infections.
One area of the genome with an unusually high concentration of Neanderthal DNA is near the genes for keratin synthesis. Keratin is an essential component of skin, hair, and nails. Our ancestors who emigrated from Africa were likely aided by Neanderthal DNA to grow a thick covering of hair and skin, making them better able to withstand the cold.
Red hair and freckles
“Wilma,” a reconstruction based on DNA, had red hair, freckles, and a pale complexion, much like other Neandertals. Credit: Joe McNally.
Neanderthals may also be responsible for our modern tendency toward fair complexions. Approximately 70% of Europeans have a Neanderthal gene variation that causes their skin to be naturally pale. Studies of Neanderthal DNA have also shown that not all Neanderthals looked like the stereotypical caveman: around 1% of Neanderthals had red hair, a pale complexion, and freckles.
While it may seem obvious that Homo sapiens and Homo neanderthalensis were able to mate and have children, the reality that these two species and their ancestors were separated for over 1.5 million years makes this conclusion very questionable. Throughout this period their genetic make ups may become incompatible due to differences.
Descendants, despite genetic distinctions
The genome provides further evidence for this theory by showing that Neanderthal genes are concentrated in our skin and hair regions but are missing from other areas. The X chromosome, one of the sex chromosomes, is essentially barren in this regard. And in terms of male reproductive organs, testicular tissue is similarly mostly devoid of Neanderthal DNA.
The position of the genetically incompatible subpopulations is a telltale indicator that two subspecies are only partly compatible genetically. When two infertile species breed, the resulting progeny are often sterile or at best produce a lower number of offspring, as shown in the case of mules and hinnies, which result from the mating of donkeys and horses.
While Homo sapiens and Neanderthals had a common ancestor, the two species were probably no longer compatible when they resided in Europe and Asia about 40,000 years ago. Our African ancestors who eventually left Africa were noticeably different from their Ice Age relatives, despite extensive interaction.
A competition between Neanderthals and Homo sapiens
Displaced by Homo sapiens
Neanderthals (on the left) and Homo sapiens (right). Credit: Matt Celeskey, DrMikeBaxter (CC BY-SA 2.0)
Between 30,000 and 50,000 years ago, Neanderthals became extinct after having dominated Central Europe for about 100,000 years. The earlier line of thinking was based on simpler reasoning: Neanderthals died out because they were too primitive in comparison to Homo sapiens.
“Shanidar 3” Neanderthal murder investigation
However, this theory has been debunked, and new research suggests that Neanderthals were on par with Homo sapiens, despite their many differences. If Neanderthals were so similar to our forebears, then what do you think ultimately doomed them?
Evidence of interbreeding between Homo sapiens and Neanderthals has been found in several locations, and the two early human species clearly interacted with one another, as evidenced by shared descendants. However, the two early human species did not always deal with each other peacefully, as shown by one downright criminal case.
Shanidar 3, a Neanderthal skeleton discovered in Iraq, has a deep cut or puncture wound that extends to the ribs. Was it a hunting accident or a murder? Almost 50,000 years later, anthropologist Steven Churchill of Duke University and his colleagues have solved the case through experiments on pig carcasses, demonstrating that the injury is consistent with a thrown spear.
Interspecies warfare
Scientists consider this murder case to be the first direct evidence of violent conflict between Homo sapiens and Neanderthals. However, this does not necessarily mean that modern humans deliberately fought Neanderthals: “We’re not suggesting there was a blitzkrieg, with modern humans marching across the land and executing the Neanderthals.”
The Iberian Peninsula was thought to be the last refuge of the pushed-back Neanderthals because Homo sapiens arrived there so late on their way through Europe. However, new research indicates that Neanderthal finds from that region are significantly older than initially assumed.
Close to extinction before the first encounter
Across Europe, the picture is similar but not as clear: the Neanderthal population density apparently declined drastically as early as about 50,000 years ago, long before first contact with our ancestors. Neanderthals almost died out in Europe long before they came into contact with Homo sapiens.
How did Neanderthals go extinct?
Climate change
However, the near extinction shows that Neanderthals were more vulnerable to climate change, and that a later-beginning climatic shift would have impacted the already weaker population considerably harder than the expanding Homo sapiens.
Volcanic winter
Ash layers in a Neanderthal cave in the Caucasus, for instance, are consistent with this theory; these layers are consistent with both a smaller volcanic eruption nearby and the much larger so-called Campan Ignimbrite supereruption in the area of present-day Italy; the ash clouds, especially of this last eruption, could have initiated a “volcanic winter”; all Neanderthal traces in the cave end with this second ash layer.
But other evidence contradicts this: the Neanderthals’ ability to adapt to climate change was demonstrated by their migration patterns. Like Homo sapiens, they sought out new territories to hunt in as food supplies dwindled. Because of this, we know that Neanderthals were flexible and adaptable.
Eventually absorbed by Homo sapiens
Museum of Natural History in Washington, DC, has a lifelike reconstruction of a Neanderthal from the Shanidar site. Credit: John Gurche (Reconstruction) / Tim Evanson (Photography) / (CC BY-SA 2.0).
Because Neanderthals and Homo sapiens relied on the same survival strategy and environment, scientists believe that the most extensive interaction between the two human species happened at this time.
A computer model developed by Riel-Salvatore and colleagues shows how Neanderthal populations were gradually swallowed up by numerically superior Homo sapiens throughout 1,500 generations. This is corroborated if we extrapolate the population densities of Neanderthals and modern humans from the locations of their respective archaeological sites, which date back to about 40,000 years ago.
Although the Neanderthals are presumed to have gone extinct due to a combination of climatic change, competition with emerging Homo sapiens, and other, as-yet-unknown circumstances, their DNA may still be detected in almost every European today.
Svante Pääbo, a pioneer in the field of paleogenetics, will receive the Nobel Prize in Medicine in 2022 for his contributions to the field. He and his team deciphered the Neandertal and Denisovan ancestors’ DNA, revealing previously unknown details about the origins of these ancient human species and their connections to our own. Only because of him do we know for sure that we all have a trace amount of Neandertal DNA.
Human history is more like a gnarled stump than a sturdily grown tree. Because the exact relationship of many ancient people to our forefathers remains unclear to this day. This was true for a very long time, even for Neandertals, and much more so for the savage Denisova-Man, of whom just a few tiny finger knuckles have been discovered.
New discoveries about our family tree and the connections between our ancestors and their contemporaries are owed in large part to Svante Pääbo, winner of the Nobel Prize in Medicine. He has made groundbreaking contributions to the field of paleogenetics, and he and his team were the first to successfully isolate and decipher the genetic material of extinct human populations.
The reason is that after thousands of years in the ground, bacteria and yeasts have colonized Neanderthal teeth to the point where up to 99.9 percent of the DNA found in these teeth is microbiological in origin. In addition, the few amounts of Neandertaler-DNA that have been recovered so far are only available in small fragments that must be pieced together like a colossal puzzle. Many researchers concluded that this problem could never be solved.
From Egyptian mummies to Neanderthals
In any case, Pääbo and his crew set sail for new techniques. In his doctoral dissertation at Sweden’s Uppsala University, the researcher had already shown that Egyptian mummies may preserve DNA for centuries. In so doing, he established the field of paleoanthropology. Pääbo and his team were able to decipher, for the first time, a short segment of the mitochondrial DNA of a Neandertal around the middle of the 1990s. This segment is located not in the cell nucleus but in the cellular power plants.
So how exactly did the Neanderthal fit into our family tree?
The mitochondrial DNA of Neandertals was clearly distinguishable from that of modern humans. This proves that Neandertals couldn’t have been our ancestors in the strict sense. So how exactly did the Neanderthal fit into our family tree? To figure it out, researchers had to decode Neandertal cellular DNA, which is even less well preserved than mitochondrial DNA and far more complex than a simple jigsaw puzzle.
Pääbo joined the newly formed Max-Planck-Institute for evolutionary Anthropology in Leipzig in 1997 as one of five Directors, where he and his team searched for techniques to isolate and sequence the fragmented, heavily contaminated DNA of early humans. They did this by using complex computer programs to piece together the DNA fragments and compare them to reference genomes from chimpanzees and humans, as well as by improving extraction methods to increase Neandertal-DNA yields.
Neanderthal genome decoded
In 2010, Svante Pääbo and colleagues were able to reconstruct an early version of the Neandertal genome from skeletal remains. Studies comparing the Neandertal genome to current human genomes have shown that most people living in Europe and Asia have around 2% of Neandertal DNA. That, in turn, meant that Homo sapiens and Neanderthals must have interbred sometime after Homo sapiens left Africa.
Indeed, researchers have uncovered the fossil remains of many ancient people who are the direct descendants of Neanderthals and modern humans. In addition, the comparison of Neandertal and modern human genes revealed which genes we inherited from our ancient ancestors and demonstrated that these genes continue to shape our immune system, skin and hair color, and metabolism even now. Even the risk of some infectious diseases, such as COVID-19, may be influenced by Neanderthal genes, as is now known.
In 2014, a group led by Pääbo at the Max-Planck Institute for Evolutionary Anthropology came close to fully deciphering the Neandertal genome. This allowed for a more precise assessment of how ancient and modern human genetic resources compare. According to Pääbo, “We have found around 30,000 positions in which the genomes of almost all modern humans differ from those of Neanderthals and great apes. They answer what makes anatomically modern humans ‘modern’ in the genetic sense as well.”
A divergence from the Neanderthal and contemporary human lineages about 800,000 years ago.
Denisova man, a mysterious figure
Pääbo and his colleagues had made another important discovery two years earlier, when they sequenced the genome of a tiny bone discovered in Denisova Cave in the Altai Mountains of western Siberia. Based on genetic evidence, it is clear that this Denisova man belonged to a branch of the human evolutionary tree that diverged from the Neanderthal and contemporary human lineages about 800,000 years ago.
In addition, modern-day Papua New Guineans, Australian Aborigines, and members of other Oceanic populations were found to possess up to 5% Denisova DNA, according to the results of genetic investigations. In addition, subsequent DNA research of additional fossil findings revealed evidence that Denisova people and Neanderthals interbred often.
Findings that provide light on our ancient past
Thus, Svante Pääbo and his study have shown that the evolution of humans included a lot of crossover and offshoots and that we still have the genetic code of multiple near ancestors of Homo sapiens. President of the Max Planck Society Martin Stratmann said that “His work has revolutionized our understanding of the evolutionary history of modern humans.”
Scientists are presently developing novel approaches to rebuild even more degraded and scarce DNA fragments. The hope is to open the door to the study of much ancient DNA, as well as genetic material from regions of the globe where DNA survival is even more unusual owing to hot and humid temperatures.
There is a true treasure mine of the world’s earliest fish fossils in China, uncovered by paleontologists. The fossils, which are as ancient as 439 million years, prove that the first animals with jaws appeared earlier than previously believed. Scientists have published their findings in no less than four separate issues of “Nature,” and among them are the earliest known examples of cartilaginous fish and jawed armored fish fossils. This provides fresh data on the evolution of fish and the first vertebrates with jaws, which includes humans.
Almost all living vertebrates have their ancestry in ancient fish since they were the first vertebrates to develop a jaw. In the end, they gave rise to the Gnathostomata group, which literally means “jawed mouth,” to which we modern humans also now belong. However, the development of the first fishes, and therefore our earliest predecessors, has been the least explored area of evolutionary biology.
Dreadful gap in fossil records
Approximately 439–436 million years ago is when the Chongqing Lagerstätte was formed. Xiushanosteus mirabilis (2a and 2b), an armored-jawed fish, and Shenacanthus vermiformis (1a, 1b), an ancient shark and ray relative, have both been discovered on this slab. (Y.-A. Zhu et al/Nature 2022)
The issue is that, according to DNA analyses, the first gnathostomes likely arose around 450 million years ago. However, fossils that would have been present in the same period are now absent. But fish fossils are so plentiful in the Devonian Period, which began about 419 million years ago, that it is sometimes known as the Age of Fishes. In the previous decade, paleontologists in China made the first discoveries of fish fossils that date back 425 million years.
According to the theory, the first jaw could be developed by the now-extinct armored fishes (Placodermi), which had a thick carapace of bone plates on the head and trunk but a still-undeveloped skullcap. This makes them, in theory, the ancestors of modern-day sharks andrays, which are cartilaginous fishes. But how about the bony fish that evolved into the terrestrial vertebrates that also eventually became our ancestors? The answers to these theories are now up for debate once again because of a scarcity of new fossil discoveries.
A prehistoric aquarium
The jawless fish Tujiaaspis vividus demonstrates how the specimen’s remarkable preservation is shedding light on the development of fins in later jawed relatives. (Heming Zhang)
A jawless species, the oldest armored fish to date, and three different early cartilaginous fish, making them the oldest known shark ancestors, were discovered in China’s Chongqing province by paleontologists led by You-an Zhu and Qiang Li of the Chinese Academy of Sciences.
During the first discovery, scientists found the first Silurian fish fossil wholly intact. Over the last two years, researchers have been able to uncover hundreds more fossils with their ongoing digs. This location has the earliest known fossils of jawed vertebrates and fish from 436 million years ago, many of which are very well preserved and complete.
The primary characteristics of the Tujiaaspis fossil and its depiction. (Zhikun Gai et al.)
A fresh perspective on the evolution of vertebrates
Scientists can now test the long-debated theories regarding the evolutionary ancestry of humans. Important as they are for their age alone, the newly found fossils are much more so since they reveal for the first time the whole anatomy of the earliest fishes, from head to tail.
The first thing we can learn from the new discoveries is when vertebrates with jaws first appeared in the timeline. The fossils show that by the early Silurian Period (from 444 Mya to 420 Mya), there was already a great deal of morphological variation among mammals with jaws and wide distribution of the major phylogenetic groupings. This shows that these fishes’ ancestry goes back far further in time than was previously believed, according to researchers.
The first jaws were little and flimsy
The tiny size of the fishes is one of the two most striking traits of this fossil collection, along with its tremendous variety. Since most species are just a few millimeters in length. This may be the reason why so few fossils of ancient fish have been found so far.
Vertebrates with jaws from Chongqing are tiny and fragile, indicating that they were likely poorly preserved outside of certain deposit types. On the other hand, it’s possible that fishes were only regionally spread at the time and the evolution of fishes with jaws was slower than that of their jawless forebears.
Fish with jaws but no frills
An artist’s conception of the complete preservation of Xiushanosteus mirabilis fossils from head to tail. (Heming Zhang)
Yet another finding regarding the early fishes’ appearance is also revealed by the fossils. More than 20 individuals of the armored fish Xiushanosteus mirabilis have been found in Chongqing. These ancient fossils are mostly intact. The tiny Xiushanosteus combines the characteristics of many different types of armored fish.
Exciting, however, is the structure of the armored plates above its skull. The plates include a unique set of sutures that set them apart from the surrounding head plates. Researchers speculate that the change to the bony fishes’ skull plates could make its first appearance here.
Ancestor fishes with shoulder pads
This reconstruction depicts Shenacanthus vermiformis, a small, armored cartilaginous fish that lived in the same ecosystem as its bony counterparts. (Heming Zhang)
Another unique trait may be seen in the remains of two primitive cartilaginous fish, the forerunners of modern sharks and rays. Shenacanthus vermiformis, a species discovered in Chongqing that is around 436 million years old, has many of the normal shark characteristics, but its shoulder region is covered by huge, hard armor plates, like those of an armored fish. Such armored fish and jawless have a full ring of thickened skin parts all the way around their bodies.
The Fanjingshania renovata, a shark fish that lived 439 million years ago and has a striking resemblance to the armored fish due to its armored shoulder region, is a pleasing example of a cartilaginous fish with a comparable structure. On the other hand, the fish has teeth and scales that are similar to those of bony fish. According to the research group led by Qujing Normal University’s first author Plamen Andreev, this combination distinguishes this ancient fish from all other known vertebrates.
New and exciting times
Together, these new fossils provide fascinating light on the timeframe during which the first animals with jaws initially appeared. There will undoubtedly be heated discussions on the unique properties of these new fossils and the complexities of their classification. After all, much remains unknown about the variety of the recently found fishes.
More jawed fishes from the Early Silurian have been found at these locations, although these have not yet been characterized. As a result, the study of primitive jawed fishes has entered a new and interesting epoch. (Nature, 2022; doi: 10.1038/s41586-022-05136-8; doi: 10.1038/s41586-022-05233-8)
Babies act like seasoned divers from the moment they are born; when their face is submerged, they immediately stop breathing and their heart rate lowers. They even do basic swimming motions at the same time. Whence, though, does this arise? Is this something you do automatically? Do we retain this ability as adults or if it disappear somewhere after infancy?
This unique ability to dive is the result of a combination of reflexes. Newborns have a respiratory response that causes them to stop breathing if even a little amount of water touches their face. The same effect is produced by blowing air into the baby’s nostrils or on the baby’s face with a hair drier.
After around five to eight months, however, this protective reflex no longer exists, possibly because by then the brain has developed enough to allow for the conscious regulation of the holding of breath in emergency circumstances. This response is no longer functional in adults and cannot be taught or regained.
Likely, the involuntary paddling and rowing actions of babies are likewise a holdover from our animal ancestors. However, they disappear after childhood.
Water on the face slows down the heart rate
The diving reflex in babies is something that everyone has, whether they are a child or an adult. It is most prevalent in marine mammals and other aquatic predators but affects all warm-blooded species. Having our faces submerged triggers the diving response, which slows our pulse rate.
Receptors on the sides of the nose and the forehead set off this reaction. These receptors respond to wet and cold conditions. For this reason, putting one’s face in a bowl of cold water was a common remedy for severe heart disturbances in the past. Their heart rates slowed down because of this diving reflex, which saved their lives in the long run.
The unconscious response of our body to water on our face may be trained if we spend enough time in the water; apnea divers, for instance, exploit this to their advantage by slowing their heart rate and therefore using less oxygen while underwater. The average heart rate of a skilled apnea diver is around 17 beats per minute. Diving goggles may reduce the effectiveness of the diving reflex because they cover the sensitive receptors in the face.
The function the diving reflex
The diving reflex has a clear ecological function for divers and marine animals, allowing them to spend more time underwater before needing to surface for air. In theory, this works to conserve oxygen. This skill may not be vital in regular life, yet it might be a lifesaver in a dire situation.
For instance, it helps people who are drowning in cold water to go longer without oxygen. In 1986, a 2.5-year-old infant was rescued after being immersed in freezing water for 66 minutes. This was due to the diving reflex, which significantly decreased the pulse rate.
