Traits Passed On from Neanderthals to Modern Humans

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According to Vanderbilt University: Since 2010 scientists have known that people of Eurasian origin have inherited anywhere from 1 to 4 percent of their DNA from Neanderthals.The discovery spawned a number of hypotheses about the effects these genetic variants may have on the physical characteristics or behavior of modern humans, ranging from skin color to heightened allergies to fat metabolism. [Source: Vanderbilt University, February 11, 2016]

In 2016, researchers at Vanderbilt published in a study that directly compared Neanderthal DNA in the genomes of a significant population of adults of European ancestry with their clinical records, confirming that this archaic genetic legacy has a subtle but significant impact on modern human biology. “Our main finding is that Neanderthal DNA does influence clinical traits in modern humans: [rquote]We discovered associations between Neanderthal DNA and a wide range of traits, including immunological, dermatological, neurological, psychiatric and reproductive diseases[/rquote],” said John Capra, senior author of the paper “The phenotypic legacy of admixture between modern humans and Neanderthals” published in the Feb. 12, 2016 issue of the journal Science. The evolutionary geneticist is an assistant professor of biological sciences at Vanderbilt University.

Some of the associations that Capra and his colleagues found confirm previous hypotheses. One example is the proposal that Neanderthal DNA affects cells called keratinocytes that help protect the skin from environmental damage such as ultraviolet radiation and pathogens. The new analysis found Neanderthal DNA variants influence skin biology in modern humans, in particular the risk of developing sun-induced skin lesions called keratosis, which are caused by abnormal keratinocytes.

In addition, there were a number of surprises. For example, they found that a specific bit of Neanderthal DNA significantly increases risk for nicotine addiction. They also found a number of variants that influence the risk for depression: some positively and some negatively. In fact, a surprisingly number of snippets of Neanderthal DNA were associated with psychiatric and neurological effects, the study found. “The brain is incredibly complex, so it’s reasonable to expect that introducing changes from a different evolutionary path might have negative consequences,” said Vanderbilt doctoral student Corinne Simonti, the paper’s first author.

According to the researchers, the pattern of associations that they discovered suggest that today’s population retains Neanderthal DNA that may have provided modern humans with adaptive advantages 40,000 years ago as they migrated into new non-African environments with different pathogens and levels of sun exposure. However, many of these traits may no longer be advantageous in modern environments. One example is a Neanderthal variant that increases blood coagulation. It could have helped our ancestors cope with new pathogens encountered in new environments by sealing wounds more quickly and preventing pathogens from entering the body. In modern environments this variant has become detrimental, because hypercoagulation increases risk for stroke, pulmonary embolism and pregnancy complications.

In order to discover these associations, the researchers used a database containing 28,000 patients whose biological samples have been linked to anonymized versions of their electronic health records. The data came from eMERGE – the Electronic Medical Records and Genomics Network funded by the National Human Genome Research Institute – which links digitized records from Vanderbilt University Medical Center’s BioVU databank and eight other hospitals around the country. This data allowed the researchers to determine if each individual had ever been treated for a specific set of medical conditions, such as heart disease, arthritis or depression. Next they analyzed the genomes of each individual to identify the unique set of Neanderthal DNA that each person carried. By comparing the two sets of data, they could test whether each bit of Neanderthal DNA individually and in aggregate influences risk for the traits derived from the medical records.

Neanderthals Passed On Their Big Noses to Modern Humans, DNA Analysis Finds

Neanderthals had tall noses that could warm and moisten the cold and dry air around them in chilly climates. They appear to have passed on these large noses to modern humans, when the two species interbred, according to a study published May 8, 2023 in the journal Communications Biology. Scientists made the discovery after analyzing DNA taken from more than 6,000 volunteers from from Brazil, Colombia, Chile, Mexico and Peru who had Latin American, mixed European, Native American or African heritage, and compared their genetic information to photographs of their faces, [Source: Jennifer Nalewicki, Live Science, May 17, 2023]

Jennifer Nalewicki wrote in Live Science: After measuring the distances between different points on each face, such as the height of a person's nose, the researchers compared those data to see if those characteristics were associated with certain genetic markers, according to a statement. The researchers successfully identified 33 new genome regions that corresponded with facial features. One in particular, ATF3, not only had Neanderthal origins but also defined nose height. They found that study participants with Native American ancestry "had genetic material in this gene that was inherited from the Neanderthals, contributing to increased nasal height," according to the statement.

"It has long been speculated that the shape of our noses is determined by natural selection; as our noses can help us to regulate the temperature and humidity of the air we breathe in, different shaped noses may be better suited to different climates that our ancestors lived in," lead author Qing Li, a faculty member in the Department of Environmental Science and Engineering at Fudan University in Shanghai, said in the statement. "The gene we have identified here may have been inherited from Neanderthals to help humans adapt to colder climates as our ancestors moved out of Africa."

In 2021, the same team of researchers conducted a related study that identified a gene that influenced lip shape. That gene, called TBX15, was inherited from the Denisovans, modern-human relatives who lived in Asia and went extinct approximately 30,000 years ago. The Denisovans interbred with Homo sapiens, passing along this genetic attribute. By examining data from this previous study, the researchers discovered that, like Native Americans, East Asians were also more likely to have the ATF3 nose gene.

So what was the benefit of having a taller nose thousands of years ago? "When you live in colder climates, your nose gets narrower so that it can warm cold air before it reaches the lungs," study co-author Kaustubh Adhikari, a statistical geneticist at University College London, told Live Science. "We think that when [Homo sapiens] came into colder regions where Neanderthals were already living, they bred with them and they passed along these [genetic] benefits to their children, which helped give them a leg up with adaptation."

Modern Human Health Issues May Influenced by Neanderthal DNA

After modern humans migrated out of Africa, researchers believe they encountered and interbred with Neanderthals in the Middle East around 60,000 years ago. As a result, modern humans of non-African descent share around 2 percent of their DNA with Neanderthals and DNA passed on from Neanderthals to modern humans appears to have influenced the health of modern humans living today. “Neanderthals contributed DNA to present-day people,” says Svante Paabo of the Max Planck Institute, “and this has physiological effects today, for example in immune defense, pain sensitivity, risk for miscarriages, and susceptibility to severe outcomes from COVID-19.”

Carl Zimmer wrote in the New York Times: “ Once Neanderthal DNA entered our gene pool, it spread down through the generations, long after Neanderthals became extinct. Most Neanderthal genes turned out to be harmful to modern humans. They may have been a burden on people’s health or made it harder to have children. As a result, Neanderthal genes became rarer, and many disappeared from our gene pool. But some genes appear to have provided an evolutionary edge and have become quite common. In May, 2020, scientists at the Max Planck Institute, discovered that one-third of European women have a Neanderthal hormone receptor. It is associated with increased fertility and fewer miscarriages. Other Neanderthal genes that are common today even help us fight viruses. When modern humans expanded into Asia and Europe, they may have encountered new viruses against which Neanderthals had already evolved defenses. We have held onto those genes ever since. [Source: Carl Zimmer, New York Times, July 6, 2020]

Daniel Weiss wrote in Archaeology magazine: “Many genes associated with diseases — in particular psychiatric and neurological disorders such as Alzheimer’s disease, autism, and schizophrenia — also appear to be activated in modern humans but not Neanderthals. Liran Carmel of Hebrew University says the activation of these genes may have produced an evolutionary catch-22: bestowing a benefit, perhaps by changing the wiring of our brains, but also introducing an increased risk of disease. [Source: Daniel Weiss, Archaeology magazine, January-February 2015]

Human and Neanderthal Brains Share a Surprising 'Youthful' Quality

Professors Stephen Wroe and Pasquale Raia wrote: Many believe our particularly large brain is what makes us human — but is there more to it? The brain’s shape, as well as the shapes of its component parts (lobes) may also be important. Results of a study we published in Nature Ecology & Evolution in January 2023 show that the way the different parts of the human brain evolved separates us from our primate relatives. In a sense, our brains never grow up. We share this “Peter Pan syndrome” with only one other primate — the Neanderthals. [Source: Stephen Wroe, Professor, University of New England, Pasquale Raia, Professor of Paleontology and Paleoecology, University of Naples Federico II The Conversation, January 5, 2023]

Mammalian brains have four distinct regions or lobes, each with particular functions. The frontal lobe is associated with reasoning and abstract thought, the temporal lobe with preserving memory, the occipital lobe with vision, and the parietal lobe helps to integrate sensory inputs. The results of our analyses surprised us. Tracking change over deep time across dozens of primate species, we found humans had particularly high levels of brain integration, especially between the parietal and frontal lobes. But we also found we’re not unique. Integration between these lobes was similarly high in Neanderthals too.

Looking at changes in shape through growth revealed that in apes, such as the chimpanzee, integration between the brain’s lobes is comparable to that of humans until they reach adolescence. At this point, integration rapidly falls away in the apes, but continues well into adulthood in humans. So what does this all mean? Our result suggest what distinguishes us from other primates is not just that our brains are bigger. The evolution of the different parts of our brain is more deeply integrated, and, unlike any other living primate, we retain this right through into adult life. A greater capacity for learning is typically associated with juvenile life stages. We suggest this Peter Pan syndrome played a powerful role in the evolution of human intelligence.

There’s another important implication. It’s increasingly clear that Neanderthals, long characterised as brutish dullards, were adaptable, capable and sophisticated people. Our results further blur any dividing line between us and them.

Experiments on Human and Neanderthal Brains Share a Surprising 'Youthful' Quality

Professors Stephen Wroe and Pasquale Raia wrote: We investigated whether the brain’s lobes evolved independently of each other, or whether evolutionary change in any one lobe appears to be necessarily tied to changes in others — that is, evidence the evolution of the lobes is “integrated”. In particular, we wanted to know how human brains might differ from other primates in this respect. One way to address this question is to look at how the different lobes have changed over time among different species, measuring how much shape change in each lobe correlates with shape change in others. [Source: Stephen Wroe, Professor, University of New England, Pasquale Raia, Professor of Paleontology and Paleoecology, University of Naples Federico II The Conversation, January 5, 2023]

Alternatively, we can measure the degree to which the brain’s lobes are integrated with each other as an animal grows through different stages of its life cycle. Does a shape change in one part of the growing brain correlate with change in other parts? This can be informative because evolutionary steps can often be retraced through an animal’s development. A common example is the brief appearance of gill slits in early human embryos, reflecting the fact we can trace our evolution back to fish.

We used both methods. Our first analysis included 3D brain models of hundreds of living and fossil primates (monkeys and apes, as well as humans and our close fossil relatives). This allowed us to map brain evolution over time. Our other digital brain data set consisted of living ape species and humans at different growth stages, allowing us to chart integration of the brain’s parts in different species as they mature. Our brain models were based on CT scans of skulls. By digitally filling the brain cavities, you can get a good approximation of the brain’s shape.

You a Morning Person? Could Be Because of Neanderthal DNA

Carl Zimmer wrote in the New York Times: Neanderthals were morning people, a new study suggests. And some humans today who like getting up early might credit genes they inherited from their Neanderthal ancestors. The study compared DNA in living humans to genetic material retrieved from Neanderthal fossils. It turns out that Neanderthals carried some of the same clock-related genetic variants as do people who report being early risers. [Source: Carl Zimmer, New York Times, December 14, 2023]

Research carried out over the past few years by John Capra, a geneticist at the University of California, San Francisco, and other scientists suggested that some of those genes passed on a survival advantage. Immune genes inherited from Neanderthals and Denisovans, for example, might have protected them from new pathogens they had not encountered in Africa. Capra and his colleagues were intrigued to find that some of the genes from Neanderthal and Denisovans that became more common over generations were related to sleep. For their new study, published in the journal Genome Biology and Evolution, they investigated how these genes might have influenced the daily rhythms of the extinct hominins.

Inside the cells of every species of animal, hundreds of proteins react with one another over the course of each day, rising and falling in a 24-hour cycle. They not only control when we fall asleep and wake up, but also influence our appetite and metabolism. To explore the circadian rhythms of Neanderthals and Denisovans, Capra and his colleagues looked at 246 genes that help to control the body clock. They compared the versions of the genes in the extinct hominins to the ones in modern humans.

The researchers found more than 1,000 mutations that were unique only to living humans or to Neanderthals and Denisovans. Their analysis revealed that many of these mutations probably had important effects on how the body clock operated. The researchers predicted, for example, that some body-clock proteins that are abundant in our cells were much scarcer in the cells of Neanderthals and Denisovans. Next, the scientists looked at the small number of body-clock variants that some living people have inherited from Neanderthals and Denisovans. To see what effects those variants had on people, they probed the UK Biobank, a British database holding the genomes of a half-million volunteers.Along with their DNA, the volunteers provided answers to a long list of health-related questions, including whether they were early risers or night owls. To Capra’s surprise, almost all the ancient body-clock variants increased the odds that the volunteers were morning people. “That was really the most exciting moment of the study, when we saw that,” Capra said.

Geography might explain why the ancient hominins were early risers. Early humans lived in Africa, fairly close to the equator, where the duration of days and nights stays roughly the same over the course of the year. But Neanderthals and Denisovans moved into higher latitudes, where the day became longer in the summer and shorter in the winter. Over hundreds of thousands of years, their circadian clocks may have adapted to the new environment.When modern humans expanded out of Africa, they also faced the same challenge of adapting to higher latitudes. After they interbred with Neanderthals and Denisovans, some of their descendants inherited body-clock genes better suited to their new homes. All of these conclusions, however, stem from a database limited to British people. Capra is starting to look at other databases of volunteers with other ancestries.

Human Pain Sensitivity May Be Related To Neanderthal DNA

According to research in 2020, one Neanderthal gene variant appears to make people who have inherited it more susceptible to pain. Zach Zorich wrote in Archaeology magazine: The variant in question affects the functioning of nerve fibers, which are responsible for sending signals to the brain that are perceived as pain. Hugo Zeberg of the Karolinska Institute cautions that the team’s finding does not necessarily mean that Neanderthals were more sensitive to pain than modern people. He says they were probably “more sensitive to stimuli,” but the sensation of pain is a product of how the brain interprets signals from nerves throughout a person’s body. How that worked in Neanderthal brains is an open question. Zeberg and colleagues at the Max Planck Institute for Evolutionary Anthropology are now studying other Neanderthal gene variants, including one linked to healthier pregnancies and another that makes people more susceptible to contracting the novel coronavirus. “People are interested in the meaning of their heritage,” says Zeberg. “This is, in a way, an archaeological excavation of our genome.” [Source: Zach Zorich, Archaeology magazine, November-December 2020]

Research, published in October 2023 in the journal Communications Biology, focused on three versions of the SCN9A gene, which codes for a protein that shuttles sodium into cells and helps pain-detecting nerves send signals. People with any of the three variants are more sensitive to pain caused by being prodded with a sharp object, but not pain caused by heat or pressure. "In 2020, researchers studied people of European ancestry and linked these Neanderthal gene variants to increased pain sensitivity," study author Pierre Faux, a geneticist at the French National institute for Agriculture, Food and Environment, told Live Science. "We extend these findings by studying Latin Americans and showing that these Neanderthal genetic variants are much more common in people with Native American ancestry."We also show the type of pain these variants affect, which wasn't known before."[Source: Carissa Wong, Live Science, October 11, 2023]

Carissa Wong wrote in Live Science: It is possible that carrying these gene variants gave Neanderthals, and the modern humans who first settled the Americas, some sort of survival benefit, Faux said. But that survival benefit wasn't necessarily related to pain sensitivity, he added. "The modern humans who first reached North America would have had to bear harsh and cold conditions, so it could be that these variants have other effects beyond pain — for example, they could have somehow helped humans to cope with the cold," he said. In other words, the heightened sensitivity to sharp objects might have been just a side effect of another evolutionary change. However, the evolutionary pressures that acted on SCN9A were likely complex, and "why Neanderthals might have had a greater pain sensitivity and whether introgression in SCN9A represented an advantage during human evolution remains to be determined," the authors wrote..

Experiment That Connected Human Pain Sensitivity To Neanderthal DNA

Carissa Wong wrote in Live Science: In the new study, the scientists analyzed genetic samples collected from more than 5,900 people living in Brazil, Chile, Colombia, Mexico and Peru. On average, the participants had 46 percent Native American ancestry, 49.6 percent European ancestry and 4.4 percent African ancestry, but these proportions varied significantly between individuals. The analysis revealed that around 30 percent of the participants had one of the SCN9A gene variants, called D1908G, while roughly 13 percent of participants had the other two gene variants, known as V991L and M932L, which tend to be inherited together.The participants living in Peru, who had the highest proportion of Native American ancestry among the countries studied, were most likely to carry these Neanderthal gene variants. Conversely, participants recruited from Brazil had the lowest proportion of Native American ancestry and were least likely to carry the variants. [Source: Carissa Wong, Live Science, October 11, 2023]

"We know that modern humans and Neanderthals interbred something like 50,000 to 70,000 years ago, and that modern humans first crossed over from Eurasia into the Americas by 15- to 20,000 years ago," Faux said. "The high frequency of the Neanderthal variants in people with Native American ancestry could potentially be explained by a scenario where the Neanderthals carrying these variants happened to breed with the modern humans who eventually migrated into the Americas," he said.

Following the genetic analysis, the researchers carried out pain threshold tests on more than 1,600 volunteers in Colombia, 56 percent of whom were women, who had on average 31 percent Native American ancestry, 59 percent European ancestry and 9.7 percent African ancestry. In these tests, participants were asked to tell the researchers to stop as soon as they felt discomfort. The team also analyzed the gene variants carried by each of these tested participants.

In one of the tests, the team applied mustard oil, which irritates the skin, to the forearm skin of participants before pushing plastic filaments of increasing widths onto the same area of skin. In this test, wider filaments exerted a stronger force on the already-irritated skin. Participants who had any of the Neanderthal gene variants tapped out after being prodded with filaments that were significantly smaller than those who did not carry the gene variants. "When we tested the participants' pain threshold by applying pressure, heat or cold, the gene variants did not affect pain sensitivity, so the Neanderthal variants only affected their response to pinprick pressure," Faux noted.

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Text Sources: National Geographic, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Nature, Scientific American. Live Science, Discover magazine, Discovery News, Natural History magazine, Archaeology magazine, The New Yorker, Time, Newsweek, BBC, The Guardian, Reuters, AP, AFP, Lonely Planet Guides, and various books and other publications.

Last updated April 2024