New Research: Modern Humans Carry the Genetic Legacy of Neanderthals

The Associated Press reports on research indicating that Neanderthals still live within us. These studies show that Neanderthals and Denisovans once coexisted, interacted, and reproduced with the early ancestors of modern humans. As a result, traces of them can still be found in our genes, and new scientific technologies have demonstrated how they shaped our lives. Scientists say that inherited traits from these ancient ancestors still influence us, affecting fertility, the immune system, and even how our bodies respond to the COVID-19 virus. According to this research, in just the past few months, researchers have linked Neanderthal DNA to serious hand diseases, nose shape, and other human features. They even added a gene that Neanderthals and Denisovans had to mice to study its effects and found that this gene gives them larger heads and an extra rib. Dr. Hugo Zberg from the Karolinska Institute in Sweden states, 'New technologies, research, and collaborations have helped scientists answer fundamental questions such as who we are and where we came from.' New research has shown that some population groups in Africa have almost no Neanderthal DNA, while those with European or Asian backgrounds possess 1 to 2 percent of this DNA. Denisovan DNA is hardly detectable in most parts of the world but constitutes 4 to 6 percent of the DNA of Melanesians, who live in the western Pacific, including Fiji, Vanuatu, the Solomon Islands, New Caledonia, and Papua New Guinea. According to the report, Neanderthal DNA is associated with several autoimmune diseases such as Graves' disease and rheumatoid arthritis. Homo sapiens, who migrated from Africa, had no immunity to diseases in Europe and Asia, but Neanderthals and Denisovans, who previously lived there, had immunity. Rick Potts from the Smithsonian Institute points out that a gene related to blood clotting, believed to have been transferred from Neanderthals to Eurasia, may have been beneficial during the Pleistocene but could increase the risk of stroke in older individuals today. Chris Stringer, a human evolution researcher at the Natural History Museum in London, says, 'By mixing with them, we repaired our immune system.' Zberg and Pääbo showed in 2020 that a major genetic risk factor for severe COVID-19 was inherited from Neanderthals. The following year, further research revealed that a set of DNA variants along the chromosome inherited from Neanderthals acts inversely, protecting individuals from severe COVID-19. Other studies have linked Neanderthal genetic types to traits such as skin and hair color, behavioral characteristics, skull shape, and type 2 diabetes. One study found that individuals who experience more pain than others likely carry Neanderthal pain receptors. Another showed that one-third of women in Europe carry a Neanderthal receptor for the hormone progesterone, which is associated with increased fertility and a lower likelihood of miscarriage. There is limited information regarding the genetic legacy of Denisovans, with some studies linking their genes to fat digestion and better adaptation to high altitudes. Scientists have even found evidence of 'ghost populations'—groups whose fossils have yet to be discovered—in the genetic code of modern humans. The old belief was that modern humans survived due to superior behavior and technology, but recent research shows that Neanderthals spoke, cooked with fire, created art, had complex hunting tools, and even adorned themselves with jewelry. Scientists say that while Neanderthals were specifically adapted to cold climates, 'Homo sapiens' managed to spread across various regions and adapt to different climates and cultures. On the other hand, modern humans had smart and efficient bodies and required fewer calories compared to robust Neanderthals, who faced challenges in mobility, especially when food was scarce. Janet Yang, a curator of physical anthropology at the Canadian Museum of History, mentions another interesting hypothesis that dogs played a significant role in the survival of modern humans by facilitating hunting. John Hawks from the University of Wisconsin-Madison states that human evolution was not about 'the survival of the fittest' but rather about 'interaction and intermixing.' With further advancements in science and more detailed exploration of human genetic heritage, scientists expect to uncover more evidence of how intertwined we are with our ancient relatives and what legacy they have left us.