Depressed? Your inner Neanderthal may be to blame. Modern humans met and mated with these archaic people in Europe and Asia there are about 50,000 years, researchers have long suspected that genes collected from these trysts could shape the health and well-being today. Now, a study in the current issue of Science details their impact. It uses a powerful new method to scan the records of 28,000 electronic health Americans to show some Neanderthal genes variants today may increase the risk of depression, skin lesions, blood clots, and other disorders.
Neanderthal genes aren 't all bad. "These variants may protect against disease, sometimes make people more susceptible to the disease," says paleogeneticist Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Two other new studies have identified three genes archaic that stimulate the immune response. and the most archaic genes persist in humans were probably beneficial in prehistoric times. But some now cause diseases because of lifestyles and modern environments are so different.
people living only carry traces of Neanderthal DNA, making its impact on the most striking health. "the Neanderthal genetic contribution to present people today seem to have the greatest physiological effects I would have thought naively "says Pääbo, who helped launch this line of research by sequencing the genomes first elders, but did not participate in these studies. On average, Europeans and Asians inherited about 1.5% of their genomes of Neanderthals. Island Melanesians are an additional 2% to 3% of the DNA inherited from another extinct group, the denisovan. Most Africans lacking this archaic DNA because the interbreeding happened after modern humans left Africa.
DEBORAH ADAPTATION Brewington / VANDERBILT UNIVERSITY
by comparing the genomes of some Neanderthals and a denisovan with people from the 1000 genomes database, biologists have recently discovered calculation about 12,000 versions of genes of Neanderthals, or haplotypes, living Europeans and Asians. The researchers clues to the function of a handful of these haplotypes, some were thought to be involved in the immune system, or the development of skin or hair, for example. But nail their precise function is required costly studies of gene expression patterns in tissues or animals.
A breakthrough came when geneticist Joshua Akey populations of the University of Washington, Seattle, and Tony Capra evolutionary genomicist of Vanderbilt University in Nashville independently realized they could catch variants of the Neanderthal gene into a medical database, the EMR Network and genomics (EMERGE). This consortium in nine US cities linking the genetic data of patients with their medical data, in the form of specific billing codes that record diagnoses for diseases and other conditions. Emerge and allows researchers to follow the correlations between genes and symptoms in tens of thousands.
Akey and Capra joined forces and tried for over 6,000 Neanderthal haplotype in the genetic data of 28.416 adults of European ancestry. After identifying pieces of DNA inherited from Neanderthals, the team used statistical analysis to link the possession of these archaic variants at a higher risk of disease or other traits captured in the billing data, says Capra .
Research has registered a dozen Neanderthal genes could cause a significant risk of disease today. For example, a variant of the gene apparently makes it sticky and prone to clot blood. This rapid coagulation may have spelled the difference between life and death when Neanderthals hunted dangerous animals or bleeding after delivery of large-brained babies. But it can also increase the risk of blood clots and stroke, which would have been much less common in prehistoric times when most people died young.
The researchers also found a number of Neanderthal genes associated with neurological disorders, including depression, which can be triggered by disrupted circadian rhythms. have been linked to precancerous skin lesions called actinic keratoses other variants. Capra speculates that the Neanderthal brain chemistry and the responses of the skin to sunlight can both were in phase with the light conditions and lifestyles of prehistoric Europe. The head variants gene may be maladaptive now that most people live by artificial light.
Other Neandertal alleles regulate the transport of thiamine, or vitamin B1, which metabolizes carbohydrates into the cells of the intestine. Neanderthal diets rich in meat and nuts, may have ample thiamine, but people chew processed foods today can not get enough, and having the Neanderthal variant may predispose to malnutrition, Capra speculates.
The study also found Neanderthal genes associated with incontinence, bladder pain, and urinary tract disorders. And a single base change was associated with addiction to nicotine, making it the second Neandertal allele found to date to strengthen the risk of tobacco dependence.
The Neanderthal health legacy is not entirely negative. Two studies published in The American Journal of Human Genetics last month identified three archaic genes that stimulate the innate immune response, which helps defend against fungi and parasites as well as bacteria. All three have been strongly selected for Europeans and Asians, said biologist Janet Kelso calculation of Max Planck, lead author of a study. The three genes work together in subtle ways to regulate the expression of Toll-like receptors on the surface of white blood cells, stimulating the innate response probably says Lluis Quintana-Murci, population geneticist at the Pasteur Institute and the Centre french National scientific research in Paris, lead author of the other study.
These examples suggest that modern humans entered new environments that host new pathogens, they took an evolutionary shortcut picking beneficial genes from other hominids. "You've taken the variety of another species or population that more had lived," says Quintana-Murci. Neanderthals had at least 0,000 years to adapt to life in the Middle East and Europe before modern got there.
But if beneficial in the Pleistocene and those living in poor condition today, stimulate immune genes may have deleterious effects even in the United States and Europe, where people face fewer pests. Kelso found that genes archaic receptors have been strongly linked to allergies "the price today is that when you increase the immune response, it can be bad for us in terms of autoimmunity, inflammation and allergies, "says Quintana-Murci.
Neanderthals Exactly how these genes affected themselves is not always clear. "This does not mean that Neanderthals were depressed," or had more skin cancer, warns the calculation Sriram Sankararaman geneticist from the University of California, Los Angeles.
These studies are just the beginning, as researchers search for more Neandertal variants transmitted in these ancient events, and broaden their modern genome databases for hundreds of thousands. "We suspect there are many more Neandertal alleles floating out there," says Capra.
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