Neanderthal DNA Got You Down? Our Ancient Ancestor DNA May Influence Depression

Throughout Europe and parts of Asia, from 400,000 to 40,000 years ago, Homo neanderthalensis roamed. This species has been called our closest ancestor. Short, stocky and cold adapted with large but not quite as complex brains, they used tools, controlled fire, created art and buried their dead. They were quite advanced for what storybooks usually depict as crude, primitive cavemen.

Then, our species – Homo sapiens – appeared. Since these early humans were much daintier and more agile with more complex brains, there is evidence that they created competition with the Neanderthals, particularly in hunting where their tools were of greater sophistication. These tools allowed for increased safety and higher success in the dangerous act.

Neanderthal were either a species or subspecies of human beings under the genus Homo. The two roamed the earth together for thousands of years in the Pleistocene. They shared much of the same DNA as the two were able to inter-breed. Some modern humans today share 1-4 percent of their DNA with Neanderthals. Recently, implications of this DNA sharing have been further explored by researchers at Vanderbilt University.

Senior author of the study, evolutionary geneticist and associate professor of biology at Vanderbilt John Capra said that this gene sharing can influence immunological, dermatological, neurological, psychiatric and reproductive diseases, among others.

According to a paper, published in Science, Neanderthal DNA could be a reason why some experience depression, mood disorders or skin diseases. It does not cause these conditions; it merely influences when these genes could be switched on or off.

The researchers used databases containing biological gene samples to analyze genotypes and phenotypes of various adults of European ancestry obtained from health records on the Electronic Medical Records and Genomics (eMERGE) Network. They integrated these data with Neanderthal haplotypes across individual human genomes. The researchers were also able to identify “Neanderthal single-nucleotide polymorphisms (SNPs)”. By comparing the samples’ SNPs and leniency towards genotypic and phenotypic traits, conclusions were drawn. By analyzing these data, they found it was evident that Neanderthal SNPs influenced, particularly, brain phenotypes.

Neanderthal DNA can lead to increased risk for precancerous skin lesions, neurological conditions like depression and nicotine addiction. It has, however, been suggested that there may be other factors affecting skin lesions and depression in modern humans as opposed to Neanderthal DNA impacting it. Neanderthals brain chemistry and skin may have been well adjusted to proper sunlight conditions whereas modern humans are now accustomed to artificial sunlight. Additionally, the study notes that Neanderthal alleles are enriched near long-term depression.

Other Neanderthal genes can put us at risk for diseases as well. One Neanderthal gene, useful when Neanderthals were hunters and healing wounds quickly was necessary, is the ability to clot blood. The blood is able to become stickier and coagulate quicker, but this also increases risk for stroke and blood clots, which were less common during the Neanderthal’s reign.

Malnutrition, incontinence and urinary issues may also be the result of Neanderthal DNA.

While modern humans and Neanderthal once shared the earth, even interbreeding creating a legacy that lives on yet today, they eventually fostered a competition that led to the extinction of Neanderthal. It is estimated that about 40,000 years ago, the Neanderthals went extinct, likely for a combination of reasons, including the ice age or lack of hunting skills. Their DNA does, however, live within us in trace amounts, influencing various diseases and disorders that researchers are still discovering.

 

More than 100 issues of JYI have been published since the journal was founded in 1997.
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