Neanderthals: Shared DNA and Variant Traits

When reviewing my DNA test results from 23andMe, the “Neanderthal Ancestry” section states “We’ve identified 272 genetic variants that can be traced to the Neanderthals, ancient humans who interbred with modern humans before going extinct 40,000 years ago – this is less than 54% of 23andMe customers and your DNA accounts for less than 4% of your overall DNA”. So, I immediately furrowed my (Neanderthal) brow, joined the 23andMe discussion forum and searched for more answers on what this DNA result actually meant. Upon reading my DNA results and the related White Paper 23-05 “Neanderthal Ancestry Inference”, some of the discussions on the topic, and further research on the Wikipedia.org: Neanderthal page, I found a wealth of information.

Neanderthal DNA
Human evolution links present-day humans and our closest evolutionary relatives, the now extinct Homo neanderthalensis, or Neanderthals by using new DNA techniques to extract hidden DNA clues from fragments of Neanderthal bones. 23andMe claims that their customers with Neanderthal variants have a direct Neanderthal ancestor – a grandparent to the 2,000th degree, and that we may have inherited some of our traits and behaviors from them.

The 23andMe White Paper suggests that one of the most debated aspects of our evolution rests on an ongoing debate about how much Neanderthals and modern humans interbred during the tens of thousands of years that we cohabited Europe and Western Asia. Research discovered that this interbreeding did in fact occur and that 1-4% of the genomes of all modern humans outside of Africa are of Neanderthal origin. Subsequent research identified specific Neanderthal-derived variants that were likely introduced into modern humans. So, the observation of these variants in a living individual indicates the presence of DNA that came from Neanderthals. 23andMe scientists then leveraged these findings with the results of their customers and identified physical traits associated with those variants that are likely to have entered modern human populations through Neanderthals.

23andMe offers the following brief history of Neanderthals to provide context to their DNA results.

Neanderthal Variants:
23andMe tests for the following Neanderthal variants: [A] Straight Hair, [B] Less likely to sneeze after eating dark chocolate, [C] Less back hair, and [D] Height. Out of the those Neanderthal variants trait influences, the test identified me as having only [D] one Neanderthal variant associated with my height. Incidentally, I found that to be accurate for the most part. [A] I have curly dark brown hair, not straight hair; [B] I do not sneeze after eating dark chocolate though, as far as I’m aware – and didn’t know that was a thing; [C] Sadly, I do have some back hair which has increased over the years…though, I would classify it as medium to less. [D] I’m of average height…5’11”, so, does that mean that I inherited Neanderthal height traits? Hmm…I guess so.

Given that the Neanderthals came from the Neander Valley in present day Germany and that they never migrated into the African continent, it makes sense that a lower Neanderthal variance contribution would exist in people with predominantly African ancestry.

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