Kelso and her team first narrowed the sample to include only the 112,338 individuals with white European ancestry (whose genomes contain Neanderthal DNA), and used these data to tease out which traits are influenced by Neanderthal genetic variants. The traits they identified included those that affect hair color, skin color, skin tanning and burning, sleeping patterns, mood, and tobacco use.Maybe I am behind the times but I did not know there was a “trait” for tobacco use. I figured you either did that or you didn't. Like Robin Williams says in Dead Again: either be a smoker or don't be a smoker. Choose it and be it.
For example, being a self-described night owl and being prone to daytime napping were both traits positively influenced by Neanderthal variants, as were loneliness, low mood, and smoking. Genetic loci associated with having red hair were found to be devoid of Neanderthal variants, suggesting red-headed Neanderthals were either rare or non-existent. The new study also supports Capra and colleagues’ previous observations that Neanderthal variants are associated with sun-induced skin lesions, mood disorders, and smoking.
That traits such as skin color, sun-burning, and sleep patterns were identified by the analyses might be explained by the Neanderthals’ adaptations to life at more northern latitudes, suggests Capra. But for other traits, he notes, determining how the effects seen in present-day people might once have affected Neanderthals themselves “is one of our crucial challenges.” For example, he says, “of course, Neanderthals were not smoking.”
I suspect we will continue to find effects of the Neandertal genome, especially since our understanding of how much interbreeding there was continues to change. It is also a testament to the stability of the human genome that, even after a separation of some several hundred thousand years, interbreeding was still possible.