On April 12th, 2018 we learned about

The adaptations Homo sapiens adopted from northern Neanderthals

Homo sapiens are the last living hominid on Earth, but some of our extinct kin “live on” in our gene pool. Many of the most obvious examples of these genetic artifacts come from Homo neanderthalensis, a species of human from Europe that we know interbred with Homo sapiens coming out of Africa. Neanderthals were generally very similar to modern humans, but they had some special adaptations that helped them live in the colder, darker reaches of Europe. Some modern humans now carry these traits as well, although the exact list of what we did, or did not, inherit from our Northern cousins hasn’t always been obvious.

DNA to deal with the dark

One common set of assumptions has to do with sunlight. Europe, particularly in the winter, receives a lot less sunshine than more equatorial regions, and so anyone living there would want lighter skin to better absorb light for the creation of vitamin D. While we do carry some Neanderthal genes associated with how our skin interacts with the Sun, they don’t overtly govern pigmentation. Red hair, often seen as tied to a very light complexion, is actually unique to Homo sapiens. On the other hand, Neanderthals did contribute genes our genome that shape how quickly you might tan or get a sunburn, so there is some logic to the idea that they carried adaptations for living with less sunlight.

Sun exposure mattered to Neanderthal mental states as well. The gene ASB1 has been linked to people’s natural circadian rhythms, making them more likely to want naps or be a “night owl.” It’s part of another set of genes Homo sapiens picked up from Neanderthals, some of which also seem to determine how exposure to sunlight affects one’s mood. It clearly wasn’t easy living up North, and makes sense that these adaptations would be appropriated by Homo sapiens looking to move to darker latitudes.

Nifty noses for better breathing

One thing Homo sapiens didn’t seem to borrow was Neanderthals’ wide nasal cavities. While both humans and Neanderthals have more sophisticated sinuses than our common ancestor, Homo heidelbergensis, Neanderthals could move, moisten and warm considerably more air per breath than we can. This is again tied to living in a cold, dry climate, but modern humans didn’t adopt these noses when they ventured north, possibly because of our metabolisms.

Neanderthals probably needed better airflow to serve their high metabolic needs. Their thick, stocky bodies are estimated to have needed as many as 4,480 calories a day, nearly twice what’s recommended for a modern human male today. To process those calories, Neanderthals would have also needed more oxygen than a modern human, so they couldn’t afford to let a cold, dry climate slow them down. So perhaps interbreeding ancestors didn’t end up with such sophisticated schnozzes simply because they didn’t need them- our lower metabolisms made us a little more flexible when it came to airflow.

Source: Neanderthals didn't give us red hair but they certainly changed the way we sleep by Darren Curnoe, Phys.org

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