Not so long ago, scientists used DNA from one of the oldest English skeletons (10,000 years old) to figure out what the first inhabitants of Britain looked like. However, it is not the first time that DNA from an ancient skeleton has been taken and reveals amazing facts about our ancient ancestors. The rapid development of genome sequencing over the past few decades has opened a new window into the past.
Our ancestors slept with Neanderthals
Archaeologists have long guessed that modern humans and Neanderthals lived together in Europe and Asia, but only recently the nature of their cohabitation became known.
In fact, after the first mitochondrial genome of a Neanderthal (DNA located in the mitochondrion of a cell) was sequenced in 2008, geneticists and archaeologists for a long time could not understand whether people are related to our closest relative in some way or not.
When the complete Neanderthal genome was sequenced in 2010, comparisons with modern human DNA showed that all non-African people have bits of Neanderthal DNA mixed in the genome. This could have happened if humans and Neanderthals intermixed just 50,000 years ago. Several years later, this was confirmed.
Mixing allowed Tibetans to live in the mountains
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Oddly enough, our ancestors communicated with Neanderthals not just as friends. When DNA was sequenced from a fossilized finger found in a cave in the Altai Mountains in Siberia, and the finger was believed to belong to a Neanderthal, genetic analysis showed that it was in fact a new species of man, different from but closely related to Neanderthals. Analysis of the complete genome showed that these “Denisovans” also had sex with our ancestors.
Tibetans, who live among the world's tallest mountains, are able to survive at altitudes where most people simply suffocate in the absence of oxygen. Genetic analysis showed that Tibetans, along with the Ethiopian and Andean highlanders, have special genetic adaptations that allow them to process oxygen in the thin mountain air.
We now know that these genetic adaptations to height in Tibetans - they have a specific variant of the EPAS1 gene - were actually inherited through ancestral mating with Denisovans.
It turned out that improved immunity, metabolism and diet among modern humans are also associated with beneficial genetic variants inherited from this cross with both Neanderthals and Denisovans.
Our ancestors evolved surprisingly quickly
Crossbreeding with other species explains only a small fraction of human adaptations. DNA analysis shows us that as our ancestors wandered around the world, they evolved in different environments and adapted to food faster than previously thought.
For example, the development of lactose tolerance is an obvious example of human adaptation. The ability to digest milk after three years is not universal - and was previously thought to have spread to Europe along with agriculture in the Middle East around 10,000 years ago.
But when we study human DNA over the past 10,000 years, this adaptation, which is now common in Northern Europe, was absent 4,000 years ago, and even then was quite rare. This means that the spread of lactose tolerance in Europe must have been incredibly fast.
The first Englishmen were black
DNA from one of the first people in Britain, the Cheddar Man, shows that he was most likely dark-skinned and blue-eyed. And he also couldn't digest milk.
While curious and even somewhat surprising to learn that some of the first humans to inhabit the island now known as Britain had dark skin and blue eyes, this striking combination is not all that unpredictable given what we have learned about Paleolithic Europe. from the DNA of the ancients. Dark skin was quite common among hunter-gatherers like the Cheddar Man, who lived in Europe for millennia after he lived - and they had blue eyes since the Ice Age.
Immigrants from the East brought white skin to Europe
So if 10,000 years ago dark skin was common in Europe, how did Europeans get their white skin? There are no more hunter-gatherers in Europe, and there are very few of them left around the world. Agriculture has replaced hunting as a way of life, and as you know, agriculture spread to Europe from the Middle East. Genetics has revealed to us that this change is also associated with significant human movement.
We also know now that about 5000 years ago there was a large influx of people from the Russian and Ukrainian steppes to Europe (geographically). Together with DNA, these people brought domesticated horses and a wheel to Europe, and at the same time, possibly a proto-Indo-European language, from which almost all modern European languages originated.
Most likely, along with them, white skin appeared in Europe. Lighter skin pigmentation is believed to help people absorb sunlight better and synthesize vitamin D from it.
Ilya Khel