People, they’re flipping everywhere. You are just one individual of a species that is seven billion strong, with people living in every corner of the world. But have you ever asked yourself where you really came from? – and no, this is not about to be another explanation of the birds and the bees – sorry guys.
“It can’t be that complicated!” I hear you howl. Humans had to originate somewhere as a new species, evolving over millennia from another species. Then those early hominid ancestors must have slowly spread across the globe, resulting in the rather crowded situation we see today. Simple logic. All we need to do is look at the evidence and join the dots – easy, right? …Wrong.
Every element of human evolutionary history has been a source of vigorous debate, due to scarce genetic and anthropological evidence – thus many different theories about what could have happened in our early history have been proposed. This is especially the case in light of recent advancements in various genetic studies. Such new technologies are capable of extracting evidence from the genomes of modern-day humans, as well as the fossils of some of our ancient ancestors. As more and more evidence accumulates, existing and ‘established’ beliefs are put into chaos. (Isn’t that all we wish for? To find out all we know is all wrong? That’s the beauty of science….)
Recent studies have contributed to a ground-breaking discovery in solving the puzzle of the origins of Native Americans. Large groups of researchers from universities and institutions all around the globe sequenced genomes (genetic information) donated by volunteers from Native American groups. The groups constituted people both from South and North America, representing both the Amerindians (American Indians) and Athabascans (a native Alaskan people), as well as volunteers from Siberia and Oceania, plus DNA from ancient bones.
Many different statistical tests were applied (I encourage you to read the paper if you are into statistics) – what they found invalidated centuries-old theories. Let’s start with the team who published their work in the journal Science. They found that Native Americans trace back to a common Siberian origin, contradicting the previously held theory that they could be traced back to multiple origins with an earlier migration from Europe.
For those unfamiliar* with the details of the previous theories and how things look in the light of the new findings – don’t worry! I’ll visualise it for you in a timeline:
Some 23,000 years ago an East Asian population split. One group moved towards Northeast Asia, then the Bering Strait; they then crossed the Beringia Land Bridge, making it finally to the Americas (that’s quite some trip…)**. About 13,000 years ago this common pool diverged into two distinct groups (Amerindians (American Indians) and Athabascans (a native Alaskan people)). This fact contradicts the original idea that the two groups (Amerindians and Athabacans) came from two different origins. Since the split, genetic and cultural diversity have arisen slowly over time.
That is, however (as always), not the end of the story. The research group who published in Nature disagree with the findings of this group (the one which published in Science – stay with me). Popcorn at the ready! As Professor Reich (from Harvard Medical School’s Department of Genetics) says in an interview with TIME, “We have overwhelming evidence of two founding populations in the Americas”. Despite using almost the same data as shown in the Science paper, the Nature team think that today’s Native Americans come from two different waves of migration. One of the waves was supposedly of Siberian origin and they refer to the other wave as Population Y. Population Y would be more closely related to “Australians, New Guineans and Andaman Islanders… than to any present-day Eurasians or Native Americans”.
One question still remains, of course: when and how this so-called ‘Population Y’ reached South America. The question becomes even harder to answer when we consider the fact that Population Y is ancient and shows “distant genetic affinity to Australian, New Guinean and Andamanese populations.” If Population Y is not particularly closely related to any of these populations, that means it is ancient enough that the source of Population Y on the Eurasian continent no longer exists. But as I said at the beginning, the answer might just be round the corner….
The two research groups agree on two things – firstly, that the previous theories on origin of Native Americans are no longer valid; secondly, the Native Americans originate from Eurasian migration and show traces of Australasian ancestry. This exciting finding has huge consequences on human evolutionary history on the Americas. Watch this space, as the biggest ever episode of ‘Who Do You Think You Are’ continues….
* Hands up guys, don’t be shy!!! S.
** This already disputes the theory that suggests initial colonisation of Alaska 35,000 years ago.