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Though it’s made up of 51 independent nations and officially recognizes 23 languages, it’s easy to view Europe as a homogenous entity. The European Union exists as a means to create unity, security, and stability between them, and common languages are shared amongst countries. Many a traveler has uttered the phrase “backpack across Europe,” in reference to the ease with which one can traverse the continent’s many states and cultures.
In fact, this homogenous identity can be traced back to prehistory. Modern humans outside of Africa belong to two giant haplogroups—genetic populations classified by letters of the alphabet—and just about everyone of European descent falls under the same letter: N. Haplogroup M is more commonly spread throughout Asia and Australia, and for years it was believed that the two separate groups left Africa at different points in time.
According to a new study published in Current Biology, Europe’s genetic history may have been more diverse than previously imagined. The findings concluded that humans with the M haplotype actually had made their way into Europe, but completely disappeared. The lineage’s dissolution coincides with an abrupt warming period 14,000 years ago, nearly 2,000 before the end of the last ice age.
Cosimo Posth, an archaeogenetics doctoral candidate at the University of Tubingen in Germany and one of the study’s co-authors, said this revelation was the most surprising finding from the research due to the way the ancient populations were previously understood.
“This was a big surprise,” he tells BTRtoday. “It’s something you could only discover with ancient DNA, because looking at modern people, you would never have thought this lineage was present in Europe before.”
Aside from the entire lineage of haplotype M being lost, there were a number of other population shifts that occurred in concert with the warming event—an event connected with a massive retraction of the ice sheet that covered the northern part of Europe at the time. Due to the ice melt and change in climate, corridors might have opened up that created contact between populations, and perhaps promoted the spread of the dominant haplotype N, and the elimination of haplotype M, on the continent.
“We thought it was a continuing population that survived throughout time,” Posth explains. “Instead we see it was a much more dynamic process, so much so that one complete lineage got lost.”
Though there wasn’t much archaeological evidence to suggest a large population turnover, the discovery of the major shift was the byproduct of another commonly held theory the study helped strike down. It was previously thought that modern humans dispersed across the world in multiple waves after leaving Africa, reaching from Europe to Australia.
The fact that members of haplogroup M were found in Europe, however, suggests that there was just a single major dispersal of non-African humans, which the study dates around 50,000 years ago, with a plus/minus of 5,000 years.
“It sounds like a lot of time, but it’s a pretty narrow interval,” Posth says. “This doesn’t mean that people came out of Africa 50,000 years ago, but actually started to spread all over the world.”
The process of accruing DNA from ancient bones is an arduous one. It starts in the ground with excavation, where prehistoric human remains are extremely rare and predictably not well preserved. It’s not common to find complete skeletons—usually, experts have only small bone fragments or teeth from which to extract DNA.
From there, the bones undergo a number of laboratory experiments to discern whether the material within them is useful. The difficulty there are the many possible exposures to contamination, both in the soil and when handled by humans.
All in all, the study took nearly three years to complete, and included collaborations with museum curators and archaeologists across Europe, as well as scores of hours behind a computer screen to analyze the data and make sense of what it says.
It goes without saying that Posth’s study provides a far more complete understanding of Europe’s population fluctuations and ancient migrations, which is enormous in the archaeogenetics field. On a larger scale, it also provides a relatable perspective for the majority of us who remain unacquainted with the complexity and scope of prehistoric humans
“It’s really hard for us to find a connection with people that lived so long ago, because we are usually thinking in days and years, maybe centuries,” he says. “It’s always good to rescale our perspective of what’s happening today, not only in time, but in dimension.”
Familiarity with these kinds of migrations in human history also puts the migration of Syrian refugees, long considered a global crisis, in better context. The circumstances surrounding current migrations are far different than the climatic motivations of prehistoric shifts, but movements of large populations are not uncommon.
“You really start to see that these are phenomena that are recurrent in our past, back in the millennia, but sometimes even closer,” Posth says. “The way to think is not to compare the two events, but that it’s something that has always happened, and the intensity of population movement has been greater in the past.”
Then, of course, there’s the idea that these ancient humans, regardless of genetic background, originated from the same place more than 65,000 years ago; that minuscule splices in our genetic code are what separate you from someone of a completely different culture halfway across the globe.
“What is really fascinating to me is how these ancestral populations are, or are not, possibly related to modern day people,” Posth says. “This is something that has a lot of implication on identity, with belonging to a specific country or culture. It’s important we try to remember people that lived before us on the same geographic areas we do now.”