No one knows for certain how many Native people were living in the Americas when the first Europeans arrived – some estimates say 18 million in North America and 40 million in the combined continents. However, we now know how many people were living in North America when the first peoples came over from Siberia – about 250. A new study examined DNA samples from both sides of the Bering Strait and found that all evolutionary models trace back to that small original population.
“Going from a few hundred founders to around 40 million inhabitants of the Americas, who eventually live under different environmental conditions to which they adapt, is pretty exciting stuff. It’s about understanding how evolution operates in terms of genetic diversity.”
Michael Crawford, the head of the University of Kansas Laboratory of Biological Anthropology, co-authored the study, “How strong was the bottleneck associated to the peopling of the Americas? New insights from multilocus sequence data” published this week in the journal Genetics and Molecular Biology. Using the term “bottleneck” implies that they expected the number of first people crossing from Siberia to be restricted, but the small number that they found, coupled with the large number the population exploded to in a relatively short evolutionary time plus the diversity of cultures that formed explains Crawford’s excitement.
The DNA samples studio came from China, ten groups in Siberia and ten Native American populations that represented various tribes in Central and South America. The genomes were sequenced over 15,000 years and the data was fed into isolation-with-migration computer simulation models based on 100 million generations. Every regressive analysis showed an initial population group was between 229 to 300 people, with the most likely being around 250.
Then what happened?
“It was a matter of population fission among hunters and gatherers. There would be about 50 people, and when the population’s fertility gets higher and higher, the population splits into the next so-called ‘county’ and then the next. After 15,000 years, you can put them all the way down in Argentina.”
Let’s just say they don’t refer to those 40 million people as “pre-Columbian” for nothing. It’s estimated that the population in the Americas dropped by almost 90% within a few hundred years after the arrival of the Europeans.
If those first 250 Native Americans could see how few of their descendants remain, they might say that their bottleneck has been wrung.