Geneticists have traced the travels of Native Americans for tens of thousands of years by sequencing the genes of ancient skeletons and mummies. They reveal a story that begins in Siberia around 23,000 years ago, and is cut dramatically short when Europeans arrived at the end of the 15th century.
Researchers from the University of Adelaide in Australia sequenced the mitochondrial genome of 92 pre-Colombian skeletons and mummies who lived between 500 and 8,600 years ago, mainly in western regions of South America. Because mitochondrial genomes are passed down directly from the mother, they give insight to matrilineal lineage. Researchers can compare the number of random mutations in separated populations, and so establish when the two groups shared a common ancestor.
In the study, published in Science Advances on April 1, researchers established that Native American ancestors were last in contact with Siberian populations around 23,000 years ago. Instead of travelling directly from Siberia to America, it seems a group of about 10,000 people spent several thousand years in isolation.
This supports the theory that early American ancestors spent several years in Beringia, a now-submerged area between Siberia and Alaska.
The geneticists found an explosion of genetic lineages around 16,000 years ago, suggesting this was when the population first arrived in America and the wealth of natural resources led to massive population growth.
Native Americans then seemed to settle down, as lineages began to diverge. But none of the 84 genetic lineages found among the 92 samples are traceable for the past 500 years. And that’s when the Europeans arrived in America.
“All of the ancient mitochondrial lineages detected in this study were absent from modern data sets, suggesting a high extinction rate,” write the authors in their paper.
Bastien Llamas, a geneticist at the University of Adelaide and first author of the study, told Christian Science Monitor that the massive reduction in genetic diversity could have been caused by disease, war, societal collapse, or another catastrophe. But this disaster took place in the past 500 years—in other words, since Christopher Columbus arrived in America.
As the genes sequences show only matrilineal lineage, they do not reveal the complete genetic history of Native American ancestors. Only a limited number of genetic samples from people currently living in South America have been studied, so researchers could find some of the lost lineages as they collect more samples. And of course, there’s a strict limit on the number of ancient samples that have survived and can be studied, which could create a data bias.
But the DNA research corroborates archaeological evidence, giving stark insight into just how devastating the arrival of Europeans was for Native Americans.