How modern-day humans dispersed on the planet and the pace of civilization-changing technologies that accompanied their migrations are enduring mysteries. Scholars believe ancient peoples on Europe and Asia moved primarily along east-west routes, taking advantage of the relative sameness in climate, allowing technological advances to spread quickly.
But what about in North and South America, with its long, north-south orientation and great variability in climate? How did people move and how quickly did societal innovations follow?
Studying the human genomeUsing advanced genetic analysis techniques, evolutionary biologists at Brown University and Stanford University studied nearly 700 locations on human genomes drawn from more than five dozen populations. They say that technology spread more slowly in the Americas than in Eurasia and that the continents’ orientation seems to explain the difference. After humans arrived in the Americas 20,000 to 40,000 years ago, genetic data shows, the migrating populations didn’t interact as frequently as groups in Eurasia.
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