Live Science reports:

Before modern humans began their major dispersal out of Africa about 50,000 years ago, they moved to places that were significantly more ecologically diverse, which may have given them the flexibility they needed to migrate across the globe, a new study finds.

Our species, Homo sapiens, originated in Africa more than 300,000 years ago. Genetic evidence suggests that all modern human populations outside Africa mostly descend from a small group of modern humans who started migrating out of Africa about 50,000 years ago.

However, previous research suggests the first waves of Homo sapiens began leaving Africa as early as about 270,000 years ago. This raises the question of why these earlier migration waves left no genetic traces in modern human populations outside Africa today.

In the new study, published Wednesday (June 18) in the journal Nature, researchers analyzed evidence from archaeological sites across Africa dated to between 120,000 to 14,000 years ago. By examining ancient plant and animal remains, the scientists reconstructed what kinds of habitats and climates people lived in across that span of time — this painted a picture of the vegetation, temperatures and rainfall a given area might have had.

The researchers discovered that modern humans began to expand the range of habitat types in which they lived starting about 70,000 years ago — they went into forests in West and Central Africa, deserts in North Africa, and places with greater ranges of annual temperatures. [Continue reading…]