Human migration: Climate and the peopling of the world
The human dispersal out of Africa that populated the world was probably paced by climate changes. This is the inference drawn from computer modelling of climate variability during the time of early human migration.
One of the most puzzling questions about the origins of modern humans has been why the dispersal of Homo sapiens out of Africa occurred so long after their first known appearance in east Africa approximately 150,000 to 200,000 years ago1. Fossil, archaeological and genetic evidence indicates that early migrations out of Africa into the Levant (eastern Mediterranean) and the Arabian peninsula occurred around 120,000 to 90,000 years ago1, but the further dispersal of our kind halfway around the world did not begin until about 60,000 years ago1. This out-of-Africa migration was pulsed, with waves of dispersal eastward to south Asia, Indonesia and Australia by 50,000 years ago, migration westward to Europe by 45,000 years ago1, migration into north Asia by 20,000 years ago and to the Americas by 15,000 years ago2 (Fig. 1). A paper online in Nature by Timmermann and Friedrich3 provides modelling insights into the potential role of climate in the human migration out of Africa.