News: More on greening of Sahara influencing early migrations

Science Daily

A team of scientists from the NIOZ Royal Netherlands Institute for Sea Research and the University of Bremen (Germany) has determined that a major change in the climate of the Sahara and Sahel region of North Africa facilitated early human migrations from the African continent. The team's findings will be published online in the Nov. 9th installment of Early Edition of the Proceedings of the National Academy of Sciences USA. Among the key findings are that the Sahara desert and the Sahel were considerably wetter around 9,000, 50,000 and 120,000 years ago than at present, allowing for the growth of trees instead of grasses. . . .

Based on analysis of plant leaf waxes the researchers could determine the relative importance of trees and grasses in the Sahara and Sahel regions. Trees generally require more water to survive than do tropical grasses, and so by analysing the plant leaf waxes to determine if they were produced by trees or grasses, the scientists could examine past precipitation changes in tropical Africa over the last 200,000 years.