A massive, earthquake-induced gash that cuts through eastern Africa contains evidence of three rainy phases during the Stone Age. They might have spurred the evolution of modern humanity's direct ancestors as well as of many other mammal species, scientists suggest.

Extended intervals of heavy rains created deep lakes in several parts of eastern Africa at times critical in human evolution, according to a team led by geologist Martin H. Trauth of Potsdam (Germany) University. Ancient lakes