( ion years ago. This time frame corr...)New analysis shows three human migrations out of Africa

"This time frame corresponds extremely well with the fossil record, which shows Homo erectus expanding out of Africa then," Templeton said.

Another novel find is that populations of Homo erectus in Eurasia had recurrent genetic interchange with African populations 1.5 million years ago, much earlier than previously thought, and that these populations persisted instead of going extinct, which some human evolution researchers thought had occurred.The new data confirm an expansion out of Africa to 700,000 years ago that was detected in the 2002 analysis.

"Both (the 1.9 million and 700,000 year) expansions coincide with recent paleoclimatic data that indicate periods of very high rainfall in eastern Africa, making what is now the Sahara Desert a savannah," Templeton said. "That makes the timing very amenable for movements of large populations through the area. "

Templeton said that the fossil record indicates a significant change in brain size for modern humans at 700,000 years ago as well as the adaptation and expansion of a new stone tool culture first found in Africa and later at 700,000 years expanded throughout Eurasia.

"By the time you're done with this phase you can be 99 percent confident that there was recurrent genetic interchange between African and Eurasian populations," he said. "So the idea of pure, distinct races in humans does not exist. We humans don't have a tree relationship, rather a trellis. We 're intertwined."