London, April 22 :
In a significant discovery, researchers have found that modern humans may have dispersed in more than one wave of migration out of Africa.
They may have done so earlier than scientists had previously thought.
Modern humans first arose between 100,000 and 200,000 years ago in Africa. But when and how the modern human lineage then dispersed out of Africa has long been controversial.
“It is really exciting that our results point to the possibility of a multiple-dispersals model of modern humans out of Africa,” said Katerina Harvati, a paleoanthropologist at University of Tubingen in Germany.
“A multiple-dispersals scenario, with earlier modern humans leaving Africa as early as 130,000 years ago can perhaps account for part of the morphological and genetic patterns that we see among modern human populations,” she added.
Scientists have suggested the exodus from Africa started between 40,000 and 70,000 years ago.
However, stone artefacts dating to at least 100,000 years ago that were recently uncovered in the Arabian Desert suggested that modern humans might have begun their march across the globe earlier than once suspected.
The researchers used four out-of-Africa models to predict how much the genes and skull measurements of different groups in Africa, Asia and Australia might have diverged from one another.
The researchers found that both the genetic and skull data supported a multiple-dispersal model involving several migrations.
“The first wave of migrations probably followed the southern coast of the Arabian Peninsula as early as 130,000 years ago to Australia and the west Pacific region, while the second wave travelled along the northern route about 50,000 years ago,” Harvati noted.