Our species appeared in Africa more than 300.000 years ago, with migration from the continent 60.000 to 70.000 years ago, heralding the beginning of the global spread of Homo sapiens. But where did these pioneers go after they left Africa?
After years of debate, a new study offers an answer.
These hunter-gatherer groups appear to have persisted for thousands of years as a homogeneous population in an area that stretched between Iran, southeastern Iraq and northeastern Saudi Arabia before settling across Asia and Europe about 45.000 years ago, scientists report. N1.
Their conclusions are based on genomic data sets extracted from ancient DNA and modern gene sets, combined with paleoecological evidence that showed the region would have been an ideal habitat.
Scientists have called the region, part of what is called the Iranian Plateau, a "hub" for these people - who may have numbered only in the thousands - before they continued to move further afield thousands of years later.
"Our results provide the first complete picture of where the ancestors of all present-day non-Africans were during the early stages of the colonization of Eurasia," said molecular anthropologist Luca Pagani of the University of Padua, Italy, who led the study published in the journal Nature Communications.
Anthropologist and study co-author Mihael Petralja, director of the Australian Research Center for Human Evolution at Griffith University, said the study was "a story about us and our history - our aim was to unravel some of the mysteries of our evolution and our spread around the world".
"The combination of genetic and paleoecological models allowed us to predict the place where the first human populations lived as soon as they left Africa," Petralja added.
These people lived in small, mobile groups of hunter-gatherers, the scientists said.
The site offered a variety of conditions, from forests to grasslands and savannas, changing over time depending on dry and wet periods.
There were enough resources available, and evidence shows that there was hunting of wild gazelles, sheep and goats, Petralja said.
"Their diet consisted of edible plants and small to large game. Hunter-gatherer groups seem to have practiced a seasonal lifestyle, living in the lowlands in the colder months and in the mountainous regions in the warmer months," Petralja said.
People who lived in the area at the time apparently had dark skin and dark hair, perhaps similar to people who now live in parts of East Africa, Pagani said.
"The cave art appeared as soon as people left the area. So these cultural achievements may have been created while they were in the area," Pagani said.
Their eventual spread in different directions outside of that area set the stage for the genetic divergence between present-day East Asians and Europeans, the scientists said.
The study included modern and ancient genomic data for Europeans and Asians.
"We found the oldest genomes dating from 45.000 to 35.000 years ago to be particularly useful," said molecular anthropologist and lead study author Leonardo Valini of the University of Padua and the University of Mainz in Germany.
Scientists have devised a way to untangle the extensive genetic mixing of populations that has occurred since the dispersal from the area in order to pinpoint the area where Homo sapiens first arrived from Africa.
There were earlier smaller excursions by Homo sapiens out of Africa before the key migration 60.000 to 70.000 years ago, but these seem to have been "dead ends".
Homo sapiens is not the first human species to live outside of Africa - including the area covered by this study.
The ancient intermingling of our species left a small Neanderthal contribution to the DNA of modern non-Africans.
"Neanderthals have been confirmed to have been in the area before the arrival of Homo sapiens, so that area may have been where that interaction took place," Valini said.
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