May 30 (UPI) -- Early humans might have never left Africa without the help of groundwater. New research suggests groundwater springs were essential to the movements of early human ancestors through East Africa.
Groundwater springs likely dictated the routes early humans followed. They also enabled the mixing of local populations, encouraging genetic diversity.
Researchers at Cardiff University in Wales mapped the effects of climatic changes on water resources in East Africa during the time when early humans are thought to have first left the region, between 2 million and 1.8 million years.
Africa's monsoons wax and wane in intensity on a 23,000-year cycle. During periods of limited precipitation, water resources would have been scarce. Groundwater springs would have likely been the only salvation for early humans on the move.
"We found that the geology is really important in controlling how much rainfall gets stored in the ground during wet periods," Mark Cuthbert, a research fellow at Cardiff's School of Earth and Ocean Sciences, said in a news release. "Modeling the springs showed that many could still flow during long dry periods because this groundwater store acts like a buffer against climate change."
"As such, we begin to see that the geology, and not just the climate, control the availability of water -- the landscape was a catalyst for change in Africa," Cuthbert said.
Researchers published their map and the related data in the journal Nature Communications.
The map revealed the likely migration routes between disparate springs, which scientists likened to modern service stations.
"Through our mapping we have found the routes on the current landscape by which our ancestors may have walked, like motorways, taking people from one water source to the next," said Matthew Bennett, a researcher from Bournemouth University. "This is another vital clue in understanding how these people migrated across the African continent, from water source to source, and how this may have impacted on gene flow and mixing."