Our Ancient Ancestors' Evolution and Survival May Have Depended on Groundwater

Groundwater could be linked to human evolution. Researchers have found that our ancient ancestors' ability to move around and find new sources of groundwater during extremely dry periods in Africa millions of years ago may have been key to their survival and evolution.

"A major unknown connected with human evolution in this climatically turbulent environment is the availability of resources, particularly freshwater," said Mark Cuthbert, one of the researchers, in a news release. "Springs and groundwater-fed habitats could have played a decisive role in the survival and dispersal of hominins in times when potable surface water was limited."

In order to investigate a bit further, the researchers examined geological evidence from the Olduvai sedimentary basin in Northern Tanzania, which formed about 2.2 million years ago. It's likely that potable water in rivers or lakes in this region would have been scarce due to salinity, drought, and the short-lived flow of streams. Yet while surface water may not have been potable, the researchers found that springs were active during the driest periods about 1.8 million years ago. In addition, models showed that these springs could have stayed active for hundreds of years without rainfall.

"As surface water sources became more scarce during a given climate cycle, the only species to survive may have been those with adaptations for sufficient mobility to discover a new and more persistent groundwater source, or those already settled within home range of such a resource," said Gail Ashley, co-author of the new study. "Such groundwater refugia may have been sites for intense competition between hominin and other animal species and hence selective pressure favoring those who could maintain access to water, something for which there is no substitute."

In fact, this competition likely drove the evolution of humans. It shows the importance of groundwater in this region, and reveals that further studies may want to focus on the role of groundwater in history.

The findings are published in the journal PLOS One.