Insert shows with arrow the location of study area in eastern Africa. Map of the Northern Tanzanian Divergence Zone depicts the East African Rift System (EARS), containing Lake Natron (north), diverging around the Ngorongoro Volcanic Highland massif and splitting into two separate rift valleys (Lake Eyasi on west) and Lake Manyara (on east). Prevailing wind is from the east. Olduvai basin lies to the west of and in the rain shadow of Ngorongoro.
Credit: Map made by Sara Mana, http://www.geomapapp.org; from Cuthbert et al., doi:10.1371/journal.pone.0107358.g001
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 the evolution of the human species, a new study shows.
The research -- published in the journal PLOS ONE -- combines geological evidence from the Olduvai sedimentary basin in Northern Tanzania, which formed about 2.2 million years ago, and results from a hydrological model.
It shows that while water in rivers and lakes would have disappeared as the climate changed due to variations in Earth's orbit, freshwater springs fed by groundwater could have stayed active for up to 1000 years without rainfall.