Across the Arabian Peninsula groundwater guided early humans on their journey out of Africa

Around two million years ago, when groups of upright people began migrating from East Africa, the journey was not just a search for food or new lands, because survival itself depended on finding water in environments that fluctuated between wet and very dry periods.

A new study suggests that groundwater, and the springs that feed it, may have been a key element in these early journeys, and that it may help explain the most walkable routes from East Africa to the Arabian Peninsula and then to Eurasia.

Therefore, the two researchers gathered published evidence of fossils, stone tools, springs and ancient lakes, and then reconstructed the water landscape of East Africa and the Arabian Peninsula to see where water could remain available when rivers and surface lakes dried up.

Mark Cuthbert, professor of Earth and Environmental Sciences at Cardiff University and co-author of the study, explains that surface water (rivers and lakes) responds quickly to declining rainfall, while large underground reservoirs can continue to feed springs for thousands of years after the onset of a drought.

Mark points out in statements to Al Jazeera Net that some of the springs in East Africa may have continued to operate for hundreds or thousands of years during the driest parts of the climatic cycles, making them “water refuges” amidst vast areas that have become less able to support life.

The earliest evidence that the researchers link to early humans using groundwater dates back to East Africa about 4.4 million years ago, as in wetlands near springs and groundwater in Ethiopia, and in Tanzania about 1.8 million years ago, where stone tools and human ancestral bones were found near wetlands and freshwater springs next to a salt lake that was not suitable for drinking.

Mark believes that early humans may have learned by observing animals that were more experienced in accessing water, such as elephants and some monkeys, and may have dug simple shallow wells with their hands in dry riverbeds to reach water hidden beneath the sand.

The researcher emphasizes that this type of behavior does not usually leave an archaeological footprint that can be found millions of years later, and therefore the absence of direct evidence does not necessarily mean that the use of groundwater did not occur.