The Sahara Desert is known as a harsh, unforgiving landscape that is inhospitable to most forms of life, but recent research suggests that the Sahara cycles through different climates, and was greener and more vegetated in the past than it is today. Ancient Saharan rock art depicts a variety of animals that are now extinct, and the archaeological record suggests that humans once thrived here, too. Life in the Sahara was made possible by changes in the location of the North African Monsoon, making some periods of time more humid and vegetated than others. American School of Prehistoric Research postdoctoral fellow Kayla Worthey is studying changes in the Saharan climate that took place over the last roughly 200,000 years in an effort to contextualize the developments that were happening among Homo sapiens populations at the time.
The past two hundred millennia brought critical changes for humans in the Sahara. The oldest anatomically modern Homo sapien was found in present-day Morocco at a site called Jebel Irhoud and dates back to about 315,000 years ago, and around 130,000 years ago, there appears to be a proliferation of new technologies in North Africa. Worked and hafted bone tools, for example, become more common at this time, as well as marine shell beads and other cultural expressions. Worthey’s research has the ability to reveal the climatic backdrop of this period of change in the Sahara. To what extent was this proliferation of technologies and ideas caused, or not caused, by climatic shifts? Her research can also shed light on the ecological connectivity of North Africa and how easy or difficult it may have been for people to cross the Sahara, as well as the debate between a single versus multiple origin points for our species. A more vegetated Sahara would suggest a more interconnected human population and would support the hypothesis that our species evolved simultaneously in multiple locations.
Worthey plans to collect the data for this project from archaeological sites to get a clearer idea of the impact that the climate was having on people. She plans to collect sediments from multiple sites in North Africa and sample them for biomarkers such as plant waxes, which can yield environmental information once their levels of carbon and hydrogen isotopes are measured. Important information about the climate can also be found in carbon and oxygen isotopes from tooth enamel. The first site that Kaula hopes to visit is Bizmoune Cave in Morocco.