One of the questions in connecting paleoclimate with transitions in human evolution is whether the changes were driven by increasing aridity or increased climatic variability.
When Middle Stone Age tools emerged between 350,000 and 50,000 years, symbolic cultures developed, Homo sapiens appeared, and human fossils from Asia indicate that the earliest modern humans dispersed from Africa between 120,000 and 50,000 years ago. Other climate records indicate that these drier climates, punctuated by wet episodes, may have supported a greener Sahara, opening the possibility of migration across northern routes.
Against this backdrop of a generally drier climate, our early human ancestors were adapting to a variable climate, changing plants and animals in the environment, and creating an ever-sophisticated stone tool technology. Though this research does not emphatically prove that these forced adaptations spurred on the evolution of our species, it does provide more evidence of the environment that our uniquely adaptive ancestors were managing to survive and thrive in.
Written by Chris Campisano