WHERE DO WE COME FROM? THE SAVANNA THEORY

In one of my previous posts I mentioned that the records from East African paleolakes revealed huge climate variability in the region which coincided with major events in human evolution. I also talked about how this discovery changed the understating of our origins and created more questions than it answered, giving a rise to numerous theories explaining our adaptation.

Before exploring these new theories though, we need to know what our understanding of early human evolution was previously. The most popular theory was the Savanna theory which was ‘officially’ developed by Raymond Dart in 1925, but it actually started with Lamarck in 1809 and Darwin in 1871, and was still widely approved in the 1980s (Bender et al.: 2012). It was founded on the assumption that the last common ancestor of humans and great apes lived in forests, but when the global climate started cooling down and African uplift and rifting took place, the forests were replaced by patches of open woodland and grassland. According to that theory, our current form is a result of adaptations to the new habitats. As the resources became more sparsely distributed, bipedality enabled carrying of food and water over long distances. The Savannah theory also explains the hominid brain expansion by food scarcity and the necessity of complex social structure for survival (Potts: 1998). As a consequence, large brains needed more fuel so, instead of eating more plants, our ancestors turned to meat. Our bipedalism makes us one of the best long-distance runners in the animal kingdom, and little hair allows sweating and facilitates cooling. These features were adaptations to chasing animals in vast open spaces, under the sizzling African sun with no or little shade due to the lack of forests. Our advantage was not speed or strength, but the ability to run after an animal to the point it became exhausted and collapsed.     

However, recent discoveries showed us that the idea of simple transition from ape to human from is not quite right – things turned out to be way more complex than that. In the next post I will focus on some more recent, more complicated hypotheses of our origins and I will also present limits to our current knowledge.

A simplified illustration of the Savanna theory (from: toknowthyself.files.wordpress.com)