Out Of Africa Theory Essay

'Out of Africa' theory

There are several theories proposed as to how human intelligence evolved, however the mostly widely accepted theory is the ‘Out of Africa’ model. This model states that all modern humans emerged from early Homo sapiens, who emigrated from Africa around 60,000 years ago and spread over the world (University of Cambridge,2007). It has also been suggested that it was due to the rapid and violent climate changes in the Rift Valley, which led to an increase in brain size of hominids and allowed them to colonise new habitats. (Cox, 2014). Around 1.8 million years ago there was a growth in brain size and an increase in the number of hominid species in the Rift; for example Homo habilis and Homo erectus. These can be linked

For instance ‘Lucy’, an extinct member of the hominid species Australopithecus afarensis, living 3.2 million years ago, was found in Ethiopia (Cox, 2014). The fossil shows that she was biped, which is thought to be an adaptation to climate change, due to the landscape becoming more savannah like and a decrease in the number of trees (Cox, 2014). Furthermore, compared to apes, the Australopithecus brain showed slight changes in size, as the neocortex begun to grow (Hawks, 2013). This shows that the brain was evolving, and becoming more complex in response to environmental changes, which leads to each successive member of the hominids being gradually more intelligent, with an increased brain

By expanding the brain it allowed hominids to be able to adapt to the varying climates and colonise new habitats.

An upward trend can be seen towards bigger brain sizes, however there are sudden jumps where it has increased dramatically in a short period of time. These jumps correlate with sudden climate changes, which occurred around 1 million years ago and 200,00 million years ago, with the emergence of Homo sapiens. The time periods also relate to when the Earth’s orbit was most elliptical (Cox, 2014). In relation to this the precession and gravitational interaction between the Moon and Earth, can also be associated with the increased brain size as they are seen to contribute to the sudden effects of dramatic climate change.

Machiavellian Intelligence