“The difference in mind between man and the higher animals, great as it is, is one of degree and not of kind,” wrote Charles Darwin, in his famous _The Descent of Man_ in 1871. And evolutionary biologists still agree. So then what makes the mental capacities of Homo Sapiens and other hominid apes so different?
Two of the most important factors are: 1.) brain size relative to body weight — that’s why elephants and great whales, with much larger brains than ours, aren’t necessarily smarter. And 2.) Longer maturation – Homo Sapiens brains take a very long time to reach full capacity. The larger size went alongside increased development of the neo-cortex — we learn with visual processing very well, have advanced areas devoted to speech, and of course we possess that fantastic pre-frontal cortex that lets us imagine a different reality and develop abstract thoughts.
The second point about Homo Sapiens’ brain development taking so long is a testimony to our potential for adaptability — because so much of our intellectual growth occurs up through our teenage years, we incorporate what we learn from our surrounding environment to a fantastic degree.
Brain size was increasing in hominids after our ancestral split from modern apes most rapidly between 1.8 million years ago-600,000 years ago, and events occurring in the environment can explain why natural selection would have favored this development. Climate change was occurring – there was a cooling of the earth that changed many ecosystems. It seems likely that our ancestors’ propensity to adapt to a quickly changing world spurred our intellectual growth.
Source(s): _Endless Forms Most Beautiful_, Sean Carroll, 2005, Norton, chapter 10.
