Figure 2.

One small step for a man, one giant leap for mankind (Neil Armstrong). Left, photograph of the footprint left approximately 3.5 million years ago by A. afarensis, probably the immediate predecessor of the genus Homo, in Laetoli (Tanzania). Right, footprint in the lunar soil made by the astronaut Neil Armstrong (Apollo 11, July 21, 1969), the first person ever to set foot on the Moon. In a relatively short period of time we have gone from taking the first steps upright in Africa to walking on the Moon. How was this possible? While the brain has certainly increased in size during evolution it is not clear that this is the sole cause. Thus, the key question is whether the increase in the number of cortical circuits or rather changes in these circuits has been the driving force behind humans’ rapid development? The schemes of the size and shape of the brains (fossil endocranial casts) of the Australopithecus africanus, Homo erectus, and Homo sapiens were taken from Bermúdez de Castro (2002).