In the absence of public funded science education and projects, did conflict and climatic uncertainty drive human evolution? http://www.bbc.co.uk/news/science-environment-19598980
What explains the extraordinarily fast rate of evolution in the human lineage over the past two million years?
A leading human origins researcher has come up with a new idea that involves aggression between groups and the boom-bust cycles that have punctuated our spread into new environments.
Speaking at this year's Calpe conference Prof Ian Tatersall said "I think it's fair to say that our species Homo sapiens and its antecedents have come much farther, much faster than any other mammalian group that has been documented in this very tight time-frame."
This phenomenon of accelerated evolution is known as "tachytely".
Among our ancestors, brain size doubled between two million and one million years ago. Then it has almost doubled again between one million years and the present day.
Along with the increase in brain size came a reduction in the size of the teeth and face along with other changes in the skull.
Such fast change is not seen among apes, and … the move our ancestors made from a tree-dwelling, to a ground-dwelling existence … is not enough to explain what is observed.
Certain evolutionary psychologists have popularised a model in which culture and brain complexity spurred each other on to greater heights in humans…But Prof Tatersall said …
Aggression between small, distinct human groups in the past is one of the major remaining agents of such changes. … He said, "Inter-group conflict would certainly have placed a premium on such correlates of neural function as planning and throwing. If we were somehow able to implicate conflict among groups as a selective agent for increasing intelligence within groups, this might explain the otherwise quite mystifying independent increases in brain size that we see in several different lineages within the genus Homo."
Such conflict could be seen as a form of predation. And, predation is regarded as a classic example of the "Red Queen" hypothesis whereby prey and predator become faster or more cunning in a self-reinforcing way.
Indeed, there are hints of such conflict from the sparse fossil record. A paper published this month in the Journal of Human Evolution http://www.sciencedirect.com/science/article/pii/S0047248412001406 suggested that ancient humans in northern Spain were engaged in predatory cannibalism against another band of people.
Prof Tatersall refers to the phenomenon as the "ratchet effect" and pointed to the large variation in human fossils from the early Pleistocene in Africa as an example, which may support his hypothesis.
At the conference, Richard Wrangham from Harvard University offered an alternative view, questioning the role of conflict as a driver. He pointed out that human hunter-gatherers had similar rates of inter-group aggression to chimpanzees.