Question

What factors do you think are responsible for the growth of the larger brain of hominins over time?

Answer 1

One of the most important feature of recent human evolution is the trend towards increasingly large brains over the pilo-pleistocene.Early hominin australopithecines had a cranial capacity slightly larger than that of extant apes,over the subsequent three million years, average brain size trebled. Brains are extremely expensive to both grow and maintain, the increase in early homo brains imposed an estimated 20 percent increase in metabolic costs.This cost is even higher in later hominin species.different factor that effect the brain size over the past two million year is considered as -

1)the pressures driving hominin brain expansion

2) quantitatively evaluate tempo change in hominin brain size

3)environmentally based hypotheses for brain size change.

Evidence in support of either the variability or arditiy hypothesis is not compelling and that the relationship between brain size and palaeoclimate is not straightforward.Environment likely played a part , wheather as a direct pressure or by forcing hominins to change their behaviour so as to be able to use more risky and peripheral habitats, to live in larger groups,or to use novel resources.However,the climate variable we have used cannot explain encephalization.Most enigmatic is the role of social evolution in the encephalization process.Evidence from language evolution studies,brain morphology and the appearance of symbolic behaviour, all suggest that language evolution is key component of human cognitive evolution and that cultural advances may have occurred in a series of steps that mirror changes in brain size and architecture.