Monkeys have relatively large brains because of mothering after birth new research suggestsHumans and other primates can thank their mothers for their big brains, research has shown.
The evolution of big-brained mammals has mostly been due to mothering, a study has found.
Scientists had thought that growing a large brain chiefly depended on having a fast metabolism.
But marsupials such as kangaroos and possums, whose young develop in a pouch instead of a womb, have relative brain sizes just as big as those of other mammals despite their slower metabolic rates.
Researchers found that brain size in both marsupials and placental mammals correlated with length of maternal care.
Marsupial brains grow slowly and mainly after birth in the mother's pouch, while the brains of placental mammals grow rapidly in the womb.
Primates such as humans and chimpanzees may benefit from the best of both worlds, the research suggests.
They spend both a long time in the womb, and a long time being cared for by their mothers after birth. This could account for their unusually large brains.
The research is reported in the journal Proceedings of the National Academy of Sciences
Dr Anjali Goswami, one of the authors from University College London, said: 'For a long time, our interest in our own large brains has focused the field on placental characteristics, such as high basal metabolic rate, and made us overlook the role of maternal care after birth on the evolution of big brains.
'However, if we take primates out of the equation, we discover that marsupials, despite having much lower metabolic rates, have similarly sized brains, or sometimes even bigger brains, than their placental mammal counterparts.
'So clearly, evolving big brains isn't just about having a high metabolism. Instead, it seems that maternal care is the most consistent factor driving the development of big brains across all mammals.'
She added: 'It appears that primate brains benefit from the best of both methods of increasing brain size - their brains grow rapidly during gestation in line with their fellow placental mammals, but also develop significantly after birth during a maternal care period which is only comparable to marsupials in terms of length.'
source: dailymail
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