Although providing milk to the new-born is the exclusive role of mothers, Charle Snowdon and his team from the Wisconsin Regional Primate Research Centre, US, have reported that the hormone prolactin increased in male monkeys 4ust two weeks before the birth of their young. Prolactin's main function is to prepare the mammary glands of females for milk production and its levels naturally rise during late pregnancy. The levels of this hormone in males could be directly correlated with their experience as fathers - the more babies their mate had the higher were the levels of prolactin. Researchers speculate that prolactin may help the fathers to tolerate the presence of infants.