> unique to humans It appears not - http://www.bbc.co.uk/earth/story/20150420-why-do-women-have-periods http://www.bbc.co.uk/earth/story/20150420-why-do-women-

> unique to humans It appears not - http://www.bbc.co.uk/earth/story/20150420-why-do-women-have-periods http://www.bbc.co.uk/earth/story/20150420-why-do-women-have-... > Apart from humans, most of the other menstruating animals are primates, the group that includes monkeys and apes as well as humans. Most monkeys living in Africa and Asia, such as rhesus macaques, menstruate. > menstruation also evolved independently in two other groups: some bats and elephant shrews. Not that any of this disproves the "evolution hackery" suggestion, mind.