Check out all the monkeys! .... And a word on BPA and behavior

Just about every day I check the snow monkey web cam at the Jigokudani Monkey Park in Japan. I've been doing it since we came back from Japan nearly a year ago. I've enjoyed seeing the changing of seasons and the comings and goings of tourists. This snapshot is remarkable for the numbers of monkeys hanging out at the hotsprings and the complete absence of tourists. The day we visited there were easily five times as many tourists as monkeys. I had a good time but it would have been way more awesome to have them all to ourselves!

The Arashiyama monkey park right outside Kyoto is far more accesible than Jigokudani and even though a similar number of tourists frequent it, the place is bigger and everyone is able to spread out more. People are also allowed to feed the monkeys at Arashiyama from inside a cage (the people are in the cage) which makes for a fun experience — at least it was for me. I had a blat hand feeding itsy bitsy pieces of apple to the babies and also observing a bit of a sense of entitlement on the part of older monkeys who displayed a considerable amount of disdain for such stingy handouts. If I offered a piece of apple that wasn't large enough, one monkey slapped it away, more than once (so I knew it wasn't an accident). He or she readily accepted larger chunks. Spoiled much?

So, monkeys are a curious bunch, and they've been on my mind again lately on account of some research that's started to make the rounds of news sites. It's on BPA — the chemical added to plastics to make them hard and is now known to pose health risks. Well, it also apparently feminizes male behavior in monkeys. The dangers appear to be most linked to prenatal exposure. In monkeys, research published this year in the journal Psychoneuroendocrinology shows that prenatal exposure of monkeys to BPA causes male monkeys to cling less to their mothers and look away more while clinging. Supposedly this is more typical of female infants in the species of monkey studied (long-tailed macaques, a close relative of rhesus macaques).

Chemicals added to plastics to make them softer are also blamed for feminizing behavior — and this time the research comes from humans. It's not experimental data, but pilot research published in the International Journal of Andrology shows that preschool-aged boys with more exposure to phthalates in utero were less likely to engage in stereotypical boyish play, specifically play fighting and playing with trucks and guns.