Sensible sheep, and cheeky monkeys

A couple of things in the most recent Animal Behaviour caught my eye.

One, Sheep self-medicate when challenged with illness-inducing foods, by Juan Villalba and colleagues, found that lambs can learn which compounds will relieve a stomach ache brought on by, say, tannins. Then, if given the same tannins in the future will choose the appropriate remedy.

I’d put this down in the cute, but not earth-shattering category. Villalba and co write that:

“From prehistoric times, people have looked to the presumed self-medicative behaviour of animals for remedies of ailments but it is still not clear whether animals seek medicinal compounds to recuperate from illness. Evidence of self-medication is based almost exclusively on observations rather than experimental analyses.”

On the other hand, there’re already whole books on animal self-medication.

The other is called Rhesus monkeys, Macaca mulatta, know what others can and cannot hear, by Laurie Santos and colleagues. The researchers set up an experiment where the monkeys competed for grapes with a human experimenter. The monkeys had a choice between picking grapes from a noisy container, and from a silent one.

If the human was looking in the other direction, the monkey preferred the silent container, presumably showing it was out to sneakily get the grape. If the human was paying attention, the monkey didn’t care which container it took — showing that the monkeys understand the connection between hearing and knowing. This also hints that they have theory-of-mind type notions of what others are thinking.