Chimpanzees enter into "deals" whereby they exchange meat for sex, according to researchers.
Male chimps that are willing to share the proceeds of their hunting expeditions mate twice as often as their more selfish counterparts.
This is a long-term exchange, so males continue to share their catch with females when they are not fertile, copulating with them when they are.
The team describe their findings in the journal PLoS One.
Interesting, and it might offer some insight into how some aspects of human sexuality came about.