Marmosets are small primates. Think of a monkey with huge fuzzy ears. Primatologists have often wondered whether nonhuman males evaluated their potential mates, or whether their sex drive was more like an on/off switch.
We may think of animals as just responding to sexual invitations without thinking, but a study conducted in both the U.S. and Germany shows this isn’t necessarily so. Male marmosets having their brains scanned were given sniffs of genital-gland secretions from ovulating females.
That’s a scent that should trigger a mating response in the brain, and it did! But guess what else happened? Many other brain areas lit up as well, such as memory formation, information integration–in other words, areas associated with decision-making.
Researchers are still studying the effect, but apparently a lot more happens in a marmoset brain than a simple “have sex now” program. The specific areas of brain activity suggest that the males are evaluating potential mates before agreeing to a sexual union.
This makes special sense for marmosets, because they are monogamous and both partners raise the offspring. Under those circumstances you wouldn’t want to enter into a relationship without any thought.