Y: You know, Don, one thing I like about you is the fact that you don't just go      mindlessly pursuing every woman who comes along.

D: It's true, I am a gentleman with refined tastes.

Y: Why, you're downright similar to a marmoset.

D: A marmoset!? What's that?

Y: Marmosets are small primates. Think of a monkey with huge fuzzy ears.

D: I'm not sure that's a compliment...

Y: 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.

D: They were making a decision!

Y: 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.

D: Well, I'll be...I guess I am like a marmoset!

Y: I hope not too much.  

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