In a study done in Indonesia, scientists found that the more grooming the male Macaque monkey indulged on a female the more he got. Doubled in fact.

If the supply of females was plentiful, the need to bestow long-lasting grooming services wasn't deemed necessary by the male monkeys. It was only when the female numbers were low and chances were slimmer that the males upped the ante with special and more thoughtful grooming techniques. The males who groomed the longest?
They got the most. Top of the food chain and the opportunity to plant more seed and produce more attentive males.

What I want to know is where do you find the scientists who want to sit around and watch monkeys mate for two years? Is there a sign up sheet or do you think they just sign up at monster.com and send in an application to National Geographic's Monkey Sex Observation Division.

And considering all that you've read here, do you still think we're the more evolved species?