|Chimps grooming, Photo credit flickr user Tambako the Tiger|
A recent study led by Melissa Emery Thompson of the University of New Mexico found that male attention comes with costs. In the world of chimpanzees, males do indeed compete to mate with females. (Chimpanzees live in groups of multiple males and females and males are dominant over females.) A female will give birth to an offspring and then raise that offspring for five to seven years, which is a pretty long time in the animal kingdom. In part because female chimps raise their young for so long, males compete seriously for access to females. It's not as though the guys always have a chance with that type of reproductive schedule. Females will mate with multiple males, some of whom will then guard her to prevent other males from mating with her, so she can receive quite a bit of attention, whether she wants it or not.
For eleven years, researchers observed chimpanzee behavior and collected their urine to analyze or study hormones (naturally occurring substances that affect or regulate the activity of other cells or organs), such as estrogen and progesterone, which are two female sex hormones important for female sex characteristics and for reproduction. Emery Thompson and colleagues also collected urine to look for C-peptides, a byproduct of insulin. Declining levels of C-peptides indicate a female is spending more energy than she is currently consuming, which is not good.
|Chimpanzees with offspring, Photo credit: flickr user Valerie|
Food for thought: Why might female chimpanzees mate with multiple males? Hint: do some research into infanticide and think about how this might protect against it.