There are two interesting things about the American Journal of Primatology. 1) It exists, and 2) it reports that Stony Brook University conducted a study on gorilla sexual habits, where a team of researchers spent thousands of dollars to
chronicle the sex lives of lowland gorillas every day for more than three years. They wondered if "pregnant females can mimic ovulating females and dupe the male into mating with them, to distract him from what those other girls are doing."
"This kind of competitive behavior may even help explain why humans evolved into a mostly monogamous species," says the study.
Explaining human behavior, indeed.

(Thanks, Hayley!)