Females Prefer Cheek Pads: Orangutans Choose Males with the Largest Cheeks
It turns out that when it comes to choosing a mate, cheek pads are the thing to watch out for. Female orangutans prefer males with large "check pads" on their faces.
Typically, only one male orangutan in any given area has cheek pads. This male is usually the dominant one in the region. Along with increased body size and a large, pendulous throat sac, which is used to bellow long call vocalizations, these cheek pads are characteristic of dominant males.
"Dominant males have to find and consume more calories," said Graham Banes, one of the researchers, in a news release. "Their movement is restricted as a result of their size, and fights with neighboring dominant males have been known to result in death. So, why would a male develop cheek pads if he can father offspring without?"
In order to find this out, the researchers spent eight years studying orangutans, collecting fecal samples. The scientists extracted DNA from these samples and identified 39 known individuals, including 12 males. Then, the researchers performed paternity testing to see which males were fathering offspring.
So what did they find? Orangutans with cheek pads father more offspring than any other male during their tenure as dominant males.
It seems as if cheek pad development is actually an evolutionarily stable strategy. Reproductive success is significantly skewed in favor of dominant, cheek-padded males, while other males simply bide their time until periods of rank instability.
The findings are published in the journal Behavioral Ecology and Sociobiology.
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