Monkey’s face says, ‘Don’t mate with me’
William L. Allen

Monkey's face says, 'Don't mate with me'

For the monkeys in the Guenon genus, breeding with another guenon species can lead to trouble. The offspring of these unions tend to be infertile, and thus a dead end from an evolutionary standpoint. If many monkeys from a single population interbreed, it could cause a sharp decline in the population. The problem is that many guenon species live in close proximity to each other, heightening the risk for interbreeding. As a result, species that live in close contact have evolved certain facial patterns to prevent any unwanted hookups, researchers report today in Nature Communications. The scientists snapped photographs of 2 dozen species of guenons (pictured) for 18 months and used face recognition algorithms to determine key features that demonstrated stark differences between neighboring species—white fur patches that cover the nose, a well-defined unibrow, or colorful ear tufts, just to name a few. The findings put to bed an alternative hypothesis that suggested environmental factors such as the lighting of a species’s habitat could be the cause of guenon facial diversity.