Flanged Orangutans

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Flanged orangutans are adult male orangutans who have developed bulbous sacs of skin around their faces called flanges. They are found in Borneo. Their puffy cheeks may appear comical, but they actually signify their dominance in their habitat. Younger males don’t develop them, and it’s believed that living near a flanged male can actually suppress the development of flanges in other males. This characterizes a flanged orangutan as a sort of alpha male, as females will pick mates with flanges over those without them in almost every case. Scientists are still trying to determine exactly how and why males grow their flanges, but studies have shown that giant bursts of testosterone coincide with their appearance.