For Howler Monkeys, Louder Calls Mean Smaller…

For howler monkeys, it appears the louder the calls, the smaller the — ahem — balls.

A research team looking into the monkeys’ incredibly loud and low vocalizations, and the physical structures that support the calls, discovered the correlation. Animals with louder and lower calls had larger hyoids, a bone in the front of the neck that appears to act as an amplifier, but smaller testes. There was significant variation in hyoid size between howler species, but also between male and females

Leave a Reply