In southern Mexico, the deep and raspy roars of howler monkeys reverberate through the lush jungles enveloping the city of Comalcalco. The sound — akin to the rumble of distant thunder or the grumble ...

Howler monkeys are relatively small primates known for their incredibly loud, low-frequency roars that sound as if they come from a much larger creature. This is useful in the animal kingdom because ...