Baby, I'm howlin' for you. Male howler monkeys make deep and boisterous calls to attract mates, but the deepest-pitched songs may come at cost: the size of their testicles. A new study in the journal ...

Yodellers of the world, you never stood a chance: Monkeys will always be better at yodelling than humans because they have a "cheap trick" hidden in their voice box, scientists revealed Thursday. When ...

Granddaughter Kyndra had a blast celebrating her 7th birthday at the Denver Zoo. The hour was getting late. We were exhausted. The roar of the sad lion and laugh of the hyena faded into the distance ...