Evolution and howler monkeys

 Seductive Bass Tones Enough to Seal the Deal in Some Monkey Species

By JAMES GORMANOCT. 22, 2015

No offense to tenors, but outside of opera, a high male voice is seldom, if ever, considered seductive. Scientific research has shown that women find deep male voices attractive, and the same is true in other species, like howler monkeys.

But evolution is often stingy in its gifts, and researchers investigating male competition to reproduce have discovered an intriguing trade-off in some species of howler monkeys: the deeper the call, the smaller the testicles.

Jacob Dunn of Cambridge University, one of the leaders of the research, said that species evolved either to make lower-frequency sounds, or have larger testicles, but none had both a very low sound and very large testicles.

“It’s a great study,” said Stuart Semple, an evolutionary anthropologist at the University of Roehampton in London who was not involved in the research. “It shows this really clear trade-off.” Read more.