A peacock's crest acts as a sensor for mating
A female peacock's crest contains special sensors that allow her to detect vibrations from a distant mate. According to The Atlantic, the feathers are "tuned to vibrate at the same frequencies as a displaying peacock rattles his tail," according to The Atlantic. When a male peacock fans his tail, he shakes it 26 times per second, creating a pressure wave that rattles the female's head in a bid for attention.
In 1931, a scientist decided to undertake an experiment in which he raised a monkey as if it were a person.