These Knees Say Watch Out

Africa's male eland antelope avoid fights by clicking tendons in their legs

WHEN AN AGING human rises from a chair and hears a knee go “click,” virility is probably not the first thing that comes to mind. But among Africa’s male eland antelopes, knee clicks correlate strongly with body size, rather than age, and can be heard several hundred yards away. The sounds serve as dominance displays that the ungulates use to settle disputes over access to females without resorting to actual violence, according to a study published recently in the journal BMC Biology. The authors say the knee tendon behaves like “a string being plucked,” with the depth of the click increasing with the animals’ size.