Head-butting is used by some pigs, sheep and goats, even whales and dolphins, to settle disputes and display dominance. Until recently, it was assumed that these animals’ thick skulls and horns protected them, but by studying the brains of musk ox and bighorn sheep, evolutionary biologist Nicole Ackermans has found signs that the repeated blows are causing injuries.
The dead and dying neurons she found inside these animals’ brains may lead to degeneration similar to that seen in humans after recurrent blows the head. But while we now know repeated head-butting can cause long-term damage, we don’t know enough about animal behaviour to tell whether they’re suffering from concussion symptoms, which include headaches, feeling dazed and memory loss.
Main image: Musk ox headbutting © Getty Images