I’m actually not sure. Based on the Wikipedia page, bulls in musth emit a characteristic low-pitched tone that females in heat seem to respond to. And the testo

I’m actually not sure. Based on the Wikipedia page, bulls in musth emit a characteristic low-pitched tone that females in heat seem to respond to. And the testosterone levels wouldn’t hurt sperm production. I don’t know much beyond the Wikipedia page and some information I learned from some guides, but it sounds like the exact evolutionary advantage/purpose isn’t well understood. It’s interesting that the females also go into heat. The musth certainly seems like the male analogue of heat. And the male aggression is certainly similar to what you see in some other herd animals during mating season (aka rutting, though I don’t know enough to be able to compare the aggression levels of musth with that of a rutting deer or bison). Elephants in musth will fight other elephants, and unlike normal mating dominance fights they will try to really kill the other. Part of me wonders if this is a part of natural selection. A grown bull elephant doesn’t really have any predators, except another bull elephant in musth. Another interesting fact about musth is it seems to effect elephant society. When young males reach adulthood and leave the herd of females, they tend to form small “bachelor herds” consisting of a few other young males and an older male, who “shows them the ropes”. And one of the things the older male teaches them is self control during musth. The Wikipedia article, and a story a guide told me, mention that young males in musth without an older male presence to help guide them (teach them?) will be more aggressive.