Musth or must ( /ˈmʌst/) is a periodic condition in bull (male) elephants, characterized by highly aggressive behavior and accompanied by a large rise in reproductive hormones – testosterone levels in an elephant in musth can be as much as 60 times greater than in the same elephant at other times. However, whether this hormonal surge is the sole cause of musth, or merely a contributing factor, is unknown; scientific investigation of musth is problematic because even the most placid elephants become highly violent toward humans and other elephants during musth, requiring segregation and isolation until they recover. Female elephants do not undergo musth.
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