The radical gender-bending life of the female spotted hyena was originally assumed to be the result of an excess of testosterone circulating in her blood. Androgens, the group of sex steroid hormones that includes testosterone, have been unambiguously branded as male: andro meaning ‘man’ and gen a ‘thing that produces or causes’. So the obvious assumption was that these big, belligerent female hyenas, much like the mole we met earlier, must be swilling with the stuff. But much to everyone’s surprise, the circulating levels of testosterone in adult female spotted hyenas do not rival those in
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