The mane of the adult male lion, unique among cats, is one of the most distinctive characteristics of the species. In rare cases a female lion can have a mane.The presence, absence, colour, and size of the mane is associated with genetic precondition, sexual maturity, climate, and testosterone production; the rule of thumb is the darker and fuller the mane, the healthier the lion. Sexual selection of mates by lionesses favours males with the densest, darkest mane.Research in Tanzania also suggests mane length signals fighting success in male-male relationships. Darker-maned individuals may have longer reproductive lives and higher offspring survival, although they suffer in the hottest months of the year.