Thursday, February 24, 2011

Monkey urine cologne

Male capuchin monkeys like to urinate onto their hands then rub their urine over their bodies and into their fur. A new study shows that the brains of female tufted capuchins become more active when they smell the urine of sexually mature adult males. That suggests males wash with their urine to signal their availability and attractiveness to females. A number of New World monkey species, including mantled howler monkeys, squirrel monkeys and the few species of capuchins, regularly "urine wash", urinating into the palm of the hand, then vigorously rubbing the urine into the feet and hindquarters. When being solicited by a female, adult males increased their rate of urine-washing. Since female capuchins - when they are most fertile - actively solicit males, urine washing by males might provide chemical information to the females about their sexual or social status. Scientists scanned the female monkeys' brains while the animals sniffed adult male and juvenile male urine. These magnetic resonance imaging (MRI) scans revealed that female tufted monkeys' brains became significantly more active when they sniffed the scent of urine produced by adult males compared to that of juveniles. Since adult males are sexually mature, they excrete higher concentrations of the male sex hormone testosterone in their urine. The concentration of this testosterone is also linked to their social status since higher status males tend to produce more. Female capuchin monkey brains react differently to the urine of adult males than to the urine of juvenile males. This may be used as a form of communication to convey social and or sexual status.

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