The Northerner thinks I have an OCD about hygiene, I like to think it’s an endearing foible.
Smelling nice is important to me. On my birthday I was given lots of lovely body and bath stuff; thankfully nobody brought any sticks to the party (see blogpost Hello Dolly!). I love using exotic scented showergels and creams and I have a wide variety of perfumes that could easily rival some department stores.
Our sense of smell however is relatively feeble compared to some animals. Capuchin monkeys (from the genus Cebus) can be found in Central and South America. The male species isn’t taking the proverbial when it comes to hygiene; in order to attract a mate, he will urinate on his hands and then rub the urine into his fur. Girls are you wincing yet?
For years this has baffled scientists, some have thought that urine lowered body temperature, while others claimed it enabled the monkeys to identify particular individuals by smell.
Most studies into this behaviour have been inconclusive, until now. A new study published in the American Journal of Primatology says it’s “a turn on” for the female species.
Dr Kimberly Phillips, an associate professor of psychology at Trinity University in San Antonio, Texas, and her team has found there is more activity in the brains of female tufted capuchins when they are exposed to the smell of the urine of sexually mature males.
Dr Phillips, who specialises in research that focuses on understanding the neurological and biological basis of primate behaviour, said: “We suggest that urine is used as a form of communication to convey social and or sexual status.”
Dr Phillips and her team investigated by using magnetic resonance imaging (MRI) to scan the brains of female capuchins. During the scans, females were exposed to the urine of sexually mature adult males and that of juveniles. The females’ brains became significantly more active when they sniffed the scent of urine produced by adult males compared to that from juveniles.
Sexually mature adult males excrete higher concentrations of the male sex hormone testosterone in their urine. The concentration of this testosterone is also linked to their social status; higher status males tend to produce more.
Dr Phillips added that it was surprising that capuchin monkeys appeared to respond to these types of cues, because this species is not known for using communication based on smell.
Other New World monkey species (found in the Americas), that regularly ‘urine wash’ include the mantled howler monkeys (genus Alouatta) and squirrel monkeys (genus Saimiri), urinate into the palm of the hand, then vigorously rub the urine into the feet and hindquarters.