What may be the most natural cologne in the world was recently discovered in a Mexican forest. The ingredients? Monkey spit and chewed up leaves.
According to a paper in this month's issue of the journal Primates, male Mexican spider monkeys chew the leaves of three aromatic plants: the Alamos pea tree, which has fragrant leaves and flowers, a flowering trumpet tree, and wild celery.
The ritual, which typically takes anywhere from 30 seconds to two minutes, was deemed monkey "self-anointing" by Matthias Laska, a professor of zoology at Linkoping University in Sweden.
Laska and his colleagues observed the behavior 20 times in two male spider monkeys that were part of a free-ranging group at the Parque de Flora y Fauna Silvestra Tropical in Veracruz, Mexico.
The researchers determined the monkeys always applied just one plant species at a time. The application was routine, not unlike a man who regularly spritzes on deodorant or cologne.
"In the majority of cases, the arm that did not hold the scent-bearing material was held high or grabbed a branch above the animal," Laska and his team wrote.
While this is the first reported case of such behavior in wild Mexican spider monkeys, similar routines have been spotted among both male and female capuchin monkeys, owl monkeys, other spider monkeys and lemurs. In most of these cases, the scientists speculated that the leaf mash might have been used to mitigate topical skin infections or repel bugs.
Laska and his team, however, found that of the plants used by the Mexican spider monkeys, only wild celery is known to have insect-repelling compounds and anti-fungal properties. The other plants simply smell good.
The scientists, therefore, concluded that self-anointing "may play a role in the context of social communication, possibly for signaling of social status or to increase sexual attractiveness."
In other words, monkeys could do it for the same basic reasons people use cologne.
While the chemistry behind this remains a mystery, the odors may mimic those of fragrant, naturally occurring primate steroids, which are presumed to act as sex-stimulating pheromones. Laska conducted an earlier study that found spider monkeys are particularly gifted at sniffing out such scents.