For better or worse, communication is essential among animal populations. It's necessary to convey information about who you are, what you do or where you are going. Monkeys use a variety of methods of communicating, from vocalizations to scent marking. When it seems like monkeys are just sniffing each other's rear ends, they're in fact sharing information with a pal.
A Little About Monkeys
Currently, there are more than 260 species of monkey in the world. Highly intelligent, they use a variety of techniques for communication. Chemical communication, or signaling, can be used to identify potential mates or rivals, to leave a trail, determine age or rank within a population or even determine reproductive status. A highly developed olfactory system allows monkey to discern different scents, gather information and ultimately use it for survival.
Something About Scents
Scent glands are generally found in the anogenital area, chest and armpits. They secrete a semi-liquid collection of chemicals. A monkey seen sniffing another's butt is simply gathering information from these glands at the base of the tail. Several different chemicals are secreted depending on species, diet, environment and sex but, within a population, the variation in the chemical concentrations secreted allows for identification among individuals.
Other Forms of Communication
Like us, monkeys use more than one form of communication. While sniffing another monkey's bottom may help with some things like identification, body language and vocalization are still necessary to express emotions such as sadness or fear. Being able to communicate several ways helps ensure survival.
Studying Chemical Communication
Olfactory processes are some of the most difficult to study, especially in the wild. It's unclear whether scent marking is deliberate -- a monkey actively producing and releasing a specific scent to achieve a goal, or simply a product of nutrition and environment. Because monkeys also use other forms of communication, such as vocalizations and body language, it can be hard to determine what cue (visual, olfactory etc), or combination of cues, is causing a result.
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