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World Monkey Day

Monkeys are cognitively complex individuals, and they are in need of our help

A guest post by Dave Neale, Animal Welfare Director, Animals Asia

Monkey, in general, refers to any of over 260 species of tailed primates, including macaques, baboons, guenons, capuchins, marmosets and tamarins. The presence of a tail (even if only very small in some species), distinguishing monkeys from apes.

Monkeys are grouped into New World or Old World monkeys. Old World monkeys live in Europe, Africa, and Asia, and New World monkeys are indigenous to the Americas.

New World monkeys are nearly exclusively arboreal, living up in the trees. Some have prehensile tails which can grasp or hold on to objects or branches. Old World monkeys also have tails, but they cannot grasp objects and they spend more time on the ground.

Monkeys are capable of sitting upright, and, consequently, their hands are free to perform manipulative tasks, and in recent years we have begun to learn more about the fascinating cognitive abilities of many of these incredible species.

The great apes are famously known to be adept at using tools, from sticks for catching termites, to leaves as umbrellas, but it is not just apes that can use tools however. Many monkey species have evolved unique and ingenious ways of using tools to access new foods, helping them to thrive in their environment and passing on their skills to their family members.

Capuchin monkeys use stones as a tool for cracking nuts. They strategically place their nuts on a flat surface before trying to crack them open, paying attention to the fit between the nut and the surface and adjusting their actions accordingly. Stone tools even fill a part of their mating rituals, with observations of female capuchins throwing stones at potential mates to get their attention as part of their sexual displays.

Researchers exploring the use of stones by these clever monkeys believe that they may have been using them in this way for some 3000 years. Not only that, they have also been refining their skills and adapting to their environments, changing the sorts of stone tools they are using depending on what they are eating. For example, soft, low resistance foods like seeds require different tools to harder, high resistant foods like cashews. Evidence of this has been found in fossils, showing how intelligent and adaptive these animals are.

Macaques have also been observed using tools to get to food. Burmese long-tailed macaques on the Islands of Piak Nam Yai and Thao in Laem Son National Park, Thailand, use stone and shell tools to crack open seafood. While the tide is out, the macaques use their tools to break open oysters attached to large boulders. They dislodge the top half of the shell using their crushing tool and then scoop out the meat with their fingers from the remaining part still attached to the rock. Once a macaque has a good stone fit for the job, they keep it to crack open other shells or nuts before discarding their tools around the same boulders where they have enjoyed their meal.

These macaques have developed specific tool-using skills to access specific foods and a variety of different techniques to make their tool use as profitable as possible. Subsequently they pass on these techniques to other members of their family through a process of social learning.

On the Japanese island of Koshima, a group of Japanese macaques have also been observed doing something that has never been seen before. These macaques have been studied since the 1950s and have been fed by researchers during the study periods. One day, a young female macaque named Imo was observed dipping sweet potatoes into a nearby river before eating it and observers concluded that her reason was simple and entirely reasonable: she saw sand on the potatoes and wanted to wash it off. Young macaques watch their elder family members and have subsequently learned this behaviour too. Evidently, this monkey family had discovered the joys of eating clean potatoes.

Over the next few years, research staff observed this new behaviour spread through the entire macaque colony, and within a decade, every capable macaque on the island was washing potatoes. But it was not only the technique of potato washing that the monkeys learned. At some point Imo discovered a second trick to make her potato consumption more pleasurable, by dipping her potatoes in the ocean instead of the river, the saltwater would season the potato and make it taste better. After each bite, she would dip the freshly exposed section of her potato back into the sea to enhance its flavour.

This same group of macaques also learnt to wash the sand off grains of wheat by throwing them into the ocean to clean them, with these new habits also spreading quickly through the macaque community.

Click here and here for video footage of macaques using tools and here to see macaques washing food in the ocean.

From these examples we can see that monkeys really are cognitively very complex animals, making use of objects and features within their environment to help them to attain and process food and passing on these behaviours through cultural transmission.

Unfortunately many species are today threatened with extinction due to habitat loss and degradation. As the habitat of monkeys is encroached upon by humans, monkeys have less access to food, and increasingly come into conflict with humans as their homes are converted to farmland. This often results in individuals being hunted and killed or individuals being captured and sold into the primate pet trade. Many of the animals taken from the wild sadly die in the process, or if they survive, are confined to a life of misery and suffering in captivity.

On World Monkey Day lets us celebrate the diversity of monkey life across the globe, acknowledge the depth of their social, emotional and cognitive abilities and do all we can to help to conserve the habitats in which they depend upon for their survival and to keep monkeys in the wild where they truly belong.

For more information about why monkeys are not suited as pets, and how you help those campaigning for the end in their trade see:

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