New study reveals why monkeys play so much

By Gwyn Wright via SWNS

Some monkeys play to reduce tension and avoid conflict and levels actually increase when resources are scarce, a new study reveals.

Researchers believe howler monkeys play more when they have to come together to forage for scarce food.

The research team found play among Mexican howler and golden-mantled howler monkeys increases in line with the amount of time they spend foraging for fruit.

They looked at seven groups of the howlers in the rainforests of Mexico and Costa Rica to form their findings.

They also found the amount of adult play is linked to the number of potential playmates and increases in line with the size of each group.

Howler monkeys tend to eat leaves and fruit is a highly-prized treat that generates competition among the creatures.

Howler monkeys have no fixed social hierarchy within which they can navigate competition and conflict, and they do not groom each other, which is used by some primates to diffuse tension and build group cohesiveness.

Instead, the researchers believe play plays a key role in helping the creatures regulate relationships within their social group and avoid conflict.

Adults spend more time playing with other adults, rather than juveniles, and adult females spend more time playing than adult males.

The researchers from the United Kingdom, Spain and Brazil examined how play varies with age and looked at the amount of time adults spend playing with older adults and young monkeys in their group.

Howler monkey play involves the animals hanging from their tails and making facial expressions and signals, such as shaking their heads.

Play is very energy-intensive for howler monkeys, whose leaf-based diet means they can afford a lazy lifestyle.

The study’s co-author Dr. Jacob Dunn said: “Despite its appearance and our own perception of what play means, play is not always associated with frivolity or education.

“Instead, we think it fulfills an important function in howler monkey society by reducing tension when there is competition over scarce resources.

“We found that levels of play are at their highest when howler monkeys are feeding on fruit – which is a valuable and dependable resource – and female adults play more than males.

“This is striking, as females would be more vulnerable to food competition than males.

“Howler monkeys are a particularly energy-conservative species, and we would have assumed females would have played less, as they are also constrained by the energy requirements of reproduction.”

Lead study author Dr. Norberto Asensio said: “One theory for the positive effect of fruit consumption on play is that a fruit-based diet simply provides the howler monkeys with more energy compared to their typical diet of leaves.

“However, if this was the case, we should have observed adults engaging in more play with all members of the group during fruit foraging, rather than just with other adults.

“Because juveniles do not pose a threat or provide competition at fruit trees, we believe that play amongst adults is a mechanism for solving conflicts within the group, in a similar way that grooming is used by some other primate species.”

The findings were published in the journal Animal Behaviour.