Credit: Norberto Asensio
” We discovered that levels of play are at their highest when howler monkeys are feeding on fruit– which is a defendable and important resource– and female adults play more than males. This is striking, as females would be more vulnerable to food competitors than males. Howler monkeys are an especially energy-conservative species, and we would have presumed women would have played less, as they are also constrained by the energy requirements of reproduction.”
Howler monkeys p [laying. Credit: Norberto Asensio
Play amongst adult howler monkeys increases throughout competitive foraging.
New research study has found that adult howler monkeys use play to avoid conflict and reduce group tension, with levels of play increasing when they are confronted with limited resources.
The research study, brought out by a team of scientists from Spain, Brazil, and the UK, and released in the journal Animal Behaviour, focuses on the activity of 2 subspecies of howler monkey: the Mexican howler (Alouatta palliata mexicana) and the golden-mantled howler (Alouatta palliata palliata).
The researchers took a look at how play differs with age, and they measured the quantity of time grownups play with other adults and with juvenile monkeys within their groups.
Howler monkey play involves individuals hanging from their tails and making facial expressions and signals, such as shaking their heads. Play is an energy-costly activity for howler monkeys, who typically have an inactive lifestyle due to their mainly leaf-based diet plan.
By studying 7 various groups of howler monkeys in the rain forests of Mexico and Costa Rica, the researchers found that the quantity of adult play is linked to the number of possible playmates, increasing in line with the size of the group. Adults spend more time having fun with other adults, rather than juveniles, and adult females spend more time participated in play than adult males.
Most importantly, the researchers found that play among adults increases in line with time spent foraging on fruit. Howler monkeys normally eat leaves, and fruit is a highly valued resource that generates competition amongst the monkeys.
Howler monkeys do not have actually a fixed social hierarchy within their groups to browse competitors and conflict, and they do not participate in cumulative grooming, which is utilized by some primates for group cohesiveness and stress decrease. Rather, the study authors believe play has a crucial function in helping howler monkeys manage relationships within their social group and avoid dispute.
Co-author Dr. Jacob Dunn, Associate Professor in Evolutionary Biology at Anglia Ruskin University (ARU), said: “Despite its appearance and our own understanding of what play ways, play is not constantly connected with frivolity or education. Instead, we believe it fulfills a crucial function in howler monkey society by lowering tension when there is competition over scarce resources.
” We found that levels of play are at their greatest when howler monkeys are feeding upon fruit– which is a valuable and defendable resource– and female adults play more than males. This stands out, as women would be more susceptible to food competitors than males. Howler monkeys are a particularly energy-conservative types, and we would have presumed women would have played less, as they are also constrained by the energy requirements of reproduction.”
Lead author Dr. Norberto Asensio, of University of the Basque Country, said: “One theory for the positive result of fruit intake on play is that a fruit-based diet plan simply offers the howler monkeys with more energy compared to their typical diet of leaves.
” However, if this was the case, we should have observed adults taking part in more have fun with all members of the group during fruit foraging, instead of simply with other grownups. Since juveniles do not present a risk or supply competition at fruit trees, we believe that play amongst grownups is a system for resolving conflicts within the group, in a similar manner in which grooming is utilized by some other primate species.”
Reference: “Socioecological correlates of social play in adult mantled howler monkeys” by Norberto Asensio, Eugenia Zandonà, Jacob C. Dunn and Jurgi Cristóbal-Azkarate, 16 March 2022, Animal Behaviour.DOI: 10.1016/ j.anbehav.2022.01.017.