Study suggests humans, apes and monkeys all expect something in return for generosity

August 14, 2013 by Bob Yirka, report

Image: Wikipedia.
( —A pair of researchers at the University of California, Santa Barbara has concluded that when it comes to sharing, there is little difference between human and non-human primates—all expect something in return. In their paper published in Proceedings of the Royal Society B, anthropologists Adrian Jaeggi and Michael Gurven describe their analysis of 32 separate studies on sharing, and found that all primates appear to have an ulterior motive when they share food with others.

The studies analyzed by the duo included field studies of monkeys, apes, and that still relied on hunting or foraging for their survival. They were searching for an answer to the age-old question: do people (and/or other primates) always have an ulterior motive when sharing a resource with someone else? Put another way, is there really such a thing as pure altruism? Jaeggi and Gurven say no; their research indicates that when primates share, they always expect something back in return.

One area where the researchers found a difference between humans and other primates was in the type of expected. According to the reviewed studies, apes and monkeys generally expect to get food in return at a later time for food shared, while humans are more likely to accept in-kind donations. This, the researchers say, is apparently due to the nature of the way food is obtained. For humans, is generally balanced across a community which means there is equal risk among the population of coming up short at any given time. Sharing by others in the group helps fill the gaps. Thus, those that share can be confident that others will do the same for them should the need arise. But unlike other primates, humans are often willing to accept in-kind donations instead of food to make things even, which led to another observation. All of the groups studied appear to maintain forms of unofficial score-keeping. Monkeys, apes, and humans all keep a tally of who gave what to whom, and who still owes someone for what they received.

This new research may or may not apply to communities of primates, most particularly humans, where the food supply is essentially limitless. Thus for now, there is still no clear answer regarding true as it applies to resources.

Explore further: New Research Investigates How Diseases Spread in Primates

More information: Reciprocity explains food sharing in humans and other primates independent of kin selection and tolerated scrounging: a phylogenetic meta-analysis, Published 14 August 2013 DOI: 10.1098/rspb.2013.1615

Helping, i.e. behaviour increasing the fitness of others, can evolve when directed towards kin or reciprocating partners. These predictions have been tested in the context of food sharing both in human foragers and non-human primates. Here, we performed quantitative meta-analyses on 32 independent study populations to (i) test for overall effects of reciprocity on food sharing while controlling for alternative explanations, methodological biases, publication bias and phylogeny and (ii) compare the relative effects of reciprocity, kinship and tolerated scrounging, i.e. sharing owing to costs imposed by others. We found a significant overall weighted effect size for reciprocity of r = 0.20–0.48 for the most and least conservative measure, respectively. Effect sizes did not differ between humans and other primates, although there were species differences in in-kind reciprocity and trade. The relative effect of reciprocity in sharing was similar to those of kinship and tolerated scrounging. These results indicate a significant independent contribution of reciprocity to human and primate helping behaviour. Furthermore, similar effect sizes in humans and primates speak against cognitive constraints on reciprocity. This study is the first to use meta-analyses to quantify these effects on human helping and to directly compare humans and other primates.

Related Stories

New Research Investigates How Diseases Spread in Primates

August 27, 2012

A new international study has investigated how diseases are shared among species of primates with a view to predicting what diseases may emerge in humans in the future. The findings aim to help in the fight against these ...

Less is more when choosing between groups of assorted items

October 3, 2012

When making decisions about the value of an assortment of different objects, people approximate an average overall value, which though frequently useful can lead to apparently irrational decision-making. A new study published ...

Recommended for you

What happened before the Big Bang?

March 26, 2019

A team of scientists has proposed a powerful new test for inflation, the theory that the universe dramatically expanded in size in a fleeting fraction of a second right after the Big Bang. Their goal is to give insight into ...

Cellular microRNA detection with miRacles

March 26, 2019

MicroRNAs (miRNAs) are short noncoding regulatory RNAs that can repress gene expression post-transcriptionally and are therefore increasingly used as biomarkers of disease. Detecting miRNAs can be arduous and expensive as ...

Race at the edge of the sun: Ions are faster than atoms

March 26, 2019

Scientists at the University of Göttingen, the Institut d'Astrophysique in Paris and the Istituto Ricerche Solari Locarno have observed that ions move faster than atoms in the gas streams of a solar prominence. The results ...

Physicists discover new class of pentaquarks

March 26, 2019

Tomasz Skwarnicki, professor of physics in the College of Arts and Sciences at Syracuse University, has uncovered new information about a class of particles called pentaquarks. His findings could lead to a new understanding ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Oct 11, 2013
If I share this on Facebook, I better get a lot of likes.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.