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Chimpanzees Help, But Only When Asked

The views expressed are those of the author and are not necessarily those of Scientific American.


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Chimpanzees have a bad reputation. Maybe it’s because humans have a thing about wanting to feel unique among primates. Some have argued that humans are the only species that truly behaves altruistically, the only species that actively helps out other individuals even when there is no direct benefit. Despite mounting evidence that other animals, including non-human primates, have various forms of theory of mind, many still believe that human altruism exists because we – and we alone among all the animal kingdom – can understand the goals of others. Or, if there are other animals that can understand the goals of others, perhaps we somehow do it more readily.

In a new paper just published in PNAS, primatologist Shinya Yamamotoa and colleagues point out that while chimpanzees are known to help others, they don’t usually help when it would mean giving up things like food, even if they’ve got more food than they need. Even between a mother and her infant!

Why do chimpanzees seem so reluctant to help others? One possible explanation is that they’re unable to understand the goals of another individual, resulting in an inability to create any sort of shared intentionality between two individuals. To that end, the researchers write, “many still believe that humans are unique in this respect because we are the only animal species endowed with unique ‘theory of mind’ abilities enabling us to understand the goals and to share the intentions of others.”

Yamamotoa and the other researchers set up an experiment designed explicitly to address this possibility. The first chimpanzee was given a task to accomplish in order to receive a juice reward. The task required the use of one of two types of tools: a stick or a straw. The stick and the straw, however, as well as five other items were found not in the first chimpanzee’s booth, but in the second chimp’s booth. There was a small opening between the two booths where the second chimp could pass the necessary tool to the first. By itself, this could test whether or not the second chimp was willing to help the first chimp.

But to see whether the ability to understand the goal of another individual modulates the potential to help, the researchers created two further conditions: half the time, the barrier separating the two booths was a transparent window, and half the time it was a completely opaque wall. If chimpanzees modulate their responses to a help request based on whether or not they can see the goal of another individual, then they should give the appropriate tool more often when in the transparent window condition.

During the transparent window condition, the chimpanzees were more likely to offer up the appropriate tool (e.g. a stick during the stick condition, or a straw during the straw condition) than any of the other tools. This result itself shows that the chimpanzees were able to understand which tool their partner would need in order to solve a given task. Importantly, ninety percent of tool offers occurred only after a request was given by the first chimpanzee, suggesting that while chimpanzees may not spontaneously engage in helping behaviors, direct requests are effective in soliciting assistance.

The results from the opaque window condition might provide some insight into how the chimps determine which tools to provide when asked for help. As in the first condition, chimps were extremely likely to offer a tool after a request was made. In fact, one of the objects (even if not the useful one) was given following a request 98.5% percent of the time, on average. While they were more likely to offer one of the two useful tools – the stick or the brush – compared with the other items, the tool that the first chimpanzee needed was not predictive of the tool they were given. In other words, the chimps were not able to infer the precise goals of their partner. They were only able to understand that their partner needed a tool, in a generic sort of way. The one exception to this trend was a chimpanzee named Ayumu, who actually pulled himself up to see through the small window, effectively turning this “cannot see” condition into a “can see” condition.

The chimps’ willingness to help was similar in both conditions. That is, following a request for help, the chimpanzees were equally likely to offer a tool whether or not they could see their partner’s situation. While a request might be sufficient to motivate a chimpanzee to help, requests did not provide enough information for the chimps to help effectively. The researchers point out that Ayumu’s behavior – selecting the appropriate tool only after looking through the hole in the wall – further reinforces the notion that chimps require visual information in order to help. The researchers conclude, “even without shared intentionality and sophisticated communicative skills, such as language or pointing, chimpanzees can understand others’ goals when situations are visibly obvious and understandable.”

In a sense, though, the findings from this experiment are a bit contradictory: even when they could not visually assess their partner’s situation, the chimpanzees were willing to help, and even persisted in offering multiple tools. But when given visual access to their partner’s booth, they rarely helped unless directly requested. That is, the ability to infer a partner’s goals is not the limiting factor in chimpanzees’ altruistic behavior. So…what is?

ResearchBlogging.orgYamamoto S, Humle T, & Tanaka M (2012). Chimpanzees’ flexible targeted helping based on an understanding of conspecifics’ goals. Proceedings of the National Academy of Sciences of the United States of America PMID: 22315399

Chimpanzee photo source, used under Creative Commons license.

Jason G. Goldman About the Author: Dr. Jason G. Goldman received his Ph.D. in Developmental Psychology at the University of Southern California, where he studied the evolutionary and developmental origins of the mind in humans and non-human animals. Jason is also an editor at ScienceSeeker and Editor of Open Lab 2010. He lives in Los Angeles, CA. Follow on . Follow on Twitter @jgold85.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. David N'Gog 11:21 am 02/13/2012

    With Bonobo being the more “friendly” ape and less competative than chimps; I’d be interested to see if Bonobo were more altruistic.

    Recently there has been lots of talk about Bonobo potentially self-domesticating themselves. Does that possibly equate to them having greater empathy?

    Link to this
  2. 2. Jason G. Goldman in reply to Jason G. Goldman 12:43 pm 02/13/2012

    Yes, someone needs to do this study with bonobos. Some evidence that you may be right comes from a post I wrote in 2010: http://blogs.scientificamerican.com/thoughtful-animal/2010/06/09/bonobos_share_their_food/

    Link to this
  3. 3. r0b3m4n 7:11 pm 02/13/2012

    Perhaps the reward is too minimal for the chimps to feel it necessary to be proactive. I would be interested to see if chimp A would still help chimp B if the stakes were raised but self sacrificing. Perhaps: If chimp A gives chimp B the key to “escape” the cage. Chimp A would be more pro-active, rather than waiting for an escape request. A step further would be to punish chimp A for every chimp B he helps, for example chimp B escapes while Chimp A receives a diminishing size to it’s cage for every time it helps another “escape”. Perhaps I’m getting a bit too close to the plot of the movie “the killing room” :)

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  4. 4. Patrick Clarkin 3:47 pm 02/15/2012

    Hi Jason,

    Thanks for this great write-up of a neat study. Whether chimpanzees and other apes have a “theory of mind” is an interesting question, but I just wanted to focus on the wrinkle that chimps did not offer a tool unless they were solicited. While this is a study done in controlled lab conditions, you’re probably aware of anecdotes (such as from DeWaal) about chimpanzees helping each other without being solicited, and in a major way. One example is that chimps have on a few occasions tried to save others who were drowning in moats surrounding zoo exhibits. I wonder what goes on in their heads during these situations. Anyway, thanks again.

    http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.0050190

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  5. 5. lakotasue 11:15 am 03/12/2012

    I understand what the article is saying. However, it is my considered opinion that there is no such thing as true altruism, because there is always a payoff for the sacrifice.

    Link to this

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