Chimpanzees will often lend a helping hand even if there's no reward, suggests research published this week, challenging theories that altruism is unique to humans.

While helping behaviour isn't uncommon among non-human primates, it's usually attributed to family relationships or selfish benefits, researchers at Germany's Max Planck Institute for Evolutionary Anthropology noted. 

Experiments with chimpanzees found that they can behave unselfishly.
(Max Planck Institute)

But in this study, "they clearly seemed to be motivated by the other person's unachieved goal and not an immediate benefit for themselves," author Felix Warneken told CBC News.

"We were quite impressed by the fact that the chimpanzees were able to help in a novel situation, i.e., showing insightful helping. This tells us that they are cognitively flexible in helping — are able to develop new kinds of helping — and thus increase their behavioural repertoire in the area of altruism."

The study, Spontaneous Altruism by Chimpanzees and Young Children, is available online from Plos Biology, an open access journal of the Public Library of Science.

The conclusions were drawn after the chimpanzees were exposed to three testing situations. Parallel studies of 18-month-old children were also conducted.

"We found that both chimpanzees and human infants helped altruistically, regardless of any expectation of reward, even when some effort was required and even with the recipient was an unfamiliar individual — all features previously thought to be unique to humans," the study said.

"The roots of human altruism may go deeper than previously thought, reaching as far back as the last common ancestor of humans and chimpanzees."

Putting it to the test

One of the scenarios used to test the chimpanzees involved two researchers loudly struggling over a wooden stick. One threw the stick behind bars where it could be reached by the chimp, but not the other researcher. The researcher then spent up to 60 seconds, either:

• Reaching for the stick, with or without a piece of banana available as a reward.
• Training his eyes on the stick, without reaching, with or without the reward.

Another took the chimps that had shown they were helpful in the first experiment and made it more difficult for them to help out. This time, the chimps had to climb on a raised platform to get to the stick.

The third test involved seeing if the chimpanzees would open a door to assist another chimpanzee.

These studies add to research released in 2006.

Given the most recent findings, "the question shifts from, 'Are chimpanzees altruistic or not?' to questions about the circumstances under which they help," said Warneken.

"It is possible that chimpanzees are in principle willing to help, but their altruistic tendencies collapse more easily when there are interfering constraints such as food or competition with group members."