Max Planck Institute for Evolutionary Anthropology/Esther Herrmann
According to evolutionary theory, we're all supposed to be selfish bastards, at least when we're dealing with people who aren't our immediate relatives. We’re programmed to do everything we can to make sure our genes aren't naturally selected out of the pool, including stomping on others. But we're not always selfish SOBs: Humans often help those in need, even when they're total strangers.
Two new studies out of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, which were published in the March 2nd issue of Science, suggest humans aren't the only species with the ability to perceive when another is in need The altruistic instinct to help others and the good sense to enlist the help of a competent partner when a problem requires a second pair of hands are apparently social traits found in chimpanzees, too. Therefore, they may have evolved before humans and apes split from a common ancestor about six million years ago.
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In the first of the two papers, graduate student Felix Warneken and professor Michael Tomasello of the department of developmental and comparative psychology ran two sets of experiments: One with 18-month-old children who had experienced minimal socialization and another with human-raised chimpanzees. In close proximity to the subject, an experimenter would perform a task such as hanging clothes on a line or putting magazines into a cabinet. Eventually, the experimenter would encounter a problem like dropping a clothespin out of reach or holding too many magazines to open a door.
Human children almost always helped the experimenter by picking up the clothespin or opening the door. Warneken noted that the experimenter did not need to ask for help or promise the child a reward to get their aide. The chimps also helped in the conditions where an object fell out of reach, but not in the case of the experimenter being unable to open the cabinet door.
Warneken posited that object retrieval is a more intuitive action to a chimpanzee than opening blocked doors.
"This suggests that chimpanzees are able to perform rudimentary forms of helping," he said via e-mail. "Humans help at a very early age, suggesting that humans might be biologically prepared for altruistic acts such as helping, not requiring much learning. The fact that our chimpanzees also help in similar tasks suggests that the evolutionary ancestor to both humans and chimpanzees already possessed some of rudimentary skills required for helping."
In the second study, a team led by post-doc Alicia Melis demonstrated that chimps also know when to solicit help in problem solving. The researchers put a food tray out of the reach of a subject. In order to bring the tray close enough to snag the food, the chimp had to pull both ends of a rope at the same time. When the ropes were too far apart for one chimp to reach both, the subject recruited help by opening a cage containing another chimp.
In a second part of the experiment, the researchers presented the chimp with a choice of two potential partners: Bwambale, who had been effective in past trials—with a fairly successful rate of food retrieval—and Mawa, the dominant chimp, who had been ineffective, never waiting for his partner to get set and pulling the rope away from the tray.
"At first, the chimpanzees chose Mawa and Bwambale equally," Melis said via e-mail. "But, when the chimpanzees learned what a hopeless cooperator Mawa was, most chose Bwambale next time."
Melis said the complex cooperation of chimpanzees in her experiment supports the theory that cooperative abilities came from an ancestor common to both chimps and humans. The ability of chimps to recall and utilize the effectiveness of past collaborators suggests that chimps may keep track of what others have done for them in the past, according to Melis.