Primate Patience: The Evolutionary Roots of Patient Humans and Chimps

First Posted: May 14, 2014 01:24 PM EDT

Humans can exhibit self-control, and now researchers have found that primates can two. The new findings shed a bit more light on the evolutionary roots of patience.

"Natural selection has shaped levels of patience to deal with the types of problems that animals face in the wild," said Jeffrey Stevens, one of the researchers, in a news release. "Those problems are species-specific, so levels of patience are also species-specific."

For example, a chimpanzee will wait more than two minutes to eat six grapes. In contrast, a black lemur would rather eat two grapes now than wait any longer than 15 seconds for a larger serving. The same can be seen in humans waiting in a long line to get into a particular restaurant.

In order to find out a bit more about patience, the researchers studied 13 primate species that ranged from massive gorillas to tiny marmosets. The scientists found that species with bigger body mass, bigger brains and longer lifespans tend to wait longer for a bigger reward. The longest waiter, though, was the chimpanzee.

"In humans, the ability to wait for delayed rewards correlates with higher performance in cognitive measures such as IQ, academic success, standardized test scores and working memory capacity," wrote Stevens in a news release. "The cognitive ability hypothesis predicts that species with higher levels of cognition should wait longer than those with lower levels."

That said, the researchers found no correlation between patience levels and relative brain size compared to its body size. Instead, it's possible that metabolic rates may be the driving factor that connects patience with body mass and related physical characteristics since smaller animals have higher metabolic rates.

"To me, this offers us interesting avenues to start thinking about what factors might influence human patience," said Stevens in a news release. "What does natural selection tell us about decision making? That applies to humans as well as to other animals."

The findings are published in the journal Proceedings of the Royal Society B: Biological Sciences.

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