Navigation Links
Primates and patience -- the evolutionary roots of self control

Lincoln, Neb., May 14, 2014 A chimpanzee will wait more than two minutes to eat six grapes, but a black lemur would rather eat two grapes now than wait any longer than 15 seconds for a bigger serving.

It's an echo of the dilemma human beings face with a long line at a posh restaurant. How long are they willing to wait for the five-star meal? Or do they head to a greasy spoon to eat sooner?

A paper published today in the scientific journal Proceedings of the Royal Society B explores the evolutionary reasons why some primate species wait for a bigger reward, while others are more likely to grab what they can get immediately.

"Natural selection has shaped levels of patience to deal with the types of problems that animals face in the wild," said author Jeffrey R. Stevens, a comparative psychologist at the University of Nebraska-Lincoln and the study's lead author. "Those problems are species-specific, so levels of patience are also species-specific."

Studying 13 primate species, from massive gorillas to tiny marmosets, Stevens compared species' characteristics with their capacity for "intertemporal choice." That's a scientific term for what some might call patience, self-control or delayed gratification.

He found the species with bigger body mass, bigger brains, longer lifespans and larger home ranges also tend to wait longer for a bigger reward.

Chimpanzees, which typically weigh about 85 pounds, live nearly 60 years and range about 35 square miles, waited for a reward for about two minutes, the longest of any of the primate species studied. Cotton-top tamarins, which weigh less than a pound and live about 23 years, waited about eight seconds before opting for a smaller, immediate reward.

The findings are based partially on experiments Stevens performed during the past ten years with lemurs, marmosets, tamarins, chimpanzees and bonobos at Harvard's Department of Psychology and at the Berlin and Leipzig zoos in Germany. In those experiments, individual animals chose between a tray containing two grapes that they could eat immediately and a tray containing six grapes they could eat after waiting. The wait times were gradually increased until the animal reached an "indifference point" when it opted for the smaller, immediate reward instead of waiting.

Stevens combined those results with those of scientists who performed similar experiments with other primates. He scoured primate-research literature to gather data on the biological characteristics of each species.

In addition to characteristics related to body mass, Stevens analyzed but found no correlation with two other hypotheses for patience: cognitive ability and social complexity.

"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," he wrote. "The cognitive ability hypothesis predicts that species with higher levels of cognition should wait longer than those with lower levels."

But Stevens found no correlation between patience levels and an animal's relative brain size compared to its body size, the measure he used to quantify cognitive ability.

Researchers also have argued that animals in complex social groups have reduced impulsivity and more patience to adapt to the social hierarchies of dominance and submission. But Stevens did not find correlations between species' social group sizes and their patience levels.

Stevens said he believes metabolic rates may be the driving factor connecting patience with body mass and related physical characteristics. Smaller animals tend to have higher metabolic rates.

"You need fuel and you need it at a certain rate," he said. "The faster you need it, the shorter time you will wait."

Metabolic rates also may factor in human beings' willingness to wait. Stevens said human decisions about food, their environment, their health care and even their finances all relate to future payoffs. The mental processes behind those decisions have not yet been well identified.

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


Contact: Jeffrey R. Stevens
University of Nebraska-Lincoln

Related biology news :

1. Good news for nanomedicine: Quantum dots appear safe in pioneering study on primates
2. Manipulation of a specific neural circuit buried in complicated brain networks in primates
3. Out of the mouths of primates, facial mechanics of human speech may have evolved
4. Transgenic technique to eliminate a specific neural circuit of the brain in primates
5. The old primates club: Even male monkeys ride their fathers coattails to success
6. Primates brains make visual maps using triangular grids
7. UTSA anthropologist honored for contributions researching primates in Africa
8. Primates too can move in unison
9. Snakes on the brain: Are primates hard-wired to see snakes?
10. CU-Boulder-led team finds first evidence of primates regularly sleeping in caves
11. Leading evolutionary scientist to discuss how genome of bacteria has evolved
Post Your Comments:
Related Image:
Primates and patience -- the evolutionary roots of self control
(Date:10/29/2015)... 2015 Today, LifeBEAM , a ... 2XU, a global leader in technical performance sports ... with advanced bio-sensing technology. The hat will allow ... key biometrics to improve overall training performance. As ... will bring together the most advanced technology, extensive ...
(Date:10/27/2015)... October 27, 2015 Munich, ... Gaze Mapping technology (ASGM) automatically maps data from mobile ... Glasses , so that they can be quantitatively ... Munich, Germany , October 28-29, 2015. ... data from mobile eye tracking videos created with ...
(Date:10/26/2015)... 26, 2015 ... adds Biometrics Market Shares, Strategies ... well as Emerging Biometrics Technologies: Global ... its collection of IT and Telecommunications ... --> . ...
Breaking Biology News(10 mins):
(Date:12/1/2015)... ROSEVILLE, Minn. , Dec. 1, 2015  The ... the recipient of the 2015 Tekne Award in the ... th at the Minneapolis ... who have played a significant role in developing new ... people living around the world. Clostridium difficile ...
(Date:12/1/2015)... ... December 01, 2015 , ... ... specializing in scientifically backed, age-defying products, is featured as the cover story ... exponential success and unrivaled opportunities that Nerium provides. Success from Home magazine ...
(Date:12/1/2015)... ... December 01, 2015 , ... Matthew “Tex” VerMilyea, PhD, HCLD, has joined Texas ... oversee all IVF lab procedures as well as continue his research efforts into the ... miles to Auckland, New Zealand to bring home a High Complexity Clinical Laboratory Director ...
(Date:11/30/2015)... ... ... announced the opening of a new core patient care hub with the opening of ... are part of GSCG’s expansion efforts in Latin America. , Both the Arica and ... from around the world. , The clinics will be headed by Victor Perez, M.D. and ...
Breaking Biology Technology: