evolved patience. He primarily studied chimpanzees, bonobos, and humans to figure out just how the trait of patience evolved. He has figured out that patience isn't just a trait however, but that it has actually evolved through genes. Natural selection has shaped levels of patience in different species based on the different types of problems that different animals face. Therefore, patience is also a species specific quality that is passed on from generation to generation. Stevens has discovered that patience depends on body mass, brain size, lifespan, and home ranges and increases as we go higher up the primate classification order. For instance, a chimpanzee will wait approximately 2 minutes for a reward (the longest of any of the primate species studied) whereas a cotton-top tamarin will wait about 8 seconds until they opt for a smaller and more immediate reward. Stevens tested his subjects by having them choose between a tray with 2 grapes that they could choose sooner, or a tray of 8 grapes that they could have later. The times to wait to have the tray of 8 grapes was gradually increased until the subject reached an "indifference point" when it opted for the smaller, immediate reward instead of waiting. Other parameters have listed cognitive ability as well as social complexity as necessary components of patience, however Stevens negates these hypotheses. This is because he 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 as well as no correlations between species' social group sizes and their patience levels. The only factor that correlated with patience was metabolic rate, and body mass. This is due to the fact that if you have a faster metabolic rate than you need food faster and are less likely to be able to wait for it to survive. This is also the theory behind how humans evolved patience yet more research needs to be conducted.
References
Rosati, A, Stevens, J, Hare, B, & Hauser, M 2007, 'The evolutionary origins of human
patience: Temporal preferences in chimpanzees, bonobos, and human adults', Current Biology, vol. 17, pp. 1663-1668.
How interesting! I found it particularly fascinating that they never found a correlation with brain size (compared to body size). What benefits do you think resulted in the evolution of patience in humans? Do you think that patience is related to the level of tolerance an individual will show to others in social species? Nice.
ReplyDeleteI believe the benefits would perhaps also be related to hunting strategies, so following herds of game and then perhaps a larger food reward to feed more people. I think that may have been how patience developed in humans, as we needed richer sources of food to maintain our bodies, we needed to wait for larger sources of game. I also believe that patience is definitely correlated to the level of tolerance an individual will show to others in a social species because of how humans have become more social and connected even just over the last 3 decades with the internet and Facebook. However, I think patience began when humans were still evolving and this resulted in larger clans and groups of people which could take down larger sources of prey with cooperation.
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