by: jon tritley
A School Psychologist Journeying into the Social World
Over the millennia, the human brain has grown larger. In fact, it is larger and is able to perform and function at a level that far exceeds what is necessary to keep us alive and kicking. Thus, the question must be asked: why is this? Why are our brains so large? Why did they evolve to a level greater than what is necessary for human survival? This article will be focused on Dunbar and Shultz (2007) theory on the social brain and why they think the brain has become what it is today. A critique, a competing theory, and an empirical study by will also be discussed.
Background
Past studies on the human brain focused on physiological and mental phenomena on explanation of brain size (Dunbar & Shultz, 2007). These studies looked at metabolic rates and complex problem solving as an explanation for the sizes of our brains. In the 80s, a new theory was proposed where our brain size came to be through socializing with each other. This idea was labeled the social brain hypothesis. Dunbar and Shultz (2007) explained empirical strengths of the hypothesis, such as the strong correlation between how complex our social lives were and the size our brains. Socializing is a cognitively demanding task that requires much brain power to carry out. As society became more socially complex, the sizes of our brains also grew.
Schaik, Isler, and Burkart (2012) believed that the social brain hypothesis failed to explain why some animals possessed socio-cognitive abilities while maintaining smaller brains, as well as how specific abilities produce a more general level of intelligence. These researchers included the social brain hypothesis into a larger framework in order to explain these shortcomings. They argue that brain size growth is not limited to social aspects – cognitive abilities used in complex problem solving may also account for the growth. Also, brain sizes by differ due to physical constraints, particularly animals that have smaller brain sizes but still possess higher socio-cognitive capabilities. The second point Schaik, Isler, and Burkart (2012) made was that the social brain hypothesis does not account as to why we have on overall general level of intelligence as opposed to only improving in very specific areas that are required for survival. Thus, the researchers put forth the cultural intelligence hypothesis that posits that general levels of intelligence are a form of social learning that are acquired through not only social means, but through cognitive means as well.
In support of the social brain hypothesis comes a study from Kanai, Bahrami, Roylance, and Rees (2011) that found a relationship between the size of an individual’s social network and the size of their brain. Particularly, the greater number of friends that they declared, the greater the density of particular areas in the brain. These particular areas had greater levels of grey matter, which serves to process information and transport nutrients and energy. If the social brain hypothesis is true, then you would assume that those who have greater volumes of brain matter would have a greater number of friends in their social network.
A critique of the social brain hypothesis was put forth by Vugt (2012). Vugt claimed that the social brain fails to address hierarchies that exist in society as well as social identity. Each individual in society has a different place in our hierarchical society, where you could be a leader or a follower. Social identity also provides different perspectives and challenges from one individual to the next. The author argued that these aspects of society have important implications in regard to the social brain but the hypothesis fails to account for it. Vugt believed that these distinctions are important. Important enough that they should be accounted for in an account on the social brain, and the current hypothesis fails to do so.
Answer
The social brain hypothesis intuitively makes sense and has evidence to support it . It is clear that the complexities of our social world have paralleled the sizes of our brains, regardless of what animal you are. Granted, as with anything in the social world, there will be variation and not everything will fit in a perfect little package that explains everything. However, the social brain seems to be the best explanation we have as why we are what we are today. As humans, our brains have grown as our social complexity increased, as is the case with other animals as well. Contemporary studies, such as Kanai et al.’s (2011) on social networks and density of the brain, tend to further support the hypothesis of the social brain. The social brain hypothesis does have its shortcomings in which case a few were presented by Vugt (2012). Regardless, it seems to be the hypothesis with the best explanation and the most evidence thus far. Overall, this hypothesis has the best explanation as to why our brains are the size that they are today.
Conclusion
The relationship between how socially complex animals are and the size of their brain has a clear relationship that has grown simultaneously throughout existence.
- Dunbar, R. I. M., & Shultz, S. (2007). Evolution in the social brain. Science, 317, 1344-1347.
- Kanai, R., Bahrami, B., Roylance, R., and Rees, G. (2011). Online social network size is reflected in human brain structure. Proc. R. Soc. B, 279, 1327-1334.
- Schaik, C. P., Isler, K, and Burkart, J. M. (2012). Explaining brain size variation: From social brain to cultural brain. Trends in Cognitive Sciences, 16, 277-284.
- Vugt, M. (2012). The missing link: Leadership, identity, and the social brain. British Journal of Psychology, 103, 177-179.