Potential Explanations for the Size of Neocortices in Humans
By: Hailey Ripple
By attempting to answer the question regarding potential reasons for the structural differences between the human brain and the brains of other animals, scientists will be able to further test and replicate studies to confirm or dispute current hypotheses. Further, it will lead to a greater understanding of the underlying motives for social behaviors in humans and animals alike. Based on the current research, it appears there are camps that believe the answer is either social or ecological (Dunbar & Schultz, 2007). That is to say, some may consider the ability to mediate relationships within a group (social) is what drives our brains to develop larger neocortices, while others may say it is related to the ability to provide for oneself and those in the group (ecological). However, Dunbar and Schultz (2007) argue when you break both of these examples down, they are ecological in nature and ultimately relate to better chances at finding a mate and reproduction.
While the APH and the SBH seem to agree the ecological factors and energy needed to engage in social behaviors has attributed to the development of large neocortices, the APH delves a little deeper into specific behaviors and cognitions underlying social behavior – specifically in terms of romantic relationships and sexual selection. Specifically, the hypothesis states there are three primary reasons for human communication: displaying mind-reading abilities, aligning and maintaining parity between persons to facilitate displays, and the exchange of propositional information (McKeown, 2013). According to the hypothesis, there are specific displays that are especially potent, such as creative displays. Further, quick, new, and relevant displays are included in other factors that are interpreted as high quality. Those individuals able to engage in high quality displays are likely more fit to be a quality mate. The APH asserts the energy needed to engage in high quality displays is considered in terms of what the ultimate pay-off will be, almost like a business transaction.
Both of the previously discussed hypotheses credit social interaction and relationships as the reason for large neocortices in human beings on some level. A study conducted by Kanai, Bahrami, Roylance, and Rees (2015) examined the relationship between the presence of gray matter in the brain and factors associated with an individual’s social networks (i.e. number of Facebook friends). Findings from this study indicated researchers were able to predict the density of grey matter based on the number of friends they claimed online. Another study by Sallet and colleagues (2011) how the size of a monkey’s social network affected their neural circuits and found that social network size had implications for brain structure and function. The results of this study indicate social relationships and networks can indeed alter or influence the composition of both human and animal brains.
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