The Social Brain Hypothesis

The Social Brain Hypothesis suggest that the different social pressures that arose from interactions and relationship among other people/groups was the catalysis of the evolutionary growth of the human brain seen today (Aiello and Wheeler 1995; Henneberg 1998). According to Aiello and Wheeler (1995) the human brain is now 4.6 times the size expected for the average mammal and constitutes a significantly higher percentage of total bodyweight than the brains of other primates. The Social Brain Hypothesis incorporates ideologies from biology, psychology, and physiology (Gibson 1986; Faulk 1990) and it has been proposed via sociocultural dynamics, that to enable adaptive forms of social interaction, the human brain must be dynamic, efficient, attentive to and capable of the deployment of appropriate social behaviours in a variety of social contexts (Cisek, 1999; Mobbs et al., 2015; Badcock et al., 2019). Much like the nervous systems, the human brain has evolved primarily for survival, (Cisek, 1999; Mobbs et al., 2015). The relative size, ability and metabolic demand of the brain has been proposed by Kanwisher and Yovel (2006) a large portion of the human brain is dedicated to social cognition. It through the solution to social problems that occurred via the development of social cohesion that the neo-cortex, the part of the brain that governs reasoning and consciousness, stores memories, and organizes social relationships (Solomon et al 1990; Dunbar 1998a; Gamble 2007) developed in size quicker and larger than other brain areas (Solomon et al 1990; Dunbar 1998a). In addition, Gamble (2007) has also proposed that the development of the social brain and in turn the neo-cortex developed faster if the social cohesion occurred within larger groups of people. Gamble (2007) also mentioned that the larger the group, the more complex the social interactions are required to maintain group cohesion and in turn the larger the neo-cortex grew to facilitate the cognitive changes that are required to handle the increased and complexity of social interactions. This social exchange between individuals is a vital adaptation to the human brain, going as far to say that the human mind could be equipped with a neurocognitive system specialized for reasoning about social change (Cisek, 1999; Mobbs et al., 2015). Three of the key computations with which the social brain contends in social interaction are (i) social perception, and (ii) social learning (Molapour et al, 2021), which suggest that they suggest that the Social Brain and consequently social behaviour is a cognitively complex and metabolically demanding process, which involves highly interconnected neurological systems. Social perception is framed as the human sensory system, like all other sensory systems, views the external world through personal adaptations (Haselton et al., 2015). One key area in which social perception have evolved is detecting social danger. When detecting social danger humans are attuned and attentive to social expressions of threat, be this through the direct expression of anger or indirectly via the observation of fear in others (Calder et al., 2011). Though in the modern age the fear of being attacked via an animal is minimal, humans have an evolved predatory defence system that has developed to cope with perceived social threats withing a social environment. These threats can be perceived as a load noise, voice, an angry face, tone of voice, body language, hostile, aggressive and belittling words as well as being isolated, talked at and down too, and ignored (Ceravolo et al., 2016). It has been mentioned by Richerson and Henrich (2012) that social learning is a major benefit when living in groups as it accelerates learning as well as leading to adaptive solutions that can be used by others, in fact it has been suggested that humans that cannot imitate others are confined to the rules of individual learning (Whiten (2005) and are limited in what and how they learn. There is a suggestion that that social learning provides a ‘secondary inheritance system’, where our capacity to learn from others lowers the energetic neurological cost of acquiring information first-hand as well as to providing greater motivation drives (Richerson and Henrich, 2012). In achieving greater social learning, much like the Social Brain Hypothesis and the enhanced development of the neo-cortex, specialized brain systems seem to exist that support the computations involved in social learning (Lockwood et al, 2020). The anterior cingulate cortex (ACC) according to Apps and Ramnani (2014); Lockwood et al (2015); Apps et al (2016); Hill et al (2016) is an integrative area relating to social learning systems and is proposed to be involved during social decision-making, reflecting information processing about self, when one receives vicarious reinforcement, evaluating the behaviours of others, estimating other’s level of motivation (Apps and Ramnani, 2014; Lockwood et al., 2015; Apps et al., 2016; Hill et al., 2016). The Ventromedial Prefrontal Cortex is involved in vicarious reward learning (Mobbs et al., 2009), vicarious prediction errors (Burke et al., 2010) and vicarious fear learning (Olsson et al., 2007; Olsson and Phelps, 2007). This fear of threat engages the amygdala and heightens the emotional attachment to the threat (Adolphs et al., 1995), while the perception of another’s joy engages the social reward circuitry (Mobbs et al., 2009). The social reward circuitry triggers the same dopaminergic systems involved in primary rewards such as food and sex (Izuma et al., 2008). The drive to be liked (Davey et al., 2010) and to have a positive reputation (Izuma et al., 2008) increase activity in the dopamine-enriched ventral striatum which has been proposed to be an important role in value-based learning and decision-making in general (Bartra et al., 2013) The development of the social learning systems has roots in representational processes that recruit motor, affective, sensory, and cognitive systems associated through first person experience in correlation with observing others performing actions, perceiving sensations or under distress, is termed the mirror neuron system (Charpentier and O’Doherty, 2018; Konovalov et al., 2018). It is proposed that through the recognition of the various actions in relationship with an explicit representation of one’s goals and one’s own knowledge, is the foundation for vicarious learning (Charpentier and O’Doherty, 2018; Konovalov et al., 2018; Olsson et al., 2007; Olsson and Phelps, 2007)