In the Light of Evolution Volume VII: The Human Mental Machinery (2014) / Chapter Skim
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7 Neuroethology of Primate Social Behavior--Steve W. C. Chang, Lauren J. N. Brent, Geoffrey K. Adams, Jeffrey T. Klein, John M. Pearson, Karli K. Watson, and Michael L. Platt
7 Neuroethology of Primate Social Behavior--Steve W. C. Chang, Lauren J. N. Brent, Geoffrey K. Adams, Jeffrey T. Klein, John M. Pearson, Karli K. Watson, and Michael L. Platt
Pages 115-134
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From page 115... ...
Evidence reviewed here indicates that ancestral mechanisms are often duplicated, repurposed, and differentially regulated to support social behavior. Focusing on recent research from nonhuman primates, we describe how the primate brain might implement social functions by co-opting and extending preexisting mechanisms that previously supported nonsocial functions.
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From page 116... ...
. Like humans, many nonhuman primates also live in large groups characterized by patterns of social behaviors like grooming, imitative and cooperative foraging, differentiated affiliative relationships, ritualized courtship and mating behavior, and competitive interactions structured by social dominance (Wilson, 1975; Smuts et al., 1987)
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From page 117... ...
and ungulates (Kendrick, 1994) , are more frequently found near the input stages of social processing (i.e., receiving social information)
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From page 118... ...
TABLE 7.1 Summary List of Selected Examples from the Current Paper on How Nonsocial Functions Are Repurposed to Serve Social Functions Throughout Evolution Type/ Nonsocial Biological Units Region Functions Social Functions Behaviors Foraging Reward seeking, Social information information seeking (Keating and seeking (Charnov, Keating, 1982; Johnson 1976; Stephens and et al., 1991; Emery, 2000; Krebs, 1986; Miller Deaner et al., 2005; and Remington, Hayden et al., 2007; 2004; Pirolli, 2007; Adams et al., 2012) Lawrance et al., 2013)
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From page 119... ...
al., 2005; Zak et al., 2007; Heinrichs et al., 2009; Averbeck, 2010; Kemp and Guastella, 2010; Bartz et al., 2011; Chang et al., 2012; Crockford et al., 2013) HPA axis Physical stress Psychosocial stress (social status)
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From page 120... ...
, the basic problems studied by foraging theory may apply to the acquisition of social information. A wealth of behavioral data indicates that both humans and nonhuman primates actively seek social information.
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From page 121... ...
We propose that, because a major function of the brain is to seek resources, it is likely that mechanisms that evolved to support foraging are readily repurposed to solve other, formally similar computational problems. With respect to social behavior, if information about others is a valuable resource, then the biological mechanisms underlying foraging decisions will be used to support social information seeking (Adams et al., 2012)
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From page 122... ...
NEURAL CIRCUITS GUIDING SOCIAL DECISIONS The neural mechanisms supporting social behaviors are broadly distributed throughout the primate forebrain, overlapping with areas involved in more general-purpose functions (Fig.
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From page 123... ...
. In the integrative stages of social information processing, studies in humans have shown that phenomena such as opprobrium and moral disgust rely in large part on circuits involved in nociception and interoception, particularly those linking the amygdala, periaqueductal gray, insular cortex, and anterior cingulate cortex (ACC)
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From page 124... ...
, consistent with a more generalized role in visuomotor behavior. As mentioned previously, both human and nonhuman primates are highly motivated by social information.
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From page 125... ...
. Thus, the observation that more neurons responded to social information than to fluid reward supports the idea that ancestral neural adaptations are repurposed to serve social functions.
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From page 126... ...
NEUROMODULATORY INFLUENCES ON SOCIAL BEHAVIOR Differences between species or between individuals within a species may reflect neuromodulatory influences on the development and function of neural circuits mediating social and nonsocial behaviors. Hormones strongly influence brain development (Keverne, 2004; McEwen, 2007)
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From page 127... ...
, suggesting that the OT system has been further specialized to process partner-specific affiliative interactions. Together, these observations endorse the idea that neuropeptides like OT, which serves basic sexual and parenting functions, can be co-opted to regulate more complex social behaviors in species that live in large, complex groups, like humans and rhesus macaques.
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From page 128... ...
FIGURE 7.3 Social functions of neuropeptide OT.
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From page 129... ...
One hint that social behavior influences change in gene pools over time is a handful of studies linking sociality with fitness. In species such as baboons and rhesus macaques, engaging in social interactions is correlated with reproductive output; the offspring of individuals that spend a greater amount of time grooming and associating with others are more likely to survive to 1 year of age (Silk et al., 2003; Brent et al., 2013)
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From page 130... ...
Not only are social components of personality heritable, but so too is the extent to which individuals are integrated into their social networks in both humans (Fowler et al., 2009) and rhesus macaques (Brent et al., 2013)
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From page 131... ...
(B) Serotonergic gene profiles predict social network position in free-ranging rhesus macaques.
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From page 132... ...
Genetic information exposes the dynamic contingencies upon which sociality is based, where the interactions between genes that lay the foundations of neural architecture and the social, physical, and biochemical environments in which those genes exist are brought to light, and wherein lie some of the greatest challenges facing future researchers hoping to understand this complex and enigmatic trait. CONCLUDING REMARKS Social information is clearly valuable -- it is worth foraging, often receives privileged attention over other types of information, and is inherently rewarding.
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From page 133... ...
Manipulations of social network size in rhesus macaques alter cortical thickness and functional coupling across brain areas that support social functions (Sallet et al., 2011)
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