Rebekah Keating Abstracts

Rebekah Keating

Ph.D. Candidate

Neuroscience GIDP

18th Congress of the International Union for the Study of Social Insects

Guaruja, Brazil

August 5-10, 2018

Attempts to link sociality and brain evolution in Hymenoptera have developed largely in response to existing theory from primate literature. Specifically, the social brain hypothesis proposes that individual cognitive demands expand with social networks size, lead to observed expansion of higher association cortices in social primates. Conversely, existing eusocial insect theory http://iussi2018.com/assumes (link is external)a reduction of or release from individual cognitive demands in eusocial lineages and predicts concurrent reductions in individual brain investment, particularly in higher association centers. The social brain hypothesis for eusocial insects suffers two primary flaws due to its origin within the framework of the theory developed for primates. First, not being derived within what is known about the evolution of insect sociality, it does not provide adequate alternate hypotheses for differences in brain region investment across lineages. Second, it neglects core questions about the nature of social neuroethology, namely “What cognitive processes are required to coordinate social behaviors?” “Does social structure provide a release from cognitive demands at the individual level?” and “In what ways do brains change in response to or as a result of these kinds of behavioral change?” Here we attempt to re-orient the conversation about sociality and brain evolution in Hymenoptera by taking a critical look at assumptions underlying current theory, discussing the cognitive and neural traits that may be unique to or uniquely modified in social Hymenopteran lineages, and outline existing alternate hypotheses for differences in brain structure across lineages varying in sociality.

Abstract for Lay Audience

The role of social behaviors and social life histories on brain evolution in birds and mammals, particularly primate lineages, has received much attention from a range of scientists from anthropologists to neuroscientists. One leading theory suggests that complex behaviors required to navigate social relationships led to the expansion of particular brain regions in certain lineages, namely frontal cortex in human ancestors. In contrast, theory addressing how living in social groups affects brain evolution in insects has taken a contrasting perspective. Social insects form obligate groups of closely related individuals, as opposed to primates that form groups with more distant relatives, and divide work across group members toward a single aim, rearing young. Given these differences, current theory in insect brain evolution predicts that social insects will have smaller brains than their solitary relatives and that their brains will continue to decrease with increasing social complexity or group size. This social brain hypothesis for insects suffers two primary flaws due to its origin within the framework of the theory developed for primates. First, not being derived within what is known about the evolution of insect sociality, it does not provide adequate alternate hypotheses for differences in brain region investment across insect groups. Second, it neglects core questions about the nature of neural circuits underlying sociality, namely “What cognitive processes are required to coordinate social behaviors?” “Does social structure provide a release from cognitive demands at the individual level?” and “In what ways do brains change in response to or as a result of these kinds of behavioral change?” Here we attempt to re-orient the conversation about sociality and brain evolution in social insects by taking a critical look at assumptions underlying current theory, discussing the cognitive and neural traits that may be unique to or uniquely modified in social Hymenopteran lineages, and outline existing alternate hypotheses for differences in brain structure across lineages varying in sociality.