1. Evolution of the Social Brain BY CASEY WATERS

2. What makes us different from chimpanzees?  Social intelligence  Sense of self  Theory of Mind  Our brains have evolved under social pressures to make us self-aware individuals who define ourselves by what we share with our group  Our brains are 3x larger than chimp brains  Increased neocortex size

3. Sense of Self  Structures in the human brain that suggest more complex systems of experiencing emotion  Our amygdalae are significantly larger  Insula- responsible for integrating emotion and bodily sensation  Thalamus > posterior insula > anterior insula  Global emotional awareness of bodily homeostasis  Salient self implies self-awareness

4. Sense of Self  In humans, insula uniquely responds to music and language  Learned social dimension of salient self  Insula activation in social exclusion and inequality  Our brains expect social equality in group membership How does this play into our hunter-gatherer history?

5. Who is Robin* Dunbar?  British anthropologist and evolutionary psychologist  Proposed the Social Brain Hypothesis  Also famous for formulating Dunbar’s number

6. Social Brain Hypothesis  Primates evolved larger brains to survive and reproduce in intricate social systems  Increased neocortex size  Initially coined the “Machiavellian intelligence hypothesis”  Response to Jerison (1973) assumption that human intelligence evolved to deal with ecological problem solving

7. Social Brain Hypothesis  Because our brains are “expensive”, difficult to justify need for larger brains to do the same ecological jobs as other species  Steep cost gradient  Human brain consumes 20% of total energy, while our brains weigh about 2 lbs.  Considering the average human weighs 150 lbs., the brain is only 1.3% of total body weight.

8. Social Brain Hypothesis  Language may have arisen as a “cheap” means of social grooming  Social grooming consists of bonding practices, reinforcing social structure, and sometimes reconciliation  Without language, humans would have to spend nearly half of their time on social grooming

9. Dunbar’s Number  Suggested cognitive limit to number of individuals one person can maintain social relationships with  150 is the magic number  Can fluctuate between 100-250 people  Numbers larger than this require more restrictive rules and norms to maintain stability  Facebook?

10. Chimpanzee Theory of Mind  Theory of Mind- ability to reason about mental states  Chimps incapable of symbolic behavior, language, and culture  Can pass on learned behaviors, can’t pass on world views  No understanding of false beliefs

11. Some rudimentary traits of social intelligence exist in chimps:  Deception  Understanding perception and intention  Social learning  Trading and roles  Cooperation  Altruism

12. Intentionality  Dates back to medieval philosophy and adopted by Edmund Husserl  Intentionality - quality of mental states (e.g., thoughts, beliefs, desires, hopes) being directed toward some object or state of affairs  Dunbar states chimps may aspire to around 1.5 order of intentionality  Humans in most situations operate around 3 rd order of intentionality  6 th order exceptionally difficult  No concrete limit to intentionality, simply limited to our cognitive capacity as humans

13. Intentionality  No intentionality: Having knowledge, but no awareness of knowledge.  First Order: Holding a belief system aside from mere knowledge.  Second Order: Awareness of your belief system; this is Theory of Mind. Children of 4 years of age and some apes operate at this order.  Third Order: Holds communicative intent. Communicating internal intentions or beliefs to others so there is common ground for communication.  Fourth Order: Awareness of a communicative act distinct from the communicative act itself. Story telling or story understanding capability.  Fifth Order: Awareness of roles and narratives distinct from the role or narrative. Can be cultures or worldviews. Dunbar considers religion and storytelling at this level.

14. Intentionality  Less than 20% of humans are able to operate on 6 th level of intentionality.  Shakespearian literature  For Shakespeare to write stories on the 5 th level, he had to be operating at the 6 th level of intentionality.

15. What makes us human? Conclusion and thoughts  We are more socially intelligent in comparison to chimps, but  Rudimentary capabilities of social intelligence and a limited Theory of Mind in chimps.