Brain & Behavior Psych 545

1. Brain & BehaviorPsych 545 • Dr David A Kaiser • Office: Bldg 6 – A116 x6773 dakaiser@mail.rit.edu • www.rit.edu/~dakgsh

3. Largest Brain on planet, 9.2 kg

4. Belongs to Sperm Whale

5. Absolute Brain Weight – Does it reflect intelligence?

6. Relative Brain Weight

7. Encephalization • Increase in brain size during evolution of SPECIES, with no concomitant increase in body size • “Of all animals, man has the largest brain in proportion to his size” - Aristotle

8. Encephalization

9. Encephalization Quotient (EQ) • Anatomical estimate of species’ intelligence (non-behavioral) • EQ = ratio of brain weight of animal to brain weight of “typical” animal of same body weight (Jerison, 1973) • EQ represents index of residual value of brain mass • Total Brain Mass = Brain for body size + Residual brain for higher functions

10. Encephalization Quotient (EQ) • Human neocortex is 3.2x larger in volume than nonhuman primate with our body size (Jerison, 1973). • Overview Quiz • TLE

11. Encephalization Quotient (EQ) 1 g brain for hummingbird • Human neocortex is 3.2x larger in volume than nonhuman primate with our body size (Jerison, 1973). • Overview Quiz • TLE

12. EQ through evolutionary time • Are we evolving into smarter and smarter creatures? Or was humanity a fluke? • In other words, was there a neural arms race in the past or an unusual mutation process in one line of primates? • Human neocortex is 3.2x larger in volume than nonhuman primate with our body size (Jerison, 1973). • Overview Quiz • TLE

13. Evolution of behavioral complexity Neural arms race in mammalian group only

14. In all mammalian orders including primates

15. Neurobehavioral “Arms race”

17. Monkeys, Great Apes, and Us

18. To Primate To Australopithecus To Hominid To Homo sapiens Four leaps in braininess

19. Brainy Newcomers

20. Convolution Index = wrinkliness • BUT: Cortex width: human 2.9 mm, dolphin 1.7 mm and conversative (not progressive) organization

21. Our “Family”

22. ...And Then There Was One • Sixteen Species of Extinct Humans • Ardipithecus ramidusAustralopithecus anamensisAustralopithecus afarensisAustralopithecus bahrelghazaliAustralopithecus aethiopicusParanthropus boiseiParanthropus robustusAustralopithecus africanusAustralopithecus garhiHomo rudolfensisHomo habilisHomo ergasterHomo erectusHomo antecessorHomo heidelbegensisHomo neanderthalensis • Homo sapiens

23. We shared planet with two other human species as recently as 25,000 years ago – Homo erectus and Neanderthals • Coincided with unstable weather (4 ice ages)

25. Can human brain get any bigger?

26. Encephalization abuse within species

27. General Features of Brain Evolution • Relative increase in brain size • Relative increase in telencephalon (cortex) over midbrain and hindbrain • Relative increase in representation of sensory information over motor responses • Relative increase in cortex involved in associative integration than (primary) reception • Greater differentiation of neocortex, with more cell diversity • Relative importance of biophysical senses over chemical senses in more sentient species Convergent evolution in all mammalian groups of these morphophysiological features

28. Neoteny – Childlike features into adulthood

29. Bonobo and Common Chimp

33. What did big brain gives us? Social or Cognitive Intelligence? • Example of cognitive: Tool Use in Animals , termite fishing by bonobo

34. Social Intelligence • The Machiavellian Hypothesis – Richard Alexander (1970s) suggested that main evolutionary pressure behind human intelligence was competition with other people, notably sexual competition between individuals of the same sex.

35. Dunbar (1992)- natural group size

36. Hominid social evolution