1. Office: Bldg 6 – A116 x6773 dakaiser@mail.rit.edu
Brain & Behavior Psych 545
Dr David A Kaiser
Office: Bldg 6 – A116 x6773

3. Largest Brain on planet, 9.2 kg

4. Belongs to Sperm Whale

5. Absolute Brain Weight – Does it reflect intelligence?
Species
Adult Brain Weight (grams)
Chimpanzee
450
Human
1,350
Bottlenosed dolphin
1,600
African elephant
6,075
Fin whale
7,200
Sperm Whale
9,200

6. Relative Brain Weight Species Brain to Body Weight Human 2.1 %
Bottlenosed dolphin
1.2 %
Chimpanzee
.7 %
African elephant
.5 %
Killer whale
.1 %
Cow
.08 %
Sperm Whale
.02 %

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)
????????
9.0
Human
7.4
Dolphin
5.6
Killer whale
2.9
Chimpanzee
2.5
Rhesus Monkey
2.1
Elephant
1.9
Whale
1.8
Dog
1.2
Cat
1.0
Horse
0.9
Sheep
0.8
Mouse
0.5
Rabbit
0.4
Human neocortex is 3.2x larger in volume than nonhuman primate with our body size (Jerison, 1973).
    
Overview Quiz
TLE

11. Encephalization Quotient (EQ)
Hummingbird
9.0
Human
7.4
Dolphin
5.6
Killer whale
2.9
Chimpanzee
2.5
Rhesus Monkey
2.1
Elephant
1.9
Whale
1.8
Dog
1.2
Cat
1.0
Horse
0.9
Sheep
0.8
Mouse
0.5
Rabbit
0.4
         
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. Four leaps in braininess
To Primate
To Australopithecus
To Hominid
To Homo sapiens

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 ramidus Australopithecus anamensis Australopithecus afarensis Australopithecus bahrelghazali Australopithecus aethiopicus Paranthropus boisei Paranthropus robustus Australopithecus africanus Australopithecus garhi Homo rudolfensis Homo habilis Homo ergaster Homo erectus Homo antecessor Homo heidelbegensis Homo 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?
Hominid
Million yrs
Weight (g)
Australopithecus
5.0
500
H habilis
2.5
725
H erectus
1.7
1000
H heidelbergensis
0.6
1200
H neanderthalensis
0.2
1500
H sapiens
1350
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