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Largest Brain on planet, 30 lbs!

Largest Brain on planet, 30 lbs!. Belongs to Sperm Whale. Absolute Brain Weight – Does it reflect intelligence?. Relative Brain Weight Of all animals, man has the largest brain in proportion to his size” - Aristotle.

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Largest Brain on planet, 30 lbs!

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  1. Largest Brain on planet, 30 lbs!

  2. Belongs to Sperm Whale

  3. Absolute Brain Weight – Does it reflect intelligence?

  4. Relative Brain WeightOf all animals, man has the largest brain in proportion to his size” - Aristotle

  5. Encephalization: Increase in brain size during evolution of SPECIES, with no concomitant increase in body size

  6. Encephalization Quotient (EQ) • Anatomical estimate of species’ intelligence based on brain/body size and not behavior • EQ = ratio of brain weight of animal to brain weight of “typical” animal of same body weight • EQ represents residual value of brain mass • Human neocortex is 3.2x larger in volume than nonhuman primate with our body size (Jerison, 1973). • Overview Quiz • TLE

  7. 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

  8. 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

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

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

  11. Brainy Newcomers

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

  13. Not a straight ascent to modern humans • Coincided with unstable weather (4 ice ages)

  14. ...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

  15. Sensory information is processed subcortically, and then first is processed cortically in primary modality areas

  16. Primary versus Association Cortex BUT the dolphin brain is organized differently

  17. General Features of Encephalization • Increase in absolute & especially relative brain size • Cortex enlarged compared to lower structures • More brain tissue for sensory functions compared to motor functions • Increase in Associative areas • Rise of importance of biophysical senses compared to chemical senses

  18. Number of olfactory receptor cells Human 40 Million Rabbit 100 M Dog 1000 M Mammals: Smell, Sight, or Sound Brains

  19. Can human brain get any bigger?Perhaps, but need to consider speciation, torque, and pelvic evolution.

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