Chapter 11: The Origins of our Big Brains

• The History around fossils
• Happened in and around the time of Darwin
• 1887 Discovery of Neanderthals 
• Virchow said the remains where a modern man with rickets
• Haeckel thought they were legit
• Dubois predicted that the "missing link" was in the Dutch East Indies
• Brain size in primates
• Body weight vs. brain weight seems to follow a logarithmic scale
• Except for humans - brain is larger than expected.
• Increase body by a factor of 10 and you get a 10 fold increase in brain size.
• 10^(x * g) where g is a constant
• Very good model for predicting brain or body weight given the other.
• Brain region sizes correlate very closely with other primates
• Gorillas and chimps are smarter than monkeys (communication, tool use).
• Humans have large brains even for a primate
• Brain size in the family of man
• 6 million years ago - start of split towards bipedalism
• 5 million - bipedal vs. non-bipedal are distinct species
• 4 million - Australiopithicus
• 450cc brain
• 2 million - Homo Habilis
• 600cc brain
• First evidence of tool use
• 1.5 to 1.8 million - Homo Erectus
• 800cc brain
• 500,000 - Homo Erectus+
• 1000cc brain
• 100,000 - Neanderthals
• 1500cc brain
• 10% larger than H. Sapiens (~1350cc)
• Mosaic theory vs. concerted
• How intelligence occurred
• Mosaic theory - evolutionary pressure for different brain regions at different times.
• Concerted - no pressure for any one region, just scale up the existing brain.
• Concerted predicts the size of various brain regions, mosaic does not.
• Big Babies
• Discussion is predicated on one accepting the concerted theory.
• Bipedalism
• required for walking erect
• Wider hip size
• Larger babies
• Birth weight determines brain size
• If you have a large brain then you must have larger babies at birth.
• Human - 1350cc brain - 3.3kg
• Gorilla - 500cc brain - 1.6kg
• Chimp - 400cc brain - 1.5kg
• Hip size
• Humans: 20% difference between men and women
• Chimps: 5% difference
• On Intelligence
• Where does all the brain power go?
• Memory
• Anecdote about memory experiment
• 10,000 picutres
• 90% accuracy (have you seen this before).