PSYC 3307 Lecture Notes - Lecture 5: Cerebral Cortex, Australopithecus, Basic Books
25 Jul 2020
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The brain size of today"s hominids has tripled since the pliocene age (5mya 2. 5mya) From an average of 450 cm3 in australopithecus to 1,345 cm3 in h. sapiens. Fossil skulls reveal that blood flow rate to the brain increased faster than brain volume (holloway, 1996) during human evolution (seymour et al, 2016) Changes in diet (initially from mainly leaves to mainly fruit, then, later, to include vegetables and meat) may have fueled brain evolution. Human saliva has more amylase# than chimpanzee saliva making possible the extraction of more useable calories from starchy vegetables such as tubers, corms, and bulbs . #amylase is a class of enzyme that catalyse the hydrolysis of starch into sugars humans have on average 6 copies of salivary amylase genes, while other primates have only two. Human brain evolution underwent an explosion starting about 100kya. Cochrane and harpending (2009) argue that the agrarian revolution (~10,000 ya) further accelerated human brain evolution.
