BIOLOGY 1M03 Lecture Notes - Lecture 26: Foxp2, Mitochondrial Eve, Y Chromosome
12 Mar 2017
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Lecture 26 brain size evolution, highly accelerated regions of dna, human genetic variation. Natural selection for larger brain size (point #3 from lass class) = cooking with fire constraints on brain size increase: temperature sensitivity of the brain, high metabolic cost of the brain. These energetic improvements over eating raw foods may have led to decreased investment in the digestive system and increased energetic investment in our growing brains . Study of mammals in general suggests that increased brain size correlated with reduced fat levels and less so with reduced digestive system. Homo may have had a reduction in both fat and digestive system: efficient bipedal locomotion, steady and high quality food supply (partly due to cooking) cognitive buffering and the less need for fat. Characteristics of homo sapiens: big brain, small face and mouth, protruding chin, long limbs, short trunk. Many dna changes can be neutral and under genetic drift. Some changes may be favoured by natural selection.
