Evolutionary Biology BIOL 3350 Dr Lisa Rapaport Lecture 16 Notes Human Evolution I II III IV V Hominidea great apes and humans A We are more closely related to chimpanzees than chimpanzees are to B The last common ancestor between humans and chimpanzees was gorillas orangutans etc about 5 7 million years ago Differences between humans and chimpanzees A There are huge differences in the brain of a human compared to the brain of a chimpanzee B A lot of the differences between humans and chimpanzees are developmental differences and regulatory differences rather than quantitative differences Evolutionary changes leading to Hominins A Encephalization increase in brain size Bipedalism A Bipedalism is very efficient and makes an individual look larger which is a protection tactic used to deter predators Tool Use A Homo habilis handy man used tools B Humans have adapted to being omnivores C Do not have to remember these dates D The human tapeworm evolved when meat that was not fully cooked was consumed E The use of tools replaced the need for large teeth for heavy lifting this allowed smaller teeth to evolve VI Larynx A Orientation of the head balanced over the spine forced the larynx to be squeezed down VII VIII IX B Orientation of the larynx of a human infant more closely resembles that of the chimpanzee until they start to walk Encephalization A Lateralization the right hemisphere and the left hemisphere have different functions Benefits to brain are large A Without the large brains we would not have the capacity and cognitive machinery for language Fossil Evidence A Foramen magnum is centered in the skull bipedalism B Similar brain size of the chimp but smaller canines flatter face larger brow ridge X Hominin Diversification 1 XI XII A Loss of selection pressure for large canines Australopithecus afarensis A Transitional intermediate mouths B Similar feet and toes to humans Australopithecus africanus A Brian size follows bipedality B Bipedalism seemed to come about before encephalization increased brain size XIII Homo ergaster erectus for over 2 million years already XIV Homo erectus postcranial morphology they were long distance runners XV Why is cooking important A See an increase in brain size even though bipedalism has been around A Long legs large lung capacity and limb proportions all suggest that A Softening of food helped lead to the evolution of smaller teeth because less selective pressure occurred on the teeth B Correlation between cooking and the size of the brain C Correlation between tool sophistication and size of the brain African Exodus A Homo erectus began taking over the world and moving out of Africa XVI XVII Theories of modern human evolution A Multi Regional Hypothesis Gene flow prevented speciation from occurring 2