Chapter 15 The Final Transformation . The Evolution of Modern Humans

Chapter 15 The Final Transformation . The Evolution of Modern Humans

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Chapter 15 – The Final Transformation: The Evolution of Modern Humans Early Discoveries of Anatomically Modern People Discovery in the Dordogne - First discovery of modern human fossils; five human skeletons buried with flint tools, weapons, seashells pierced with holes, and animal teeth perforated to make ornaments - The rock shelter in which they were found was Cro-Magnon – this name would soon include all anatomically modern people inhabiting Europe between 40,000 and 10,000 years ago, during the Upper Paleolithic - The inhabitants of the Cro-Magnon cave dated to 30,000 years ago; anatomically modern humans have existed since approximately 195,000 years ago The Anatomy of Homo sapiens - Cranium 1. relatively small face (compared to H. heidelbergensis and the Neandertals) 2. neurocranial globularity 3. flexed cranial base 4. vertical forehead 5. small brows 6. canine fossa (shallow depression on the upper jaw lateral to the bulge that marks the canine root) 7. distinct chin - Dentition 1. premolars and molars that are small (absolute size, and also relative to body mass) 2. smaller and weaker jaws than in archaic humans - Postcranial body 1. vocal tract with low larynx and long pharynx 2. reduced body mass compared to archaic humans 3. linear physique 4. short pubic ramus but large pelvic inlet - Brain and mind 1. mean brain size of 1,330 cc (10% larger than H. heidelbergensis but 8% smaller than Neandertals) 2. Jerison encephalization quotient (EQ) score of 8.1 3. enhanced working memory (EWM) now in place, allowing “higher levels of innovation, thought experiment, and narrative complexity” - The main changes are the shape of the skull and quality of the brain - Modern cognition and communication (due to the altered cranial shape and vocal tract dimensions) allowed for an explosion of cultural innovation - Over time, H. sapiens became the sole large-brained hominin species left on eart Selection for Modern Human Anatomy - Humankind’s anatomical modernization was a multifaceted adaptation to enhance speech and language
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- Daniel Lieberman determined that a single evolutionary change – shortening of the sphenoid bone in the cranial base – triggered the final steps in the modernization of the human skull - A shorter sphenoid led to reduced facial prognathism, which led to smaller brows, a more vertical forehead, and a rounded skull shape. Most importantly, the sphenoid would have contributed to the unique proportions of the human vocal tract - The human chin may have also been influenced by selection for modern speech. It provides external reinforecement at the mandibular symphysis against the streses of lateral grinding by the molars (other primates show internal reinforcement at the symphysis in the form of either a
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This note was uploaded on 04/07/2008 for the course ANTH 145 taught by Professor Gatewood during the Fall '07 term at Lehigh University .

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Chapter 15 The Final Transformation . The Evolution of Modern Humans

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