co32 - CHAPTER 32 HUMAN EVOLUTION Chapter Outline 32.1...

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CHAPTER 32 H UMAN E VOLUTION Chapter Outline 32.1 Evolution of Primates A. Primate Characteristics 1. Primates differ from other mammals by being adapted for arboreal life (life in trees). 2. Mobile Forelimbs and Hindlimbs a. In primates, the limbs are mobile and the hands and feet have five digits each. b. In most primates, flat nails replace claws and sensitive pads develop on the underside of fingers and toes. c. Many primate hands have to some extent an opposable thumb; some also have an opposable big toe. d. These features allow the free grasping of tree limbs and easy harvesting of fruit. 3. Binocular Vision a. Primates have a reduced snout and the face is relatively flat. b. The sense of smell is generally reduced. c. The eyes are moved to the front of the face for overlapping views that provide stereoscopic vision. d. Cone cells provide greater visual acuity and color vision but require bright light. 4. Large Complex Brain a. Better senses requires both sense organs and a more complex brain to process the input. b. More of the brain becomes devoted to processing information received from the hands and thumb, less to smell. 5. Reduced Reproductive Rate a. Primates have more single births, which reduces the need for care for several offspring. b. The period of parental care is extended with an emphasis on learned behavior and complex social interactions. B. Phylogenetic Tree 1. All primates at one time shared one common ancestor; prosimians were an early group to diverge and African apes were the last group to diverge from our lineage. 2. Prosimians diverged first and are most closely related to the original primate. 3. Anthropoids a. Surviving anthropoids are classified into three superfamilies: New World monkeys, Old World monkeys and hominoids. b. New World monkeys reside in South America and Old World monkeys evolved in Africa. c. New World monkeys (e.g., spider monkey and capuchin) have long prehensile tails and flat noses. d. Old World Monkeys (e.g., baboon and rhesus monkey) lack prehensile tails and have protruding noses. e. It is hypothesized that a common ancestor must have arisen earlier than the Oligocene when a narrower Atlantic would have made dispersal possible. 4. Ape Evolution a. During the Miocene epoch, dozens of hominoid species arose. b. Proconsul was one of several ape species prevalent in Africa during the Miocene and is believed ancestral to apes and humans. c.
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This note was uploaded on 10/24/2009 for the course BIO 172 taught by Professor Clark during the Fall '08 term at University of Michigan.

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co32 - CHAPTER 32 HUMAN EVOLUTION Chapter Outline 32.1...

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