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McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 1 5 Human Variation and Adaptation Anthropology: The Exploration of Human Diversity 11 th Edition Conrad.

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Presentation on theme: "McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 1 5 Human Variation and Adaptation Anthropology: The Exploration of Human Diversity 11 th Edition Conrad."— Presentation transcript:

1 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 1 5 Human Variation and Adaptation Anthropology: The Exploration of Human Diversity 11 th Edition Conrad Phillip Kottak

2 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 2 Human Variation and Adaptation Race: A Discredited Concept in Biology Human Biological Adaptation

3 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 3 Race: A Discredited Concept in Biology –Members of race or subspecies share distinctive physical characteristics based on common ancestry and inheritance of same genes Human populations have not been isolated enough from one another to develop into discrete races Race refers to geographically isolated subdivision of a species

4 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 4 Race: A Discredited Concept in Biology Human biological variation distributed gradually between populations along clines –Human populations vary biologically, but because of extensive gene flow and interbreeding, there are no sharp breaks between populations

5 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 5 Race: A Discredited Concept in Biology Race is supposed to reflect shared genetic material Early scholars used phenotypical traits (skin color) for racial classification –Scientists have trouble grouping people into distinct racial units

6 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 6 Race: A Discredited Concept in Biology –Obvious problem with color-based racial labels is that terms dont accurately describe skin color –Another problem with tripartite scheme is that many populations dont neatly fit into one of the three great races Races Are Not Biologically Distinct

7 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 7 Race: A Discredited Concept in Biology –Racial classifications based on phenotype lack credibility because similarities and differences dont necessarily have genetic basis

8 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 8 Race: A Discredited Concept in Biology –Natural selectionprocess by which nature selects the forms most fit to survive and reproduce in a given environment Explaining Skin Color

9 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 9 Race: A Discredited Concept in Biology Melaninprimary determinant of human skin color; chemical substance manufactured in the epidermis Prior to 16th century, darker skinned populations closest to the equator Explaining Skin Color –Skin color influenced by several genes

10 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 10 Race: A Discredited Concept in Biology Unprotected humans in tropics face threat of severe sunburn –Increases susceptibility to disease –Impairs the bodys ability to withstand heat by reducing the skins ability to sweat –Light skin is more susceptible to skin cancer. Loomis suggested that in tropics, dark skin color protects body against overproduction of vitamin D Explaining Skin Color –Skin color influenced by several genes

11 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 11 Human Biological Adaptation Abundant evidence for human genetic adaptation and evolution through selection working in specific environments

12 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 12 Human Biological Adaptation –According to World Health Report, tropical diseases affect more than 10 percent of worlds population Malaria300 million to 500 million people Schistosomiasismore than 200 million Filarisasis120 million Genes and Disease

13 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 13 Human Biological Adaptation After food production emerged, infectious diseases pose mounting risk and became foremost cause of human mortality ABO blood groups vary in resistance to disease Genes and Disease –Microbes major selective agent for humans, particularly before arrival of modern medicine

14 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 14 Human Biological Adaptation There is probably genetic variation in susceptibility to HIV Genes and Disease –In diseases for which there are no effective drugs, genetic resistance maintains significance AIDS could cause large shifts in human gene frequencies

15 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 15 Human Biological Adaptation –Natural selection also affects facial features Long noses seem to be adaptive in arid areas and cold environments Thomsons Nose Ruleassociation between nose form and temperature Facial Features

16 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 16 Human Biological Adaptation –Allens rulerelative size of protruding body partsears, tails, bills, fingers, toes, and limbsincrease with temperature Size and Body Build –Bergmanns rulesmaller of two bodies similar in shape has more surface area per unit of weight Average body size tends to increase and cold areas and decrease in hot ones

17 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 17 Human Biological Adaptation Size and Body Build –Human populations use different, but equally effective, biological means of adapting to environmental stresses associated with high altitudes

18 McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 18 Human Biological Adaptation –Phenotypical adaptationadaptive changes that occur during individuals lifetime –Genes and phenotypical adaptation work together to produce a biochemical difference between human groups in ability to digest large amounts of milk Adaptive advantage when other foods are scarce and milk available Lactose Tolerance


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