Human Adaption and Variation
Human Adaption and Variation ANTH 1102
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This 3 page Class Notes was uploaded by Carina Sauter on Sunday February 14, 2016. The Class Notes belongs to ANTH 1102 at University of Georgia taught by Dr. Birch in Winter 2016. Since its upload, it has received 69 views. For similar materials see Introduction to Anthropology in anthropology, evolution, sphr at University of Georgia.
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Date Created: 02/14/16
Human Adaptation and Variation • Biological Variation o biological differences between human beings are real, important and apparent o historically, scientists have approached the study of human biological diversity in two ways: § racial classification: the attempt to assign humans to discrete categories, purportedly on the basis of common ancestry • Western Europeans used to be the “pinnacle” of humans § explaining and understanding specific differences • clines: gradual shifts in gene frequencies between neighboring groups o What is a “race”? § Cultural and biological § Supposed to reflect genetic material • But wee use phenotypes § Races are not biologically distinct • Combination of genetics and growing up in the environment • “color based” racial labels are not accurate • many populations don’t fit neatly into any one of the three “great races” o mongoloid, negro, Caucasian • no single trait (i.e. Skin color) can be used as basis for racial classification § Great variation • Genetic histories and phenotypical variation § Biologists and anthropologists • Didn’t approve of marriage between races and classes § Human biological variation is a product of • Adaptation and natural selection • Population genetics § Racial classification is a product of • Socially constructed categories • Race-based colonial-era and modern politics § Genetic Markers do not correlate with Phenotype • 94% of all human genes are the same • 6% vary from one group to another • haplogroups: lineage or branch of human family tree marked by one or more genetic mutations § Why we have different skin colors • Skin color is a complex biological trait influenced by several genes • Assumed was determined by heredity • Does not mean common ancestor o Ex. same color skin in Africa and Australia • Melanin: a “natural sunscreen” produced by skin cells responsible for pigmentation o By screening out ultraviolet (UV) radiation from sun, melanin offers protection against, for example, sunburn or sin cancer o Why did light skin evolve? § Vitamin D: produced from contracting sunlight – allows you to absorb calcium for bones § Misconception that white people are more evolved o Why are people in Antarctica tanner than N. Europe even when there is less sunlight? § Cultural adaptation • Diet of fish and sea mammals o Key Points § Race is a recent human invention § Race is about culture not biology § Race and racism are embedded in our institutions and our everyday life • Biological Diversity o Natural selection affects facial features o Noses § Long noses seem to be adaptive in arid areas and cold environments so the air can warm by the time it enters the air ways § Thomson’s nose rule: association between nose form and temperature for those who have lived for many generations in areas they now inhabit o Body size and build § Larger bodies can conserve heat as small bodies can release heat § 2/3 of a pound = one degree Fahrenheit § Bergmann’s rule: smaller of two bodies similar in shape has more surface area per unit of weight • Within warm-blooded animals, populations with smaller individuals in same species are more often found in warm climates § Allen’s rule: relative sizes of protruding body parts increase with temperature • Keep heat away from body • 1877 Zoologist: first to write about body shape and temperature o ears, horses, height, etc. o > height = tropical climates o > stockier bodies and shorter limbs, larger chests = cold o does not hold all the time o Adaptation to Altitude o Lactose tolerance § Biochemical difference among human groups involved the ability to digest large amounts of milk § There is an adaptive advantage when foods are scarce but milk is available § Different genotypes capable of producing the same phenotype § Most people were lactose intolerant years ago o Genes and Disease § Blood – genetic passwords so we can see what does not belong when fighting a disease • A/AB: o susceptible to smallpox • O/B: o susceptible to plague o Susceptible to cholera o Protects against syphilis o Microbes major selective agent for humans, particularly before the arrival of modern medicine
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