1. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 1 4 Evolution Anthropology: The Exploration of Human Diversity 11 th Edition Conrad Phillip Kottak

2. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 2 Evolution Evolution Genetics Mendel’s Experiments Biochemical, or Molecular, Genetics Population Genetics and Mechanisms of Genetic EvolutionPopulation Genetics and Mechanisms of Genetic Evolution Natural Selection

3. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 3 Evolution Polymorphisms Understanding Ourselves Mutations and Variety Random Genetic Drift Gene Flow The Modern Synthesis

4. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 4 Evolution Many scholars became interested in biological diversity and our position within the classification of plants and animals during 18th century Humans have uniquely varied ways— cultural and biological—of evolving, of adapting to environmental stresses

5. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 5 Evolution Linnaeus (1707-1778) developed first comprehensive and still influential classification, or taxonomy, of plants and animals Fossil discoveries during the 18th and 19th centuries raised doubts about creationism Creationism—biological similarities and differences originated at the Creation

6. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 6 Evolution Catastrophism—modified version of Creationism accounts for the fossil record by positing divinely authored worldwide disasters that wiped out creatures represented in the fossil record The alternative to creationism and catastrophism was transformism, also called evolution

7. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 7 Evolution Natural Selection—process by which nature selects the forms most suited to survive and reproduce in a given environment Darwin influenced Lyell’s Principle of Uniformitarianism—explanations for past events should be sought in the long-term action of ordinary forces that still work today

8. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 8 Evolution –Variety within that population –Competition for strategic resources For natural selection to work on a given population, there must be: Process of natural selection continues as long as the relationship between the population and its environment remains the same

9. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 9 Genetics –Mendelian Genetics—studies ways in which chromosomes transmit genes across generations –Population Genetics—investigates natural selection and other causes of genetic variation, stability, and change in breeding populations Genetic science emerged after Darwin

10. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 10 Mendel’s Experiments –Studied inheritance of seven contrasting traits in pea plants –Discovered heredity is determined by discrete particles or units Austrian monk Gregor Mendel began a series of experiments that revealed basic principle of genetics in 1856

11. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 11 Mendel’s Experiments –Basic genetic units Mendel described were factors (now called genes or alleles) located on chromosomes –Concluded that although a dominant form could mask the other form in hybrid, or mixed, individuals, the dominated trait—the recessive—was not destroyed

12. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 12 Mendel’s Experiments Heterozygous—dissimilar alleles of a gene in an offspring Homozygous—two identical alleles of a gene in an offspring Dominance produces a distinction between genotype—hereditary makeup and phenotype—expressed physical characteristics –Alleles—biochemically different forms of a given gene

13. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 13 Mendel’s Experiments –Independent Assortment—Mendel’s discovery that traits are inherited independently of one another –Recombination—combination of genetic traits in an offspring; creates new types on which natural selection can operate Independent Assortment and Recombination

14. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 14 Mendel’s Experiments Mendel’s Second Set of Experiments with Pea Plants –Insert Figure 4.1

15. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 15 Mendel’s Experiments Simplified Representation of a Normal Chromosome Pair –Insert Figure 4.2

16. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 16 Mendel’s Experiments Punnett Squares of a Homozygous Cross and a Heterozygous Cross –Insert Figure 4.3

17. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 17 Mendel’s Experiments Determinants of Phenotypes (Blood Groups) in the ABO System –Insert Figure 4.4

18. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 18 Biochemical, or Molecular, Genetics –Mutations—changes in the DNA molecules of which genes and chromosomes are built –Gametes—sex cells that make new generations Studies structure, function, and changes in genetic material

19. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 19 Biochemical, or Molecular, Genetics –RNA carries DNA’s message to its cytoplasm (outer area) –Structure of RNA, with paired bases, matches DNA DNA, with RNA’s assistance, initiates and guides the construction of hundreds of proteins necessary for bodily growth, maintenance, and repair DNA molecule is a double helix

20. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 20 Biochemical, or Molecular, Genetics A Double-Stranded DNA Molecule –Insert Figure 4.5

21. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 21 Biochemical, or Molecular, Genetics Crossing Over –Insert Figure 4.6

22. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 22 Biochemical, or Molecular, Genetics Cell Division –Mitosis—ordinary cell division, wherein one cell splits to form two identical cells

23. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 23 Biochemical, or Molecular, Genetics Fertilization allows the products of meiosis from one parent to recombine with those from the other parent Chromosomes sort independently Cell Division –Meiosis—special process by which sex cells are produced 4 cells produced from one Each cell carries half the genetic material of the original cell (i.e., twenty-three chromosomes instead of forty-six)

24. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 24 Biochemical, or Molecular, Genetics –Process where homologous chromosomes exchange segments by breakage and recombination Independent assortment of chromosomes permits parents’ genotypes to be assorted in more than 8 million different ways Crossing Over

25. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 25 Population Genetics and Mechanisms of Genetic Evolution –Gene Pool—refers to alleles and genotypes within breeding population Population genetics studies stable and changing populations in which most breeding normally takes place

26. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 26 Population Genetics and Mechanisms of Genetic Evolution Any factor that contributes to a change considered mechanism of genetic evolution Natural selectionMutation Genetic driftGene flow –Genetic Evolution—change in the frequency of alleles in breeding population from generation to generation

27. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 27 Natural Selection Phenotype is the organism’s evident biological characteristics –Natural selection only act on phenotypes –Environmental influence in this interaction extremely important –Lends great plasticity to human biology Genotype refers to the genetic makeup of an organism

28. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 28 Natural Selection –After several generations of selection, gene frequencies change Natural selection will have occurred Adaptive—favored by natural selection Directional Selection

29. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 29 Natural Selection –Directional selection—long-term selection of the same trait(s) Directional selection continues as long as environmental forces stay the same –Sexual selection—certain traits of one sex selected because of advantages they confer in winning mates Directional Selection

30. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 30 Polymorphisms Balanced polymorphism—frequencies of two or more alleles of a gene remain constant from generation to generation Sickle-Cell Anemia HbA and HbS alleles largely determines hemoglobin production in humans Homozygous HbA produces normal hemoglobin Homozygous HbS produces lethal sickle-cell anemia Heterozygosity for this gene produces (in some circumstances) deleterious but nonlethal sickle-cell syndrome

31. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 31 Polymorphisms Heterozygous form produced phenotype resistant to malaria –Demonstrates relativity of evolution through national selection –HbS existed at surprisingly high frequencies in certain populations in Africa, India, and the Mediterranean

32. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 32 Polymorphisms Distribution of Sickle-Cell Allele and Falciparum Malaria in the Old World –Insert Figure 4.7

33. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 33 Understanding Ourselves Plasticity through culture steps in to complement human biological plasticity Human biology is plastic, but only to a degree

34. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 34 Mutations and Variety Variants produced through mutation can be especially significant if there is change in selective forces Mutation major source of genetically transmitted variety

35. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 35 Random Genetic Drift Random genetic drift—loss of alleles from a population’s gene pool through chance Lost alleles reappear in gene pool only through mutation

36. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 36 Gene Flow Exchange of genetic material between populations of the same species Alleles spread through gene flow even when selection not operating on the allele

37. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 37 Gene Flow –Species—group of related organisms whose members can interbreed to produce offspring that live and reproduce –Gene flow tends to prevent speciation— formation of new species Important in study of origin of species

38. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 38 Gene Flow Gene Flow between Local Population –Insert Figure 4.8

39. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 39 The Modern Synthesis –Microevolution—small-scale changes in allele frequencies over just a few generations –Macroevolution—large-scale changes in allele frequencies in a population over a longer time period Microevolution and macroevolution happen in the same way and for the same reasons Currently accepted view of evolution

40. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 40 The Modern Synthesis Gradual or Rapid Change –Darwin: minor alterations in gene pool, accumulating generation after generation, added up to major changes

41. McGraw-Hill © 2005 The McGraw-Hill Companies, Inc. 41 The Modern Synthesis Gradual or Rapid Change –Punctuated equilibrium—long periods of stasis, during which species change little, interrupted by evolutionary leaps Sudden environmental change, rather than extinction and replacement, presents possibility for pace of evolution to speed up Species can survive radical environmental shifts, but more common fate is extinction