Evolution of Culture Capacity

1. Evolution of Culture Capacity Human Evolution

2. Theory of Natural Selection • Theory formulated by Charles Darwin. • Changes in living organisms occur over time as a result of reproduction. • The most convincing scientific explanation of the variety and history of life on earth.

3. Theory of Natural Selection • No two living things, even those of the same species, are alike. • Sources of variation: • Mutation • Sexual reproduction • Genetic drift

4. The chemical structure of DNA consists of two long backbones made of alternating sugar and phosphate molecules.

5. There are two pools of genetic variation, hidden and expressed.

6. This computer simulation demonstrates that genetic drift causes isolated populations to become genetically different from one another. Figure 03.23

7. Theory of Natural Selection • Most creatures did not survive long enough to have offspring. • Creatures who won the struggle for survival passed traits that led to their success to their offspring.

8. Life in a nutshell: the cells of organisms are composed of a large number of very complicated chemicals

9. Types of Natural Selection

10. Common Examples of Selection In Action

11. Selection can carry a population far beyond the original range of variation. Illustration of Artificial Selection for Oil Content in Corn. Selection For Oil Content Selection Against Oil content

12. HARDY-WEINBERG EQUILIBRIUM THEORY A MATHEMATICAL MODEL OF AN IDEAL POPULATION IN WHICH GENE FREQUENCIES ARE.NOT INFLUENCED BY EVOLUTIONARY PROCESSES. THE MODEL.MAKES THE FOLLOWING ASSUMPTIONS: • A LARGE (INFINITELY?) POPULATION. • NO MUTATION • NO MIGRATION • NO SELECTI ON • COMPLETELY RANDOM.MATINGS

13. EVOLUTION TERMINOLOGY • GENE POOL: THE TOTAL NUMBER OF ALLELES IN A POPULATION. THE GENE POOL REPRESENTS THE AVAILABLE GENETIC VARIATION. • BREEDING ISLOLATES: A POPULATION THAT IS ISOLATED, OR SEMI- ISOLOATED, FROM OTHER POPULATIONS FOR GEOGRAPHIC, BEHAVIORAL, OR OTHER.REASONS.    • ENDOGAMY: MATING WITHINA SOCI.AL GROUP.   • EXOGAMY: MATING OUTSIDE A SOCIAL GROUP.

14. Figure 04.02a Gene flow among populations destroys differences between them. Island 1 Island 2

15. Figure 04.02b Island 1 Island 2 Now suppose two populations of finches live on different islands, one wet and one dry, with no gene flow between the two islands

16. In the Galápagos, selection maintains three species of ground finches despite the fact that there is substantial gene flow among them Figure 04.03

17. EVOLUTION TERMINOLOGY • NEGATIVE ASSORTIVE MATING: INDIVIDUALS OF UNLIKE PHENOTYPE MATE MORE OFTEN THAN THOSE OF SIMILAR PHENOTYPES. • POSITIVE-ASSORTIVE MATING: INDIVIDUALS OF LIKE PHENOTYPE MATE MORE OFTEN THAN THOSE OF SIMILAR PHENOTYPES. • INBREEDING: THE SYSTEMATIC SELECTION OF MATES FROM CLOSE GENETIC RELATIVES. • CONSANGUINITY: THE DEGREE OF RELATION BETWEEN INDIVIDUALS.

18. Types of Speciation Allopatric speciation occurs when a species is divided into two reproductively isolated populations that subsequently diverge. If the divergent populations regain contact, they cannot interbreed and two new species exist. Figure 04.10 Parapatric speciation occurs when a species experiences different environments in different parts of its geographic range. Natural selection causes different populations of the species to diverge while adapting to these different surroundings, and eventually reproductive isolation is achieved. Sympatric speciation occurs when selection strongly favors different adaptations to a similar environment within a single species.

19. EVOLUTION TERMINOLOGY • FOUNDER EFFECT: THIS OCCURS WHEN A.VERY SMALL NUMBER OF INDIVIDUALS (AND THEREFORE A VERY SMALL GENE POOL) ARE THE ONLY INDIVIDUALS TO CONTRIBUTE GENES TO THE .FOLLOWING GENERATIONS.

20. An illustration of sampling variation.

21. Anagenesis and Cladogenesis • There are two types of change. These are depicted here as anagenesis and cladogenesis. The latter, of course, implies the process of speciation. The former relates to changes over time in a species. • There are three terms that you should know relative to evolution. These are: Divergent Evolution, Convergent Evolution, and Parallel Evolution. The keys to understanding the differences between these terms is to contrast ancestry, adaptations, and eventual forms. If you do this, you will find these terms easy to understand. DIVERGENT EVOLUTION • Evolution of DIFFERENT adaptive traits in forms that were once related but then diverged, developing along different lines. • In terms of ancestry, adaptation and form: • there is similar ancestry, • different adaptations and • resulting different forms. CONVERGENT EVOLUTIONEvolution of SIMILAR adaptive traits In terms of ancestry, adaptation and form - consider convergent evolution to reflect • different ancestries, • similar adaptations and • resulting similar forms. PARALLEL EVOLUTIONEvolution of similar adaptive traits in forms that were once related but then diverged, developing along similar lines. In terms of ancestry, adaptation and form: there is • similar ancestry, • similar adaptations and • resulting similar forms.

22. Debates on Evolution • Most debate about evolution is religious rather then scientific. • Evolution challenges religious creation stories. • In 1950, the Catholic Church declared evolution compatible with Christianity.

23. Common Ancestors • Humans, gorillas and chimpanzees evolved from common ancestors. • All animals are equally evolved in different ways and under different circumstances. • Human ancestors diverged from those of chimpanzees and gorillas 5 to 8 m.y.a.

24. Primates For our purposes, Primates have the following features: • Limbs and Locomotion • Retention of Five Digits (pentadactyly) • Nails instead of claws on at least some digits. • Flexible hands and feet with considerable prehensility • Retention of the Clavicle • A tendency towards erect posture, especially in the upper body • Teeth and Diet • A generalized dental pattern • A lack of specialization in diet • Senses, Brain, and Behavior • A reduction of the snout • An increased emphasis on vision • Expansion and increased complexity of the brain • A more efficient means of fetal nourishment, lengthening of the entire life-cycle, especially of gestation and infancy. • Dependency on highly flexible learned behavior • Adult males often associate with the group permanently

25. Grades of Primate Evolution • Suborder Prosimii • Grade One: Tree Shrews (primitive mammalian grade) • Live in southeast Asia, India to Indonesia • Have claws, not nails, on all digits • Have grasping hands • Probably resemble some of the earliest primates • Grade Two: Lemurs and Lorises • Lemurs: Only on the island of Madagascar. Extinct elsewhere • Lorises: Very similar to Lemurs, but are distributed over much of • Southern Africa • Summary of the Prosimians: 1. Have nails on at least one digit 2. Well developed vision, but not completely stereoscopic. 3. Prolonged life spans 4. Projecting nose 5. Well-developed sense of smell 6. Expressionless faces 6. Grooming dentition 7. Unelaborated social structure.

26. Suborder Anthropoidea • Grade Four: Monkeys • A. New world Monkeys: Ceboidea • Exclusively Arboreal • Southern Mexico, Central America, South America • Some have prehensile tails • B. Old world Monkeys: Cercopithecoidea • The most widely distributed of all primates other than humans • 2.1.2.3 dental formula • All quadrapedal, mainly arboreal • No prehensile tails in adults • Grade Five: Hominoids • A. Lesser Apes: Gibbons and Siamangs • B. Great Apes: Orangutans, Gorillas, Chimps • C. Humans

27. Primate Social Behavior • Core of society is the bond between mothers and their offspring. • Play becomes central to the interaction of older primates with their age-mates. • Primates have displays of aggression and means of reconciliation.

28. Primate Social Behavior Mother-Infant Relationship: The basic social unit in all primates. • Males may consort with females for mating, but they may or may not participate as members of a social unit. • In most other animals infants are left behind in dens or nests. • In Primates:  • 1.    Infants cling to mothers while they move about. • 2.    The bond is often for life, and is reflected in adult grooming behavior. • The role of the mother-infant attachment is not just one of social stability, it is absolutely essential for the proper development of primate infants.

29. What are some of the basic types of non-human primate social groups? • 1.  ONE MALE GROUPS • a.    A single adult male, several adult females and their offspring. • b.    The most common primate mating structure • c.     Only one male actively breeds. • d.    Usually formed by a male or males joining a kin group of females. • e.     Females usually form the permanent nucleus of the group. • f.      Examples: Guenons, Orangs, Gorillas, pottos (some), spider monkeys (some), patas. • 2.    MULTIMALE GROUPS • a.    Several adult males, several adult females and their young. • b.    Several of the males reproduce. • c.     The presence of several males may lead to tension and to a dominance hierarchy. • d.    Examples: Lemurs(some), macaques, mangabeys, savanna baboons, vervets, chimpanzees. • 3.    FAMILY, or MONOGAMOUS • a.    A mated pair and their young. • b.    Usually arboreal • c.     Minimal sexual dimorphism • d.    Frequently territorial; Adults do not tolerate other adults of the same sex. • e.     Not found among the great apes, and least common of breeding structures in non-human primates. • f.      Examples: gibbons, indris, tarsiers, owl monkeys, titis, pottos, marmosets(some).

30. ASPECTS OF SOCIAL BEHAVIOR Grooming: The manual cleaning of skin and fur. 1.    Almost all primates groom one another 2.    Grooming occurs in other species but SOCIAL grooming is a unique primate activity and plays an important role in the life of most primates. 3.    Eases interaction between male/female and lower/higher ranks: “social lubricant” 4.    The social cement for all primates: helps maintain social organization of the group. 5. Often reciprocal with roles interchanged; groomer becomes the groomee

31. ASPECTS OF SOCIAL BEHAVIOR Displays: Stereotyped behavior what serves to communicate emotional signals. 1.    Animals often display when excited 2.    They use displays a.   when outsiders are present b.   in reaction to another member of the group.

32. ASPECTS OF SOCIAL BEHAVIOR Dominance (dominance hierarchy): The physical domination of some members of a group by other members. • 1.    Measured by priority access to a desired object such as food or a mate. • 2.    The dominant individual is given priority in confrontations. • 3.    Dominant individuals compete more successfully in the group than others: net reproductive success.

33. Females first develop tool-using skills and become more adept than males. Tool use is learned behavior and passed along by the social group. Some groups of chimpanzees do some activities and others do not. Primate Tool Use

34. Examples of Primate Tool Use • Use sticks to threaten others or defend themselves. • Use water to separate grains of wheat from sand. • Use twigs or blades of grass to fish termites from their mounds.

35. Early Human Ancestors • Few in number and geographically confined to Africa. • Did not depend heavily on tools, and left few material remains. • Spread from African origins to inhabit most of the globe.

36. Evolution of Humans • Humans have adapted to many different climates and ecosystems. • All humans are members of the biological family Hominidae. • Humans fall into two genera: Australopithecus and Homo.

39. Homo Habilis • Expanded cranial capacity (relative to africanus). • Reduced postcanine tooth size. • The presence of a precision grip (determined from the hand bones present in OH 7), which provides the anatomical basis for tool-making.

40. Homo Habilis • Found in Africa between 2.5 and 1.8 million years ago. • Made sophisticated sets of tools as early as 2.3 million years ago. • Stone rings indicate that habilis probably built shelters for protection.

41. Homo erectus • An increase in brain size (erectus approximately 900 cc., sapiens approximately 1350 cc.). • A reduction in postcanine dentition, and a correlated decrease in jaw size. • Vertical shortening of the face. • Shortening of armbones (especially the forearm) to come to a very humanlike limb proportions (postcranial proportions are very similar to tropically adapted modern humans). • The development of a more barrel-shaped chest. • The formation of an external nose. • Reached modern human size in terms of height.

42. Homo erectus • Found in Africa, Asia, and Europe between 1.8 million and about 200,000 years ago. • Became increasingly dependent on culture to survive in the Ice Age. • Capable of controlling and using fire. • Lived by hunting, scavenging, and gathering.

43. Amud 1 Neandertals • Flat zygomatic arch. • The supraorbital torus projects at midline. • Retreating chin. • A long low brain case. . • An occipital bun. • A broad and projecting nose. • Larger cranial capacity (but due to larger body size, Neanderthals are less encephalized than modern humans).

44. Neandertals • Members of a population of archaic Homo sapiens. • Lived between 130,000 and 35,000 years ago. • Pollen found in graves show bodies were buried with flowers, suggesting rituals and belief in the afterlife.

45. Homo sapiens sapiens • A high, rounded cranium. • A steep forehead. • Large cranial capacity (1600 cc.). • A short face with rectangular orbitals. • A tall and narrow nasal opening. • A parabolic palate. • A prominent mental eminence.

46. Homo sapiens sapiens • Tools were more sophisticated and efficient than any prior species. • Left symbolic and artistic remains in form of cave paintings and Venus figures. • Turned to the domestication of plants and animals about 10,000 years ago.

47. Human Variation • Human traits change in frequency geographically. • Blood type and skin color vary geographically. • The sickle cell gene is common in areas that have a high incidence of malaria.