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Brief Overview of Evolution

Brief Overview of Evolution. Slides graciously prepared by…. Meghan McCune

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Brief Overview of Evolution

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  1. Brief Overview of Evolution

  2. Slides graciously prepared by… Meghan McCune Anthropology/sociology instructor on the Jamestown Community College, Cattaraugus County Campus. A doctoral candidate at Michigan State University. She earned a bachelor’s degree at Wells College and a master’s degree at Michigan State University. She taught previously a lecturer and adjunct faculty member at Alma College, Michigan State University, and Wells College.

  3. Defining Anthropology • Anthropology is derived from the Greek words anthropos- meaning human and logos-meaning study. • The study of humankind in all times and places.

  4. The Four Field Approach • Physical/Biological • Cultural • Linguistic • Archaeology • (Applied Anthropology)

  5. What is “Evolution?” • Changes in the genetic makeup of a population over generations.

  6. Greco-Roman Influence • Universal Laws • Humans part of natural world; all organisms comprise one system • The idea that early humans were “brutish”

  7. Judeo-Christian Influence • Humans separate from natural world • Idea of stasis • Earth is young • Judeo-Christian ideas overshadowed early ideas about evolution until the Renaissance when Greek and Roman texts were revived.

  8. How did Evolutionary Theory Develop? • Increased exploration and travel as a result of new technology and colonialism • The Renaissance led to a Scientific Revolution (a main characteristic of the Enlightenment); Europeans began to record, in systematic detail, observations about the natural world • Many early evolutionary scholars were involved in geology, anatomy, and paleontology

  9. Examples of Early Scholars • Carl von Linne’/Linneaus (1707-1778) • Binomial nomenclature –two part naming system used to classify organisms • For example Homo sapiens

  10. What did Linnaeus use as a basis for his system of classification? • Body structure • Body function • Sequence of body growth

  11. Defining “Species” • Species – A population or group of populations having common attributes and the ability to interbreed and produce live, fertile offspring. Different species are reproductively isolated from one another.

  12. Early Scholars, cont. • George-Louis de Buffon (1707-1788) – Idea of adaptation; organisms are influenced by the natural environment. This idea is the foundation of Natural Selection • Erasmus Darwin(1731-1802) – Variation exists in all species

  13. Early Scholars, cont. • Jean-Baptiste de Lamarck (1744-1829) – Inheritance of Acquired Characteristics; New traits develop out of need.

  14. Early Scholars, cont. • Charles Lyell (1797-1875) – “Father of Geology” • Earth can be aged using stratigraphy

  15. Charles Darwin (1809-1882)

  16. Darwin’s Observations • There is variation among species • Fossils have similarities to current species • Change occurs over a large span of time • Through competition over environmental niches, species change

  17. Natural Selection • Resources are finite, individuals must compete over resources, and some are better than others at obtaining resources • The environment “selects” traits; this is known as “Selective Pressure” • Species change is “Survival of the Fittest” (fitness is defined as reproductive success). • In turn, natural selection only acts on traits that are both inherited and affect reproduction • Changes are adaptations • “A series of beneficial adjustments of organisms to their environment.”

  18. Example: The Peppered Moth

  19. “What a trifling difference must often determine which shall survive, and which perish!”-Charles Darwin

  20. How did variation begin?

  21. Inheritance • Gregor Mendel (1882-1884) – Laws of Segregation and Independent Assortment

  22. Law of Segregation • Each parent has a pair of genes (alleles) for traits such as pea color and flower color, but each gamete (egg or sperm) only has one of the two versions

  23. Cross of True Breeding Plants Purple & White Flowers Purple – Homozygous Dominant (PP) White – Homozygous Recessive (pp) P F1 Offspring All Purple – Heterozygous (Pp) F1

  24. Law of Independent Assortment • During the formation of gametes, chromosomes and the genes they carry are distributed randomly

  25. Examples of Evolutionary Forces

  26. Mutation • The ultimate source of evolutionary change. • Mutation = improper copying of DNA • Mutations are how new genes are created • Rates of Mutation are slow and many are affected by Environmental factors

  27. Founder Effect • Occurs when a small “founding” population interbreeds • Or when populations decreased due to war, famine, plague, and disasters = Bottleneck • Example: Hawaii Nene Goose genetic bottleneck event

  28. Gene Flow • Introduction of new alleles from nearby populations

  29. Human Evolution

  30. Defining Hominins • Hominin = humans and ancestors • Hominins differ from other primates because of… - Large brain size (Chimp = 400 cubic cm, Humans 1,200-1,400 cubic cm) - Changes in dentition - Change in Diet - Bipedal locomotion

  31. Bipedal Locomotion • Physical Changes: Foramen Magnum

  32. Bipedal Locomotion, cont. • Physical Changes: Spinal Curves

  33. Bipedal Locomotion, cont. • Physical Changes: Pelvis shape

  34. Bipedal Locomotion, cont. • Physical Changes: Arched Foot and Big Toe

  35. Africa – Origin of Humanity • Chimpanzees and Bonobos • Fossil Record • Rift Valleys

  36. Environment • Early primates and ancestors to chimps and modern humans most likely lived in dense forests • Early hominins most likely lived in open woodland sites

  37. Australopithecus afarensis • 1.1 – 4.3 mya • Brain size 420 cubic cm • Upper limbs long • 3.5 - 4 feet tall • Fossil remains suggest sexual dimorphism • Lucy

  38. Homo habilus • 2.5 – 2.6 mya • Habilis translates to “Handy Man” - Oldowan Tools * used for meat cutting and plant grinding

  39. Homo erectus • 1.8 – 2 mya • Heavy brow ridges • Face is more gracile • First Hominin found outside of Africa

  40. Neanderthals • 200 kya • Large Brain (1520 cubic cm) • Vertical forehead, no chin • Body characterized as robust: barrel shaped chest, short limbs, evidence for strong muscles

  41. Neanderthals • Most likely first hominins to bury their dead

  42. Settlement Patterns • Settlements: • Small family camps

  43. Modern HumansSomething new & different • Between 200,000 – 150,000 BP the first modern humans (H. sapiens sapiens) evolved in Africa Neander v. Human

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