The document summarizes key aspects of Charles Darwin's theory of evolution by natural selection, including his observations that led to his conclusions. It discusses how Darwin proposed that individuals with variations better suited to their environment were more likely to survive and pass on their traits, leading to evolution over generations. The document also reviews early human fossils and ancestors, including Australopithecus afarensis, and how the discovery of fossils like the Laetoli footprints provided evidence that early humans were bipedal.

1. Chapter 1: Out of the Woods

2. Theory of Evolution Charles Darwin 19th century British scientist Voyage of the Beagle: 1831-1836 “On the Origin of Species by means of natural selection”: 1859

3. Charles Darwin

4. H.M.S. Beagle

5. On the Origin of Species 1859

6. The Reaction to Darwin 1860

7. Darwin’s Argument for the Evolution of Species Observation # 1 Most species produce far more offspring than could possible survive Example: One pair of mice could produce about 40 babies a year and these babies could have their own offspring after only six weeks Imagine what would happen if this process kept going indefinitely

8. Darwin’s Argument for the Evolution of Species Observation # 2 An individual’s chances of survival will be affected by the environment in which it lives Example: The environment includes the weather, finding food and a mate,finding somewhere to live and other animals and plants

9. Darwin’s Argument for the Evolution of Species Observation # 3 Individuals vary. Some will be better adapted to their environment and will stand a better chance of surviving. Darwin did not know what caused variation—we now know it is caused by mutations and the mixing up of genes during sexual reproduction.

10. Darwin’s Argument for the Evolution of Species Conclusion # 4 If the better-adapted individuals survive long enough to reproduce … and if they pass the characteristics [genes] that helped them to survive on to their offspring. . . Their offspring will also stand a better chance of surviving. This idea is sometimes called “the survival of the fittest”

11. What is a species? Is it just animals and plants that are “similar”? How similar do they have to be? Who decides? How?

12. Are these animals from the same species?

13. Here is their offspring

14. So why aren’t horses and donkeys part of the same species? Because mules are not fertile!

15. How did the giraffe get such a long neck?

16. Lamark’s Answer: they stretched their necks to reach food: inheritance of acquired characteristics

17. Darwin’s Answer: giraffes with mutation for longer necks were able to reach food—>survived in greater numbers—>lived to reproduce and pass along their long-necked gene

18. Did Humans Evolve? Traditional religious answers spotlight human’s place at center or peak of creation Modern scientific accounts focus on the emergence of all life forms as equally important: inter-relatedness of all life Link

19. What is the subject and the source for the picture on p. 8-9? Australopithecus scientific and artistic re-imagination and reconstruction of 5 million years ago based on scientifically informed guess work

20. A real picture?

21. What are the Laetoli footprints? made by ancient human ancestors 3.5 million years ago several hominids walking in a group made footprints in soft volcanic ash that were covered up, buried, preserved, and came to light Link

22. Laetoli Footprints

23. Laetoli Footprints 2

24. Laetoli Footprints 3

25. Where were the footprints found? the lakebed of an ancient lake in northern Tanzania (East Africa)

28. What do they show us about our earliest ancestors? he/she was a two-legged mammal with upright posture—>"bi-pedal” Link

29. Bi-pedalism

30. Bi-pedalism 2

31. Who directed the team that found them? When? Where? Mary Leakey—>wife to husband Louis Leakey: British archaeologists 1976—> after more than 40 years of looking! Tanzania

32. Why are teeth so commonly found among fossils? Why are they so important to archaeologists? teeth are the hardest material in human body—> enamel slowest to decompose—>lasts much longer than the rest of the body chewing marks on teeth indicate diet—>infer ecological niche, lifestyle, intelligence

33. By the way, what is a fossil? a mineral replica of a skeletal piece of an animal

34. Why are early human fossils rarer and more precious than diamonds? original population of early hominids was tiny compared to human population today after death, corpses here usually displaced and devoured by larger predators and scavengers if skeleton intact, it is usually decomposed ("eaten") by microorganisms—>"circle of life and death" if intact, it must be rapidly covered by protective sediment if protected, it must be fossilized by mineral replacement of organic material if fossilized, it must come to light and be discovered by someone who knows what it is!

35. How are fossils made? Link

36. What is the name of the species that made the Laetoli footprints? Australopithecus afaransis—> "Southern ape of the afari people"

37. Australopithecus afaransis

38. Australopithecus afaransis

39. When were the fossils originally made? How? 3-4 million years ago footprints made in soft volcanic ash and immediately covered Link

40. What are three anatomical differences between apes and humans that make it possible for humans to walk upright? extended knee and hip joint allow straight leg walking, not ape waddling center of gravity centralized under skull, not thrust forward as in apes curved lower spine to support skull, not attached as in apes parallel big toe, not opposable grasping toe, in order to distribute weight while walking Link

41. The First Couple?

42. Why is the artist's picture on p. 16 controversial? sentimental pairing of male and female "couple" more likely pair: mother and child

43. What is a hominid? member of human "family" of ancestors walked upright

44. Why was bi-pedalism such a significant change in human history? frees forearms for carrying tool-making gesturing intricate manipulations ability to walk upright large brains Link

45. What are the three most significant unique human characteristics? ability to walk upright large brains ability to make tools speech

46. Why did scientists used to think that larger brains were the first uniquely human characteristic? bigger brains precondition for higher intelligence intelligence precondition for tool invention, making, and speech

47. Which of these three differences do scientists today believe emerged first? upright posture but brain size remained unchanged for millions of years

48. What does the Latin term "Homo sapiens" mean? Who does it describe? "man the wise, the intelligent" modern humans like us!

49. How large is the average adult brain? [No jokes, please!] Homo sapiens: 1200-1600 cc.

50. How large were the brains of Australopithecus afaransis? Australopithecus: 350-500 cc

51. Comparative brain sizes

52. What is the difference between tool using and tool making? What does either indicate about intelligence? improvisation or imitation vs. invention and planning highly developed time sense for tool making

53. How long ago did the chimp line of evolution split from the human line? What is the evidence for this? 5-6 million years ago comparison of blood proteins and genes of chimps and humans

54. What is the "foramen magnum"? How does it differ in humans and apes? humans: entry of spinal chord in center of skull chimps: entry further back in skull—>head thrust forward, not balanced—> limitation of size and weight

55. The foramen magnum

56. The foramen magnum compared

57. Brain size compared

58. Brains compared

59. What significance did this difference have for the direction of human evolution? brain growth depended on balance—>built-in limitation on brain-size of other apes

60. What percentage our DNA do humans share with chimps? 98% of human and chimp DNA is identical—> chimps and gorillas share 97%

61. Why did upright posture have to precede the evolution of upright brains? larger brain size cannot be balanced or held up by ape posture—> neck and spine not able to support it larger brain useless without free forelimbs to carry out instructions from brain

62. What was the most significant environmental change around 10-15 million years ago that favored apes with upright posture over more traditional apes? How did it do this "favoring" long term drought reduced forests—>increased grasslands/savannah predator/prey advantages and disadvantages of survival

63. What is the "key process" that drives evolution forward? changes in environment—>upsets settled patterns of survival of plants, animals, humans constant process of mutation—> reproduction never perfect—>mutation supplies new variations that might be beneficial in dramatically new circumstances

64. What survival advantages did a more upright posture give those apes who had it? minimized skin exposure to harsh ultraviolet sunlight cooled brains and conserved water

65. Are there other candidates for the title of "our earliest human ancestor"? Why don't we know for certain who the earliest actually is? Ardipethecus ramidus—> 4.4 million years old & Australopithecus anamensis—> 4.2 million years old new fossil discoveries very likely—> ALL SCIENTIFIC KNOWLEDGE IS PROVISIONAL!

66. Why is the Great Rift Valley in East Africa such a great place to explore for early human fossils? Africa continent of origin during prehistory it was a wet region that supported abundant plant & animal life during our time it is a dry region where spring rains wash away surface sediment to expose the layers beneath long-buried fossils are brought to light for those with the eyes to know what they are seeing

67. The Great Rift Valley

68. Name four of the best-known paleoanthropologists in the 20th century? Louis Leakey Mary Leakey Richard Leakey Donald Johansen

69. Four Great Paleoanthropologists

70. What was the main staple of the Australopithecus diet? vegetarian—>roots, tubers, nuts, berries occasional small rodents, lizards, insects

71. What was the probable key to the survival of Australopithecus against powerful, hungry predators? social nature lived in groups of 20-30 safety in numbers

72. Who is "Lucy"? Why is she such a significant archaeological find? she is the most complete skeleton of Australopithecus afaransis "Lucy In the Sky With Diamonds" by Beatles playing on a cassette player the night she was discovered Link

73. Why is the controversy about the fossilized bones of the "first family"? remains of 13 individuals—> 9 adults & 4 children 200 fragments dramatic disparity between male and female height—> sexual di-morphism or separate species? Link

74. How does Lucy's lower jawbone (mandible) show she is an evolutionary midpoint between the other apes and modern Homo sapiens? smaller jaw size indicates different diet different diet indicates different lifestyle and ecological niche

75. The Change in Teeth

76. Change in Jaws