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Human Evolution

Human Evolution. Van Roekel IB BIO II 4/14/14. How to date rocks and fossils. Use radioisotopes 14 C, 40 K, or 238 U Living organisms and rocks contain radioisotopes in small quantities Stop taking in new carbon products when dead Over time, radioisotopes decay to stable isotopes

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Human Evolution

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  1. Human Evolution Van Roekel IB BIO II 4/14/14

  2. How to date rocks and fossils Use radioisotopes 14C, 40K, or 238U Living organisms and rocks contain radioisotopes in small quantities Stop taking in new carbon products when dead Over time, radioisotopes decay to stable isotopes Using proportion of radioisotopes to stable isotopes, we can determine the age

  3. Half-Life • Half-life is the amount of time it takes for half the radioactive isotope in a substance to decay • 14C – 1 half life = 5,730 years • By looking at proportion of isotopes, can get an idea of age of fossils. • More radioisotopes = younger • Less radioisotopes = older

  4. Decay Curve

  5. Humans as Primates • Humans possess physical features that define primates • Opposable thumbs allow us to grasp objects • Long, thin, straight fingers to use tools • Finger pads and finger prints • Lack claws, have fingernails • Shoulder sockets increase movement in arms for greater mobility • Forward facing eyes which allow for stereoscopic vision (3-D)

  6. Trends in Hominid/human fossils In the skull

  7. Trends in Fossils • Ardipithecusramidus • 4.4-5.8 million years ago in Ethiopia • Close to split between humans and chimps • Canines shorter, not sharp, less projecting • Skull fragments indicate bipedalism

  8. Trends • Australopithecus afarensis • 2.5-4 million years ago in Eastern Africa • “Lucy” dated 3.5 million years ago • Tall lower jaw, large molar teeth, & projecting face • Cranial capacity 380-430 cm3 • Australopithecus africanus • 2.5-3 million years agoin Southern Africa • Tall, thick lower jaw, large molars and projecting face • Cranial capacity 435-530 cm3

  9. A. afarensis • A. africanus

  10. Trends • Homo habilis • 1.6-2.4 million years ago in Tanzania, Kenya, Ethiopia, and South Africa • Flatter face, larger molars, and cranial capacity 600 cm3

  11. Trends • Homo erectus • 100,000-1.8 million years ago in Europe, India, China, Indonesia, and Africa • Smaller Jaw, Receding Forehead, large brow ridges, and smaller molars • Cranial Capacity 1000 cm3 • First migratory ancestor because of the spread of fossils

  12. Trends • Homo neanderthalensis • 30,000-200,000 years ago in Europe and Western Asia • “Neanderthal man” • Smaller jaw, lower forehead, smaller brow ridges, and smaller molars • Cranial capacity of 1600 cm3

  13. Trends • Homo sapiens • Archaic forms 70,000-140,000 years ago in Africa, Europe, and Asia • High Forehead, no brow ridges, flat face, small molars, very small jaws • Cranial capacity 1300 cm3 • Developed art in the form of cave paintings and technology in form of finely crafted tools and weapons

  14. Coexistence of Several Hominid • Dating techniques show overlapping of species on Earth • A. afarensis and A. africanus approximately 3 million years ago • H. erecuts, H. neanderthalensis, & H. sapiens approximately 100,000 years ago.

  15. Uncertainties in Human Evolution • Gaps and questions about human evolution exist because of gaps in fossil record • Many for some species, few for others • Characteristics between males, females, and youths are difficult to interpret • Problems in accessing fossils • Physically accessible • Preservation • Politically or legally accessible • Leads to multiple hypothesis with different variations on evolution

  16. Changes in Brain Size • Bigger brains = more energy • More foods in diet • Foods richer in energy and protein • Earliest hominids were foragers, and occasionally eat meat • Hominids evolved to hunt in groups and use more sophisticated tools to increase meat in diet • Large quantities of animal bones found at sites of early humans • Increase in meat in diet and complexity of tools show direct correlation between changes in diet and brain size • High-protein, high energy foods fulfilled nutritional requirements of demanding brains • Bigger brains resulted in better tool making and hunting techniques to supply more energy • Practice of cooking food also improved diet and brain capacity

  17. Genetic vs. Cultural Evolution Genetic Evolution Cultural Evolution • Inherited characteristics passed from parent to offspring • Body morphology (cranial capacity, skull shape, height, etc) • Number of chromosomes • Biochemicals such as blood proteins • Acquired knowledge and characteristics passed within a social group or family • Language (spoken and written) • Rituals (ethnic & religious) • Art (sculptures, pottery, painting) • Technology (hunting, comfort, food)

  18. Significance of Genetic & Cultural evolution • Table on pg. 443 shows different tools used by different species • As brain increased, so did complexity of tools • Genetic evolution precedes cultural evolution • Past 30,000 years, majority of evolution has been cultural • Few genetic evolutionary changes • Many cultural evolutionary changes, such as languages, rituals, arts, shelters, agricultures, as well as using metals and obtaining energy

  19. Significance of Genetic & Cultural evolution Cultural evolution can lag behind genetic evolution Hominid’s brain has been roughly the same size for 140,000 years Major cultural advances haven’t appeared until 35,000 years ago Recently, most changes have been cultural evolution with much greater advances without any major genetic changes.

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