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Human Evolution

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  1. Human Evolution www.okc.cc.ok.us/deanderson/index/human_evolution.ppt

  2. The Evolution of Humans

  3. Theory of Evolution • Science has overwhelming evidence that all life is constantly evolving

  4. Natural Selection • One mechanism of evolution • Main concepts of natural selection • Overproduction of offspring • Inherited variation in offspring • Competition • Best adapted in a given environment survive and reproduce to increase their kind • They are naturally selected

  5. Overproduction of Offspring • Elephants (very slow reproductive rate) • If all the offspring of one elephant pair survive and all their offspring survive then: • 750 years = 19,000,000 elephants • 1200 years = Enough elephants to cover the earth! • Beetles • A handful that weighs 10 mg each • 82 weeks • 61,000,000,000,000,000,000,000 ton • The weight of the earth!

  6. The Evolution of Humans

  7. Variation of Offspring • Offspring of the same parents are different from each other

  8. Competition • Since more individuals are born than can survive for an extended period of time, they compete for resources • Food • Living space • Mates

  9. Best adapted to a given environment are selected to survive • Brown bears • Adapted to survive in Oklahoma • Polar bears • Adapted to survive in Alaska

  10. The Evolution of Humans The Ecological Theatre • The Stage: East Africa • The Setting: A time of unrest... • Geologically… • The rift zone - uplifts, rifting, volcanoes • Climatically… • A series of glaciations • Global climate change • Changes in sea level

  11. Sequence of Human Evolution • Hundreds of fossils have been found • Some of the major fossils will be discussed in this presentation

  12. Australopithicus afarensis • 3.5 million years ago • Nicknamed Lucy • Walked upright • Small brain • Skeleton human like • Feet • Pelvis • Upright stance

  13. Comparative Anatomy Lucy Gorilla Human • Gorilla pelvis adapted for knuckle walking • Human pelvis adapted for upright walking • Lucy’s pelvis very similar to human pelvis

  14. Knuckle Walking • Requires an elongated pelvis and long arms

  15. Lucy’s pelvis allowed her to walk like a human instead of an ape.

  16. Fossilized Footprints • Footprints left when a a pair of Australopithecines walked in the ash of a recently erupted volcano

  17. Lucy Chimp Skull Anatomy • Thick brow ridges like a chimpanzee • Cranial capacity 400 cc. Chimp 350 cc. • Teeth similar to human teeth

  18. Lucy: A Transitional Fossil • Transitional fossil shows characteristics of two kinds of animals • Represent the transition from one organism to another • Ape characteristics • Skull • Cranial capacity • Human characteristics • Walked upright • Feet • Pelvis

  19. Australophithicus africanus • 2.8 million years ago • Cranial capacity 460 cc

  20. Homo habilis • Cranial capacity 630 cc • Flatter face than Australopithecines • Used tools • Nicknamed handy man

  21. Homo erectus • 1.8 million to 35,000 years ago • 1,000 cc cranial capacity • Large brow ridges • Sloping forehead • More advanced tools than H. habilis

  22. Homo erectus • Skeleton very similar to modern man • Used fire • Traveled • Fossils found in Africa, Europe, China, Indonesia

  23. Homo neanderthalensis • 135,000 to 25,000 years ago • Cranial capacity up to 1750 cc • Larger than modern man • No chin • Sloping forehead • Buried dead with tools and flowers

  24. The Evolution of Humans The Cro-Magnons and the Neanderthals

  25. Homo sapiens • 200,000 years ago to present • Photo is a skull 100,000 years old • 1400 cc cranial capacity • Vertical forehead • Pronounced chin

  26. The Evolution of Humans • What about the Neanderthals?

  27. The Evolution of Humans • What about the Cro Magnons?

  28. Modern Homo sapiens • Small front teeth • Small brow ridges • Rounded cranium

  29. Homo neanderthalensis Australopithicus afarensis Australopithicus africanus Homo erectus Homo habilis Common ancestor Modern apes Sequence of Human EvolutionOne of several possibilities Homo sapiens

  30. Evolution of Skull • Cranial capacity increases for a larger brain • Face become flatter • Brow ridges become smaller • Forehead becomes higher • Chin develops

  31. Tools used to learn about our evolutionary past • Study of fossils • Comparing DNA • Comparing chromosomes • Comparing protein sequences

  32. Paleontology • Study of fossils • Allows us to see anatomical similarities between us and organisms that lived in the past • Allows us to see how our ancestors have changed over time

  33. Comparing DNA • Human DNA compared to: • Chimpanzee 99% same • Gorilla 97.7% same • Orangutan 96.3% same • Another human 99.9% same

  34. The Evolution of HumansThe Great Leap Forward • Due to evolution of a mechanism that allows speech and language? • Characterized by the appearance of... • Use of symbols... • Complex tools... • Innovations in hunting techniques and strategies... • Increased population size, development of social systems... • Houses, boats, long distance trade, ornaments • Art, music, rituals...

  35. The Evolution of Humans