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Evolution of Life on Earth

Evolution of Life on Earth. Chapter 11-12. How old is the Earth?. About 4.5 billion years old Time scale is divided into: Eons Eras Periods Epochs. Fossil Evidence of Life. Oldest fossils found in the lowest rock layers How do you find the real age of a fossil?

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Evolution of Life on Earth

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  1. Evolution of Life on Earth Chapter 11-12

  2. How old is the Earth? • About 4.5 billion years old • Time scale is divided into: • Eons • Eras • Periods • Epochs

  3. Fossil Evidence of Life • Oldest fossils found in the lowest rock layers • How do you find the real age of a fossil? • Carbon-dating using half-life (you’ll learn more about this in Chemistry)

  4. Life on Earth • Precambrian Era- Before 600 million years ago • Limited life on earth • Evidence of bacteria

  5. The First Prokaryotes • Prokaryotes were Earth’s sole inhabitants • From 3.5 to about 2 billion years ago • As prokaryotes evolved, they exploited and changed young Earth

  6. The oldest known fossils are stromatolites • Rocklike structures composed of many layers of bacteria and sediment • Date back 3.5 billion years ago

  7. Lynn Margulis (top right), of the University of Massachussetts, and Kenneth Nealson, of the University of Southern California, are shown collecting bacterial mats in a Baja California lagoon. The mats are produced by colonies of bacteria that live in environments inhospitable to most other life. A section through a mat (inset) shows layers of sediment that adhere to the sticky bacteria as the bacteria migrate upward. (a) Some bacterial mats form rocklike structures called stromatolites, such as these in Shark Bay, Western Australia. The Shark Bay stromatolites began forming about 3,000 years ago. The insetshows a section through a fossilized stromatolite that is about 3.5 billion years old. (b) Figure 26.11a, b

  8. The origin of eukaryotes • Symbiotic relationships • Large cell engulfs cyanobacteria (chloroplast?) • Large cell engulfs aerobic bacteria (pre-mitochondria?) • Small cell becomes dependent on genetic material present • Animal cell may have evolved from a plant cell that lost its chloroplast

  9. Cytoplasm DNA Plasma membrane Ancestral prokaryote Infolding of plasma membrane Nucleus Endoplasmic reticulum Nuclear envelope Engulfing of aerobic heterotrophic prokaryote Cell with nucleus and endomembrane system Mitochondrion Mitochondrion Engulfing of photosynthetic prokaryote in some cells Ancestral heterotrophic eukaryote Plastid Ancestral Photosynthetic eukaryote Figure 26.13 • The prokaryotic ancestors of mitochondria and plastids • Probably gained entry to the host cell as undigested prey or internal parasites

  10. Cambrian Period • Began 590 MYA (Million Years Ago) • Huge increase in the number and diversity of living things

  11. From Water to Land • In order of appearance: • Plants • Fungi • Arthropods • Amphibians

  12. Where did the rest of us come from? Amphibians Reptiles Birds Mammals

  13. Extinctions • Permian extinction • 250 MYA: 90% of ocean species and many land insects • Cretaceous extinction • 65 MYA: Majority of dinosaurs, sea and land species • Why???

  14. Monkey Business! • What do you know about primates? Write down each type of primate that you can think of. See how many you can get!

  15. Mammals • First appeared 220 MYA • Evolved from small, active, meat-eating reptiles • What are the characteristics of mammals?

  16. Primates • 65 MYA • A group of mammals that include all monkeys, apes, and humans • 2 groups: • Prosimians • Anthropoids

  17. Prosimian • Pre-monkey • Small, monkey-like primate • Large, forward-facing eyes

  18. Anthropoid • “Humanlike” • Monkeys, apes, humans

  19. Characteristics of Primates • Make a fist: opposable thumb • Sensitive finger tips and protective nails • Arms move freely in shoulder joint • Binocular vision: use both eyes at once with overlapping fields • Relatively large brains • Some species make and use simple tools • Complex social behaviors and family relationships

  20. ADAPTATION OF THE PRIMATE (& HUMAN) HAND Living things have bodies that are adapted for the places they live and the things they do. • Fish have gills to obtain oxygen from water • Birds have hollow spongy bones so that they will be light enough to fly. • Arctic animals have layers of fat and thick coats of fur to keep warm in the frigid Arctic climate. Primates, too, are adapted for the things they do. One of our adaptations is our hand. Humans, as well as monkeys, gorillas, and other primates, have a hand that can grasp objects.

  21. Adaptation of the Human Hand YOUR TASK Do each of the following activities and have your partner time how long it takes you to do each one. Record the times in a data sheet. A. Tie a knot in a piece of string. B. Remove one shoe and replace it on your foot. C. Unbutton two buttons and button them again. D. Open a door. E. Write your name on a piece of paper.

  22. NEXT, firmly tape or band your thumb to the palm of your hand and complete the same activities again, timing how long it takes you this time. Enter the times in your data table.

  23. Time to perform various actions:

  24. 1. Describe how your hand is adapted for doing the actions you tested. 2. You have an opposable thumb. Explain what you think this means. 3. Why do you feel that human hand adaptations have helped to make humans such a successful species on earth? (List and explain at least 2 reasons.)

  25. Anthropoids that evolved to become the human family 5-8 MYA Many different species existed at once Today, only Homo sapiens Hominids

  26. Lucy, a famous fossil • Discovered in 1974 • Small female hominid skeleton • 3-4 MYA, dubbed by some as the “Missing Link” • Australopithecus afarensis

  27. Homo habilis • “Handy Man” • Discovered in 1964 • Used and made tools • 2.4 - 1.6 MYA • Direct ancestor to Homo sapiens

  28. Homo erectus • “Upright Man” • Migrated out of Africa into Asia and Europe • Taller with a larger brain • Built fires, wore animal skin clothing, lived in caves, made stone tools • 1.8 MYA

  29. Neandertals • 300,000 – 200,000 years ago • 1856, fossils found in Neander Valley, Germany • Europe, Asia, Middle East • Cold-weather adapted • Social structure, tools, buried dead, hunted

  30. Cro-Magnon • Appeared 40,000 years ago • H. sapiens archaic • Taller and lighter than Neandertals, like modern humans • Complex tools, culture, well-designed dwellings, language, art, trade • Tools from bone, antler, wood, stone, ivory

  31. Us! • Homo sapiens sapiens • Appeared 100,000 years ago • “Out of Africa” • Supported by fossil and DNA evidence

  32. Now/Homework • Read pp. 280-294 • P.284 #1-3 • P.289 #1-4 • P.294 #1-3

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