Origins of Life 3 - Age of Earth


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  • So why do we study something that cannot be proven? Scientific Method = “best guess” theory is tested over and over until disproved. Whether right or wrong, a lot is learned along the way.
  • In 1859, Darwin proposed a theory that all life is related and has descended from a common ancestor in his book, "The Origin of Species" Darwin’s theory was not readily accepted because Earth was not believed to be old enough for the evolutionary processes he described to occur Scientist then began looking for clues that might suggest our planet is very old Since Darwin proposed his theory of evolution, scientists have used the fossil and geologic records to construct a very long history of life on Earth
  • In 1654 Bishop Ussher calculated that the Earth was created 6000 years ago (in 4004 BC) using evidence from the Bible and other Middle Eastern literature Based on all know scientific data available, most Creationists now estimate earth’s age to be about 10,000 years old
  • Organic macromolecules: lipids, carbs, amino acids, nucleic acids
  • Proposed first by American biologist Lynn Margulis in the early 1960's.
  • There have been around 22,000 documented meteorite discoveries on Earth and many have been found to hold organic compounds. In 1996, a group of scientists announced they had spotted strong evidence of microfossils on a Martian meteorite found in Antarctica showing that life may have existed on the Red Planet some 3.6 billion years ago. After years of intense debate, the issue whether the Martian meteorite contains life or not remains unresolved.
  • solid Iron inner core, liquid outer core, semi-solid Mantle (magma)
  • Why do you think very few fossils are found in igneous or metamorphic rock? Fossils are usually found in sedimentary rock. Since most sedimentary rock is laid down by water, it follows that most fossils were laid down by water as well. The vast majority of the fossil record is made up of clams and other hard-shelled creatures. Most of the remaining fossils are of either water-dwelling creatures or insects. Only a tiny, tiny fraction of the fossils we find are of plants, reptiles, birds, and mammals. Many of the fossils we find are of plants and animals which are still alive today. Some of the fossils we find are of plants and animals which are now extinct. The fossils found in one layer of stratified rock can be considerably different than the fossils found in another layer of the same stratified rock.
  • Mt . St. Helens displaced huge amounts of dirt, rock and snow, carving a mini grand canyon and leaving over 50 feet of sediment deposited across the valley within a matter of minutes
  • K: Animalia P: Chordata C: Aves
  • Archaebacteria ("ancient" extremophiles) are genetically more similar to eukaryotes than bacteria.
  • adaptations that increase fitness are "chosen" by the environment to be passed on via reproduction
  • Origins of Life 3 - Age of Earth

    1. 1. Origins of LifeGeology & Evolution Review - Age of Earth Theories -
    2. 2. Age of the Earth Assumptions  Science involves a lot of guesswork  Presuppositions affect research outcomes  Scientists with different beliefs look at the same data and come to very different conclusionsAssumption of Assumption of All theories of Evolution Creation Earth’s origins are based on Scientific Data assumptions & theories that can never be Evolution is Intelligent Design proven Seen is Seen
    3. 3. Age of the Earth: EvolutionMany scientists today believe that:• Humans began to evolve 1.4 million years ago• Fish were seen about 500 million years ago• Earth’s first life forms appeared 3.5 billion years ago• Our planet is roughly 4,600,000,000 years old
    4. 4. In 1859, Darwin published his theory of evolution in "The Origin of Species"• Theory not readily accepted  Earth not believed to be old enough  Scientists look for clues that suggest Earth is very old• Now scientists use fossil and geologic records to construct a very long history of life on Earth
    5. 5. Age of the Earth: The Bible• Bishop Ussher (in 1654) estimated Earth was created 6000 years ago (in 4004 BC) - based on the Bible & historical documents • Most Creationists now estimate earth’s age to be about 10,000 years old - based on historical documents & scientific evidenceBishop Ussher (1581-1656)
    6. 6. Age of the Earth: Theistic EvolutionSome scientists think evolution and the Bible fit together perfectly • Genesis creation account a metaphor (not a literal 6 days) • God supernaturally initiated the evolutionary process  created universe  "planted" DNA on Earth
    7. 7. Age of Earth Research All these theories still being researched • Theories change based on new data and findings • Don’t be too hasty to judge until youve really studied all the facts All these theories require a certain amount of faith
    8. 8. Primordial Soup Assumes ancient earth atmosphere of ammonia, hydrogen, methane and water vapor • volcano-like environments Lightning striking methane gas could form organic compounds • Amino acids, ATP, sugars and nitrogen bases synthesized from cyanide in lab experiment These simple molecules could arrange themselves into small, single-stranded strips of RNA which in turn produce DNA Problems: • 2nd Law of Thermodynamics (entropy) • Early atmosphere now believed to contain CO2 & O2
    9. 9. Endosymbiont Theory If a prokaryote ingested some aerobic bacteria, its possible that they formed a symbiotic relationship that helped them both survive better.
    10. 10. Extraterrestrial Seed Theory Complex DNA coding would have been necessary for even the hypothetical first simple cells. DNA evidence speaks of intelligent, information-bearing design. • Extra-terrestrial civilization sent/brought DNA to earth  Panspermia - "seeds everywhere" • archaebacteria, which can be dormant and withstand harsh environments, could have existed on another planet, making its way to Earth via space dust (meteorites) instead of originating here
    11. 11. Big Bang Theory A cosmic explosion (or expansion) hurling matter in all directions created the universe 10-20 billion years ago Evidence • distant galaxies are traveling away from us at great speeds • Cosmic radiation (from the explosion?) can be observed Problems • 1st Law of Thermodynamics – energy can neither be created nor destroyed • Entropy (2nd Law) – every life process increases the disorder and disorganization of matter (unless there is some sort of intervention) • Doesn’t account for organic (living) matter, only gas Probably will never be proven or dispelled – not a testable theory
    12. 12. Review: Earth/Fields of Study Archeology • The study of Artifacts Paleontology • The study of Fossils Geology • The study of Rocks & Earths composition/history Embryology • The study of embryos (pre-born organisms) Which parts of Earth are • SOLID inner core & crust • LIQUID outer core • SEMI-SOLID mantle
    13. 13. Review: Rock Cycle What are the 3 major rock types? • Sedimentary • Metamorphic • Igneous What are the steps involved in the formation of Sedimentary rocks? • Weathering • Erosion hint: WED B/C/C • Deposition • Burial/Compaction/Cementation Give an example of weathering • physical, chemical & biological (tree roots, freezing water, animals burrowing, rust, acid rain, waves crashing, etc.) What is erosion? • soil and sand carried away by water, wind, glaciers, landslides, etc. Name some ways sediments are deposited. • settling of biogenic ooze, melting icebergs & glaciers, volcanic eruptions, estuaries, evaporation
    14. 14. Review: Rock Cycle Describe the process of Burial, Compaction & Cementation. • Layers buried under new sediment • Particles pressed together by weight of water/sediment above • Sediment cemented by minerals crystallizing between particles What forces produce metamorphic rock? • Heat & Pressure What types of rock can become metamorphic rock? • all types What is produced when rock is melted into a semi-solid form? • magma What is the difference between an igneous intrusion & igneous extrusion? • intrustion: magma that comes up but never reaches the surface (dike/sill/batholith) intrustion • extrusion: magma that is spewed or flows out of the crust (lava) extrusion
    15. 15. Review: Fossils What is a fossil? • Evidence of organisms that once lived on Earth Where are most fossils found? • In sedimentary rock (also tar pits, amber or frozen in ice) Explain what a MOLD & CAST fossil is? • organism is buried in mud and disintegrates, leaving a hollow mold which later fills with sediment Give an example of a TRUE FORM fossil. • insect incased in amber or frozen wooly mammoth How does PETRIFACTION occur? • plant or animal remains are covered with water, and over time minerals from the water are absorbed into it and solidify Name some examples of TRACE FOSSILS. • T-Rex footprints, feeding marks, dino poo, tree root cavities, roundworm burrows
    16. 16. Review: Geologic Time What are some ways a scientist might estimate the age of a fossil or rock layer? • Stratigraphy • Dendrochronology • Radioisotope dating • Molecular clocks • Index fossils Explain the difference between RELATIVE AGE and ABSOLUTE AGE. • Relative: compares index fossils and rock layers (stratigraphy) to give an "older Relative than" or "younger than" estimation • Absolute: uses Dendrochronology & Radioisotope dating to give an estimated Absolute number of years old What does the principle of superposition assume? • that younger rock layers and fossils are deposited on top of older fossils & rocks
    17. 17. Review: Geologic Time What assumptions have been made in the formation of the GEOLOGIC COLUMN pictured here? • slow, even sedimentation rates (no hydrologic sorting or catastrophic events) • radiometric dating of rock layers is accurate • index fossils are reliable indicators to date rock layers • lack of transitional fossils & gaps in fossil record are due to periods of rapid evolution
    18. 18. Review: Paleontology ViewpointsPhyletic Gradualism (Uniformitarianism) "The present is key to the past" Slow sedimentation rates remain relatively constant throughout history • .2 - 100 cm of sediment laid down per 1000 years • takes millions of years for sedimentary rock layers to formPhyletic Discontinuity (Catastrophism) Catastrophic events cause rapid, widespread sedimentation • volcanoes, floods, ice ages, etc. • hydrologic sorting produces distinct rock layers with different fossilsPunctuated Equilibrium Slow sedimentation rates and evolutionary changes "punctuated" (interrupted) by catastrophic events and rapid evolution • Explains mass extinctions, "Cambrian Explosion" & lack of transitional fossils  Sudden disappearance of certain species  Sudden appearance of new species (fossils)  Rapid evolution triggered by sudden environmental changes
    19. 19. Review: Classification What are the 8 levels of classification? Hint: Did King Philip Came Over For Good Soup? Domain Kingdom Phylum Class Order Family Genus Species What is the type of evolutionary grouping shown here called? • a cladogram (Tree of Life)
    20. 20. Review: Phylogenetic Classification 3 Domains in the "Tree of Life" • Bacteria • Archaea • Eukarya 6 Kingdoms? • True bacteria • Ancient bacteria • Protists • Fungi • Plants • Animals What do scientists look at when trying to classify organisms into clades? • morphology  homologous & analogous features • embryological development • genetic similarities • the fossil record
    21. 21. Review: Evolution What does "descent with modification" mean? • Given enough time, many small changes in the gene frequency of a species result in big changes within a population, resulting in speciation What adaptations are passed between generations? • Only inherited (genetic) traits are given to offspring What are 3 mechanisms of evolutionary change? • genetic variation • natural selection  adaptations that increase fitness are "chosen" by the environment to be passed on via reproduction • genetic drift  random changes in gene frequency
    22. 22. Review: Genetic Variation Evolutionary change can ONLY happen with changes to the genes of a population. What are 3 sources of variation? • Mutation  caused by errors in DNA replication, increased by exposure to mutagens • Gene Flow  genetic exchange due to migration of individuals • Sexual Reproduction  meiosis: • crossing over • independent assortment
    23. 23. Review: Natural Selection How does it work? • A change in traits occurs  due to genetic variation  i.e. a green beetle has brown baby • There is differential reproduction  environmental changes affect who survives to reproduce  i.e. green beetles get eaten by birds, so only brown beetles survive to reproduce • Inherited traits are passed on  i.e. surviving brown beetles have brown babies because this trait has a genetic basis What is an ADAPTATION? • a feature that becomes common in a population because it provides some improved function necessary for survival and/or reproduction What is evolutionary fitness? • the ability to survive and reproduce
    24. 24. Review: Evolution What is the likelihood of a mutation being beneficial? • extremely small - most mutations are neutral, harmful, or lethal Which cells in an organism pass on their DNA to offspring? • gametes (egg, sperm, pollen, etc. - reproductive cells) What contributes to an organism "FITNESS"? • ability to compete for resources • health/hardiness • reproductive success • predator evasion • resistance to disease, starvation, effects of aging What is extinction? • when a species (and their DNA) fails to survive (they all die)
    25. 25. Review: Types of Evolution What is microevolution? • changes in traits (and gene frequency) within a species Name some examples of microevolution. • Peppered moth industrial melanism, beetle colors, Darwins finches, antibiotic-resistant bacteria What is macroevolution? • changes above species level Name some examples of macroevolution. • ferns  pine trees, fish  amphibians, dinosaurs  birds, whales  horses **never observed in nature What is coevolution? • when two different species affect each others adaptations What close relationships between organisms could contribute to coevolution? • Competitive, mutualistic, predator/prey, parasite/host
    26. 26. Review: Age of Earth Theories• How old do "Young- • How old do Evolutionists Earth" Creationists estimate earth’s age to believe earth to be? be: about 10,000 yrs about 4,600,000,000 yrs • What is Theistic Evolution? a theory of creation that assumes each "day" of creation was perhaps millions of years long incorporates the idea of evolutionary formation of living species but identifies a Creator (God) as the instigator (DNA-planter?)