Basic premises for this discussion

Transcription

1 Only a theory?

2 Basic premises for this discussion Evolution is not a belief system. It is a scientific concept. It has no role in defining religion or religious beliefs Evolution is a theory but you don t get any better than that in science There is a lot of contention about evolution, but not among scientists or scientific organizations.

3 Some basic definitions Fact: an observation that has been repeatedly confirmed Law: a descriptive generalization about how the physical world behaves Hypothesis: a testable statement that can be used to build inferences and explanations

4 Some basic definitions Theory: a well-substantiated explanation that incorporates facts, laws, inferences and tested hypotheses. In science, you don t get any better than a theory.

5 What is evolution? Let s start by seeing what evolution is not.

6 What is evolution? A basic definition of evolution evolution can be precisely defined as any change in the frequency of alleles within a gene pool from one generation to the next." - Helena Curtis and N. Sue Barnes, Biology, 5th ed Worth Publishers, p.974

7 So what does the definition mean? Evolution is a change in the number of times specific genes that code for specific characteristics occur within an interbreeding population Individuals don t evolve, populations do There is no implied improvement in evolution

8 So what does the definition mean? Things don t change because organisms want or need them to (Lamarkism) There is no difference between macroevolution and microevolution. Macroevolution is merely a collection of microevolution events.

9 Definition problems Part of the problem is that a number of different definitions for evolution can be found both within and without the scientific community. These can easily confuse laypeople.

10 Definition problems "evolution: The gradual process by which the present diversity of plant and animal life arose from the earliest and most primitive organisms, which is believed to have been continuing for the past 3000 million years." -Oxford Concise Science Dictionary "evolution:...the development of a species, organism, or organ from its original or primitive state to its present or specialized state; phylogeny or ontogeny" - Webster's "evolution:...the doctrine according to which higher forms of life have gradually arisen out of lower." - Chambers

11 Definition problems In addition to being simply wrong, these definitions can cause confusion since it is common for non-scientists to enter into a discussion about evolution with such definitions in mind.

12 A brief history of evolution Charles Darwin was born on February 12, 1809 in Shrewsbury, England. From 1831 to 1836 Darwin served as naturalist aboard the H.M.S. Beagle on a British science expedition around the world. He observed much variation in related or similar species of plants and animals that were geographically isolated from each other. These observations were the basis for his ideas.

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14 A brief history of evolution Contrary to popular belief, Darwin was not the first person to describe the concept of evolution, but he was the one who gave it its driving force.

15 Darwin presumed that populations of individuals changed over time, and, in 1844, he developed the concept of the driving force for evolution. It wasn t until many years later that he published his idea. I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection. Charles Darwin from "The Origin of Species,

16 Natural Selection Darwin knew nothing of genes, but what he did have were two observations and a little inference that provided the motive force for evolution.

17 Natural Selection Observation 1: Organisms generally have more offspring than can survive to adulthood. Observation 2: Offspring are not identical. There is variation in their appearance, size, and other characteristics.

18 Natural Selection Inference: Those organisms that are better adapted to their environment have a greater likelihood of surviving to adulthood and passing these characteristics on to their offspring. Survival of the fittest.

19 Darwin s dilemma Darwin was hesitant to publish his theories because of the backlash that previous authors received. If this book is true, religion is a lie, human law a mass of folly and a base injustice; morality is moonshine. -Adam Sedgwick s response to Robert Chamber s 1844 book, Vestiges of the Natural History of Creation, in which Chamber s hinted that organic creation was the result of natural laws, not God s intervention.

20 Darwin s dilemma It was a letter Darwin received on June 18, 1858, that precipitated the publishing of The Origin of Species. Alfred Russell Wallace, exploring in Asia, had come to the same conclusion as Darwin.

21 Darwin s dilemma Darwin, with a strong sense of honor, arranged for a simultaneous reading of his and Wallace s papers before the Linnean Society. The readings were met with silence, so Darwin published the full text of his ideas. then it hit the fan.

22 tell me, is it on your grandfather s or grandmother s side that you are descended from an ape. -Bishop Samuel Wilberforce to Darwin defender, Thomas Huxley If the question is put to me would I rather have a miserable ape for a grandfather or a man highly endowed by nature and possessed of great means and influence and yet who employs these faculties and that influence for the mere purpose of introducing ridicule into a grave scientific discussion I unhesitatingly affirm my preference for the ape. -Huxley s response

23 In Darwin s lifetime he would be recognized as one of the great masters of science. By the 1870s almost all serious scientists in England had accepted evolution.

24 Observation and Inference Let s do a little exercise niak.com

25 Dinosaur tracks are common occurrences in the southern and eastern U.S. Here is a section of tracks that were recently uncovered. Can you answer the following questions?

26 What is the size and nature of the organisms? Were the tracks made at the same time? How many animals were involved? Can you reconstruct the events that occurred?

27 In what direction did the animals move? Did they change speed or direction? Was the soil moist or dry? In what type of rock were the prints made?

28 The following summer some more digging revealed more of the track. What additional information have you gained that allows you to refine your answers?

29 Were the tracks made at the same time? How many animals were involved? Can you reconstruct the events that occurred? In what direction did the animals move? Did they change speed or direction?

30 In the final summer of the excavation one last part of the footprint trail was uncovered. Does this section provide additional information to refine your hypothesis?

31 So what happened? What part of your hypothesis is observation? What part is inference? What part is conjecture?

32 This is how science is done.

33 Ten questions about teaching evolution in the classroom Teaching evolution in the K-12 classroom can pose pitfalls for a teacher. What follows are responses to 10 very common questions about evolution and its place in education.

34 4. Why is evolution considered a scientific fact? A scientific fact may be defined as a theory that has been repeatedly confirmed and never refuted. Evolution fits this description, but that does not mean that new evidence couldn t refine or disprove the theory. Science is a progression, not a destination.

35 9. Does the evidence really exist? In short, overwhelmingly. Numerous examples of discovery of predicted intermediate forms, genetic similarity studies, and new molecular mapping have only confirmed the theory There are no cases where evolution has been found to be false

36 A copy of this presentation is available for download at: Thank you for your interest, attention, and input. Carl Wozniak,

37 Ch Evolution

38 Unit 4 Evolution (Ch. 14, 15, 16) 1. Define Evolution 2. List the major events that led to Charles Darwin s development of his theory of Evolution by means of Natural Selection 3. Summarize the major events of the Geologic Time Scale 4. Compare and contrast early experiments that support the concept of biogenesis and disproved spontaneous generation 5. List some examples of direct and indirect evidences of evolution 6. List the 6 different types of fossils & the technique used to identify the age of them. 7. Explain what the first cells were thought to be and give characteristics of them 8. Summarize the effects of the different types of Natural Selection on gene pools 9. Relate changes in genetic equilibrium to mechanisms of speciation 10.Explain the role of natural selection in convergent and divergent evolution 11.Analyze the Endosymbiotic Theory - including why the Mitochondria and Chloroplasts were thought to be on their own. 12.Compare and contrast modern theories of the origin of life 13.Explain how the structural and physiological adaptations of organisms relate to natural selection 14.Identify adaptations of primates 15.Distinguish the evolutionary relationships of primates 16.Summarize the major anatomical changes in hominids during human evolution 17.List the phylogeny of the human species from Australopithecus to Homo sapiens. 18.Identify what probable explanation allowed humans to get to North America

39 SWBAT Scale 4: Same as a 3.0 but I can make inferences & application to the SWBAT s 3: I COMPLETELY understand all parts of the SWBAT 2: I understand MOST of the SWBAT s with teacher help 1: I understand a little of the SWBAT s but need teacher help 0: I do NOT understand any part of the SWBAT s and need help!

40 History of Life The record of life Early history of earth High temps, active volcanoes, Atmosphere consisted of carbon dioxide, methane, nitrogen, ammonia water vapor; very little free O 2 Some scientists propose that organisms formed 3.9 billion years ago

41 History of Life The History of Rocks Fossil evidence of life found in rocks, 10,000 year minimum Paleontologists scientists who study ancient life Most fossils are found in what type of rock? - Sedimentary Fossils reveal evidence of environment that existed when the organisms lived

42 History of Life The age of the fossil Relative dating if rock & fossil lay has not been disturbed, the surface must be younger than deeper layers.

43 History of Life Radiometric Dating Measures the age of rocks by measuring the decay of a radioactive isotope Half-life rate of decay C-14 takes 5,730 years for its ½ life Dating technique frequently produces inconsistent dates because the initial amt. of isotope can never be known for sure.

44 History of Life Fossils types Mold Depression left (no organism) Cast minerals fill in space replica of organism Petrified mineral replace hard parts fine detail Imprints thin objects leave delicate patterns Amber/Frozen actual material in ice or sap Trace fossils footprints, wormholes Evidence of an organism

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46 History of Life Trip through time Geologic time scale divided into 4 eras Precambrain life begins Paleozoic enormous increase in diversity Mesozoic changes in organisms Cenozoic where we are now Mass extinction entire groups of organisms disappear from fossil record almost at once

47 Geologic Time Scale

48 1. Precambrian Era 0.5bya to 4.6 bya Age of Bacteria Earth s first living organisms appear 3.5 bya What type of organism were these? Prokaryotes No life anywhere, no oxygen in the air

49 Precambrian Era 4 BYA Water covers almost the entire Earth 2.2 BYA Stromatolites and Blue-Green Algae begin to fill the air with oxygen What cellular process allowed the algae to fill the air with oxygen? Photosynthesis 2.5BYA The first continents form

50 Precambrian Era 1.4 BYA the first organisms with an enclosed nucleus and membrane-bound organelles appear. These organisms are known as? Eukaryotes

51 The Paleozoic Era mya Age of Invertebrates, Fish, & Amphibians Geological Events 380MYA Oxygen levels reach about 20% (where they are today) MYA- Abundance of sea life is what turns into the oil we use for cars today 575 MYA - Appalachian mountains formed Colorado was covered in oceans

52 The Paleozoic Era mya Life Events 500 MYA First fish 400MYA First insects 360 MYA First Amphibians 350 MYA First Trees form 300 MYA First Reptiles. Life moves out of the oceans

53 Paleozoic Era The End of an Era 248 mya fossil records show that: 95% of all marine species died off 75% of all land vertebrates died off Evidence shows that this was the result of a large amount of volcanic eruptions causing CLIMATE CHANGE This marked the end of the Paleozoic era and the beginning of the Mesozoic Era What do you think happened to life on Earth after this point?

54 3. Mesozoic Era 248mya -65mya The Age of Reptiles Geological Events 200 MYA - Pangaea begins to break up 65 MYA - The Rocky Mountains begin to form heavily Ferns and Gymnosperms are dominant Plant Life

55 The Mesozoic Era Began approximately 245 million years ago after a major mass extinction. Is subdivided into 3 periods: Triassic Jurassic Cretaceous Ends about 66 million years ago with a major mass extinction

56 Key theme: Pangea breaks up Process will take 150 my and will extend into the Cenozoic Laurentia/Baltica and Australia/Antarctic a are still joined at the end of the Mesozoic

57 The Triassic Period million years ago Immediately after the Permian Mass Extinction Lots of new area is open for animals to live

58 The Jurassic Period Million Years Ago Giant plant-eating dinosaurs Vicious carnivore dinosaurs Oceans full of fish, squid, sharks, etc. Ichthyosaurs and Plesiosaurs Pterosaurs Birds

59 The Cretaceous Period million years ago Ends with a mass extinction around 66 million years ago Approximately 60% of all species went extinct. Affected many land animals/plants Affected fewer marine animals First flowering plants!

60 4. Cenozoic Era 65mya - Present The Age of Mammals Geological Events Life Events Continents continue to move apart 1.6 MYA major ice age Mammals become dominate species on Earth Flowering plants (angiosperms) become dominate plants on Earth

61 Cenozoic Era 35MYA Early Primates 2.8 MYA Homo habilis 500,000 years ago - First Homo sapiens

62 History of Life Earth began around 4.6 billion years ago Life appears ~ billion years ago Plate tectonics Earth contains several rigid plates that drift on top of molten rock

63 History of Life Origins of life Early Ideas Spontaneous Generation the idea that nonliving material can produce life

64 History of Life Francesco Redi Disproved spontaneous generation of large organisms Fly's on meat Louis Pasteur disproved spontaneous generation of small (micro) organisms Biogenesis - Idea that living organisms come only from other living organisms

65 History of life Origins Many theories Can never be proven One theory simple organic molecules formed, then become organized into complex organic molecules; nucleic acids, proteins, and carbs. Tested by Miller & Urey

66 History of Life Formation of the Protocell Large, ordered structure enclosed by a membrane that carries out some of life s activities (growth and division) Evolution of cells Proposed characteristics of original cell Anaerobic No Oxygen needed Heterotrophs Cannot make their own food Prokaryote No nuclei Archeabacteria Live in harsh environments

67 History of Life Cells Eventually used up food supply. Needed to start making their own food Photosynthesis (autotrophs) Photosynthetic Autotrophs Produce O2, which helps produce O3 Endosymbiotic Theory Eukaryotes evolved from symbiotic relationships between prokaryotes Bacteria with Chloroplasts & Mitochondria

68 History of Life Endosymbiotic theory click to watch animation Video: How we think complex cells evolved - Adam Jacobson

69 Unit 4 Evolution (Ch. 14, 15, 16) 1. Define Evolution 2. List the major events that led to Charles Darwin s development of his theory of Evolution by means of Natural Selection 3. Summarize the major events of the Geologic Time Scale 4. Compare and contrast early experiments that support the concept of biogenesis and disproved spontaneous generation 5. List some examples of direct and indirect evidences of evolution 6. List the 6 different types of fossils & the technique used to identify the age of them. 7. Explain what the first cells were thought to be and give characteristics of them 8. Summarize the effects of the different types of Natural Selection on gene pools 9. Relate changes in genetic equilibrium to mechanisms of speciation 10.Explain the role of natural selection in convergent and divergent evolution 11.Analyze the Endosymbiotic Theory - including why the Mitochondria and Chloroplasts were thought to be on their own. 12.Compare and contrast modern theories of the origin of life 13.Explain how the structural and physiological adaptations of organisms relate to natural selection 14.Identify adaptations of primates 15.Distinguish the evolutionary relationships of primates 16.Summarize the major anatomical changes in hominids during human evolution 17.List the phylogeny of the human species from Australopithecus to Homo sapiens. 18.Identify what probable explanation allowed humans to get to North America

70 SWBAT Scale 4: Same as a 3.0 but I can make inferences & application to the SWBAT s 3: I COMPLETELY understand all parts of the SWBAT 2: I understand MOST of the SWBAT s with teacher help 1: I understand a little of the SWBAT s but need teacher help 0: I do NOT understand any part of the SWBAT s and need help!