Video Questions- What Darwin Never Knew

DNA, Genetics, and Evolution- Documentary on the Living Science of Evolution

Answer Key

PART 1- Darwin

  1. What is the full name of the famous book written by Charles Darwin, and when was it published? The Origin of Species by Means of Natural Selection published 150 years ago.
  2. What is the relationship between Darwin’s ideas and our modern understanding of genetics? Have we found Darwin to be fundamentally correct or incorrect in his understanding of how new species develop? The study of genetics affirms Darwin’s ideas. He was correct, but did not have the knowledge of how or why species evolve.
  3. Describe Darwin’s childhood and early career pursuits. He was fascinated by animals, didn’t like school. Was sent to medical school but was too squeamish for it. Failed at studying for the priesthood as well.
  4. What was the HMS Beagle, and what was its mission? A Navy ship, with mission to survey the waters around S. America.
  5. Describe the Galapagos Islands. Cluster of 13 isolated islands, 600 miles off coast of Ecuador. Home to unusual animals not found elsewhere.
  6. What tools did he use to record his observations? Collected samples, drew pictures, wrote descriptions in his diary.

NOTE: Questions 7, 8, and 9 skip around in order in the video. You will have to go back and forth between observations and conclusions/reasoning.

  1. Describe Darwin’s key observations on the Galapagos Islands, as well as upon return to Britain. What specifically did he notice about the following?
  2. Tortoises- learned from locals that you can tell what island they’re from by shell markings. Recorded the speed of their movements.
  3. Finches- collected a variety of specimens, 13 different species of finch, again depending on which island they lived on
  4. Fossils of extinct organisms as compared to living organisms- found fossils of obviously extinct organisms that showed close relationships to living organisms
  5. Embryos of developing organisms- unity of early embryonic stages among diverse species, similar original structures develop into related but very different structures
  6. Animal breeding (dog example)- observed artificial selection/ selective breeding in dogs
  7. His own family- even though children are descended from the same parents, there is variation in their traits
  8. Explain Darwin’s reasoning, based on the evidence above. How did he arrive at the following principles?
  9. Descent with modification- species change over many generations
  10. Natural selection/ adaptation- species adapt to their environment to help them survive
  11. Variation
  12. How were Darwin’s views different from the Victorian thinking of the time? How did they differ with the religious thinking of the time? Victorian- sentimental view, Darwin- fight for survival. Religious- God created all species perfectly so they must not change. Darwin- species change. Also moved from romanticized or religious view, to one based on facts and observation.

Part 2- Genetics- What Darwin Didn’t Know

  1. What is the Snickers Bar of the desert? The rock pocket mouse.
  2. Describe the evolutionary change that has been observed in the mice in the AZ desert. rock pocket mice have evolved light and dark fur to adapt to the light and dark backgrounds of the desert where they live.
  3. Describe the evidence and reasoning to support this claim: rock pocket mice have evolved light and dark fur to adapt to the light and dark backgrounds of the desert where they live.
  4. Evidence: larger number of dark mice on dark background, light on light background, DNA evidence- looked for a mutation changing light to dark mice
  5. Reasoning: (comes later in the video) chance mutation to dark fur allowed mice to survive on dark-colored rock
  6. What is the vital quality of DNA that leads to evolutionary change? It doesn’t stay the same. Mutation
  7. Give 1 other example of a mutation that led to evolutionary advantages for specific species. Colobus monkey can see in color allowing it to distinguish red edible leaves from green inedible ones, a fish with antifreeze in its blood allowing it to survive in colder water,
  8. What was one erroneous assumption made at the beginning of the Human Genome Project? That humans would have far more genes than less complex organisms.
  9. Compare the number of genes in the human genome to one other organism described. Humans have 23,000- identical to chickens and nemotodes, less than bananas and some plants
  10. What big question did the results of the Human Genome Project present scientists with? How do we account for such genetic diversity with the surprisingly small number of genes?
  11. Explain how the study of embryology has led to a greater understanding of animal diversity. Use same set of genes to develop their bodies (shape, patterning). Diversity doesn’t come from the # of genes, but how they’re used.
  12. How much of the human genome is non-coding or “junk” DNA? 98%
  13. Explain the experiment that led to flies with glow-in-the-dark spots on their wings. Gene for wing spots was attached to jellyfish gene for fluorescence, and injected into non-spotted flies. This turned on the gene for spots in the non-spotted flies.
  14. What is a switch? A segment of DNA that turns coding genes on and off
  15. How has the discovery of switches contributed to our understanding of evolution? Give an example. Switches turn genes on and off. So an organism with the gene for legs, for example, that doesn’t express that gene, may evolve to not have that body part if it helps it survive over time. Examples: snakes evolved from lizards (orgs with legs), whales have a vestigial pelvis,
  16. What is the difference between ocean and lake sticklebacks? Gene for defense spike got turned off in the lake stickleback due to a mutation that broke the switch that turned on the spikes.
  17. What is the connection between lake sticklebacks and manatees? Same switch that causes sticklebacks to lose their spikes may have caused manatees (and other organisms) to move hind legs. Looked for lopsided vestigial bones.
  18. What were scientists able to discover by returning to the study of Darwin’s finches? They looked at the embryologic development of the beaks and determined that the difference in beak development was in intensity and timing of a specific gene being turned on. (how much you turn a gene on, when you turn it on, when you turn it off)
  19. Describe the 3 possible roles of genes, or segments of DNA:
  20. Coding genes- code for specific proteins
  21. Switches- turn coding genes on or off
  22. Segments of DNA that flip switches- DNA that tells other DNA what to do (example- body plan genes)
  23. Give evidence for the “great transformations”- the large evolutionary changes that have taken place over time
  24. Archaeopteryx- fossil with features in common with both birds and dinosaurs
  25. Embryologic evidence- ear slits become human ear bones, fish gills (suggests land animals evolved from fish)
  26. What is the story, and significance of the fossil of the flat-headed fish found in the desert? They were looking for a transitional organism to show evolution from fish to land-dwelling animals. They found a fish (named tectolic) with a flat head with vestigial arms, allowing it to push itself up out of the water. There were fossils of fish that appeared to be predatory.
  27. If you’re a prey species your choices are to get ___big_, get ___armor___ or get ____out of the way____. Which did Tectolic seem to do? Get out of the way
  28. Why was the paddlefish selected for study? They needed an evolutionary relative of tectalic to study its DNA. It has a fleshy fin that may be similar genetically to the Tectalic fin/arm.
  29. What are hox genes? Found in all complex animals, give orders to developing embryos, activating networks of switches and genes, critical to shape and form of a developing creature
  30. From a genetic and evolutionary perspective, how are humans unique as a species? Ideas of right and wrong, think about what others think of us, advanced technology
  31. Explain our current understanding of the similarities and differences between humans and chimpanzees. 99% identical genomes, and yet functionally very different. Key differences are opposable thumbs, brain
  32. How did the Human Genome Project help with the quest for a cure for muscular dystrophy? Discovered a damaged gene that codes for development of muscle cells. Found a mutation common in the human genome, which turned out to be connected to jaw muscle strength (a difference between humans and apes)
  33. Explain the reasoning connecting discoveries of jaw strength to human brains. Apes have huge, strong jaw muscles that force growth plates to fuse early in development, limiting the possibility of a large brain.
  34. How did the study of the genetic disorder microcephaly aid in the understanding of brain development? Has identified 21 mutations responsible , all stop brain cells from dividing early in development. Normal gene in humans is radically different from apes
  35. Describe Katie Pollard’s work. Biostatistician, identifying genetic differences between chimps and humans. Has found most diffs to be in switches, most of which are near genes relating to DNA, especially in development of frontal cortex.

Reflect After Viewing

  1. How does this video help illustrate the principle of unity and diversity among living things? Use at least 3 specific examples.
  2. How does this video help illustrate the idea that structure reflects function? Use at least 3 examples.
  3. Explain your understanding of the relationship between genetics and evolution.