The Evolution of Life on Earth Video Discussion
Question Description
Exercise 1: Geologic Time and Scientific ReasoningObjectives:After completing this exercise you should be able to:•Recognize the immensity of time that has transpired so far in the history of the Earth•Organize a series of key Earth history events along a geologic timeline in the correct relative order•Use scientific principles to construct hypotheses about the world around you•Explain the difference between an hypothesis and a scientific theoryGeneral Instructions:This exercise consists of threeproblems. Each problem includes background information and reading/video interactions followed by specific instructionsand questions to complete. Use the material provided in the Lectures1 and 2, the textbook, or online resourcesto complete this exercise. Type your answers into the “Answer Sheet” Word document for Problems 1 and 3. Photograph or scan your answers for Problem 2. Upload the (1) completed answer sheet and (2)image and/or scan for Problem 2 to Blackboard. Your answers to this exercise must be uploaded to Blackboard by the due date listed on the syllabus. Credit will not be given for late work.Problem 1: A first look at Geologic TimeThe Earth has existed for 4.6 BILLION YEARS. That is an incredibly long time. The human brain has substantial difficulty actually comprehending numbers on this scale. Therefore, geologists often use analogy to try and explain the enormity of geologic time. Two typical analogies that we use are distance and time. For example, here is a clock-like metaphor which illustrates major intervals in Earth history over the span of a single 360° rotation.One thing to notice from this first look, is that MANY of the Earth history events on this diagram occur between 10:00 and 12:00 in clock time. A key thing to understand about the history of our planet is that major events are not evenly spaced out. There is even one interval we’ll learn about later called the “Boring Billion” because so few “exciting” things happened during that time.Another important point to make at this juncture is that many Earth history events are contingent on earlier events. That is the later event could not have happened if the first one did not happen first. For example, before the evolution of photosynthetic organisms, there was almost no oxygen in the atmosphere. The oxygen we (and all other animals) enjoy breathing today accumulated slowly from hundreds of millions of years of photosynthesis [*as a reminder, photosynthesis uses carbon dioxide and sunlight to make food and gives off oxygen as a waste product]. So the evolution of photosynthesis had to occur beforethe evolution of animals.For this problem, you will watch three short (less than 2 minute) videos about geologic time1.”Our Story in 1 minute” This video places a series of key Earth history events in the correct relative order
are three impressions you have from this video? (no wrong answer here, just write the three things that stick out in your mind from the video)__________________________________________________________________________________________2.”The Evolution of Life on Earth”This video introduces key Earth history events at the correct time in Earth’s history
is your impression of Earth’s history from this video? How does that compare with your impression from the first video?__________________________________________________________________________________________3.”The Evolution of Life on Earth”
what time in the 24 hour day did the first life begin? ____________________________________________b.When did animals first appear? ________________________________________________________________c.When do reptiles dominate the land? ___________________________________________________________d.When do humans appear? ____________________________________________________________________e.What is your impression of Earth’s history from this video? _____________________________________________________________________________Problem 2: Geological Time Scale ChallengeAs you learned in Problem 1, major events in Earth history are not evenly spaced throughout geologic time and many key events require specific conditions to be in place before they could have occurred. We will learn a great deal about lots of exciting Earth history events this semester. However, before we do, it’s important that you gain a general familiarity with the timing of certain key events. To complete this activity, print out the 12 geologic events cards and cut them apart. Then measure out 4.6meters of string/yarn or draw a 4.6m line on the floor using chalk/pencil. Mark one end of the line at 0–this end represents today. Mark the other end 4.6 billion years ago–this end represents the formation of the Earth. Place the cards in the correct position along your line relative to when they occurred in Earth history. You may use any resources you like to identify the