History of Evolutionary Theory
DIRECTIONS: As you read, click on the links. Each link will open a new browser window that connects you to the Internet. Be sure to close the new browser window when you are finished. Throughout this activity, you will be prompted to answer questions on the History of Evolutionary Theory Worksheet which has been provided to you. Please make sure that you answer the questions on your worksheet with the information learned from this webquest.
Not far from the rocky shore of one of the Galápagos Islands, a massive 120-year-old tortoise lumbers out from the shade of a mangrove shrub to munch slowly on the juicy flesh of a Galápagos tomato. In a nearby pool of seawater, luminescent sea cucumbers and boldly colored crustaceans shimmer beneath the water's surface. A red and yellow crab passes dark gray iguanas as it scuttles along the porous black lava rocks rising out of the water. Farther down the beach, a sea lion plays with her pup while a lone heron looks on serenely.
Take a look at some photos of the Galapagos Island Wildlife. It's no wonder Charles Darwin was intrigued when he first sailed among these islands a century and a half ago. Then go to your worksheet and answer question #1.
Read the following biographies of the individuals that helped Darwin form his ideas about evolution. When you are done reading these biographies, answer question #2 on your worksheet.
Lyell's theory of geologic gradualism influenced Darwin's thinking about changes in living things over time. Examine Lyell's biography, and then take a look at this simulation of glacier movement in North America from about 20,000 years ago to the present. After viewing the simulation, answer question #3 on your worksheet.
Read a brief excerpt from Lamarck's Zoological Philosophy and the biography of Lamarck. Once you have done this, answer questions #4, #5, and #6 on your worksheet.
Darwin was fascinated by the hundreds of species he saw throughout his travels. How had very similar yet different species come to exist in so many parts of the world? Darwin came to think that such species must somehow be related—they must share common ancestors but then have somehow changed over time.
For
instance, Darwin noticed that bird species on various islands off of the coast
of Brazil were very similar to mainland Brazilian species, but with slight
modifications. He reasoned that the ancestors of the island species must have
come from the South American mainland. He recognized that the conditions and
food sources varied from island to island, and hypothesized that only birds with
the most useful characteristics would survive. The offspring of these birds that
inherited these useful characteristics would be best adapted to conditions on
the islands.
Explore Darwin's Origin of Species and make your own observations. Answer questions #7, #8, #9, and #10.
Darwin put together many pieces to build his theory of evolution. Today, scientists continue to contribute ideas to evolutionary theory. For example, watch this video to learn what some contemporary paleontologists hypothesize about Whale Evolution. Then answer questions #11, #12, #13, and #14.