Science B-16: The History of Life
Final Exam
May 26, 1999

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1.  For each of the following, provide a descriptive drawing.  You may annotate as needed.

EXTRA CREDIT: What the Earl of Dunraven

has the world’s largest set of

2.  The Italian philosopher Giordano Bruno once remarked that theories could act as both vehicles and chains.  In so saying, Bruno was making a profound statement on the way that theories can affect how we look at data.  Briefly explain how each of the following theories allowed scientists to look at the data of the fossil record in a completely new and different way – i.e. how each of these theories acted as a vehicle to new insights and broke chains imposed by previous views.

a) Punctuated equilibrium

b) Seilacher’s “Vendobionta” hypothesis

c) The Alvarez impact hypothesis

3. This diagram shows the basic floorplan of the Harvard Museum of Comparative Zoology.  Since its opening in 1859, the museum has undergone numerous expansions and additions.  Of the two strategies for size increase discussed in lecture, which one has the MCZ consistently used?  Explain two functional reasons why the architects of the MCZ’s additions might have chosen this growth strategy.  What alternative strategy, used in most modern buildings, was not available when the MCZ was being constructed?

4. Darwinian theory assumes that the differences between species evolve by small steps through intermediate forms.  This view of evolution is contrary to a saltation hypothesis, which states that differences between species evolve in single leaps, without intermediate forms between ancestors and descendants.  Many people believe that punctuated equilibrium is a saltation hypothesis.  Briefly explain why this is not the case.  If the punctuations of punctuated equilibrium are not saltations, then what are they?

5. The Ediacaran fauna to the right (Rangea and Charnia, left to right) dominated the large, multicellular animal world during the late Proterozoic, yet they are morphologically distinct from essentially all Phanerozoic fauna.  Dolf Seilacher would argue that they are so different that they cannot be pigeonholed in good conscience into any modern phylum.  Others would argue that the Ediacaran fauna (especially the ones to the right) are ancient relatives of the Cnidaria (jellyfish, etc.).  Suppose that Prof. Seilacher is right.  In this case, would the Ediacaran fauna represent a failed experiment in the evolution of large multicellular life?  What evidence do we have that, during their time of domination (600-543 Ma), the Ediacaran animals could compete successfully (or at least hold their own) against triploblastic animals of modern form?

6.         How would the following conclusions, if true (although they probably are false), diminish the role of contingency in human evolution and support a claim that the current status of Homo sapiens could have been predicted from the nature of these past events:

a)      If Neanderthals arose from European populations of Homo erectus and then became the direct ancestors of the Caucasian race of Homo sapiens.

b)      If the 6 to 8 names species of Australopithecus living between 1.9 and 2.6 million years ago really belonged to a single species that was the direct ancestor of Homo.

c)      If soils and climates determined which human groups would invent agriculture, and if no credible threat to European domination had ever arisen after the origin of agriculture among Caucasian people of the Near East.

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7. You have been selected to judge this year’s science fair at the Emmett Brown Academy for Gifted Young Time Travelers.  Coincidentally, this year’s three finalists have all chosen to do the same project.  Each has traveled back in time to a different geologic era and set up a webcam to send back images from that time period.  Before coming to the fair, you’ve been warned that two of the finalists are suspected of cheating by making up the images themselves.  Based on the description of the three images below, please determine who has cheated and who deserves the blue ribbon.  Briefly explain your answer.

Image 1: Labeled “Paleozoic Reef”, Archaeocyathids are the primary constructors of this reef, while crinoids baffle, bryozoa bind and trilobites dwell.

Image 2: Labeled “Mesozoic Terrestrial”, Dinosaurs move about in herds, while birds fly overhead and small mammals scurry about in the savanna grassland.

Image 3: Labeled “Cenozoic Marine”, Fish swim about in schools, past bivalves, sponges, and brachiopods on the bottom.

8.         Your roommate, a staunch advocate of determinism, is looking through your B-16 notes.  “Aha!” he says, “One finds evidence for life in the oldest rocks that could possibly contain such evidence.  Clearly, evolution is not contingent.”

a.       Explain to your friend why it is possible for the origin of life to be non-contingent, while evolution is contingent.

b.       Draw the “tree of life” -- based on actual branching order in time, not on grades of structural organization -- indicating clearly the relative placement of the prokaryotes and eukaryotes.

9). You have a very large and diverse pencil collection.  Sometimes, when your little brother is particularly annoying, you use one of your pencils to poke him in the arm, in an attempt to get him to leave you alone.  Your friend sees you doing this, and remarks that the pencil is so effective at brother persuading that it was clearly invented for that purpose.

a.       What is the fallacy in your friend’s argument?

b.       Some time later, your little brother steals your collection and sets it on fire.  Only your large souvenir pencil from Niagara Falls survives, because you keep it in a separate box (due to its large size) and your brother didn’t see it.  To which model of survival through mass extinction is this analogous?

10 ) You work for the gaming commission of a state with legalized gambling.  Unfortunately, one of the casinos in your state has been accused of cheating by using loaded dice on its craps table. In order to test to see if the dice being used by the casino are “honest dice”, you have devised an experiment.  You roll every die used by the casino in the last six months all at once, remove every die that comes up six, and repeat the process ten times.  You plot your results on a loglinear plot and get the following results:

 Is this casino using “honest dice”?  On what are you basing this?  Briefly explain the property of random systems which makes this sort of test possible.

11) The fictional professor Cotwall has just discovered two previously unknown organisms from the Burgess Shale, and has named them Harria and Briggsia.  Both Harria and Briggsia appear to be metameric (segmented) animals, with multiple jointed appendages.

Harria seems to have four distinct body regions, a small head with six pairs of antennae, and nine pairs of flattened appendages behind the head – one pair for each body segment.  Each appendage in the last four pairs resembles a rubber swim flipper, similar to one you would use to go snorkeling or scuba diving.

The head and thorax of Briggsia seem to be fused together into a single body region, separate from the abdomen.  It has six pairs of uniramous (unbranched) appendages, but no antennae.  Each of the two appendages in the first pair (closest to the front) looks like a little pair of jaws or pincers.

Given your knowledge of the Burgess Shale Fauna, where would you place each of these two organisms in the classification of life?  Make sure you explain your reasoning for each animal.

Harria	Briggsia

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a.       Explain why the interpretation of fossils played a central role in Leonardo’s justification for time’s cycle.

b.       Explain why Hutton used no fossil evidence at all to establish his version of time’s cycle in his theory of the earth.

c.       Thomas Burnet also included aspects of time’s cycle in his version of the earth’s history, but his richer theory included important components of time’s arrow as well.  Explain two feature’s of Burnet’s theory that express the “time’s arrow” component of his general view.

13) Your friend brings you this cartoon that he found in the newspaper. “It’s a cute idea,” he says, “but when you get right down to it, who would ever need such a thing.  After all, scallops don’t have eyes.”  You impress your friend by explaining to him, that not only do scallops have eyes, but eyes are fairly common in the animal kingdom, appearing in the chordates, molluscs, arthropods, and cnidaria, among many other phyla.  “Wow,” he says, “that’s pretty amazing, but I’m surprised they would teach you that in a course about evolution.  After all, the fact that something as complex as the eye appears in so many different groups of animals sounds downright anti-Darwinian.  Eyes are too complex to have evolved from simpler structures without some sort of external direction.”  Explain to your friend why the evolution of such complex structures as the eye does not necessarily require an exception to Darwinian evolution.  Why might the wide range of eyed creatures actually strengthen this argument?

14. Reproduce the geological time scale, including all eons, eras, and periods, and the epochs of the Cenozoic.  Give the absolute ages for the three era boundaries.