Thursday, February 26, 2015

A quiz on Darwin's Theory of Evolution

Someone named James Lewis at a blog named American Thinker seems to be upset about journalists who question politicians about evolution. He wrote a little quiz for journalists. There are ten questions. He claims that "Any biology student should ace it." Denyse O'Leary liked the questions [Quiz for media on Darwin’s theory of evolution]. She's a journalist but she didn't give us her answers. I can't imagine why.

I think I can give reasonable answers to most of the questions except #3 and #6. Question #10 is hard and so is question #1. I'm not sure if James Lewis would like my answers. What do you think?
  1. What is a biological species? How does it differ from a variety? Give examples.
  2. How has Darwinian theory changed since Darwin? (Be specific.)
  3. Define the two criteria for "Darwinian fitness."
  4. What are "Darwin finches?" Where are they found?
  5. What is the function of HOX genes?
  6. What is meant by "ultra-conservation" in evolution? Give two examples.
  7. Give an example of a recent evolutionary change in humans, within the last 10,000 years.
  8. What is parallel evolution? Give an example.
  9. What is meant by "genetic drift"?
  10. Why are there two sexes in most species?
Notice that random genetic drift has recently penetrated the thick sculls of many creationists. That's pretty amazing. I wonder if they can explain it?


  1. I would more so bet that "very few biology students would ace it".

  2. Isn't the American Thinker, aka the American Finger, the conspiracy rag that recently accused Obama of giving a secret Muslim gang sign to African leaders?

    Why, nothing racist about that at all.

  3. On #1 I'd probably say that a biological species is hard to define precisely because evolution happens. On #10 I'd say "no, there aren't, unless you restrict yourself to animals".

    I have no idea what answer #3 is even looking for.

    But #6 seems simple enough: it just means very, very conserved, as in "ultra-conserved elements" whose sequences tend to be, for example, 99% identical between humans and chickens. What's the problem with that? Unless you want names for the sequences, and I'm not aware that they have names.

  4. Re #6: If you follow the quiz back to its source, you find that the author picked his answers from Wikipedia, on which this appears:

    "Fitness (often denoted w in population genetics models) is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment. In either case, it describes the ability to both survive and reproduce, and is equal to the average contribution to the gene pool of the next generation that is made by an average individual of the specified genotype or phenotype."

    So I'm guessing the answer is supposed to be either "genotype and phenotype" or "survival and reproduction". Not sure which. Moral: you probably shouldn't try to design a quiz on a subject you don't understand.

    1. I give you 9/10 for that answer. In order to get 10/10 you would have to pick just one of the answers.

  5. I could answer those, but they are really poor questions. Some of them are a "read my mind" type question.

    I know very few high school students who could answer those. I know even fewer HS teachers who could answer those questions.

    You could write epic essays for some of those too.

  6. Isn't the American Thinker, aka the American Finger, the conspiracy rag that recently accused Obama of giving a secret Muslim gang sign to African leaders?

    Why, nothing racist about that at all.

  7. #10 - as far as multicellular organisms are concerned, gender is marked specifically by dimorphism in size and motility of the gametes. It requires a multicellular soma to allow this dimorphism, because only this can provide nutrition for the larger or amplification of the smaller. But given that precondition, two strategies can emerge: produce few large well-provisioned gametes which sit and wait, or produce many 'seekers'. Since genes alternate between presence in such packages, they get to invest in both strategies. The alternative is to invest solely in equal-sized gametes, which lack the dispersal capacity of the smaller member of the dimorphic pair, and hence are subject to inbreeding, and equally are unable to provide the equivalent nutrition of the larger part. Isogametes fall between these two stools, and so isogamy is undermined by asymmetry.

    Of course, in unicellular organisms, lacking a nutritional/amplifying soma, such options for asymmetry are restricted, and so isogametes are the norm. Nonetheless, there is likely selection for mating type incompatibility because (among other things) it reduces the opportunities for pairing deleterious recessives among the inbred products of a 2-step meiosis. There are often more than 2 'sexes' here, though.

    1. That's a fine answer if you interpret the question that way. Hard to say what the author of the quiz was trying to get at. Is he really referring to anisogamy? Does he count hermaphroditic and monoecious species as having two sexes? Are mating types "sexes"? Does he even know this stuff exists?

    2. Aye, true enough. But that gamete dimorphism is diagnostic, regardless whether the diploid line from a given zygote can generate both or just one. So even if the author wasn't aware, that's what 'two sexes' means - 2 sizes of haploid genetic package. Grosser morphological differences, and the trend towards dioecy, have their roots in that binary distinction.

  8. I'd have to rephrase some of the questions to even be able to answer them. Take #7, what counts? Must the change have spread to the entire human population? If so I'd be hard pressed to come up with something.

    1. I think that question is asking specifically about lactose intolerance.

    2. I had read some pop science articles about malaria and lactose tolerance but didn't know much more, so I decided to take a little look.

      The paper How Malaria Has Affected the Human Genome and What Human Genetics Can Teach Us about Malaria claims that "Malaria is ... the strongest known force for evolutionary selection in the recent history of the human genome."

      The paper Genetic Signatures of Strong Recent Positive Selection at the Lactase Gene claims that "LCT represents one of the strongest signals of recent positive selection yet documented in the genome."

      A more general search was performed in A Map of Recent Positive Selection in the Human Genome. It looks like other important areas of recent selection are: fertility and reproduction, morphology (esp. skin pigment+skeletal development), metabolism (for alcohol, lactose and other sugars, and fatty acids), and the brain.

  9. I just don't get what was the journalist's rational in preparing this quiz.

    1. Presumably to argue that any journalist who can't answer all of these questions shouldn't be allowed to criticize politicians for being creationists. Which isn't really valid -- I'm not a rocket scientist, and presumably couldn't answer a quiz about the workings of Saturn V but I can still criticize conspiracy theorists who refuse to believe that the moon landings were real.

    2. Shouldn't there be an evolution Credo so that politicians and others know what they need to believe in order not to risk excommunication for heresy?

    3. "Shouldn't there be an evolution Credo so that politicians and others know what they need to believe in order not to risk excommunication for heresy?"

      So I take it you agree concepts like "excommunication" and "heresy" are bad? Otherwise I don't see why you'd bring it up.

    4. Tread carefully Rumraket, in another thread you expressed belief in random adaptation, i.e. that random mutations and genetic drift was an example of adaptation. It may not qualify as heresy but it's at least an oxymoron.

    5. Actually what I wrote was that genetic drift could also lead to adaptation, not that it was adaptation by definition.

      Explain what's an oxymoron about it.

  10. The answer to number 10 is not obvious. There is a moderately successful theory for this which is in this paper:

    Parker GA, Baker RR, Smith VG. 1972.
    The origin and evolution of gamete dimorphism and the male-female phenomenon.
    Journal of Theoretical Biology 1972 Sep; 36(3): 529-553.

    Let's see the hands of all of the biologists in the audience who knew that was the answer. I see a few hands but ...

    Of course, as John Harshman already noted, many organisms are monoecious. Don't tell the slugs, snails and earthworms, let alone most flowering plants, that they have to have the sexes be in two different individuals. And of course don't corrupt your children by telling them what those cute clownfish from Finding Nemo do about maleness and femaleness.

    1. We're going to discuss this in class in a couple of weeks. I get my students to read an even better paper by some dude named Joe Felsenstein.

      Pethaps you know him?

    2. Don't understand him: he's always been an enigma to me. Besides, although he wrote about the evolution of recombination, he never addressed Why There Are Two Sexes.

    3. Alan: Indeed. I had not read carefully enough -- your explanation involving gamete dimorphism is of course describing the argument of Baker, Parker, and Smith.

  11. Is ultra conservatism just a word/concept to explain away lack of evolution/change in biology estimated to be too longed lived to otherwise have avoided evolving/
    Are creationists any thicker then anyone new to the idea of genetic change without selection being involved / It seems to contradict the whole point of selectionism as a origin for change.
    The quiz for evolutionists IS Name your top three evidences for actual important biological change by evolutionary concepts. Or one.
    That is a quiz to pay attention too.

  12. Thanks to Professor Larry Moran, I have rediscovered my former enthusiasm for Stephen Jay Gould’s essays. Doing so has made me revisit my presentation of sexual reproduction to my students.

    Sexual reproduction as commonly understood has two components, a package deal as it were: genetic exchange and recombination together with an increase in the number of individuals into the next generation.

    The more I think about it – the more I am convinced that that a vertebrate-centric notion of “EXCLUSIVE Sexual Reproduction” as a “package deal” represents a rare oddity indeed and perhaps an evolutionary “dead-end”.

    Consider Bacteria, and many unicellular Eukaryotes. Conjugation occurs without increase in cell number… or at least any increase in cell number is incidental to any genetic exchange and recombination that just occurred.

    Alternation of Generations as a Biological phenomenon is significant not only in plants but also in animals! Consider Polyps and Medusa in Cnidaria. I am about to teach Taxonomy and I am reminded that so-called “primitive” organisms (forgive me – “I mean simpler and less derived”… OK you know what I mean! ) employ asexual reproduction in constant environments as their default setting and sexual reproduction kicks in under scenarios of environmental stress.

    In other words; if environment changes, not only may offspring be poorly adapted but ALL offspring will be poorly adapted because they are identical.

    Zygospores are quiescent resting bodies awaiting environmental conditions to return to "normal" ...

    or alternatively...

    ...allow genetic recombination resulting in novel variable offspring, some of which can to adapt to the “new normal”.

    I can imagine zygospores as some evolutionary quiescent exaptation that eventually gave rise to sexual reproduction… the exaptation possibly being DNA repair.

    The repertoire of species that indeed exclusively employ sexual reproduction as rigorously defined above is rapidly diminishing.

    1. Then as Joe Felsenstein and John Harshman already noted, many organisms are monoecious. But I find that merely curious from an vertebrate-centric POV – and not remarkable when considering the evolutionary question at hand.

      What I find very remarkable is the notion that sexual reproduction can in fact be an exemplar of clonal expansion bringing me back to Gould’s essays, especially Hen’s Teeth and Horse’s Toes! In his fourth essay Quick Lives and Quirky Changes, Gould examines the haplodiploidy of the mite Histiostoma murchiei that parasitizes earthworm cocoons.

      Mothers incestuously mate with their sons, which constitutes from a genetic perspective, clonal expansion. While inside an earthworm cocoon, the female lays two rounds of eggs. The first round develops without being fertilized, and produces two to nine males, but no females. These offspring then mate with their mother, and die shortly afterwards. The second round of egg- laying produces about 500 offspring – this time all females.

      How are we to understand such behavior in terms of question #10? Vertebrates only include some 50 000 species while haplodiploidy arose independently several times and now include over 100 000 named species.

      I presume his version of clonal expansion by zygote production represents a subtle version of alternation of generation. While times are good and earthworm cocoons are in plentiful supply, clonal expansion (i.e. the absence of genetic exchange and recombination) is the order of the day. When times get tough and cocoons dwindle in abundance, the likelihood of a solitary cocoon being simultaneously parasitized by more than one female rises; only then providing opportunity for genetic exchange and recombination.

      So back to the original question: Why are there two sexes in most species?

      Uhmmm perhaps the correct answer is that sexual reproduction as performed by vertebrates happens to be most peculiar, very atypical and a possible evolutionary dead-end.

      I would appreciate any feedback or correction before I inflict any of this upon my students.

      Best regards to one and all.

  13. There is no single correct definition of ‘species’ but a plurality of equally correct definitions.

    Check out page 180 on this link:

  14. Re: Question #1

    Indeed a revolution happened in the late 1960s that reshaped the 1950s version of the Modern Synthesis but for all intents and purposes – the First Principles of Darwin’s thesis according to what Darwin actually said, as opposed to how “Darwinism” or “Neo-Darwinism” is speciously defined in many textbooks leaves one inescapable conclusion:

    Darwinian theory really has not changed since Darwin with the sole exception of introducing a correct understanding of Genetics and Population Genetics.

    Darwin himself recognized that “Natural Selection” was NOT the be-all-and-end-all of Evolution, and stated as much himself on more than one occasion.

  15. Regarding Question 7 -

    The last glacial period or Ice Age was approximately 110,000 to 12,000 years ago resulting in huge selection pressure for fair skin and more efficient Vitamin D deposition.

    However, human populations over the past 50,000 years have changed back and forth from dark-skinned to light-skinned as populations colonized different UV zones, and major changes in pigmentation may have happened in as little as 100 generations (~2,500 years)

    I other words - Adam and Eve were Black!