No this is not going to be a post on Bloom’s taxonomy of questions memorized or conceptual, useful as that is. Here I’m talking about the kinds of material students struggle with.
If ever there was a clear book surely it is Richard Dawkins‘s The Selfish Gene. I use it to begin my course in behavioral ecology and just gave a test of short essay questions, only two weeks into the semester. The class had read the whole book, guided by study questions I wrote that you can find here. They answered 10 of 20 possible questions. Here are some things they had the most trouble with. I am guessing these are general patterns, not specific to this assignment.
1. If part of the question has a numerical answer, they will get it correct. Worker relatedness to sisters, hymenopteran sex ratios, sister to self relatedness, they get it all. For a more specific example, the main cost of sex is you pass on only half your genes. I’ll count that as right for that half of the question because they forget about the costs of hunting for a mate and other such things and they are less essential. But they are quite confused about how to phrase the benefit and have a hard time deciding if it is in the interest of the gene or the individual.
2. They are not strong on considering the framing of the question and can slip over to considering the interests of a different party. The answer to why female mice eat their babies when a new male takes over should be about why this might be advantageous for the female, not the male. A female should behave according to the interests of an unrelated male only if it is her interests also, or she is forced into it. Eating babies may be the best of a bad job if the male is going to kill them anyway, for example. If a question asks about plasmids and nuclear genes, bacteria are unlikely to be the correct context. I could go on.
3. Students assume they know more about the organism than they do. They assume the organisms are more like people than they are. I wish they would all start by assuming plankton, drifting in time and space, more or less. Or bacteria. Or amoebae and only add on other attributes when they as specifically mentioned. They always seem to assume attributes about an organism that they do not know. This ties to the general point that true wisdom comes from understanding your own ignorance. In the mouse example above, many students assume the male will help mom with the babies, in total absence of evidence.
4. After reading Dawkins, if you ask students directly what the unit of selection is, they will say the gene, but their thinking on subsequent questions will clearly show they don’t get the consequences of this answer. They will mention species helping if you ask about some kinds of cooperation. They will consider the group for advantages to sex. It reminds me of what Ross Nehm said about their minds being like a room full of furniture. What we add has to fit with what is there before. Most of them will read Selfish Gene, get direct questions correct, yet not change their thinking about natural selection and evolution very much at all. How to encourage this to happen is my challenge for the rest of the semester. I’m guessing that what will be most effective is helping them learn how to nudge furniture around in their beautiful minds, maybe occasionally adding a lovely table or new chair.
But it is only the second week of class. In some ways what they have done is impressive. After another 13 weeks of discussion, quizzes, writing, and teaching, I’m betting some will never forget why a slug might chew off its hermaphrodite mate’s penis as being about the female, not the male function.