About a year ago, I wrote a blog post about the pervasive misrepresentation of natural selection, not only in the mass media but also by professionals who should know better. My main problem is with the depiction of natural selection as an intentional process, as in “The cockroaches evolved a clever solution in order to avoid the pesticide” or “The cockroaches had to evolve in order to survive.”
Last week, my husband and colleague Doug Gaffin provided evidence from his class that this misconception is common, but that good teaching can start to turn it around. Before he began his unit on evolution, he asked the hundreds of students in his introductory zoology class to respond to several true/false clicker questions:
- Evolution results in progress; organisms are always getting better through evolution.
- Humans are the pinnacle of evolution and have stopped evolving.
- Evolution is not science because no one has observed it happen.
- Organisms adapt when needed so they can increase their survival.
- Natural selection gives organisms the traits they need.
- If humans evolved from apes, then all apes should have evolved into humans.
He asked the questions again after the evolution unit was complete. Most students (82-92% of them) already knew that #2, #3, and #6 were false before the unit even started; their responses were virtually unchanged in the “before” and “after” sessions.
Question #1 also showed virtually no change; about half of the students agreed with the statement before and after instruction in evolution. However, I find the question confusing. It is false because organisms don’t necessarily get “better,” whatever that might mean, and mutations will continue to occur. But it is also true because natural selection tends to weed out the harmful mutations. So that one doesn’t seem very informative to me.
The most interesting responses were to questions #4 and #5. Before instruction in evolution, a whopping 92% of students incorrectly agreed that “organisms adapt when needed so they can increase their survival.” Afterwards, that number dropped to 41%. The improvements were less dramatic for question #5. About 66% of students incorrectly thought that “natural selection gives organisms the traits they need” before the evolution unit started. Only 32% of students agreed with that statement after the unit was complete.
Both #4 and #5 get at the heart of the “organisms can evolve on purpose” misconception. On the one hand, it’s nice to see that good teaching can make a difference. On the other hand, it’s frustrating that more than a third of the students held onto that misconception even after weeks of instruction.
I will continue to look for resources and activities to help students overcome this difficulty. If you have any to share, please add them to the comments section. I thank you, as will your teaching colleagues.