Teaching genetics first improves understanding of evolution

Teaching genetics first improves understanding of evolution

Laurence HurstA new PLOS Biology study investigated whether teaching genetics before evolution improved understanding of evolution in U.K. schools. To learn more, I interviewed the corresponding author, Laurence Hurst, professor of evolutionary genetics and director of the Milner Centre for Evolution at the University of Bath.


What sparked your interest in studying how evolution is taught in U.K. secondary schools?

LH: When I go into schools to speak about evolution I am always encouraged by the strong appetite and interest in the subject amongst the students. However, I repeatedly see a few issues. One is that evolution is being taught as a separate module and perhaps made to look rather distinct from all other subjects. Connections were often not being made. The second was that there appeared to be quite a few misconceptions. Many of these are easy to see: the language of evolution can be confusing, as we tend to use familiar terms in unfamiliar ways. I remember when I was young being confused by “survival of the fittest.” Was this an encouragement to go to the gym?…So this stimulated me to ask whether there were some simple changes that could be made that could improve understanding of evolution but not at a cost to the students’ understanding of other subjects.

You hypothesized that teaching genetics before evolution would improve student understanding of evolution. What was your rationale for this hypothesis? Why do you think that evolution might be taught before genetics in some classrooms?

LH: To answer the second question first, this relates to what I mentioned above. There appears to be a tendency to consider evolution as a separate and distinct subject and so teach it in isolation. In some cases we found teachers rather marginalize it, teach it last and prefer not to give it much attention. This seemed very odd to me. To my mind microevolution is simply a branch of genetics. If you understand DNA, you can understand mutation and the concept of the allele. It is then a very small leap to understanding that alleles change frequency and, bingo, you have arrived into population and evolutionary genetics. This logical order is also there in “On the Origin of Species” although Darwin, naturally, was rather fuzzy on the genetics. In addition, there had been a news piece in Science that mentioned in passing that understanding of evolution was correlated with understanding of genetics. Naturally there could be many explanations for this, but it laid a seed of curiosity in my head.

Aside from the logical ordering, another possible advantage of the genetics-first approach is a reduction in what the psychologists call cognitive dissonance, the idea that, in the clash of beliefs and ideas, understanding is the first victim. That short leap from allele to allele frequency change allows much of the groundwork for understanding evolutionary change to be done under the banner of uncontroversial genetics. When students then switch to evolution – which many told us they were anxious about studying – the effective degree of clash of ideas could be reduced.

Why do you think there is a weak correlation between understanding and acceptance of evolution? What were some of the factors that you found might increase a student’s acceptance of evolution?

LH: We were very struck by this result. Indeed, in our pilot survey the correlation between evolution acceptance and understanding was negative! In our experimental data set the correlation is positive but weak, both before and after teaching. Indeed, genetics understanding is a much better predictor of acceptance of evolution. In short, we found students who understood evolution very well but didn’t accept it and others who accepted it but didn’t understand it all that well. The qualitative data repeatedly pointed to a role for authority figures with both tacit approval by teachers and parents being important. But external figures, be these TV personalities such as David Attenborough and religious figures, were also important to some. Indeed, in one school the teacher reassured the class that the pope approved of evolution and students told us what a relief this was. For some schools, a simple word like that might help.

What struck us most, however, was that while many students accepted the scientific view of evolution (over 80 percent after teaching), few could provide the evidence when quizzed in focus groups. We wonder if the act of teaching the subject in a scientific context by trusted people who provide tacit approval (i.e., teachers), is actually more important than understanding per se. In the primary school context, a study we are currently in the middle of, our analysis to date suggests that teacher acceptance of evolution is the only class-level predictor of student improvement in understanding. This fits with the notion of tacit approval/disapproval from the teacher as being a key parameter. This is a worry for countries were many teachers reject the scientific view of evolution.

Were you surprised by anything in this study?

LH: We were surprised by how clear, strong and repeatable the results were. For example, analysis at the class level (rather than at the student level) finds that genetics-first is best despite the limited sample size (70-plus classes). The genetics-first approach works both for high- and foundation-ability students. Indeed, for the foundation-ability students, genetics-first was the only teaching order that resulted in an increased understanding of evolution. This was something we didn’t expect. That for the foundation students teaching evolution then genetics leads to no improvement in evolution understanding is concerning if schools don’t now adopt the genetics-first approach.

Were there any limitations to your study?

LH: Work like this is difficult on this sort of scale…Getting schools involved is so difficult given the pressures on their time. But a consequence of this is that the sample of schools may well be biased towards more ambitious and energetic ones. We also found problems in fully implementing the randomization. Some schools needed to order in supplies to teach one or other subject and so while chosen to teach in a given order couldn’t do so. Likewise, there were a few cases where a class had been selected to teach in a given order but taught in the reverse order. We thus faced problems that don’t normally face medical randomized control trials. Conversely, as the material had to be taught regardless, we didn’t have the more common problem of biased dropout.

How might we modify current curriculum to improve understanding of evolution, if at all?

LH: Simple: teach genetics first! The effect seems to be so robust, it is a cost free intervention and minimally disruptive. The magnitude of the effect, a 5 to 10 percent improvement for genetics first above evolution first, is for schools a big difference. It is what the Americans might call a “no brainer.”

I am however interested in whether an explicit lesson bridging genetics and evolution making the link really explicit might help. Becky has developed such a lesson plan but we need to do more preliminary work to see if teachers would be willing to incorporate this. I should add that in our trial we asked teachers to teach what they need to teach for the syllabus for their particular exam board – so we didn’t change any lessons, just the ordering.

I’d suggest two other possible changes. It seems clear that while concepts of evolution are going in well, the evidence for evolution is not. I could imagine many ways to correct this. The other change I’d love to test is whether teaching evolution by stealth improves acceptance (i.e., call it population genetics upfront and only later mention that population genetics is evolution). If acceptance is conditioned by approval from authority alone then this change should make no difference to acceptance but could improve understanding by removing any cognitive dissonance components. If, however, understanding of evolution could precede any cognitive dissonance, it might improve acceptance as well.

Reference: Mead R, Hejmadi M, Hurst LD (2017) Teaching genetics prior to teaching evolution improves evolution understanding but not acceptance. PLoS Biol 15(5): e2002255. https://doi.org/10.1371/journal.pbio.2002255

Image Credit: Caroline Davis 2010, Flickr; Imogen Hurst.


Tessa is the Journal Media Manager at PLOS. She graduated from the University of California, Berkeley with degrees in Rhetoric and Music. She can be reached by email at tgregory@plos.org and on Twitter at @tessagregs.

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