Kostas Kampourakis is a respected scientist who is being promoted by the National Center for Science Education (NCSE) as an excellent communicator of evolution. Here's a short video (below) where he explains why teachers are making a mistake by saying that Mendel is the father of genetics and that simple Mendelian genetics can explain complex traits.
I'm struggling to understand his point. Here's what I think he means.
I believe that the fundamental trait is the lack of an enzyme for degrading chlorophyll and this is what I would teach my students. I would also show them that the phenotype can be easily explained once you understand the biochemistry. It shows you that the connection between the fundamental trait and the visible phenotype can be mysterious so you should be careful about jumping to conclusions.
I think that Kampourakis sees this differently. He thinks that the example of green vs yellow peas is used to teach students that the color of peas is completely determined by a single gene. He thinks that the "trait" is the develpment of seed color in peas.
Kampourakis believes that "people looking for explanations and whatever happens to them in terms of disease and their own features, they find hard to reconcile the simplistic model that they have been taught with the realities of life." I think what he means is that students are being taught that single genes will always determine complex characteristics. He attributes that to the teaching of Mendelian genetics.
If he is correct, then that kind of teaching has to stop but I don't think it's the fault of Mendelian genetics. Mendelian genetics—indeed the entire field of genetics sensu stricto—is about the segregation of alleles. It is not about development even though we have come to learn a lot about development through genetics and the phenotype of mutants. I think that genetics and development are separate topics.
Kampourakis disagrees. He says, "we need, I think, to teach genetics from a developmental perspective. We need to show that genes do not determine traits but they are implicated in development." I believe this perspective comes from a more fundamental bias that distinguishes his worldview from mine. I tend to see genetics as a subject that covers all of biology and that includes all species such as bacteria, viruses, and single-cell eukaryotes. He tends to see things from a human perspective, which is much more complex than dealing with simple organisms. I think we should concentrate on teaching students about simple well-understood model organisms and then move on to explaining how this applies to more complex organisms. Kampourakis seems to be implying that we should jump right into reaching high school students about the most challenging issues in biology.
1. Actually, the common allele for white eye in Drosophila (see image) is X-linked so it doesn't follow the standard rules for Mendelian segregation!
5 comments :
I suppose we could teach intro to economics without discussing microeconomics....
With you on this, as usual
The idea that there is one gene for eye color, one for earlobe shape, one for this, one for that died in about 1920 as geneticists found more and more examples of pleiotropy. Over the next decade or two quantitative geneticists came to understand that a simple model of determination of traits by adding up effects of alleles was a very useful approximation, even though of course these loci did interact too. In 1917 Sewall Wright published a series of papers reviewing coat color genetics in multiple species, and suggesting that the genes acted by producing enzymes, and that one could explain the interactions by the action of these enzymes in the coal pigment pathways. (I once asked Sewall Wright if he had been the first to suggest that genes produced enzymes, and he said oh no, Cuenot had suggested that in 1904). So Kampurakis is a bit out of date.
Oops: "coal pigment" --> coat color pigment
"Kampurakis" --> Kampourakis
William Bateson began correspondence with the physician Archibald Garrod in January 1902. The latter developed the one-gene-one-enzyme idea in his 1909 text Inborn Errors of Metabolism. In 1934 Garrod noted that "it was Bateson who saw the daylight". For details see p. 195 of "Treasure Your Exceptions." The Science and Life of William Bateson (2nd edition 2022).
Post a Comment