A recently posted YouTube video tries to make the case that you were lied to about genetics. I'll get to than in a little while but first let me summarize what I was taught in a university genetics class in 1965.
Like many of you, I was taught the rudiments of Mendelian genetics in high school. This view was emphasized in my university course where we learned about Mendel's laws of inheritance in diploid species. I also learned about population genetics and exceptions to the standard rules governing the segregation of alleles. We covered 'phage and bacterial genetics where Mendel's laws mostly don't apply and we learned about sex-linked alleles that show more complicated inheritance.
There are hundreds of excellent examples showing a direct link between genotype and phenotype but there are also many examples where this connection is obscure, especially in complex multicellular organisms such as fruit flies, plants, mice, and humans. For example, there's no obvious reason why a deficiency in a starch branching enzyme should cause wrinked peas [Biochemist Gregor Mendel Studied Starch Synthesis]. And there's no obvious reason why mutations in the same gene in humans causes a liver disease in children that's usually fatal (Anderson disease) [Glycogen Storage Diseases]. The mutant alleles still segregate according to Mendelian genetics.
Genes interact to form networks and some of these networks are complicated. We usually teach simple examples such as how suppressor genes can mitigate the effect of stop mutations in bacteria. There are more complicated examples such as the large number of alleles and different genes that affect eye color in humans [The Genetics of Eye Color]. When the number of different loci is low, you can still work out the Mendelian probabilities using Punnett Squares but in some cases there are just too many loci with low penetrance.
In order to make his case, he focuses on the complicated examples of multigene inheritance in humans. The interesting part of the video is his version of Waddington's genetic landscape and his toy model illustrating the concept. I think he's dead wrong about the death of Mendelian genetics but it's still worth watching the video.
This whole "you were lied to" trend is one of the most annoying and frustrating aspects of social media and society in general of late. At worst, information taught in the past may have been expanded or updated, but were people actually lied to?
ReplyDeleteAs Larry notes, the popular science media seem to need to tout each science discovery as revolutionary and overthrowing all previous knowledge. Headlines like "Scientists astonished as new study [of the number of hairs on the ass of the wombat] gives amazing results.". Of course university press releases don't do much to fight this ...
ReplyDeleteHi Joe, how are you ? I previously inboxed you on facebook and you never responded actually I want to clarify something. In my country Pakistan , I see a lot of creationists misuse your advisor Dick Lewontin's qoute to set their own agenda. Now I do not know that in which context Lewontin said so, so you are the best person who can clarify what actually Lewontin tried to say in the given qoute. Thanks in advance ! Here's the qoute :
Delete.‘We take the side of science in spite of the patent absurdity of some of its constructs, in spite of its failure to fulfill many of its extravagant promises of health and life, in spite of the tolerance of the scientific community for unsubstantiated just-so stories, because we have a prior commitment, a commitment to materialism. It is not that the methods and institutions of science somehow compel us to accept a material explanation of the phenomenal world, but, on the contrary, that we are forced by our a priori adherence to material causes to create an apparatus of investigation and a set of concepts that produce material explanations, no matter how counter-intuitive, no matter how mystifying to the uninitiated. Moreover, that materialism is an absolute, for we cannot allow a Divine Foot in the door.’
The entire "You were lied to" format is efficient clickbait, used in politics to generate mistrust of democratic institutions, and used in creationism, often by the same people, to generate mistrust in the whole of evolutionary and deep time science
ReplyDeleteJake Brown's video refers to the works of historian, Gregory Radick, who has recently summarized his views in Disputed Inheritance. The Battle over Mendel and the Future of Biology (2023. Univ. Chicago Press). Celebrating the bicentennial of Mendel's birth, in 2022 there appeared the second edition of Cock and Forsdyke's Treasure Your Exceptions. The Science and Life of William Bateson (Springer, New York). Here, Bateson - who coined much of the genetic terminology we use today - explains a key point that Jake Brown makes, namely that Mendel began by selecting lines of peas that "bred true."
ReplyDeleteA century later, the research principle that interpretating data is likely to be easier by either making the studied system simple or choosing a simple one at the outset. This became abundantly evident with the increased entry of physicists into biology. Thus, studies of the viruses that infect bacteria created an important grounding for the later DNA studies of Watson and Crick.