This segment introduces Waddington's landscape metaphor as a more accurate representation of gene-trait interactions. It explains how genes, environment, and chance interact to shape traits, using a marble rolling down a landscape as an analogy. The segment highlights the complexity of gene networks and how multiple genes and environmental factors contribute to the development of a trait, contrasting this with the simplistic Mendelian model. It specifically uses examples to illustrate the limitations of the "gene for" concept. Weldon tried to do in 1902, their peas looked nothing at all like Mendel's. Weldon found that pea colour actually existed on a spectrum from yellow to green. it definitely didn't seem like a binary trait like we see in today's textbooks or Mendel's original paper. Weldon wrote in a letter to statistician Karl Pearson that Mendel must either be a truly astonishing man, or a black liar. but this is being a little harsh on Mendel because, remember, he was only directly interested in plant hybridisation, not heredity itself. and to study hybrids, he first had to purify his pea plants to remove any intermediate variation. this wasn't easy and took him 2 years of artificial breeding to get purebred lines that maintained their colour across generations. unknowingly, Mendel was essentially fudging the Waddington landscape of the pea colour genes to the very boring case of a marble going into the same bin everytime. and once he'd done that, the patterns we retrospectively call 'Mendel's laws of inheritance' do indeed emerge. but only in this very particular context. to quote Annie Jamieson and Greg Radick, "these patterns do arise; but they arise only under special conditions, notably when humans [like Mendel] have engineered artificially purified lineages into being, by deliberately excluding unwanted variability." it's therefore a pretty big mistake, you could even call it a misinterpretation of Mendel's experiments, to extend these patterns to the entire biological world in the wild. I can hear some of you saying: "Jake, this is the second video you've done critiquing models in biology that have been hugely successful. yes ok, they have their flaws, but aren't we supposed to teach students the oversimplified model first?" and to that, I'll respond with a resounding no. this line of thinking is based on the idea that students are these silly naive souls that are only ready for the truth once they're grown up. truth is, students are extremely receptive to being taught a more accurate and modern genetics curriculum. the genetics pedagogies project did just that. they created an introductory genetics course that placed the entangled nature of genes, environments and organisms, front and centre and contextualised Mendelian traits as a rare, special case. and, compared to students who took the more traditional course, the 28 students who were taught the new curriculum: "emerged as less believing of genetic determinism, and … better prepared to understand the subtleties of modern genetics." surely the point of a good scientific education should be to do just that. to teach students how to do modern science, not dwell in outdated paradigms. anyone that can understand how a marble run works is capable of understand how our genetics *actually* work. there's no need to lie. plus even if we eventually teach students the modern picture of genetics in later courses, there's a very good chance that students never get exposed to these subtleties because they never end up taking the more advanced courses. i'm sure the vast majority of you only got exposed to the Mendel's peas style of genetics at school and that was it. with the Mendelian blueprint picture firmly ingrained in the minds of most students, the public at large is much more prone to believe questionable headlines like: "genes determine how young use internet and social media" and "scientists find 24 ‘golden’ genes that help you get rich." if instead we placed better metaphors, like Waddington's landscape, in the curriculum from the beginning, these headlines would be quickly dismissed as nonsense. hopefully most of you realise there's something dodgy going on with the claim that something as complex as income could be determined by genetics. not to mention how deterministic thinking like this can easily move across into talk of /'good genes'/ and 'bad genes' and then blaming the poor for being poor because of some innate genetic characteristics. AAAand we've mindlessly just slid into
