Mendel & quantitative heredity

6:32>> Okay. >> So, we're going to start actually all the way back in the 1800s with a man named Gregor Mendel. >> Back then, you know, everyone knows about like inheritance, right? Like you get stuff from your parents, but nobody really knew how. Gregor Mendel is this guy. He's an Austrian monk and he does experiments on pea plants and he starts noticing that actually when you do these quantitative experiments you can really mathematically say how much of the next generation is going to get a certain trait from their parents. He was doing very selective breeding where for example let's say a pea pod had green

7:13and then there was another pea plant that had yellow pods right if you selectively breed them together how many of the next generation are going to inherit the yellow versus the green how many are they of the next generation are going to inherit tall versus short how many are going to do this or that right and there was a mathematics to it >> there was an understanding that you could glean Mhm. >> Which means that there's it wasn't random. >> It wasn't it wasn't completely random. There's some mechanism that's happening. And this is before the whole mechanistic view about biology. Got it? >> Right. This is biology was still kind of a dark science of like things are just

7:54happening and we're trying to figure it out. But here, this is one of these first clues that something as fundamental as inheritance could be put into a mathematical language. And if it's being put into a mathematical language that means there must be some like physical thingy >> that is that is that is going on >> that is facilitating the structure that allows you to make those effectively predictions. >> Yes. Exactly. >> About about what will happen based on initial conditions. >> Exactly. Yeah. So it started out as a statistical abstraction that represented inheritance and pretty soon people started asking well what is the thing what is the material >> that is conferring this inheritance