 So what says I'm right? I keep arguing that evolution has made these changes happen and everything, but we don't really know that, right? I can't go a billion years back and check. Well, don't fool yourself. There is nothing that says evolution has to take a billion years just because some important parts of evolution have taken that long. There was a really cool paper published about a decade ago about Tomcott. So Tomcott is an Atlantic type of cod, in particular abundant outside the north-eastern US coast. It's sadly also an animal that's very sensitive to other poisons such as PCBs. So the common way PCB, for instance, act as such, have a protocol ARH, the aryl hydrocarbon receptors. These receptors, the green one here, they sadly bind the PCB. When they bind the PCB, they tend to go into the nucleus of the cell and sadly activate incorrect genes. I'm not even sure why that happens, but the point is that this now leads to errors in the proteins we're expressing, possibly errors in the duplication of the genomes in the cell and everything, and eventually you start having disease and the animals might even die. So they will not be able to duplicate their genes to as many generations if they're subject to PCB. Partly the reason why PCBs are now increasingly prohibited. Eventually, after billions of years, you could imagine that if we keep having PCBs around this version, maybe they would evolve some sort of resistance to this. Maybe you can have a different version of this ARH protein that didn't bind PCB. The cool thing is that this hasn't taken billions of years, but it has happened in a few decades. So I think this was in 2011. Yes, I even had a reference there. This was a really cool science paper that they've been sequencing COD outside the northeastern US coast. Then it turns out that there are two alleles. Remember these two chromosomes, the two pairs in each chromosome. So that the tomcord expressed two slightly versions of this ARH receptor, where one of the copies was resistant or at least more resistant to PCB. And normally in the clean waters up there in the northeast, you have the normal ARH receptor, there's nothing special at all, no pressure. But look here down, in particular on Hudson River, which is likely not the cleanest part of the Atlantic coast, the second allele has taken over completely. So that the tomcord has evolved resistant to PCB in a few decades more or less. We haven't used PCB more since the mid-20th century. It's a super cool paper that I've also shared with you. So evolution can happen in decades, sadly, because the evolutionary pressure in this case is extremely strong. The tomcord wouldn't survive in the Hudson otherwise.