 So you might think that the number of genes that a critter has will determine how complex it is, how wild it is. And this isn't the case. The reason why it isn't the case is because we know that just through the act of transcription, we can produce many different kinds of messenger RNA molecules. There are sequences associated with the genes that are going to be transcribed. They're called the promoter region that indicates, hey, this is where you got to start to make the messenger RNA. There's also enhancer regions in a gene, or possibly R-enhancer regions in a gene, that actually increase the amount of transcription that happens at that gene. Enhancers, the promoters, can be turned on and off by other molecules. So you can imagine that the whole thing can get extremely complicated, especially when you start thinking about the fact that all of it is regulated by molecules, and most likely proteins. There's evidence to the fact that the number of genes that you have doesn't directly impact your complexity, and they've actually counted the number of coding genes in critters, and humans have between 20,000 and 25,000 coding genes. And actually, I say that, and I'm looking at this 2009 copyright by Pearson Education on this image, knowing that, dude, that's like five million years ago. It might as well be as far as research goes, so I would imagine these numbers very well might be updated. But you can imagine our little yeasty friends. We actually grew these guys in the Cellular Respiration Lab, and they've got about 6,000 genes, and these are single-celled critters. And then you go up to a fruit fly, which is pretty cool, has about 13,000 genes. Then you go up to a roundworm, which I don't know, I kind of feel like, dude, the fruit fly has got to be more complicated than the roundworm, but the roundworm has about 19,000 genes, and then you go to a mustard plant, which has the same number as our top level of, or our top estimate for how many genes we have, and it has 25,000 genes. Now, mustard plants are cool. Plants are cool, but I tend to think that, you know, our processes are the things that go on in our brain, and the things that go on in us physiologically are a little bit more complex than what goes on in a mustard plant. And that may be a very human-centric thing to say. The point is the number of genes you have does not directly indicate or directly imply complexity. More genes doesn't mean more complexity. More regulation means more complexity. And in fact, the regulation is happening, I think, by those introns that got spliced out of the messenger RNA in the first place. So an intron that gets cut out might be actually regulating the whole, like who gets built and what gets built. And if the introns are able to regulate things like that and do some mixing and matching and some mixing and matching, we can end up with more diversity than the same number of genes in the first place. Okay, let's take one really quick look at critter diversity and then we're done.