字幕列表 影片播放 列印英文字幕 Good morning, John. It is time for another bizarre beast this time have taken a different tactic, and I am approaching on animal that you are familiar with. But that is way weirder than I thought. Just because something is common doesn't mean it's not bizarre. And John Horses, horses, the camp puke. They can't breathe through their mouths. I mean, I'm not saying they aren't beautiful animals, though. In part they were bred to be beautiful. It's important to note that there are kind of no wild horses now. There's two reasons for that. Kinda. First, there are lots of feral horses, these air wild individuals of a domesticated species, and there are tens of thousands of feral horses in North America. The second reason it's a kind of is more interesting in Mongolia. There's a species of horse that went extinct in the wild but has now been reintroduced. It's called Pres Wachowskis Horse or the Taki, and it's often called The Last Wild Horse. But first, this probably isn't the horse that modern horses were domesticated from, at least not entirely. And second genetic studies indicate that the talk he might actually be a feral descendant of an ancient domesticated horse. But here's the thing. For thousands of years, wild horse herds and domesticated horse herds existed in the same space is there isn't really a clear, sharp line between domesticated horses and wild horses. But the Taki, with its short legs and zebra like Maine, is likely a good approximation of what horses looked like before we got our hands on whether or not modern domesticated horses are descended from prison Wall Skis horse, maybe some, but probably not entirely. A big piece of that would also be tar pins, a wild horse that is now entirely extinct. And maybe we have a photo of, but we definitely have a drawing of one single drawing. That's that's what we have. Or we could look to cave paintings because these are actually the only images we have of pre domestication horses. So we often think of horses is being a Eurasian thing, but they actually evolved in North America before barely getting out over the Bering Land Bridge before going extinct. And then we humans brought them back because they were useful. And then they escaped and became wild. And so that famous North American Mustang is kind of an invasive species, but it's also kind of a re introduced species. As far as I know, that is the only example of that ever happening in history. All that is very cool. But the thing that really freaks me out about horses is their legs. OK, a thing you have to understand. All terrestrial vertebrates have a really similar body plan. We have to four limbs and we have two hind limbs and we have a middle trunk and we have a head on top and at the end of each limb we have feet. Okay. In a few species there are hands which are just like feet that you don't walk on or in bats. You have feet that you fly with birds. Their feet just became this like little nubbin on the end of their arms. It sounds strange, but to an evolutionary physiologist like hands air just feet that you type with whatever. I don't have time to talk about how weird hands are. The point is there's a very similar body plan in all animals. In us we have bone, bone, foot in ostriches, bone bone, foot in mice, bone bone, foot in Tyrannosaurus rex bone bone foot. But then you got a horse leg. It's bone, bone, bone, bone, bone foot. Where's the Where's the foot? The species in Equus, which includes horses and zebras and donkeys, are just not closely related to any living species. But in the fossil record, we can see their toes becoming less and less necessary until they're left walking around on just one big tow. Those two top bones are leg bones. All of the rest of these bones are foot, their foot bones, and the horse hoof is just a big old Tony. So the next time you see some beautiful galloping stallion's just note, they're all just walking around on one finger. If you look close enough, John, everything is a bizarre be. So next time we will return to some beasts. You are less familiar with John.