Why Domesticated Mammals Have Floppy Ears?

Here's a strange things, wolves and coyotes have these upright ears. All the better to hear you with. But dogs has a floppy ears. Why the difference? Doesn't dogs need to hear too?

Charles Darwin himself actually thought a lot about this question. A 150 years ago he published a book "The Variation of Animals and Plants Under Domestication", Darwin noted that tame animals have floppy ears; shorter snouts; and their fur tends to be paler or have patches with color missing. All these mysterious traits put together have been called "Domestication Syndrome."

The story starts thousands and thousands of years ago, when humans were surrounded by animals. Some animals were scary, and some were a bit more approachable, even potentially useful. Our ancestors wanted them to be tamer, so sometimes they tried breeding the friendliest ones. At some point, strange side effect started to show up. Thousands of years later, good old Darwin noticed the domesticated syndrome pattern. But all he'd learned about change in the animal kingdom, couldn't explain this connection between behavior and appearance. Scientist who came after him couldn't figure it out either. But for the past few years, scientist have been throwing around a fascinating hypothesis. They think the answer to this whole puzzle lies in a special group of cells. They're called "Neural Crest Cells", and coincidentally they were discovered by Wilhelm His Sr. the exact same year Darwin published his book.

Neural crest cells show up very early in the development of all vertebrate embryos. As the embryo grows into a goat or a pig or a wolf, these special cells travel to every corner of the body and take on all sorts of different jobs. Now, here's the thing; some of these cells end up right above the kidneys, they become the cells that secrete adrenaline (that famous fight-or-flight hormone). Wild animals are always fighting or fleeing to survive, and that makes it hard for human to get close. But what if an animal was born with fewer of these neural crest cells? Or those cells didn't work so well? That animal would have less adrenaline, it would probably be less freaked out by humans and it would pass that behavior on to its offspring.

The idea is that this is what's going on in domesticated animals. Their neural crest cells have been dialed back. And this would explain all the appearance stuff too, because neural crest derived cells do a lot more than just make adrenaline. Some of the cells end up forming parts of the face. Some of them become cells that control the color of skin and hair. And some of them make their way into the ears, and help make cartilage.

But the neural crest cells hypothesis doesn't quite explain every bit of domestication syndrome. Like, what's going on with other tame species that do have upright ears? This might be the excuse scientists need to spend more time with their pets.

Source : [Skunk Bear]