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from the animals-that-clean-up-after-themselves dept.
In domesticated animals, regardless of species, certain traits eventually appear over and over again. White faces, white body spots, reduced facial skeleton, shorter snout, smaller jaws, smaller teeth, and, yes, Floppy Ears. One would almost think that humans selected animals for cuteness. In fact, people, even primitive prehistoric people, domesticated animals based on nothing more than selecting the least aggressive, or least fearful, and cross breeding those for generations. Those that bolt or bite either escaped, or got eaten, but weren't kept around for breeding.
So why do these traits appear so often in almost all domesticated animals, from horses to rabbits, and from dogs to hogs?
Scientists from Harvard, Vienna, Berlin, and South Africa have a new theory.
These traits are called Domestication Syndrome (DS), and it turns out that selecting for tameness — lack of fear or aggression — is actually a proxy for selecting for reduced functionality (hypofunction) of a specific type of stem cell called Neural Crest Cells (NCCs).
NCCs are the vertebrate-specific class of stem cells that first appear during early embryogenesis at the dorsal edge ("crest") of the neural tube and then migrate ventrally throughout the body in both the cranium and the trunk, giving rise to the cellular precursors of many cell and tissue types.
In a nutshell, we suggest that initial selection for tameness leads to reduction of neural-crest-derived tissues of behavioral relevance, via multiple preexisting genetic variants that affect neural crest cell numbers at the final sites, and that this neural crest hypofunction produces, as an unselected byproduct, the morphological changes in pigmentation, jaws, teeth, ears, etc. exhibited in the DS.
No genetic evidence indicates that all the changes seen in domesticated animals are the result of mutations in any one specific "domestication" gene. The data strongly support a multi-gene cause of DS, centered upon the under-development of neural crest cells.
So when selecting for docile genes the Floppy Ears and White Blaze come along for the ride.
(Score: 5, Insightful) by evilviper on Saturday July 19 2014, @03:08PM
There's plenty of reason to believe that humans weren't involved in systematic breeding that created domestic dogs, at all.
http://www.pbs.org/wnet/nature/episodes/dogs-that-changed-the-world/what-caused-the-domestication-of-wolves/1276/ [pbs.org]
That's nonsense. Cat's weren't tigers (or other large cat) that was selectively bred to be smaller and safer. Instead, domestic cats are basically identical to their wild cousins like the desert cat. [wikipedia.org] Over millennia of human cohabitation and breeding, they've genetically diverged a bit, but are still very close to their wild roots, unlike dogs.
It didn't happen like that with dogs, either. They're 100% grey wolf. There was no mixing of various canine species to get sizes or other traits:
http://www.pbs.org/wgbh/nova/nature/dogs-decoded.html [pbs.org]
Hydrogen cyanide is a delicious and necessary part of the human diet.
(Score: 1) by anubi on Sunday July 20 2014, @07:32AM
I have had a street cat adopt me... and she proceeds to have kittens.
Some of these kittens have taken to me... they became adorable little pets, and I gave them to anyone who wanted a kitten. I see these kittens years later, loved, and some making more kittens.
And some of her kittens are more like an electrical short-circuit... all full of spitz. Scary little things. They won't have a thing to do with me, and I won't force them into anything they don't want because I do kinda want to keep my fingers.
The way I see it, the neighborhood coyote has to eat too. He usually ends up with them.
I could see as long as cat, dog, and man have hung around each other, there is going to be a lot of ones with desirable traits cared for and have a significantly greater chance of reaching maturity and breeding. Those wild little spitzers, even if they do survive, are usually trapped and given to farmers to release in the barn for mice control where the little spitzer does not have to tolerate being handled by a human. Or at least around here, that is usually the fate of an unloved cat. Its a short tough life...
By doing this same thing countless others before me have done, I am just another link in the refining process. Selectively breeding without even thinking about it.
Not all cats are loveable. You may try, but all you will end up doing is contaminating the gene pool genes for nasty dispositions.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]