|How do you take this guy ... and make this guy?|
The traits that make them different are their eyes, ear cartilage, fur color, jaw shape and temperament. Scientists have discovered that all five traits are directly controlled by one small cadre of cells (called the neural crest) that tell these parts of the body how to grow. And because these traits are pre-packaged in one bundle, if one changes, they all do.
|Mild neural crest cell defincies create weakened ear and tail cartilage, |
reduced brain, jaw and muzzle size, pigment change,
and adrenal changes reducing fearfulness.
An article in the journal Genetics outlines this theory and scientists are confident, that when tested, it will account for the mystery of domestication.
From Science Daily (July 14, 2014): More than 140 years ago, Charles Darwin noticed something peculiar about domesticated mammals. Compared to their wild ancestors, domestic species are more tame, and they also tend to display a suite of other characteristic features, including floppier ears, patches of white fur, and more juvenile faces with smaller jaws. Since Darwin's observations, the explanation for this pattern has proved elusive, but now, in a Perspectives article published in the journal Genetics, a new hypothesis has been proposed that could explain why breeding for tameness causes changes in such diverse traits. … The underlying link between these features could be the group of embryonic stem cells called the neural crest, suggest the authors. Although this proposal has not yet been tested, it is the first unified hypothesis that connects several components of the "domestication syndrome." It not only applies to mammals like dogs, foxes, pigs, horses, sheep and rabbits, but it may even explain similar changes in domesticated birds and fish."
This would explain the curious outcome of the fox-farm project. Foxes are by nature aggressive and fearful. Biologists began to breed only the least aggressive and most docile. In about twenty generations they ended up with foxes that were piebald (spotted), some with floppy ears, curly tails, and shorter legs.
|Coat color, ear and tail cartilage, and pigment were affected when biologists|
created a population of silver foxes with docile temperaments.