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Neural crest hypothesis may explain domestication syndrome

Caption: This is Helios, an approximately 3-year-old cattle dog/greyhound mix with Lucky Dog Animal Rescue.
Caption: This is Helios, an approximately 3-year-old cattle dog/greyhound mix with Lucky Dog Animal Rescue.
Credit: Lucky Dog Animal Rescue www.luckydoganimalrescue.org

Domestication syndrome was noted by Charles Darwin about 140 years ago. The majority of domesticated animals have some similar traits that Darwin could not explain because the genetic sciences had not developed sufficiently in Darwin’s time. Adam Wilkins from the Humboldt University of Berlin and Richard Wrangham of Harvard University proposed that domestication syndrome is caused by manmade change in a group of embryonic stem cells called the neural crest. The initial research was published in the July 14, 2014, edition of the journal GENETICS.

Neural crest cells develop near the spinal cord of developing vertebrate embryos and migrate to a variety of sites in the developing body. Neural stem cells alter pigmentation in most parts of the head, minimize jaw size, change facial shape, and reduce the development of the adrenal glands. The researchers propose that domesticated animals share a variety of common traits due to the changes in neural crest cells that human breeding efforts have produced.

The scientists contend that domestication of animals has impaired the normal movement of neural crest cells throughout the bodies of domesticated animals. This change in function has retarded the development of some physical characteristics in domesticated animals compared to wild animals from the same species. The concept explains why the majority of domesticated animals share similar traits in physical appearance that are apparent in domestication syndrome.

One of the more important aspects of the change in domesticated animals caused by neural crest cells is a reduction in adrenal gland function. The “friendly” behavior of domesticated animals is the result of lower levels of adrenaline being produced. Wild animals are known to have higher levels of adrenaline than domesticated animals and that explains in part the ferocity of some wild animals.

The concept has not been tested completely but the development of the genomes of domesticated animals and their wild relatives is expected to provide proof in the near future. The white facial spots, floppy ears, endearing face, and mild disposition of your dog or cat may be the result of genetic manipulation by man. Breeding domestic animals for specific traits was in reality a lucky coincidence that produced a change in domesticated animal’s genetic structure.