Scientists from Harvard University and Tecumseh Fitch of the University of Vienna have discovered the genetic link between Darwin's observations of domesticated animals as compared to their wild counterparts.
Some 140 years ago, Charles Darwin observed domesticated animals were more tame compared to their wild ancestors. They also showed patches of white fur, had more juvenile-looking faces, and floppier ears. During that time, scientists were unable to explain the cause of those differences.
A new study introduced a hypothesis to explain these variances. Richard Wrangham of Harvard University and Tecumseh Fitch of the University of Vienna claimed the differences may have been due to a set of embryonic cells called the neural crest.
Neural crest cells are developed near the spinal cord during the early embryonic stage of vertebrates. As the embryo matures, these cells are transferred to various parts of the body and produce tissue masses. These tissues influence the pigments of the ears, teeth, jaws, and skull, and also affects the animal's fight or flight response.
Researchers concluded poor development of the neural crest or an affected distribution of cells may have caused differences between domesticated animals and their wild counterparts.
"When humans bred these animals for tameness, they may have inadvertently selected those with mild neural crest deficits, resulting in smaller or slow-maturing adrenal glands," said Adam Wilkins, co-author of the study from the Humboldt University of Berlin. "So, these animals were less fearful."
The neural crest can also produce a deficit in pigment production, which explains the white patches of fur or skin observed in domesticated animals. Poor development of the neural crest also results in abnormal ear cartilage, changes in the animal's jaw development, as well as malformed teeth.
Further findings of this study were published in the July 15 issue of Genetics.
