Small domestic dogs emerged in the Middle East at least 12,000 years ago as a result of the domestication of gray wolves ( Canis lupu s). To reach this conclusion, Melissa Gray and Robert Wayne, from the University of California, have identified variations in a gene called IGF1 that is associated with dog size. "Our results show that the version of the IGF1 gene found in small dogs is closely related to that found in wolves in the Middle East," says Gray, confirming that these domesticated breeds originated in this area.
The artificial selection of small dogs would have begun in the territory that today occupies Iraq. "Small size would be more desirable in agricultural societies where dogs spent a lot of time indoors and in confined spaces," the study authors state in the journal BMC Biology .
The domestication of some farmyard animals and cats also took place between 12,000 and 8,000 years ago. However, large dogs could be an exception, since evidence has been found that large dogs lived with our ancestors at least 5,000 years before, when humans were still hunters and nomads.
