Changes

<ref>Vila, Carles; Carles Vila, Peter Savolainen, Jesus E. Maldonado, Isabel R. Amorim, John E. Rice, Rodney L. Honeycutt, Keith A. Crandall, Joakim Lundeberg, Wayne, Robert F. (1997-01-30; accepted 1997-04-14). [http://www.mnh.si.edu/GeneticsLab/StaffPage/MaldonadoJ/PublicationsCV/Science_Dog_Paper.pdf Multiple and ancient origins of the domestic dog], ''Science'' 276: 1687-1689. Retrieved on 2006-12-09.</ref>

<ref>Vila, Carles; Carles Vila, Peter Savolainen, Jesus E. Maldonado, Isabel R. Amorim, John E. Rice, Rodney L. Honeycutt, Keith A. Crandall, Joakim Lundeberg, Wayne, Robert F. (1997-01-30; accepted 1997-04-14). [http://www.mnh.si.edu/GeneticsLab/StaffPage/MaldonadoJ/PublicationsCV/Science_Dog_Paper.pdf Multiple and ancient origins of the domestic dog], ''Science'' 276: 1687-1689. Retrieved on 2006-12-09.</ref>

Secular archeology has placed the earliest known domestication at potentially 12,000 BC-10,000 BC and with certainty at 7,000 BC.<ref>Scott, John Paul (1965), Dog behavior: The genetic basis, University of Chicago Press. ISBN 0-226-74338-1.</ref>

Secular archeology has placed the earliest known domestication at potentially 12,000 BC-10,000 BC and with certainty at 7,000 BC.<ref>Scott, John Paul (1965), Dog behavior: The genetic basis, University of Chicago Press. ISBN 0-226-74338-1.</ref>

 

Dogs are also viewed as being the single most genetically diverse species on Earth - largely thanks to human-imposed selective breeding, the vast array of dog breeds surpasses any other creature on the planet. Due to selective breeding by man, however, many breeds of dog have significant [[gene]]tic disorders. These include hip dysplasia (particularly common in German Shepherds, although common in most big breeds), and respiratory problems caused by shortening of the face, as seen with Boxer dogs and the Bulldog's lip and Pugs smashed faces with wrinkles that collect dirt that must be washed out regularly or may become infected. To overcome the prevalence of genetic disorders rendered common by inbreeding, many breeders regularly practice outcrossing, or introducing new material into a breed line via mating with other kinds of dog. This restores vigor to a breed and can decrease the likelihood of genetic disorders manifesting.

Dogs are also viewed as being the single most genetically diverse species on Earth - largely thanks to human-imposed selective breeding, the vast array of dog breeds surpasses any other creature on the planet. Due to selective breeding by man, however, many breeds of dog have significant [[gene]]tic disorders. These include hip dysplasia (particularly common in German Shepherds, although common in most big breeds), and respiratory problems caused by shortening of the face, as seen with Boxer dogs and the Bulldog's lip and Pugs smashed faces with wrinkles that collect dirt that must be washed out regularly or may become infected. To overcome the prevalence of genetic disorders rendered common by inbreeding, many breeders regularly practice outcrossing, or introducing new material into a breed line via mating with other kinds of dog. This restores vigor to a breed and can decrease the likelihood of genetic disorders manifesting.