Mongrel
Purebred dogs have been, for the most part, artificially created from random-bred populations by human selective breeding with the purpose of enhancing desired physical, behavioral, or temperamental characteristics.
Unlike mixed-breeds, crossbreed dogs are often the product of artificial selection – intentionally created by humans, whereas the term mongrel specifically refers to dogs that develop by natural selection, without the planned intervention of humans.The words cur,[7] tyke,[8] mutt, and mongrel[9] are used, sometimes in a derogatory manner.
In the Bahamas and the Turks and Caicos Islands, the common term is potcake dogs (referring to the table scraps they are fed).
In South Africa, the tongue-in-cheek expression pavement special is sometimes used as a description for a mixed-breed dog.
In Sweden these dogs might be humorously referred to as a gatu korsning, which translates to intersection, but literally to 'street crossing'.
The companies claim their DNA-based diagnostic test can genetically determine the breed composition of mixed-breed dogs.
The theory of hybrid vigor suggests that as a group, dogs of varied ancestry will be generally healthier than their purebred counterparts.
If the dog breed is popular, and the line continues, over hundreds of years diversity increases due to mutations and occasional out-breeding.
The artificial selective force favors the duplication of the genetic disorder because it comes with a desired physical trait.
Inbreeding among purebreds has exposed various genetic health problems not always readily apparent in less uniform populations.
Mixed-breed dogs are more genetically diverse due to the more haphazard nature of their parents' mating.
The offspring of such matings might be less likely to express certain genetic disorders because there might be a decreased chance that both parents carry the same detrimental recessive alleles, but some deleterious recessives occur across many seemingly unrelated breeds, and therefore merely mixing breeds is no guarantee of genetic health.
[24] Data from Denmark also suggest that mixed breeds have greater longevity on average compared to purebreds.
The median age at death was determined for purebred and mixed-breed dogs of different body weights.
[27] In 2013, a study found that mixed breeds live on average 1.2 years longer than purebreds, and that increasing body weight was negatively correlated with longevity (i.e. the heavier the dog, the shorter its lifespan).
[29] Studies that have been done in the area of health show that mixed-breeds on average are both healthier and longer-lived than their purebred relations.
