Concept
Breeding back is a form of artificial selection by the deliberate selective breeding of domestic (but not exclusively) animals, in an attempt to achieve an animal breed with a phenotype that resembles a wild type ancestor, usually one that has gone extinct. Breeding back is not to be confused with dedomestication. It must be kept in mind that a breeding-back breed may be very similar to the extinct wild type in phenotype, ecological niche, and to some extent genetics, but the gene pool of that wild type was different prior to its extinction. Even the superficial authenticity of a bred-back animal depends on the particular stock used to breed the new lineage. As a result of this, some breeds, like Heck cattle, are at best a vague look-alike of the extinct wild type aurochs, according to the literature. The aim of breeding back programs is to restore the wild traits which may have been unintentionally preserved in the lineages of domesticated animals. Commonly, not only the new animal's phenotype, but also its ecological capacity, are considered in back-breeding projects, as hardy, "bred back" animals may be used in certain conservation projects. In nature, usually only individuals well suited to their natural circumstances will survive and reproduce, whereas humans select animals with additional attractive, docile or productive characteristics, protecting them from the dangers once found in their ancestral environment (predation, drought, disease, extremes of weather, lack of mating opportunities, etc.). In such cases, selection criteria in nature differ from those found in domesticated conditions. Because of this, domesticated animals often differ significantly in phenotype, behaviour and genetics from their wild forerunners. It is the hope of breeding-back programs to re-express, within a new breeding lineage, the wild, ancient traits that may have "lain buried" in the DNA of domestic animals. In many cases, the extinct wild type ancestors of a given species are known only through skeletons and, in some cases, historical descriptions, making their phenotype poorly understood.