Some clear examples of selection that has gone too far can be found in dog breeding. Selective breeding in dogs has a long history and some dog breeds are selected mainly on looks. And most extreme looks tend to be considered the best when judged in shows. E.g. the shape of the skull in some breeds make it difficult for them to eat normal food because the upper jaw is much shorter than the lower jaw. This is the case in the Boxer and the Bulldog breeds. Other breeds have problems with breathing in case of the breeds with a short upper jaw resulting in a flat face. Some breeds can only give birth or mate with medical intervention (e.g. Bulldog). Some breeds have the risk that the eyes pop out of the socket because the skull is too small for their eyes (e.g. Pekinese, Chihuahua). These are clear examples of selection that has gone too far. And most of these examples are only related to the skull. Other breed characteristics that are not increasing the dog's wellbeing are, for example, too long ears so that infections are common (e.g. Basset Hound), or long back and neck so that intervertebral disc disease has become common (e.g. Dachshund), or too much skin so that inflammation in between the folds becomes common (e.g. Bulldog), or sloping back so that hip problems are common (e.g. German Shepherd Dog). All examples relate to selective breeding and taking breeds more and more too an extreme, because that is the dog you win the show with. Looking back only we realize that we have gone too far. And that realization comes only very slowly because people get used to animals with certain features. They don't consider them abnormal for a very long time. Important is to realize that these effects can be reversed by selecting in the opposite direction.
Algemeen
Inhoud
Integraties