[Home] [Headlines] [Latest Articles] [Latest Comments] [Post] [Sign-in] [Mail] [Setup] [Help]
Status: Not Logged In; Sign In
|
Science/Tech See other Science/Tech Articles Title: How much is that neurotic in the window? Steve Jones Of all the revolting pets I know, the Xoloitzcuintli takes the dog biscuit. Also known as the Mexican hairless dog, it was sacred to the Aztecs, who used it as a bedwarmer and a convenient snack. It lives up to its name, for it is entirely bald, with black skin. Although several of its teeth are missing, its owners love the breed, and resent it being a frequent winner of ugly dog contests. Ancient statues show it has been around for 3000 years, unusual for dog breeds, many of which are less than a century old. The gene responsible for its appearance has just been found, and it has an almost exact equivalent in our own DNA where it causes a rare inborn disease whose symptoms involve loss of hair, bad teeth and an inability to sweat. There are 400 million dogs in the world and over the centuries their owners have conducted a gigantic experiment in biology. Within the canine population, 400 distinct breeds are recognised, and several trace their identity to a single mutation. The largest dog, the Irish wolfhound, is almost 90 centimetres tall at the shoulder. Sixty chihuahuas would fit into one of them (and probably have, when it got hungry) but the difference in size is due to a single gene, which comes in one form in the wolfhound and another in the chihuahua. Most dog breeds, however, have a different origin. They owe their appearance not to single genetic errors, but to the accumulation of many small changes. Wolves, the ancestors of dogs, are, like people, much the same from place to place. Because humans select their favourite animals from a tiny pool, some dog breeds can trace their ancestry to a very few progenitors - and that can cause problems. The 300,000 golden retrievers in Britain have descended in the past 30 years from only 7000 males. Other kinds have lost 90 per cent of their variation as a result of inbreeding in the dozen or so generations since the 1970s. Such dogs pay a high price for their owners' prejudices. Determined - or deranged - insistence on breeding each line to a standard has led to King Charles spaniels with brains too big for their skulls, and to pugs whose eyes pop out so far they are scratched whenever they bump into something. Pugs are so inbred the 10,000 in Britain share recent ancestry with only around 50 animals. The Xoloitzcuintlis are, say their owners, "calm, tranquil, aloof and attentive". Other breeds look tranquil but are less so. Mating like with like has exposed rare genes, with undesirable effects. In an echo of human obsessive-compulsive disorder, bull terriers chase their own tails for hours until they collapse, while springer spaniels may savage their masters as they fall into sudden attacks of rage. Some Dobermans are too tranquil and fall into a heavy slumber after a snack. They have narcolepsy, a distressing condition also found in people. Their problem involves damage to a certain protein on the surface of brain cells - and the human equivalent is due to a fault in the same gene. Why fanciers wish to own a pet with genetic abnormalities, I do not know, particularly when the problem makes it hard to deal with tough conditions. A quick glance at the Xolo owners' web page reveals a picture of an animal wearing pink frilly pyjamas to keep it warm. The sight is enough to make any aesthete quiver. I wonder what they taste like?
Post Comment Private Reply Ignore Thread Top • Page Up • Full Thread • Page Down • Bottom/Latest Begin Trace Mode for Comment # 1.
#1. To: Tauzero (#0)
Pugs should not be wall-eyed or pop-eyed, but have eyes that point forward.
There are no replies to Comment # 1. End Trace Mode for Comment # 1.
Top • Page Up • Full Thread • Page Down • Bottom/Latest |
||
|
[Home]
[Headlines]
[Latest Articles]
[Latest Comments]
[Post]
[Sign-in]
[Mail]
[Setup]
[Help]
|
||