Wednesday, 18 July 2012

Foxing Creationists.

Here's a fascinating story which gives an insight into how man may have domesticated wolves and which illustrates a basic principle of evolution - how apparently unrelated characteristics can be linked so that, with the right pressure, a feature evolves for no obvious reason, dragged along with by the evolution of something else, and sometimes unavoidably.

Look at this picture on the right. Is it a dog? A wolf, maybe?

Well, no. It's a fox, Vulpes vulpes.

That's right. That uneatable sentient 'little gentleman in a red jacket' that unspeakable people enjoy pursuing to exhaustion then watching being killed by being torn apart in a tug-o'-war between dogs. (Sorry, I couldn't resist that. I think people who enjoy the suffering of a sentient animal are amongst the lowest forms of human life).

Foxes come in a rare 'siver' (actually, melanistic) form which was prized for its fur, especially in Russia and China. It was in Russia, during the Soviet era, that a program was started to domesticate the silver fox and breed it for its fur.

This video tells the story:

The scientists had decided the way to tame a fox was to selectively breed from those animals which showed less fear of humans already. Animals which are afraid of humans, or any potential predator, must somehow weigh up when to run away. Animals which have less fear will leave it longer before fleeing so, those with a shorter 'flight distance' will have less fear. The scientists assumed this would have some genetic basis and so would be an inherited characteristic. Part of domestication also involved making them less aggressive and safe to handle, so they were also bred for 'passivity'. By selectively breeding from tame animals they expected the foxes to become progressively more tame, i.e. domesticated, with each generation.

Indeed, this is exactly what happened, but so did something completely unexpected: the foxes changed in their physical appearance and behaviours too, not just tameness. A range of coat patterns emerged, never seen in the wild, in addition to the 'silver' coats, which had, after all been the point of the breeding program in the first place. They retained juvenile traits like a broader skull and submissive behaviour, held their tails up and barked and whined.

These differences are believed to be due to physiological changes, associated with adrenaline production, but forty differences have been found between the genome of the domesticated foxes and farm-raised 'wild' foxes.

These have all arisen in a mere fifty years, simply by selecting for 'tameness'. Clearly, there is a set of genes controlling the development of physical and behavioural characteristics, even influencing colour patterns in the fur which are either so closely linked on chromosomes with those controlling 'tameness' that they get dragged along with those for tameness when they are selected for, or, more likely, the same genes affect different aspects of the common fox phenotype. It is rare for a single gene to only control one discrete thing, hence we commonly get a whole syndrome associated with a single mutation on a single gene.

The fact that these features emerged during domestication of the common fox, and are so similar to the same characteristics which have emerged during domestication of the closely-related wolf, strongly suggests that this linkage has a long history and would have been present at least in the common wolf-fox ancestor.

Of course, creationists are going to dismiss this example of rapid evolution and the evolution moreover of characteristics which may not have given any particular advantage; indeed may have been disadvantageous but less so than the advantage gained with the evolution of the characteristic being actively selected for. They will no doubt call it 'artificial' or man-made, but what are humans if not part of the fox's environment? How does it differ significantly in any material way if humans are providing the selection pressure and not some other animal or environmental factor?

Our selection for tameness of wolves, pigs, sheep, cattle, etc., was what caused them to evolve to their present forms no less so than did bees selection for colours cause plants to evolve their flowers to their present form or a bird's startle reflex in response to a mammalian eye caused the peacock butterfly to evolve eye marking on its wings.






submit to reddit




Income from ads will be donated to charities such as moderate centre-left groups, humanist, humanitarian and wildlife protection and welfare organisations.

3 comments :

  1. Video is not available.

    ReplyDelete
    Replies
    1. Thanks.

      That's YouTube for you. I've found another copy.

      Delete
  2. Some creationists would also flip this and suggest it supports their warped view of Evolution - That 'Kinds' diversified quickly after the 'Flood' into their current forms. When you are able to concoct lies, ignore overwhelming evidence and cherry-pick it seems that even the most absurd claims can be supported. Nice post though ;-)

    ReplyDelete

Obscene, threatening or obnoxious messages, preaching, abuse and spam will be removed, as will anything by known Internet trolls and stalkers or by known sock-puppet accounts.

A claim made without evidence can be dismissed without evidence. Remember: your opinion is not an established fact unless corroborated.

ShareThis

Related Posts Plugin for WordPress, Blogger...
Web Analytics