I was rereading the post and realized my answer for the hybridization part was a bit terse. The thing you have to realize is that ferrets were domesticated to do exactly the same things polecats did, ONLY to be more manageable by humans. Do do that, you simply breed out fearfulness, which, coincidentally breeds in domestication. But there is an important implication as well, and it is that ferrets did not change much in terms of their body structure, fur color, and size or proportions. What changed was the BEHAVIOR of the animal. That doesn't make the ferret any less domesticated than the dog; even the cat has undergone relatively few external or physiological changes in 3600 years. All it means is that it defines most causes of domestication; that is, behavioral changes. Now, don't feel dumb if this is hard to understand or easy to miss, because Darwin missed it as well, classifying the ferret as "semi-domesticated" because of the lack of external changes. (<sigh> My heroes are only human...) So, when I argue that polecat hybridization with ferrets doesn't cause external changes, but DOES cause behavioral ones, it is based on the knowledge that the allelic frequencies coding for behavior are quite different between polecats and ferrets, but the allelic frequencies governing external morphology and physiology are quite similar. Many recent studies show most of the changes in physiology and morphology between domesticates and their progenitors are due to timing changes during fetal development, NOT in genetic changes to the genes governing physiological or morphological processes (it is very complicated, involves polygene interactions, neurochemicals and hormones, and is not fully understood). Strangely, breeding for tameness also causes a change in development, resulting in a juvenilization (or neotony) of the animal. And that is what is confusing when you breed a polecat to a ferret. You think you have achieved a darker black or more muscles, but there has been no change in those genes, only in their expression. Here's an example. Domesticated animals are generally lighter in color than their progenitors, especially in the blacks, which typically turn to a dark brown under initial domestication. But there may be no change in the actual color genetics of the animal. One of the changes caused by domestication is when the embryo is initially developing, and pigmented cells are migrating to the skin. The timing of the migration is subtlety disrupted, so cells which would result in black fur now only produce dark brown. This timing disruption is also thought to result in those white patches you see on the foreheads of so many domesticated animals, including dogs, cats, pigs, cattle, horses, ferrets, bunnies and rats. In other words, domestication doesn't change the genes to stop coding for black and to start coding for brown, what it does is change the expression of the same gene so black only expressed as brown. Why? Because when you select for behavior to increase tameness, you accidentally tap into the animal's development center. That is why neotony is a universal trait of domestication. But you also get a tame, fearless animal. Which brings you back to the hybridization issue. If the major selective change in ferrets was for behavior, what happens when you cross a ferret with a polecat? You get a change in behavior, maybe not as positive as you might think. The problem is, the changes in morphology are not so much due to the introduction of new genes, but in the expression of the old ones. Because the timing differences which make the ferret domesticated influence the expression of many physical traits, many times when you think you have introduced a new gene, all you have actually done is change the expression of an old one. The problem is, with domesticated ferrets, that can only mean you have lost the traits of domestication, namely fearlessness. The resulting offspring are usually not well suited for children or most adults. The bottom line is, crossing ferrets to polecats in the hope of finding a new gene, or to help eliminate a bad one, actually results in behavior changes of a potentially profound nature, and at the receiving end of many a mink and weasel bite, I can confirm the action is potentially dangerous. If bad genes exist in a population, the easiest way to get rid of them is not to breed the traits in; simply neuter than animals and it is the same effect as killing them (reproductive culling). Those genes will never splash in the gene pool. If you want new traits, you have to do it the old fashioned way, which is careful and selective breeding, detailed breeding records, and the realization that it ultimately depends on a favorable mutation which can be conserved and passed on to future offspring (like long fur on angora ferrets). But your chances of getting those types of traits from polecats is somewhere between "nil" and "slim". All you will do is breed a less trustworthy, less dependable animal, which harms all of us. Bob C and 15 Mo' Melano-Mistakes [Posted in FML issue 3251]