If genes determine what you look like, then how can there possibly be so many different kinds of dogs, from a chihuahua to a great dane? There must be something genetic that makes a collie’s head narrow, for instance. Except for pygmies, all humans look alike more than a weimeraner looks like a border collie or a dachsund. But come to think of it, now I’m wondering why some people are white and others a re black, etc. That must be caused by a gene too!
Signed Mr. Confused-About-Genes
With many animals it takes a high amount of inbreeding to express the desired traits. In fact most dalmations are inbred to the point where most are deaf and blind.
Imagine what 7 generations of an inbred human may look like, and you see where the differences come from.
Dogs all look different because they all possess different genes. Every stable population has a certain amount of genetic variation which makes it healthy and adaptable. If all dogs were exactly the same, then they would loose the ability to adapt. If the earth were to suddenly get cold, and all the dogs looked like chihuahuas, then they would most likely die out. If, however, there was a range of variation, then the chihuahuas would die out but the huskies would survive. The genetic average would shift to a bigger, furrier dog as a result of the selection pressure of the cold, and so most new dogs would be big and hairy, but they would survive.
It is this natural genetic variation which allows a species to be adaptable to changing environments. That being said, all dogs are very similar. The posesses the same bone structure, the same organs performing the same tasks, the only major differences are mostly just scale and appearence, and disposition.
The different human races are another good example of this. People from tropical climates possess genes which are more suited to that environment; things like long limbs, tall frames, and dark skin. People from up north tend to be shorter, stockier, hairer, and lighter-skinned because they have adapted to that environment. We’re all the same species because we still all possess the ability to interbreed (and have fertile offspring), but we don’t necessarily possess the exact same genes. Again I want to reiterate that almost all of the genetic differences between a Sweede and an African are cosmetic.
Of course after posting and reflecting I realized that dogs (and cats) were a bad example of genetic variation because most of their genetic differences are due to artificial selection; man-made breeding choices. Somebody somewhere wanted a small dog so they kept breeding the runts of the litter with the runts of other litters and eventually voila, you get a chihuahua. All modern dogs decended from wolves that lived about 30,000 years ago, and while most wolves look alike (natural genetic variation), most dogs look very different from each other (artificial selection).
That brings up something that’s been nagging at me about the Human Genome Project. Where did they get the ‘regular’ human DNA sample from? There are many different genes possessed by many different people. Did they sequence them all or did they just pick the most common. How would you sequence the ‘correct’ gene for eye color?
In answer to the last question, I heard that if the whole human race was wiped out except for say one (any) European country, even a small one, let’s take Latvia, minus any of the Pakistanis and other Asians that are there, eventually all the different human types would appear, that is, long heads, tall, short, round heads, hair, less hair, skin, pretty, and ugly. Even people who look like Indians would be born without any Indians in their background. Well a little, because the point is that any group is already mixed somewhere back when and so all types would come forth. I don’t know if this includes Chinese or Blacks but probably it does and of course they are found in any urban area of the world anyway. Either that or what I heard was even ifyou took a homogeneous population with reallyno mixture in the background if you could find such a thing all the types would evolve. Plus if they lived in Africa they would eventually be completely blackd eventually because any lighter ones would die from skin cancer, which is an epidemic already in Australia.
Cite?
We don’t need no cites, it’s common knowledge and seen on tv on PBS about how each breed of dog has something wrong with it compared to the natural dog. Thus collie’s heads are too narrow for their brains, labs and german Shepherds have practically automatic hip displasia as do probably all other larger dogs, poodles have runny eyes,
various organs in other breeds are squeezed by their outward shaping of the bodies, and so on. You’re better off with a cross-breed or a curbstone setter. Border “collies” are an unrecognized “breed” and are a nice dog, I hear. Cocker spaniels are mean and very stupid and unpredictable.
There was a program on PBS that showed from all parts of the world what dogs look like who are of several generations back of mixed breeds. They’ve been mixed back into being the original dog, and they are thin, medium sized, I think the ears stick up, AND THEY ALL LOOK MORE OR LESS THE SAME. This is the average dog before mankind ruined them. Not that I believe in animal rights and I’m not a vegetarian but look what has been done with pigs and cows to make grotesque swuffering creatures out of them by man’skinds’s breeding practices. No doubt sheep have been ruined from having any kind of life by breeding them with heavier wool coats.
Pigs in nature are lean and run around happily in the mud, but on farms they sit in these boxes and aren’t even allowed to leave. Back to dogs, when I get into Congress or become President, I’m going to see to it that there is a law that NO DOG’S TAILS CAN BE CUT OFF, no matter what the #@%$ kennel society says. Also, no I think it is a certain color labrador puppies can be killed, which is what breeders do with a labrador puppy who comes out a new color in labradors, :“in order to preserve the breed.” Ptui on all that. As I say I don’t even believe in animal rights but cutting an animal’s tail off should come under general rules of cruel and unusual activities in the world. By the way, it turns out that the average normal original dog has the best disposition and health.
And how does that demonstrate that “most Dalmatians are born deaf and blind?”
Sure we do, don! In fact, here’s one which states the following:
Hardly qualifies as “most”, now does it? Also from that site:
Again, that rather deflates your “most dalmations are inbred to the point where most are deaf and blind” claim, doesn’t it? I, for one, would like to see support for your contrary claims.
The American Kennel Club would beg to differ…
And, re: the OP, keep in mind that it is not genes in and of themselves which determine appearance, but the expression of those genes. Gene expression can be affected by other genes, either by stopping their expression entirely (e.g., multiple toes in horses), or by slowing or speeding up growth during development (which could account for, for example, differing snout lengths in various breeds).