Cross Breeds

Why do different breeds of dogs look so much different?

I once heard that many dogs can be physically different due simply to nutritional differences. However, this doesn't really explain dogs of different breeds. So, why do different breeds of dog look so much different from each other? To compare, humans do not have that much diversity.

Public Comments

1. Its because of thousands of years of selective breeding of wolves from all over the world :) ADD: According to The New Encyclopedia of the Dog (aka my bible) modern dogs originated from four species of wolf- North American Wolf, Chinese Wolf, Indian Wolf and European Wolf. Heres a passage from the book; Natural environmental pressures resulted in the wolf becoming small, relaxed with humans and sociable, but it was only after many generations of selective breeding by humans that the great diversity of dog breeds developed. Intensive selection increased barking, valuable as a warning signal. Lopped ears and different tail carriage were also selected to distinguish domesticated dogs from wild canids. The size of the frontal sinuses on the head increased for no apparant reason, other than to make the dog appear more intelligent. Initially, dogs were diminished in size, with the creation of miniatures and dwarfs. At a later stage, size was enhanced, producing todays giant breeds
2. its genetics.. dogs just have a wide variety of genetics.. and combinations of genes that produce different appearances.
3. Bred for different purposes. Some can dig well, some can swim well, etc. It's all from thousands of years of breeding.
4. People bred each breed of dog with a purpose in mind, from the fluffy lap dogs to the big tough guard dogs. Each dog had a purpose and the people kept on until they achieved that look or type,The herding dogs had to have a different movement,eye, and intelligence to work with the owner and on their own.To make snap decisions on how to move stock that didn't always want to move. The hunting dogs had to have a great nose and the grit to keep up looking for something until it was found. And a way to let the hunter know it was time for him to come in and finish the job. Ratters for keeping rats out of ships and homes, just a few examples that tell me the reason for the huge diversity in the breeds.
5. The reason is due to humans breeding dogs for certain looks and appearances. Over the centuries, humans finally are getting breeds of dogs that look the way they want them to by cross and inbreeding. Did you know that the English Bulldog was NOT the short statured breed it was back in the 1800's? It was actually a very tall, still stocky, dog bred for taking down lions. But humans have bred them over the years to still weigh the 80lbs but are 3 times smaller, have breathing problems and prone to all sorts of hereditary health problems.
6. After years of artificial selection (when humans bring two dogs with qualities they like together to "do the do") fur color, eye color, body build, etc., etc., has become greatly differed After hundreds of years of artificial selection there are so many mixed up breeds (not to mention the thousands of types of mutts out there) it's not really that unbelievable that different breeds look so different..... Course I'm pure bred, copper-red, Red Fox!!! =3 LOL! Nice Avatar!