Question: Why is there different types and breeds of dogs?

@berries45: Great question – thank you!
Any differences in animal shapes and forms are due to external influences. For dogs – the main influence deciding how they breed is – us! People.

Initially we selected them for working roles – hunting / retrieving / guarding, but over time, companionship and then, more recently, we’ve also placed influences based on their looks. This has had some very bad outcomes for dog welfare.

For example, pugs are considered super cute by people with their big eyes and squishy faces, but having selected for dogs with short faces and big sticky-out eyes has made that breed prone to lots of health issues. They find it hard to breathe effectively and can get lots of eye issues.

Certain physical traits have become popular and then been emphasised as they’ve been selected for over breeding generations. A good example of this is the documentary ‘Pedigree Dogs Exposed’ – you can see a picture of basset hounds a few decades ago versus now: http://www.uogain.com/2012/03/26/pedigree-dogs-exposed/

When we select for physical traits (like coat colour or leg length or ear shape) we are selecting genes that also link to the behaviour of the dog. Read about the classic fox study that taught us this here: http://en.wikipedia.org/wiki/Domesticated_silver_fox

Some dogs that have exaggerated physical traits also have funny temperaments because the emphasis has been on their looks rather than how they behave.

Messed up, huh? There has been a lot of scientific interest in this area in the past five years and pressure is now on to change breeding practices.

I think it would be way smarter to breed healthy dogs that are suited to being good companions in terms of behaviour, rather than worrying about looks.