Why do small dogs live longer than large dogs?

Factual Questions
#1

???

#2

Cite?

#3

This page shows life expectancies of various dog breeds. I don’t know where they got the data, but I think I’ve seen the exact same data elsewhere.

Based on that data, breeds with life expectancy < 9 yrs are:
[ul]
[li]Bernese Mountain Dog (7.0)[/li][li]Bulldog (6.7)[/li][li]Bullmastiff (8.6)[/li][li]Great Dane (8.4)[/li][li]Irish Wolfhound (6.2)[/li][/ul]

Life expectancy > 14 yrs:
[ul]
[li]Bedlington Terrier (14.3)[/li][li]Miniature Dachshund (14.4)[/li][li]Miniature Poodle (14.8)[/li][li]Tibetan Terrier (14.3)[/li][li]Toy Poodle (14.4)[/li][li]Whippet (14.3)[/li][/ul]

To me it looks like a pretty strong correlation between size and life expectancy.

#4

I’ve always assumed it was because, since volume increases by cube while surface area increases by square, a big dog’s heart has to work a lot harder than a small dog’s does.

#5

Does anyone know how they get those numbers?

#6

Here is a bigger list to check when Fido will peg out.

#7

It’s exactly the same as the list I linked to.