Why do larger animals have longer lifespans?

Question

Small animals like hamsters only live 2-3 years (as pets) while animals like crocodiles live on average for 30 to 40 years. Is it because their bodies age or get weaker slower because they have a larger surface area or something?

Thanks for answering

In: Biology

Answer 1

Large mammal = slower metabolism & slower heart rate.

Small mammal = faster metabolism & faster heart rate.

I read an interesting tidbit from Stephen Jay Gould (in “The Panda’s Thumb, iirc) that if you look across all mammals, regardless of size, we each get approx 1 million heartbeats in our lifetime. The faster the heart rate, the shorter the lifespan.

EDIT: Goulds approximation was a billion heartbeats, not a million.