Do you think that a huge body or a little body is better for survival ?
Which one do you prefer ? and why ?
Mostly, I think it's the luck of the draw, just like the best soldiers don't necessarily survive war.
If I had to answer, I'd guess the following in order of importance:
-mental toughness
-endurance
-pulling strength
-pushing strength
-overall power
-overall speed
I've seen seemingly overweight guys running marathons in decent times. Those same guys didn't seem to have the body type to be healthy at a lower weight. To some extent, you can't judge someone based on looks.