It remains tautological. You'll need to define what you mean by 'strongest'. In a situation in which normal state controls have broken down, people may survive for all kinds of reasons. Some will control resources, simply because they are there. Others will be persuasive, others will use violence, and so on. If we look at the characteristics that may lead to survival, we could list :
- Physical strength (Fast runners - the Rincewind solution : Good fighters - the Popeye solution)
- Mental strength (Interpersonal intelligence - the Witch solution : Technical competence - the Geek solution)
- Rhetorical strength (The good story-teller - the Puss-in-Boots solution)
... and so on.
If we look at such natural experiments as failed or failing states, what seems to be true is that people survive best who have already got good networks in place - family, associates, political links and so on.
And then, there's always luck.