Asthma is so common that this is not only easy to test, but has been. That's what the article was about.

Anyway, by your own line of thinking, wouldn't sensitive lungs be an advantage? The incentive to find cleaner air is also breaking away from the pack. Since humans are social creatures, that's more likely to look like new leadership for followers who have their own reasons to break away.

Every civilization in history has started out that way. It takes more than mere brute force to beat the competition. Survival is just as much about picking your battles and working smarter.