First it needs to be established what you mean by "stronger" as a species? How far back in human evolution would we need to go back to and start examining our alternative path for humanity? There are isolated tribes out there in the jungles today, who pretty much live like pre-historic man, have they been more successful and become more stronger? Or do we need to go even further back in time? Wouldn't a strong species be one that can survive and thrive in any environment? And if this species can't survive at a certain place at first, it can manipulate the environment until it can survive there. If that's the case humans have managed to be a pretty "strong" species. On the other hand we have bacteria and cockroaches that are even more successful than we are. It all matters on how you measure success.
To me, the definition of a "strong(er)" specie is one that doesn't have a future in question. Gentic stagnation, outstripping needed environmental resources per population size and density, and low genetic diversity would mean a weak specie. I wouldn't say humanity is that weak, but an argument can be made that wer are breeding into genetic stagnation and we are most definitly too large of a population to maintain with the current allocation of environmental resources.
Couldn't it be argued that the forming of a civilization is inevitable? At first small separated tribes and packs of humans live on their own and let nature take it's course, weeding out those that can't survive. What happens if two tribes join to take out a third tribe or assimilate it, now they are a bigger tribe and so on? Strength in numbers, more people, larger genepool, more traits. What happens if one of the weaker members of the tribe happens to be an expert in medicinal plants and can help heal the strong and fit warriors of the tribe? Have him teach his knowledge to a fit and strong person who would be more useful out in battle or have him teach someone that is "weaker".
What I am saying is that to me, civilization and somekind of organized society is an inevitable result of our human evolution. Had we stayed as isolated tribes fighting daily for our survival we wouldn't even have this discussion, would we? Organizing ourselves into larger groups and helping out each other has allowed some of our ancestors to spend their time thinking and figuring out things instead of hunting for food and struggling to survive. And over the generations this knowledge has moved on and been refined until we can have this discussion over the interweb.
The converse argument to this is that since civilization could be getting too large to be sustainable, that it could be the death of the human specie--and that backing off civilization into a more antisocial paradigm might bet better for the specie as a whole.