Our book examines the nature of cooperation at all levels, from molecules on up (although in fact we did not say much about social cooperation) so it is interesting that a variety of scientists are reacting to the excessive focus on competition in biological thinking (and even today, political columnist David Brooks in the NY Times, discusses cooperation in the sense of social and moral behavior). The centrality of cooperation is our basic theme, and we agree with Mr Zimmer and Brooks on its importance.
It should be said that the defenders of darwinian orthodoxy generally argue that, one way or another and call it what you will, if something proliferates something else doesn't, and that's called 'natural selection' and is the very definition of 'competition'. Since that is a socially loaded word, that is then used to justify aspects of our social structure, we like the equally loaded word 'cooperation' for what is actually going on most of the time--even if there is always some element of 'competition.' In our book we outline ways things can come about other than by classical selection, including drift, which is much more important to the evolution of traits (not just DNA sequence) than is usually credited. Cooperation is a much more accurate word to describe what goes on every day in every organism and every cell, even if over very long time periods, the effects of competition and chance add up to divergence.
We could unload this discussion somewhat if we used terms like 'differential proliferation' and 'interaction' instead of competition and cooperation.