It's really difficult to get this to work, since the selection pressure at the individual level tends to outweigh the pressure at the group level; every group will eventually produce mutants that don't have the trait; these then come to make up an increasing proportion of the group, since they have higher fitness.
Out discomfort with it is due to this.
Also, I wonder if built in variability with social roles (e.g. a human might be a leader or follower for reasons NOT determined by genetics -- debatable, but I/ many others would hold that early childhood and culture might trump DNA in many important cases ) might alter the equations? Perhaps we evolve past genetic determinism in order to allow for larger group structures to feel the selection pressure more than individuals.
If I had another lifetime, I would study evolution enough to know what I am talking about.... Thanks for the interesting comment
Because "I had 1.8 viable offspring before I died" is more fit than "I had 1.5 viable offspring before I died", no matter how you slice it. Any trait that moves an individual from the former statement to the latter makes that individual less fit, even if it benefits the group, and since the individual is less fit, that trait is less likely to be passed on, resulting (asymptotically) in more fit individuals massively outnumbering less fit ones, irrespective of the impact those individuals have on group fitness.
(EDIT: I am speaking of the hyper-individualistic capitalism popular in America and (I think) Britain, not the lets-have-unions-and-govt-cooperate capitalism of Germany or Japan. Also, I still remember driving for 100 miles with a biologist who told me that group selection violated the basic premises of evolutionary theory, which is basically "selfish gene" only.)