Hence "depending on how broad a view of "biology" you're talking".
In any case, by "biology" you're referring to the biosphere? If so, the (potential) risk is that "biology work[ing] itself out" may involve working humans out of the picture as well.
In any case, by "biology" you're referring to the biosphere? If so, the (potential) risk is that "biology work[ing] itself out" may involve working humans out of the picture as well.
In addition, there's the question of whether the variability in human DNA affects the originally described "nasty self-centered" behavior; if it doesn't, no amount of "natural" variability will achieve the described desired outcome.