Yes, we have decided which species will and will not live, but in so doing, we have almost assured (up to this point in time) that every person who wants to reproduce in our culture can? This point is made again in My Ishmael.
The culture which arose from the agricultural revolution broke the rule of erratic retaliation because they could. Julie determines that the erratic retaliation strategy is preferable to the total annihilation strategy because if a tribe took the annihilistic strategy, others would team up against them and destroy the subversive tribe.
So, only the threat of destruction is what prevented tribes from adopting the annihilation strategy. Once a tribe found a way to have unlimited resources, did it not make sense for them to destroy those around them, securing those tribes’ resources for their own progeny?
I guess both of my questions sum up to this–although our culture (and our species) is on the brink of destruction, did we not just take a logical step in terms of reproductive success?