parameter typically fluctuates around zero and group fitness holds about where it

parameter typically fluctuates around zero and group fitness holds about where it started. Hamilton’s rule, applied to diploids like us where closest relatedness r absent inbreeding is %, forbids investment where fitness gained (benefit) is less than twice fitness given up (cost). I see no escape from the inference that fitness would double with each generation, or more to account for cases where relatedness fell below ¥%. | see no relief in an interpretation, say, that each successive generation cures this imbalance by investing only half or less of its fitness and letting the rest lapse. Fitness is likelihood of leaving descendants of equal fitness. It is not strictly conserved, because likelihood is generally not identical to outcome. There is ex ante and ex post fitness. But the ex ante kind is meaningless unless potency, in Aristotle’s terms, is expected to converge to act. Hamilton’s rule should not have escaped this critique for half a century. It clearly has merit, but needs some different expression. Such a reformulation might treat rb/c as a maximand within practical constraints. We can see how it might be by looking at the context. Darwin’s idea is a competition for breeding success. This biological imperative is a powerful predictor in nature. It predicts that traits are selected for successful reproduction to the exclusion of all else. Evidence is impressive. “Semelparous” creatures who breed only once and do not invest postpartum care, like salmon and soybeans, die within hours. An octopus mother breeds only once, cares for her young a few weeks, and dies as they disperse. Nature is on a tight budget. Resources wasted soon become resources lost to thriftier lineages. Hamilton saw this. He was right in stressing the role of competition among individuals and individual heritable traits. Darwin did the same. One thing Hamilton’s rule leaves out, which is not to claim that he overlooked it, is that traits and their genes best at prioritizing self-replication might for that reason hurt chances of achieving it. We know this happens. Human tradition everywhere resists and punishes nepotism when it crosses a line. Jane Goodall reported the same for Chapter 7 Petty’s Idea 2/3/16 5 HOUSE_OVERSIGHT_011064