Or imagine that you are literally the first organism who by random mutation achieved a gene for “helping your siblings”. How specifically does this gene increase your fitness, or the fitness of the gene itself, if your siblings do not have a copy of this gene?
Even if being the first one to have that gene would make you have fewer children than average, (half of) your children will have the gene too and they would help each other and benefit from that and as a result you’d still have more grandchildren than average.
Good_Burning_Plastic comments on Open Thread May 30 - June 5, 2016