A particularly interesting question is, what would people of e.g. Roman empire or mediaeval France think about today's society. We can compare the morality of the past with contemporary standards, but we can't see the future. I wonder whether mediaeval people would find our morality less despicable than we find theirs. If such comparison was possible, one could define some sort of objective (or subjectively objective?) criterion - simply put together two societies with different moral codes and watch how many will convert from first to the second and vice versa. Anyway, it is probable that different moral codes are not all equally well suited for human nature. If so, tha apex can be defined as the moral code which is perfectly stable, i.e. does not evolve (given we stop human biological evolution) and in contact with different moral code becomes dominant.