OK, thanks. Even so, IMHO this is 'simple' evolution through natural selection because a hive is equivalent to a single individual, not a population, evolutionary-speaking since a single individual reproduces and all the bees are also the offsprings of a single individual. So ultimately, IMHO the characteristics and behaviour of the hive only depend on the Queen and its survival. Which can also explain in part why sacrificing individual bees might be a successful strategy.