How did it evolve?

Hamilton's rule states that because diploid worker bees reproduce less frequently than queens and have high relatedness between each other, then eusociality would have evolved to make haplodiploidy an evolutionarily stable strategy. Two scenarios can explain this: diploid workers will altruistically help each other and will replace the queen's haploid sons with their own haploid sons.

However, when the first scenario expressed mathematically(Alpedrinha et al 2014) where sex ratio and haplodiploidy is used to predict the benefit of altruistic helping, a sex ratio where diploid workers are favored also increases the worth of few haploid males, counterracting any gain from helping. Whether or not haplodiploidy can be compatible with helping is determined by the "worker revolution". There were two ways the "worker revolution" could occur: fast revolution(workers begin helping quickly) or slow revolution(workers appear and gain control through helping slowly). In fast revolution, sex ratios remain constant. In slow revolution, the ratio approaches stability over time.

The second scenario describes workers denying the queen production of haploid males, so they can focus their energy on raising nephews instead of brothers. An unseen consequence to this is that an individual male's reproductive value, which is lower than that of females due to haploid inheritance, increases many fold when workers' sons pass on their mother's father's genes. Thus, helping is reduced.