Re:

http://www.sciencedaily.com/releases/2015/06/150616215956.htm seems that as populations grow, indiv intelligence might go down, as mob rule becomes the norm. Gas a speed measure. might also assume that it takes 2 men with iq of something less than 100 to accomplish the same task in the same time as an indiv with an iq of lets say 100.

This is fascinating. Could we get a quantitative measure on the cost of individual brains, with respect to resource consumption and quality control? The former would be mostly brain size, i.e. how hard it is to feed it, but also how long it takes to develop and train it. The latter would apply to individual differences in intelligence etc. with roughly the same brain size.

Insect societies should be special, because the absence of individual chances for reproduction removes evolutionary competition between them. Individual intelligence benefits the other members, too. In social species where every individual has a chance of reproduction, individual intelligence in addition gives an edge over competitors in the same population. Why would mob rule encourage lower intelligence in individuals? We still have competition among the mobsters, so there is always an evolutionary pressure towards higher intelligence.

Intelligence is a tool for many uses, it may be used for abstract problem solving or for power. The latter might imply that being too intelligent is dangerous. If an individual is powerful, it might benefit from getting rid of competition, especially smarter but currently less powerful potential rivals. In a species with social dominance hierarchies, it might be a survival advantage for the vast majority to be either less smart than the ones in power, or to be smart and totally disinterested in power. It is tempting to ponder if that could explain nerds, i.e. people with high intelligence but low social skills and little interest in dominance.