I have just finished reading No Two Alike by Judith Rich Harris. A review will be forthcoming, after I’ve digested the material and can offer up some coherent reflections. But one of the things that is great about Harris’ book is that its review of the literature is both thorough and engaging. In one of the last chapters she points to the research of Mary Cover Jones published in 1957 in Child Development, “The later careers of boys who were early- or late- maturing.” In short, the research suggests that late maturing boys are disadvantaged in the dominance game for their whole lives in comparison to early maturing boys. In this case Jones found a group of boys who varied greatly in height in their teens, but where the late bloomers eventually caught up. But, even later in life they tended to exhibit a lack of dominance, while the early maturers translated their social ease and grace into more high status careers. This is reminiscient of research which shows that men who are tall as teenagers tended to make more money than those who were short, and that the correlation between height and income as adults was simply a byproduct of the fact that most tall teenagers matured into tall adults (ie., males who peaked early and were not particularly tall as adults were still high earners, while males who had a late growth spurt were not).
Now, stringing together correlations can be a sketchy game…but the reason I thought of this is because of the recent Nature paper which suggested that delayed brain development correlates with intelligence. I don’t know if delayed brain development indicates delayed development in general, but as I noted before, the normal distribution in intelligence suggests strongly that there must be braking selective factors against the drive toward high IQ. Life history analysis seems to be very difficult in general, but these are the sort of angles that might be very interesting to explore at some point in the future.