On Height

In Blink, Malcolm Gladwell points out that men over six feet tall are more than disproportionately represented among the ranks of Fortune 500 CEOs. He attributes this to something called the “Warren Harding Error,” where individuals make a positive or negative snap-judgment based on physical attributes. In this case, Gladwell claims that we subconsciously attach positive attributes - competence, bravery and other niceties - to height. (The Warren Harding reference speaks to the fact that these snap judgments can be quite wrong. At least with respect to height, for every James Hudspeth there is a Warren Harding. The former is one sharp bloke; the latter was the one of the worst presidents the U.S. has ever seen.)

But do these labor market returns to height simply reflect the views of our unconscious minds? I think there is more to the story than this. Check out this interesting paper by economist Anne Case and coauthors. The study tries to break down the relationship between height and labor market success (in this case, wages) by examining how accounting for, among other things, cognitive development (results from some kind of IQ test) influences the observed relationship. It turns out that a very large part of this relationship is explained by the cognitive status.

How does this work? An individual’s attained height depends on a variety of factors. On the one hand, there is a large genetic component. The power of the mid-parental approximations used by pediatricians speaks to the salience of this factor. Indeed, most studies for developed nations suggest that 90% of attained stature can be accounted for by genetic factors.

However, environmental factors play a large role as well. In some of the fast growing East Asian countries, average height has increased by about 2-4 cm per generation. Most of this is attributable to improving overall economic conditions that come with growth in per capita income (its probably way too fast for population genetic changes). One way to conceptualize environmental effects is to posit that a good environment allows an individual to reach his/her genetic potential in height. (Also, to the extent that height reflects economic conditions, one could also use skeletal records to infer the level of socioeconomic development for societies in the past for which no economic data is available. Check out this paper by Richard Steckel.)

At the level of a single child his/her height is a function of health and nutritional investments and shocks made in the womb and during other critical periods of growth and development. It turns out that these same investments are germane for cognitive development and, in that sense, attaining or exceeding one’s genetic potential in height may be reflective of having obtained the very investments that make strong cognitive development possible.

This research is part of an emerging trend in economics to study how investments made during birth and early childhood influence the socioeconomic trajectory of an individual over his/her lifetime. I’ll have a separate post about that sometime in the future.