Welfare recipients at the opera, the Jimmy Carter fad, who wins the long-legged beauties. LEGS

(FORTUNE Magazine) – Arthur Jensen, the psychologist and perennial center of the IQ controversy, was somewhat off the mark in the note he sent your correspondent a while back. The note, attached to a scholarly paper entitled ''Physical Correlates of Human Intelligence,'' predicted that we would find this document difficult and dull. Not so. The paper proved to be difficult and fascinating. (It will be published next year, as a chapter in a volume called Biological Approaches to the Study of Human Intelligence, edited by P. A. Vernon.) Furthermore, it contained unexpected good news for heterosexual males with above-average IQs, a category presumably covering most FORTUNE readers. The paper, written by Jensen and S. N. Sinha -- an Indian psychologist and chancellor of the University of Rajasthan -- is indeed tough going in places. Exhaustive and heavily statistical, it represents the authors' effort to bring together all serious studies relating IQ to various physical attributes: height, weight, brain size, myopia and eye pigmentation, age of puberty and menarche, blood chemistry, basal metabolism, presence of allergies, tongue- curling ability, and more. The relationships between these attributes and IQ are typically expressed in the form of correlation coefficients, an instant eye-glazer for many folks who took the liberal arts curriculum but generally inescapable any time you want to see how one variable is related to another. The coefficients range from -1.0 to +1.0. If myopia, for example, were perfectly correlated with IQ, then the coefficient would be +1.0, and anybody who was x% above (or below) average in nearsightedness would also be x% above (or below) average in IQ. In fact, none of the traits described in ''Physical Correlates'' are anywhere near the 1.0 level, and most are under 0.5. The coefficient for myopia is about 0.25, and for tongue-curling, which we confess to not having heard of before reading the paper, about 0.2. (Tongue-curlers are people, apparently possessed of a particular gene, who in varying degrees are able to curl their tongues into a tubelike shape.) A correlation of 0.2 may sound like small potatoes; still, any positive correlation at all tells us that the physical trait in question is associated with above-average intelligence, and you want to know how come. In the case of tongue-curling, the link to high IQ is, alas, not clear. But about the good news for FORTUNE readers. Among the studies cited by Jensen and Sinha are a number gauging the relationship between height and IQ. Most such studies have found a modest positive correlation of about 0.2. Of special interest is an exercise performed in the mid-Eighties by several scholars -- one was Lloyd G. Humphreys of the University of Illinois, another heavyweight of IQ studies -- who reanalyzed earlier data and pointed up an arresting fact. It seems that the correlation between height and IQ disappears entirely when ''sitting height'' is what's being measured; only standing height is correlated with intelligence. What would account for this difference? Obviously, leg length (which is not reflected in sitting-height measurements). The finding tells us that the long- established correlation between height and IQ is really not reflecting measures of over-all height, only measures of leg length. But why? Why would there be an association between long legs and smart heads? Jensen and Sinha confess to being less than certain about the answer, but offer a hypothesis that seems utterly plausible. They note that the women who are rated most attractive in Western cultures (as evidenced in Petty-girl calendar art and Miss America contest results) have traditionally been long- stemmed. Which men will be most successful in pursuing these extended-gam beauties? Obviously the men who are most successful in general: those with high incomes and high IQs. (The income-IQ correlation is about 0.5.) The result, says ''Physical Correlates,'' would be ''cross-assortative mating between IQ (of men) and leg length (of women), resulting in a . . . genetic correlation between IQ and leg length in the offspring generation.'' Junior, in other words, figures to be above average in both brains and leg length -- and there are enough juniors fitting this description to explain the positive correlation in the population as a whole, including business-magazine readers.