Human intelligence and the IQ scales used to measure it once again are becoming the focus of fiery debate. As argument rages over declining test scores in the nation's schools, an old but explosive issue is reappearing; What is intelligence — and is it determined largely by genetics? The controversy erupted more than a decade ago when some U. S. scholars saw a racial pattern in the differing scores of students taking intelligence and college-entrance tests. Now, the racial issue is being joined by others. Teachers, psychologists, scientists and lawyers argue over the question of whether IQ — intelligence quotient — tests actually measure mental ability, or if findings are skewed by such factors as family background, poverty and emotional disorders. Moreover, some authorities assert that the rise in the number of college-educated Americans and their tendency to marry among themselves are creating a class of supersmart children of brainy parents — and, on the other side of the scale, a lumpenproletariat of children reflecting the supposedly inferior brainpower of their parents. Critics such as Harvard University biologist Richard C. Lewontin disagree. If mental ability were largely determined by inheritance, he says, efforts to enhance intelligence through the betterment of both home and child-rearing environments could only be marginally effective. He comments : ' Genetic determinism could be used to justify existing social injustice as predetermined and inevitable and would render efforts made toward equalitarian goals as useless. ' Supporting Lewontin in this is J. McVicker Hunt, a professor at the University of Illinois, who maintains that IQ levels can be raised significantly by exposing children at an early age to stimulating environments. Hunt's studies show that early help in such areas as education and nutrition can raise a child's IQ by an average of 30 to 35 points. At stake in the uproar over IQ is the national commitment to improve the capabilities of the poor by investing billions of dollars annually in educational, medical and job programs. The controversy over IQ tests is reappearing because of