Educability-and-Group-Differences-1973-by-Arthur-Robert-Jensen

338 Educability and Group Differences
Assume further that all 9 percent of this group afflicted by malnutrition
has thereby had its IQ lowered by 20 points (which is the
difference between severely malnourished and adequately nourished
groups in South Africa - the most extreme IQ difference reported
in the nutrition literature). Assuming the present Negro mean IQ
in the U.S. to be 85, what then would be the mean if the 20 points
of IQ were restored to the hypothetical 9 percent who had suffered
from intellectually stunting malnutrition It would be 86-70, or a
gain of less than 2 IQ points as an outer-bound estimate. Thus it
seems unlikely that nutritional factors could carry much weight
in any explanation of the average Negro-white IQ difference. This
is not to say that cases of malnutrition do not exist in the U.S.,
or that all possible means should not be applied to ameliorating
poor nutrition wherever it is found. It simply means that a nutritional
hypothesis of average Negro-white IQ differences has little
or no basis in fact, even as a minor contributory factor.
Actually, no one yet knows what the net effect of undernutrition
in an entire large population is under natural conditions in which
many concomitant factors are free to operate. One might even
hypothesize that the net effect of extreme nutritional depression
in a population (not for an individual) might actually be to raise
the IQ due to increased fetal loss and infant mortality along with
natural selection favoring those who are genetically better endowed
physically and mentally. Such a hypothesis could be tested by
analysis of physical and mental measurements on individuals
conceived and born during the months of severe protein starvation
in various European countries, particularly Holland and Poland,
toward the end of World War II. Such studies, sponsored by the
U.S. Department of Health, Education, and Welfare, are presently
underway.
But there are also less speculative reasons for believing that the
role of nutrition should not be overrated as a factor in Negrowhite
IQ differences. For example, children who are malnourished
show a long developmental lag, registered in physical as well as
psychological characteristics (Cravioto, 1968). No such lag is
found in Negro children and what little evidence there is shows
no difference between Negroes and whites in the degree of
correlation between physical and mental traits. Malnutrition
retards the ossification of cartilage; yet representative samples of
Negro infants have been found to be advanced over whites in