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

Language Deprivation 289
the presentation of data and the statistical analyses thereof make it
probably the best single study available to date. Summarizing the
results on the Developmental Motor Quotient (DMQ), derived from
her infant tests, Bayley (1965, p. 405) reports: ‘The means for the
Negroes are higher at every age (from 1 to 15 months) except 15
months. The difference reaches significance at the 0-01 level of
confidence at months 3, 4, 5, and 9 and at the 0-05 level at months 7
and 12. After 12 months this difference disappears.’ Bayley concludes:
‘Although there is considerable overlap of scores among whites and
Negroes of the same age, a genetic factor may be operating. That is,
Negroes may be inherently more precocious than whites in their
motor coordinations’ (pp. 408-9). Cravioto (1966, p. 78) has noted
similar results in Indian infants of Guatemala and Mexico, commenting
that on the Gesell tests of infant behavior ‘their development
at two or three weeks is similar to that of Western European infants
two or three times as old’. It is also interesting that Orientals
(Chinese-Americans) who, as school age children, equal or exceed
the white population in the most heavily g loaded intelligence tests
and in the most abstract scholastic subjects, as infants are significantly
less motorically reactive than white infants, though they show
no significant difference in neuromuscular maturity per se (Freedman
& Freedman, 1969). Chinese and Caucasian neonates in the nursery
of the same hospital were ‘tested’ shortly after birth. Marked
differences in reactivity showed up, for example, when a loosely
woven cloth was placed on the face of the supine baby. The typical
Caucasian neonate ‘immmediately struggled to remove the cloth by
swiping his hands and turning his face’; the typical Chinese-American
neonate ‘lay impassively, exhibiting few overt motor responses’. This
behavioral difference was significant beyond the 0-0001 level.
‘Similarly, when placed in a prone position, the Chinese infants
frequently lay as placed, with face flat against the bedding, whereas
the Caucasian infants either turned the face to one side or lifted the
head.’ Similar studies of Negro neonates suggest that the three racial
groups lie on a developmental continuum on which the Caucasian
group is more or less intermediate. A related fact is that there is an
inverse relationship throughout the phylogenic hierarchy between
the tendency for multiple births and the prolongation of immaturity.
In the course of evolution there has been genetic suppression of
multiple births in all hominids, including man, through natural
selection, although twins and other multiple births still occur with
low frequencies. As Harrison, Weiner et al. (1964, p. 91) have noted,
‘Single young is a pre-adaptation for progressively increased
maturation time, and in this respect man shows a clear continuity
with the pongids’ (the phylogenically closest group having the most