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Brain maturation and cognitive development Comparative and cross-cultural perspectives. Edited by Kathleen R. Gibson and Anne C. Petersen. New York Aldine de Gruyter. 1991. ix + 390 pp. $69.95 (cloth)

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DEVELOP-mans and macaques damage to a restricted
region of frontal association cortex results in
Edited by Kathleen R. Gib- specific and profound functional impairson and Anne C. Petersen. New York: ments.
Aldine de Gruyter. 1991. ix + 390 pp.
Diamond’s work ties the maturation of a
$69.95 (cloth).
particular region of cortex to the development of a particular functional capacity. But
This collection of papers comes from a what specific changes do neural structures
workshop on human cognitive development undergo that permit the expression of maheld in 1985. In keeping with the eclectic ture cognitive function? This topic is consid“biosocial))perspective of the meeting’s orga- ered in separate reviews by Kathleen R.
nizers, the authors represent a broad range Gibson and Melvin Konner, who both conof scientific disciplines, including anthropol- clude that cognitive development can be reogy, developmental and cross-cultural psy- lated to the degree of myelination of fibers in
chology, and the neurosciences. The title is cortical association areas. This is a very
somewhat misleading, as only one of the attractive possibility, particularly because
chapters is devotedly primarily to cross-cul- myelination can be studied with standard
tural studies, and if the term “comparative” histological stains in postmortem human or
suggests to the reader that evolutionary is- nonhuman material. (Readers should note
sues will be considered in detail, the reader that it is not possible to directly investigate
will be disappointed. Nevertheless, there is neural connections or their development in
much here to interest physical anthropolo- humans; such studies require the use of
gists, as the volume’s focus is on the identifi- invasive techniques in experimental anication of universally shared features of hu- mals.) I remain unconvinced about the merman cognitive organization and their neural its of myelination studies, however. The deunderpinnings.
velopment of myelin in association areas (in
How can universal characteristics of hu- contrast to sensorimotor structures) is typiman cognition be recognized? Cross-cultural cally gradual and very protracted, spanning
studies of development provide one line of many years. I can perceive no discrete, wellevidence. The premise is that when individ- delineated stages of myelin development
uals from cultures with very different child- which correspond to the stages of cognitive
rearing practices undergo similar changes in development identified by psychologists,
cognitive functioning at a specific age, those such as, for example, a change in frontal
changes can be plausibly attributed t o association cortex that occurs in concert with
shared processes of neural maturation, the maturation of spatial working memory
rather than to shared features of the envi- function. On the plus side, however, Gibson
ronment. This approach is represented by makes a very persuasive case, based on her
Charles Super’s comparison of children in review of the human and nonhuman develrural Kenya and in suburban New England. opmental literature, that there is little eviSuper argues that visual, linguistic, and dence to support Gould’s contention that the
mnemonic functioning undergo fundamen- human brain is paedomorphic.
tal changes at 6-7 years of age which cannot
Arnold Scheibel takes a different tack to
be attributed to the effects of formal school- the structure-function problem, using the
Golgi technique to study dendritic morpholSeveral authors adopt an explicitly neuro- ogy in postmortem human tissue. His results
logical approach. Most satisfactory in this indicate that neurons in Broca’s speech area
regard is the chapter by Adele Diamond, who of the left hemisphere are more richly
compares the ontogeny of frontal lobe func- branched than neurons in right Broca’s area
tions in humans and macaques. Her studies or in the primary motor cortex of either
indicate that both taxa follow a common hemisphere. The hemispheric asymmetry
course of development on tests of spatial evidently develops in the second year of life.
working memory, displaying characteristic Scheibel attributes the greater “branchedtypes of error prior to the emergence of ma- ness” of neurons in left Broca’s area to the
ture functioning (by about 12 months of age great information-processing demands of
in humans, by 4 months in macaques). Addi- language. This conclusion is certainly sustional evidence that the neural systems un- pect, given that only two cortical areas on
der investigation are homologous comes each side of the brain were examined. It
from studies demonstrating that in both hu- might be that case, for example, that branch-
ing is higher in premotor and prefrontal
areas generally, relative to motor cortex.
Moreover, Scheibel’sdata indicate that there
are differences between the left and right
hemispheres which are not restricted to language areas. Still, this study represents a
potentially fruitful approach to relating cortical and cognitive development in humans.
Language is a central element of human
cognitive organization, of course, and it is
widely accepted that human children are
innately predisposed to acquire language. It
is appropriate, therefore, that two of the
most interesting and provocative chapters in
this volume are the work of linguists.
It is now known that congenitally and
profoundly deaf children, who can acquire
spoken language only with the most laborious and prolonged training, can nonetheless
rapidly acquire a gestural language, such as
American Sign Language (ASL). What is
more, the course of sign language acquisition
shows important parallels to the acquisition
of spoken language by hearing children. But
what happens to deaf children who are not
exposed to a signed language? They invent
their own gestural systems, termed “home
sign.” What is remarkable about home sign,
accordingto Susan Goldin-Meadowand Carolyn Mylander, is that although it is a very
impoverished form of communication compared to ASL or a spoken language, it nonetheless shows language-like structure at the
level of the word (words being constructed by
combining specific handshape and motion
morphemes, as in ASL) and at the level of the
sentence. The authors take this as additional
evidence that “the human brain is strongly
canalized to produce linguistic systems with
hierarchical organization.” One could go a
step further: the readiness of deaf children to
sign raises the possibility that humans have
a dual linguistic capacity, with innate propensities for both signing and speech.
The experience of language acquisition
plays an important role in shaping cerebral
organization, as dramatically illustrated by
Helen Neville. For example, Neville reports
that whereas hearing individuals display a
right hemisphere advantage for detecting
moving visual stimuli, individuals who have
acquired ASL (whether deaf or hearing)
show a left hemisphere advantage. She suggests that in acquiring sign language, the
language zones of the left hemisphere, which
are dominated by auditory inputs in most
individuals, become specialized for the visual analysis of hand movements. Language
thus provides a very clear example of how
heredity and environment interact to shape
the phenotype.
Several of the chapters in this volume deal
with health-care and educational matters
which are probably not of paramount concern to physical anthropologists. They do
have features of interest, however. For example, Julia Graber and Anne C. Petersen
remind us that even the most patently silly
biological ideas can influence social and educational policy. The authors relate how one
group of educators in the 1970s reasoned
that learning is less likely to occur during
early adolescence than at other periods, because the brain undergoes a growth spurt at
that time (as inferred from increases in head
circumference). Consequently, the educators
developed a school curriculum which requires no new learning by students in early
adolescence. Before reviewing the evidence
which refutes the premises of the curriculum, Graber and Petersen note that it “has
been widely adopted throughout the country.” Is there any mystery why Danny can’t
Department of Psychology
Vanderbilt University
Nashville. Tennessee
whom the festschrift was organized. As
Edited by Sperber states in the Preface, “[tlhe wide
Geoffrey H. Sperber. New York: Wiley- range of topics covered by these contributors
reflects the astounding array of interests
Liss. 1990. 347 pp. $59.95 (cloth).
that Phillip Tobias has assiduously pursued
Probably the only person capable of being and contributed to in his academic career.”
interested in all 24 papers in this book, as This is indeed the case given that the subwell as able to understand and appreciate jects range from the archaeology of early
their significance, is Phillip V. Tobias for hominids in the Malawi Rift to an analysis of
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development, cloth, gruyter, kathleen, cultural, 390, aldine, gibson, brain, cross, cognitive, new, 1991, york, petersen, maturation, anne, edited, comparative, perspectives
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