Hello again, Paul.
This was a very meaty question for me, since I was once a professional
administrator and interpreter of intelligence and aptitude tests for a
government agency.
There are some studies which indicate that the timing of puberty and
physical maturity may have an effect on such things as body build,
mental illness, various intelligence factors, sexual orientation, and
even right- and left-handedness. However, these studies do not all
lead to the same conclusions by researchers, some of the links are
tenuous, and many of the studies used rather small samples, so I would
advise taking this evidence with a grain of salt. I've gathered some
material that I hope you'll find useful. Thanks for giving me
something good to chew on!
"Progenesis and Human Puberty: Pubertal Timing as a Heterochronic Variable
An abbreviation of the prepubertal growth period by some 4 years might
have had a parallel effect on brain development... There is a relation
between age at puberty and body build. Early maturers tend to be
broad-built pyknic (most 'feminine' or 'masculine'), while late
maturers are of a more linear leptosomic (androgynous) build (Marchall
& Tanner 1986). There is also a relation between body build and mental
illness. Pyknic body build predominates (90%) in classical
manic-depressive psychosis (MDP) and leptosomic-dysplastic body build
(80%) in schizophrenia (S) (Kretschmer 1921, 1961). In comparison,
only around 20% of the general population were of true pyknic or
leptosomic build. It is suggested that MDP is a disorder affecting
very maturers (early puberty) and S affects extremely late maturing
individuals (late puberty)."
Neoteny: Human Puberty and Pubertal Timing
http://www.neoteny.org/a/progenesispuberty.html
"Visuospatial Patterns and Heterochronic Theory
In these non-industrialized populations, visuo-spatial ability as
measured by Performance IQ scores predominates over verbal ability
(Verbal IQ scores), and there is no sex difference (Berry 1966, 1976).
More particularly, Kaerine (1981) studying an Australian aboriginal
population with a semi-nomadic hunter and gathering life-style found
that the aboriginal children performed at a significantly higher level
than the Australian white children from high school she used as
controls, when their spatial competence was compared. They used a
visual (non-verbal) strategy, and their unusual spatial competence was
combined with self-reliance and there was no obvious sex-difference.
In contrast, there is a sexual dimorphism in cognitive ability in
Western industrialized countries today. Females are reported to excel
at tests of fluency, articulation, coding and perceptual speed (Verbal
IQ scores) and males at tests of spatial visualization (Performance IQ
scores). Male visuo-spatial ability is consistent, whereas the female
verbal superiority varies. It seems therefore as if the decline in
mean pubertal age by some 4 years (raised maturational rate) has
reduced visuo-spatial ability, and may ask: what evidence do we have
that there is a relation between rate of maturation and cognitive
profile? There is an inverse relation between rate of maturation and
spatial ability, whereas verbal ability is unaffected by maturational
rate (Waber 1976, 1977). Late-maturing girls and boys (pubertal age 14
1/2 years & 16 1/2 years, respectively = mean + 1 SD according to
Marchall & Tanner 1969,1970) invariably scored higher on spatial than
on verbal tasks, regardless of sex. They also performed better than
early-maturers 12 1/2 years & 14 1/2 years respectively = mean -1 SD)
on tests of spatial ability, also regardless of sex. Maturational rate
had no particular influence on verbal scores."
Neoteny: Visuospacial Issues
http://www.neoteny.org/a/visuospatial.html
"A final piece of evidence linking non-right-handedness with
immaturity comes from Coren et al. (1986), who obtained questionnaire
data on handedness and retrospective reports of age at puberty form a
sample of 1180 university students. There was a significant
association between left-handedness and late puberty in both sexes."
Neoteny: Testosterone, Estrogen, Related Hormones
http://www.neoteny.org/a/androgens.html
"The hypothesis of a neurodevelopmental aetiology of manic-depressive
psychosis and schizophrenia is based on the relation between onset of
puberty and the final regressive events in the central nervous system
(elimination of 40% of neuronal synapses), and the discrepancy in body
build in the two disorders which is similar to that between early- and
late-maturing individuals. The marked rise in manic-depressive
psychoses and decline in schizophrenia, particularly the non-paranoid
categories, accompanying the decline in mean pubertal age by some four
years during the past hundred years are taken as evidence that manic-
depressive psychosis affects early maturers and schizophrenia
particularly affects late maturers. Gender differences and social
differentials accord with this theory. Redundancy of neuronal synapses
characterises manic-depressive psychosis, and reduced density of
synapses is a characteristic of schizophrenia, whereas 'normality',
with optimal synaptic density, is in between."
British Journal of Psychiatry: Age at puberty and mental illness
http://bjp.rcpsych.org/cgi/content/abstract/155/4/536
"Several authors have proposed that early and late puberty are risk
factors for later adult disorders, particularly brain dysfunction.
Over the years, differences in cognitive ability and susceptibility to
psychopathology have been attributed to early and late maturers.
Influential hypotheses have been advanced concerning the role of
delayed or faulty adolescent brain maturation in the etiology of
schizophrenia, and some direct evidence has been presented. These
hypotheses are prompted by evidence that neural substrates implicated
in schizophrenia mature during adolescence. Other outcomes for which
age at puberty may be a risk factor include short stature, obesity,
breast cancer, and polycystic ovary syndrome.
Finally, the regression of clinical problems at adolescence bears
consideration. A small body of research has also developed to
investigate the regression of symptomatology of hyperactivity,
attention deficit disorders, and minimal brain dysfunction syndromes
at the time of puberty. Several interesting hypotheses concerning the
role of growth factors and steroid hormones have been proposed. Thus,
failure of the normal pattern of symptom regression in these disorders
could also be a consequence of environmental toxicant exposure."
Environmental Health Perspectives: Adolescent Health and the Environment
http://ehp.niehs.nih.gov/members/2000/108p355-362golub/108p355.pdf
"The relations between sexual orientation and age of puberty in both
men and women were examined in a national probability sample of the
United States. The sample was the National Health and Social Life
Survey (E. O. Laumann, J. H. Gagnon, R. T. Michael, & S. Michaels,
1994), which contains 3432 cases. Gay/bisexual men reported an earlier
age of puberty (e.g., age of first pubic hair) relative to
heterosexual men, but lesbian/bisexual women did not report a
different age of puberty (i.e., age of menarche) than heterosexual
women. These results confirm findings from prior research examining
age of puberty using nonrepresentative samples and add to a body of
literature suggesting that gay/bisexual men may score, on average, in
the female-typical direction on certain sex-dimorphic physical and
developmental characteristics."
IngentaConnect: Age of Puberty and Sexual Orientation
http://www.ingentaconnect.com/content/klu/aseb/2002/00000031/00000001/00365187
"Onset of puberty is usually considered to coincide with the last
major step in brain development: the elimination of some 40% of
neuronal synapses.... There is an inverse relation between spatial
ability and rate of maturation, whereas verbal ability is unaffected
by maturational rate. From a previous predominance in both sexes,
spatial ability (Performance IQ scores) has been reduced to below
verbal ability (Verbal IQ scores) in the female sex and in early
maturing males."
PubMed: Mental illness and cognition... (abstract)
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2676267&dopt=Abstract
"The relationship between spurts in height and in mental performance
was studied by following a sample of Swedish urban schoolchildren from
age 10 to 14 years. The children were grouped into early, average and
late maturers with peak height velocity age (PHV age) as the
criterion. A mental arithmetic test was administered once a year from
grade 3 to 7 inclusive (10-14 years). Gain/year and level of
performance were analysed both for a pure longitudinal sample
(examined every year) and for mixed longitudinal samples. Early- and
average-maturing girls had a maximum gain/year in performance about
one year earlier than late-maturing girls. In boys, only early
maturers seemed to have a peak in performance gain."
PubMed: Peak velocities... (abstract)
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=547883&dopt=Abstract
"Neuropsychological sex differences have since long been under debate.
Support for the relation between behavioral differences and biological
variables like hormone influence is, however, emerging. Sixteen men
and sixteen women, all university students, were tested with
computerized neuropsychological tests (APT), the Bem Sexual Role
Inventory, and asked about pubertal age. The results were in line with
earlier findings of sex differences in neuropsychological tests, men
being faster and women more cautious. The assumption that women tend
to use left-hemispheric, verbal/serial strategies also in spatial
tasks was also partly supported. In women, late onset of puberty was
related to better spatial performance, and there were also more
intercorrelations between verbal and spatial tests in the female than
in the male group, indicating that women use less specific strategies
(more g-factor intelligence) in problem solving, or that aptitudes are
less compartmentalized in women than in men."
PubMed: Sex differences in strategy and performance... (abstract)
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10870426&dopt=Abstract
"Studies relating to the psychosocial aspects of short stature and
pubertal delay are reviewed. Although IQ scores show a statistical
correlation with stature, significant intellectual, psychological, or
academic deficits have not been consistently demonstrated for short
children. However, hypopituitary growth failure is associated with
poor social adjustment as an adult despite growth hormone therapy. The
reasons for this remain unclear. Constitutional pubertal delay in boys
can lead to social and academic problems. Treatment with a short
course of testosterone can be beneficial in selected cases.
Psychosocial considerations should play a major role in the treatment
of short stature and pubertal delay."
PubMed: Psychosocial correlates of short stature... (abstract)
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3302895&dopt=Abstract
"Research data on IPP [idiopathic precocious puberty] girls suggest
that they do not significantly differ from girls who are early
maturers but within the normal range. Research on these girls
indicates that most negotiate their puberty without severe problems.
There has been less research on IPP boys because it occurs so rarely.
Most of what is understood about precocious puberty in boys comes from
boys with precocious puberty secondary to poorly controlled CAH
[congenital adrenal hyperplasia]. Behavioral data on individuals with
delayed puberty come almost exclusively from boys. Although CD
[constitutional delay] appears to be the most frequently diagnosed
form of delayed puberty and does not reflect a known pathologic
process, men with CD as well as those with organic disorders appear to
be at risk for psychosocial and psychosexual difficulties."
PubMed: Pubertal disorders... (abstract)
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2029887&dopt=Abstract
"Physical maturation appears to have little correlation with cognitive
development. Many developmental psychologists, most notably Jean
Piaget, have documented an expanded capacity for abstract reasoning
during adolescence. Today's adolescents are often capable of complex
reasoning and moral judgment; their capacities frequently astonish
parents and teachers. Indeed, IQ tests show an overall gain in
cognitive capacities since the 1940s, when military personnel were
tested in large numbers and achieved a median score of about 100.
However, there appears to be little relationship between physical and
cognitive maturation.
Researchers have tested the hypothesis that growth across the
developmental pectrum--physical, cognitive, social, and
emotional--proceeds on a similar timetable, and they have found little
evidence to support this hypothesis. However, the research in this
area is relatively weak, in part due to a lack of reliable, valid,
easily administered instruments for assessing cognitive development."
National Academies Press: Forum on Adolescence
http://books.nap.edu/html/ado_dev_bio_pub/
"Based on European and North American school studies, children who are
slightly advanced toward maturity score slightly higher in mental
ability. This is consistently true for children of all ages.
Fast-maturing children have a significantly better chance than
slow-maturing children.
Physically larger children score higher on IQ tests than small ones.
Part of this height/IQ advantage seems to persist into adulthood.
Being an early or late maturer has repercussions on behavior.
Advanced boys are often leaders; small boys are at a disadvantage in
the playground. Youths tall before puberty tend to start puberty
earlier than those who are short."
University of Illinois at Chicago: Growth and Development II
http://www.uic.edu/classes/osci/osci590/9_09Notes%20for%20Week%209.htm
"While the earlier onset of puberty is often viewed with dismay by
adults, it may actually benefit some young people. Early maturers
score slightly higher on IQ tests than their later maturing
counterparts and this small advantage appears to persist into
adulthood (Newcombe and Dubas, 1989)...
Newcombe, N and Dubas, J.S. (1989) Individual differences in cognitive
ability: are they related to the timing of puberty? In Lerner, RM,
Foch, TT ( Eds.) Biological- psychological- interactions in early
adolescence , Hilldale, NJ : Lawrence Erlbaum and Associates. 249-302"
Andrew Fuller: Don't Waste Your Breath
http://www.andrewfuller.com.au/research/wasteBreathe.pdf
My Google search strategy:
Google Web Search: "age at OR of puberty" iq
://www.google.com/search?hl=en&q=%22age+at+OR+of+puberty%22+iq
Google Web Search: "age at puberty OR maturation" mental OR intelligence
://www.google.com/search?hl=en&q=%22age+at+puberty+OR+maturation%22+mental+OR+intelligence
Google Web Search: "delayed OR early OR late puberty" intelligence OR cognition
://www.google.com/search?hl=en&q=%22delayed+OR+early+OR+late+puberty%22+intelligence+OR+cognition
I hope this is on-target. Please let me know if you'd like me to
refocus my efforts; I'll be glad to offer further assistance.
Best wishes,
pinkfreud |
