Michigan State University
Malina
教授の紹介
Malina教授は、現在Michigan State University のDepartment of Physical Education and Exercise ScienceとDepartment of Anthropologyの教授で、Institute for the Study of Youth Sportsの所長です。体育学と人類学の博士号をとり（Ph.D., 1963, Physical Education, University of Wisconsin, Madison； Ph.D., 1968, Anthropology, University of Pennsylvania, Philadelphia）、ベルギーのKatholieke Universiteitの名誉教授でもあります。また、1991年よりAmerican Journal of Human Biology編集長を務め、 Yearbook of Physical Anthropology, 1981-1986の編集もされていました。
Our studies
in the Valley of Oaxaca began in 1968 and continued through1979. The studies have focused primarily on school children. They represent to a large extent the survivors of a reasonably intense selection process in the area associated with a history of chronic undernutrition and high mortality rates during infancy and early childhood (preschool, birth to 5 years). Less extensive data were collected on adults. Results of the studies are as follows:
A. Growth Status
The composite sample of approximately 1450 children 6-16years of age from the two rural Zapotec-speaking communities, two rural Ladino communities, and two colonias populares surveyed between 1968 and1972, can be viewed as typical of the public, primary school population in the Valley of Oaxaca at the time of the surveys. The sample does not include better off children of professional and business people in the city of Oaxaca. Oaxaca children have statures that are, on average, consistently below the 5th percentile of U.S. (NCHS) reference data. Mean statures deviate further from the 5th percentile with advancing age after11-12 years reflecting a later adolescent spurt. Body weights of girls, on average, fall between the 5th and 10th percentiles, while weights of boys approximate the 5th percentile from 6-11 years and then fall below the 5thpercentile. In contrast, weight-for-stature in boys and girls is, on average, appropriate and matches the median for prepubertal U.S. (NCHS) children. The results suggest that growth stunting has occurred during the preschool years. The statures and weights of Oaxaca children are also smaller compared to middle class children of Mexico City. These general comparisons suggest that Oaxaca school children are, by Mexican standards, smaller than average but similar to Mexican children from the poorest economic conditions.
The estimated median age at menarche (probit) for the composite sample is 14.4=B10.23 years , which is later by more than 1.5 to 2.0 years compared to better-off girls in Mexico, and comparable to median ages for poor and/or not well-off girls in various parts of the world.
Children from the rural Zapotec communities are consistently shorter and lighter, and have smaller estimated midarm muscle circumferences than rural Ladino and urban colonia children. Differences between rural Ladino and urban colonia children are not significant. The results suggest that children in rural, indigenous communities in the Valley of Oaxaca probably experienced a history of more severe undernutrition compared to children in Ladinoized and urban communities, and that rural-to-urban migration does not necessarily result in improved growth status. The latter suggestion must be tempered by the fact that the rural-to-urban migration in the Valley of Oaxaca was relatively recent at the time of the surveys. The estimated median age at menarche for one of the Zapotec-speaking communities (14.7=B10.32 years) is slightly later than those of urban girls in the city of Oaxaca (14.5=B10.45)==2E
Boys and girls from the rural Zapotec community have absolutely lower levels of strength and motor fitness compared to well-nourished children. Grip strength of Zapotec children is appropriate for their body size. Running and jumping performances are less than expected, while throwing performance per unit body size is better than expected for their small body size. The results are not consistent with the postulate of superior effieciency in association with reduced body size in undernourished populations. Rather, they suggest variation with performance task.
Surveys of school children in a rural Zapotec community in 1968 and 1978 indicated no differences in stature, weight, arm and estimated midarm muscle circumferences, triceps skinfold, and grip strength over the 10 year period . It is interesting that the mean heights and weights of Oaxaca children in the 1970s are consistently less than middle class children in Mexico City in the 1920s. The results for school children were consistent with adult stature in adults, largely males, which showed no evidence of secular change between the 1890s and the1970s .
Although data are less extensive, mean retrospective ages at menarche for adult women in a single rural Zapotec community grouped by age (20-29, 30-39 ...>60 years) did not significantly differ, and the mean age for the total sample, 14.5=B10.08 years, did not differ from the status quo(probit) estimate for school girls in the community, 14.7=B10.32 years.
The results
thus indicate no short term or long term secular change in body size of children and adults, and in age at menarche in samples from the Valley of Oaxaca.
Robert M. Malina
Professor and Director
Institute for the Study of Youth Sports
Michigan State University
213 IM Sports Circle
East Lansing, MI 48824-1049