A great deal of data on human physical growth exist in the literature and some of this has been collected into two volumes by Eveleth and Tanner (1976,1990). Also see Ulijaszek, Johnston, and Preece (1998). There is relatively little difference between individuals cross-culturally in growth before birth, as birth length clusters at 50 cm and mean birth weight ranges from 2.4 kg to 3.4 kg. To be sure, infants born to smaller, undernourished, or ill mothers may be shorter and weigh less than infants born to taller, heavier, or healthier mothers. Indeed, birth weight serves as an indication of the overall health of the infant, and epidemiologists use the mean birth weight of a social group as an indication of its general quality of life. Even so, more variation between individuals and populations develops with time after birth. By adulthood, the range in stature is from 184 cm for young men in the Netherlands (Fredriks et al., 2000) to 145 cm for Efe Pygmy men (Dietz, Marino, Peacock, & Bailey, 1989). In these and other populations, adult women are from 8 cm to 14 cm shorter than men. Population variation in many other body measurements is detailed in the Eveleth and Tanner volumes cited above.
The African pygmies are short for genetic reasons: they do not produce enough growth hormones or their cells are not sensitive to these hormones. Genetic causes cannot easily explain growth variation between other human populations. The research concerning growth variation is far too copious to review here (see Bogin, 1999; Gray & Wolfe, 1998). Much attention is focused on specific determinants, such as disease and nutrition. Some cross-cultural work cites physical and emotional stress, or child-rearing practices. Children and adults tend to be taller in societies that practice some sort of painful ritual (e.g., scarification, piercing, vaccination) early in life or separate infants from their parents by swaddling or creching them (Landauer & Whiting, 1981).
These individual factors are important, but the consensus of research is converging on the total quality of life as the main explanation for growth variation. This is because nutritional status and disease are highly correlated with the social, economic, and political conditions of life. The poverty rate, the infant mortality rate, the literacy rate for adults, the school attendance rate for girls, and the mean birth weight of any society may predict child and adult stature as well or better than measures of specific diseases or food intake. Conversely economic and social historians use growth data to assess the quality of life in past centuries, when standard indicators of health and economic development were unavailable.
Since 1992, my own research has focused on the social, economic, and political conditions that influence the growth and health of children of Guatemala Maya immigrants to the United States. Some scholars have called the Maya "Pygmies of the Americas" or otherwise asserted that the Maya are genetically shorter in stature. Our research finds that Maya children between the ages of five to 12 years old, living in Los Angeles, California, and Indiantown, Florida, average 10-11 cm taller than their age-mates living in Guatemala (Bogin, Smith, Orden, Varela Silva, & Loucky, 2002). Our Los Angeles and Indiantown sample includes children born in Guatemala and Mexico, and Maya Americans born in the United States. Greater time in the United States results in greater stature, meaning that the Maya American children are the tallest of all the Maya. This height increase following migration is the largest that has ever been recorded for any human population, and expands the known range of plasticity in human growth. The height increases show that the social, economic, and political conditions of Guatemala holding back human growth are very severe. The increase in stature attests to improvements in nutrition, healthcare, water quality, education, reduced physical labor, and increased physical and emotional security in the United States. However, the Maya children are still, on average, shorter than European Americans, African Americans, and Mexican Americans living in Indiantown, Florida (ethnic group names are based on self-identification by the people of Indiantown). We predict that it will take three or four generations of growth in the United States until Maya Americans achieve the same average height as these other ethnic groups.
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