Steckel believes a variety of factors contributed to the drop — and subsequent regain — in average height during the last millennium. These factors include climate change; the growth of cities and the resulting spread of communicable diseases; changes in political structures; and changes in agricultural production. Steckel analyzed skeletal data from 30 previous studies. The bones had been excavated from burial sites in northern European countries, including Iceland, Sweden, Norway, Great Britain and Denmark.
In most cases, the length of the femur, or thighbone, was used to estimate skeletal height. The longest bone in the body, the femur comprises about a quarter of a person's height. According to Steckel's analysis, heights decreased from an average of Reasons for such tall heights during the early Middle Ages may have to do with climate. Steckel points out that agriculture from to benefited from a warm period — temperatures were as much as 2 to 3 degrees warmer than subsequent centuries.
Theoretically, smaller populations had more land to choose from when producing crops and raising livestock. Also, populations were relatively isolated during the Middle Ages — large cities were absent from northern Europe until the late Middle Ages.
This isolation in the era before effective public health measures probably helped to protect people from communicable diseases, Steckel said. European emigrants to North America enjoyed a low population density, few disease outbreaks and an increased income and by the s their descendants had reached a peak in terms of height.
However, the average height of Americans dropped about 2 inches in the following 50 years, as increased transportation and migration facilitated the spread of disease like whopping cough, scarlet fever and cholera. Heights would not increase again until the end of the 19th century, when government implemented water purification and introduced measures to deal with waste and sewage.
People living in different parts of the world exhibited different heights. In the early s, the Cheyenne people of North America were among the tallest in the world, with an average male height of about 5 feet 10 inches. Steckel puts this down to the availability of protein in the form of buffalo. The Cheyenne stood taller than the genetically similar Assiniboine of Manitoba in present-day Canada, but this can be explained by the milder climates enjoyed by the Cheyenne, which enabled them to hunt for longer periods of the year, according to Steckel.
Meanwhile, the average height of Japanese men between and is estimated at only 5 feet 1 inch. Rita Kennedy. Rita Kennedy is a writer and researcher based in the United Kingdom.
This initial decrease in height, the researchers noted, correlates with a time of population replacement and these new groups may have been shorter because of cold adaption or changes in resource availability. Meanwhile, the second change in height, an increase, correlates with the influx of Steppe ancestry into Central and Western Europe. When they broke their PRS down into a score for sitting height and a score for standing height, the researchers noted that, as predicted by the genetic scores, sitting height changed less than standing height.
But they also noted that the genetic score predicted a slight sitting height increase in the post-Neolithic era, which was not represented among their skeletal samples. This, they noted, could be due to the influence of environmental factors, opposing genetic effects, or their limited skeletal data. They also uncovered shifts in height that correlated with geography, noting that even today Northern Europeans tend to be taller than Southern Europeans. In particular, they found that genetically predicted height did not increase with latitude in the Early Upper Paleolithic through Neolithic periods, but does in the post-Neolithic.
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