According to the report, “Mean Body Weight, Height, and Body Mass Index (BMI) 1960-2002: United States,” from the CDC (Center for Disease Control), the average height of a man aged 20-74 years increased from just over 5’ 8” in 1960 to 5’ 9 ½” in 2002. At the same time, the average height for women increased from slightly over 5’ 3” in 1960 to 5’ 4” in 2002.
If you visit houses built in the 18th century, however, door frames were much lower than they are now. The obvious assumption, then, is that people were much shorter then, than they are now. And they were. But according to Richard Steckel, a professor at the Ohio State, it hasn’t been a steady change over time. From his research, the average height of people who lived in the 9-11th centuries was comparable to ours today. It then declined slightly during the 12th through 16th centuries, and hit an all-time low during the 17th and 18th centuries–when those doorframes were made.
By the 1700s, Northern European men had lost an average of 2.5 inches of height compared to the Dark Ages, a loss that was not fully recovered until the first half of the 20th century.
He came to this conclusion by analyzing height data from skeletons excavated from burial sites in northern Europe dating from the ninth to the 19th centuries.
The real question is . . . Why?
It has to do with health, primarily. According to Steckel, height is an indicator of overall health and economic well-being. From the study of human growth, “average height reflects the overall health of a population-its diet, wealth, quality of housing, levels of pollution, disease, and stress-particularly for infants and adolescents.”
Over the last 50 years, according to statistics kept by the Japanese Ministry of Education, the average height of Japanese 11-year-olds has increased by more than 5 1/2 inches. The height of girls, who grow faster at that age, meanwhile, has increased even more. This is attributed to general better health, less disease, and the doubling of protein intake by the average Japanese person since 1960. http://www.nytimes.com/2001/02/01/world/tokyo-journal-the-japanese-it-seems-are-outgrowing-japan.html
Further, “The Dutch are currently tallest, measuring about two inches taller than Americans,” Steckel states. “Why? They have very high income levels, they have perhaps the best pre-natal and post-natal care in the world, and they have a relatively equal distribution of income.”
Height research conducted with European populations appears similar to American studies. A study of nearly 10,000 5-to-11-year-old English and Scottish children found a clear connection between a child’s height and whether the father had a job. In each social class group, children with unemployed fathers were shorter.
People reached heights comparable to ours during the Dark Ages because, despite our lack of information about those years (thus, the term, ‘dark’), people were healthier in terms of food quantity and quality of life then they were later. The 17th and 18th centuries were the beginning of the industrial revolution. If you think about the squalor and poverty of London, for example, in the 1800s, that conclusion is not at all surprising.
Thus, a man born in the Middle Ages would have been equally likely to reach the height of 6 feet as a child born in Wales today.