We can chart the average height of women 100 years ago by country. For example, the average woman born near the beginning of the 1900s in South Korea was 142 centimeters or 4'7", while the average American woman was 159 centimeters or 5'2". We can see that people a century ago were pretty short for today’s standards, but over the next hundred years, humans grew. Many of the countries that saw the most growth were European and North American countries, while the countries that grew the least were in Africa and Asian countries were mostly in the middle. However, one outlier was South Korea, where women grew nearly 8 inches in the last century.
So why did humans grow so much in such a short amount of time? And why did this happen in South Korea? For most of the last 2000 years human height didn’t change much, but in the last 200 years we started to see some growth. We know a lot about why and it all starts with our genes. One study from 2006 found that 80% of the difference in sibling height is genetic, but the other 20% are external forces that affect our height. These external forces include childhood living conditions, such as nutrition, sanitation, medicine, and overall quality of life.
In the 1950s, South Korea had poor nutrition and a high infant mortality rate, but their wealth skyrocketed in the 1960s and their food supply rapidly improved and soon exceeded the world average. As a result of these improved conditions, especially for children, South Koreans kept growing and growing. I want to show you one more chart. This is the height of South Koreans and North Koreans in the 1930s. Back then, they were one country so naturally they were about the same height. The North is where my maternal grandparents and their siblings grew up. Then, in 1945 the North and South were split up and in 1950, the Korean War began. The war ended in a stalemate and North Korea shut its borders, walling itself off from the rest of the world. In the 1990s, millions of North Koreans starved to death. We only have data on North Korean height today because of the thousands of people who escaped to the South during that period. And, in the generations since the division, the height gap between the two Koreas has continuously widened. My grandparents were lucky; early in the war, they fled their home in North Korea and escaped to the southern tip of South Korea, and a few years later, my mother was born. My mom is a bit taller than her mother and my generation is taller than hers. Height is inherited, written into our very genetic code, but height is also something history gives to us.