Numbers Don't Lie: 71 Things You Need to Know About the World

by Vaclav Smil

Abundant anthropometric data available for 200 countries show an average gain over the 20th century of 8.3 centimeters for adult women and 8.8 for men. The population of every country in Europe and North America got taller, while South Korean women recorded the century’s largest average female gains (20.2 centimeters) and Iranian men topped the male sequence with 16.5 centimeters.

The two large animals we have mainly used for transport perspire profusely compared to other quadrupeds: in one hour, a horse can lose about 100 grams of water per square meter of skin, and a camel can lose up to 250 g/m2. However, a human being can easily shed 500 g/m2, enough to remove between 550 and 600 watts’ worth of heat. Peak hourly sweating rates can surpass 2 kilograms per square meter, and the highest reported short-term sweating rate is twice that high.