Average height is related to both food intake and the prevalence of disease in the population. Archaeologists can use fossils to calculate the height of individuals who lived in the past. The most useful bone for estimating height is the femur, or thighbone, which makes up one quarter of an individual's height and is the longest bone in the human body. In 2011, the average American man measures 69.4 inches and the average woman 63.8 inches.

Archaeologists have used fossil evidence to piece together information about the earliest humans. Homo Heidelbergensis lived in Europe and Africa between 700,000 and 200,000 years ago; males stood at an average of 5 feet 9 inches, while females were shorter, with an average height of 5 feet 2 inches. Homo floresiensis, nicknamed "the hobbit," lived in Asia between 95,000 and 17,000 years ago and was much shorter; evidence from a female skeleton suggests an average height of a little more than 3 feet. Neanderthals, man's closest relative, lived in Europe and Asia between 200,000 and 28,000 years ago. Evidence suggests an average height of 5 feet 5 inches for males and 5 feet 1 inch for females. Scientists believe the short, stocky bodies of Neanderthals helped them stay warm, allowing them to survive the harsh Ice Ages.

Perhaps surprisingly, research by a team from Ohio State University suggests that people living in the Middle Ages — between the ninth and 11th centuries — were taller than those living in the early 19th century. Using skeleton evidence from Europe, the team found that average height decreased from 68.27 inches in the Middles Ages to a low of 65.75 inches in the 1600s and 1700s. According to team leader Richard Steckel, increased height in the Middle Ages is due to warmer than average temperatures in Europe during this period, extending the growing period by up to four weeks each year and ensuring improved supplies of food. People also lived what we would consider very stationary lives, so outbreaks of communicable disease did not have the opportunity to spread over large areas.

Height did not begin to increase again until the 18th and 19th centuries, according to Steckel. The reasons for this remain unclear, but it is likely that lower temperatures in Europe between the 1300s and the 1800s, combined with higher levels of trade and movement between places, held height down during this period. European emigrants to North America enjoyed a low population density, few disease outbreaks and an increased income and by the 1830s 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 1800s, 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 1602 and 1867 is estimated at only 5 feet 1 inch.