Human beings have evolved in many ways over the thousands of years we have lived on the planet, including many physical developments. The average height of humans has increased over time, though this is usually attributed to environmental factors rather than evolution.
Evolution as we understand the term takes place over millions of years, whereas changes in human height have been detected over periods of hundreds of years and even between generations. Early man was around 167 to 170 cm (5 foot 6 to 5 foot 7 inches) on average, though much taller individuals have been found. Gristhorpe Man, remains discovered in Yorkshire, England in 1843, is over 183 cm (6 feet) tall and is the tallest Bronze Age skeleton ever measured.
The average height of males in 17th century Britain was just 167 cm (5 foot 6 inches) -- no increase at all on his prehistoric predecessors, while early U.S. settlers had only reached an average height of 170 cm (5 foot 7 inches). You can see this difference visibly when you visit historic houses in the UK, as all the doorways are shorter and even the beds look like they would be too short! Different diets and living conditions created different physical conditions in populations.
The height myth
The myth is that the average human height has increased because of evolution, whereas it is far more likely that we have attained our current average height of 175 cm (5 foot 9 inches) because of improvements in diet, medical care and even the introduction of inventions such as central heating. That average height applies to the UK and other western countries, while nations that are less developed tend to have smaller average heights. For example, the average height of older adult males in Brazil is only 167 cm (5 foot 6 inches), while younger males who have been brought up in improved living conditions have an average height of 175 cm (5 foot 9 inches).