WWI soldiers
British soldiers wounded in the trenches on the Western Front during the First World War make their way back from the front lineReuters

Economic historians at the University of Essex and IZA studying soldiers from England and Wales who enlisted in World War I have concluded that we have grown by four inches in the last century.

The study, entitled "Health, Height and the Household at the Turn of the 20th Century", looked at the health and height of men born in England and Wales in the 1890s who enlisted in the army at the time of the First World War (1914-18).

They cross-referenced this information with data about the recruits when they were children in the 1901 census and discovered that 100 years ago, the average height of young men around the age of 20 was 5ft 6in (168cm). Today, the average height is 5ft 10in.

The researchers say several socioeconomic circumstances affected the height and health of those born in the 1890s. The factors included social class, the number of earners in a family, literacy and how many children were born.

Those who battled repeated infections during their infancy and childhood were more likely to be shorter as growth was slowed by the body fighting off diseases.

Overcrowding in the home affected height and health, as did literacy and education about nutrition and hygiene.

Between 1890 and 1940, the height of males increased by about two inches, which researchers put down to a period of rapid decline in fertility. The average family size fell from five children to two, there was a decline in infant mortality and there were improvements in housing and sanitation.

The increase in average height is not limited to the UK.

A study of young adult men in 15 western European countries between the mid-19th century to the end of the 20th century also found that the average height grew by 11cm (four inches), for the same socioeconomic reasons.