Lewis Wolpert: 'Short men do not do well in US politics'

How tall we are seems to matter a great deal.

How tall we are seems to matter a great deal. There are claims that, for men at least, being taller than average carries advantages in terms of relationships with other workers, earning more and getting promoted quicker. Short men do not do well in American politics - only five presidents have been shorter than the average.

A study once showed that Americans may be very aware of height, for in every age category, from the ages of 20 to 84, the subjects claimed to be taller than they actually were. Why people overstated height is complex. One reason may be the belief in Western culture that height is a good thing, being taller may equate with being stronger and more fit. All this relates to men; there is less information on women.

A surprising phenomenon in relation to height has been discussed in a recent article in The New Yorker (which I take for its cartoons - one of its best cartoonists, Roz Chast, now has her own page in Scientific American. It also pleases me that a non-specialist magazine such as The New Yorker also carries scientific and medically related pieces). Our height is determined by the growth of our legs and body. That of the legs is best understood. The leg - from femur to toes - grows out from the body of the embryo as a small structure initially about a centimetre long, and continues growing till the end of adolescence some 16 years later. The growth characteristics of the limb are specified when it is still very small. There are special growth plates near the ends of the bones and these determine the growth, and muscles are pulled along by the growing bones. In these growth plates, it is cartilage cells that are growing, which are then replaced by bone.

What is remarkable is that at the end of growth, for the vast majority of people, the two legs are very similar in length, yet there was, in all those years, no communication at all between them. That growth should be so reliable over all those years that they end up the same, without any interaction between them, was something that a distinguished physicist refused to believe. But that is what the evidence strongly supports. It is also true of our two arms. Growth is affected by hormones and environmental influences such as diet, and these affect both limbs equally.

There are records of heights of soldiers in Northern Europe going back over a thousand years. Height was up in around AD800, and low in the 17th century. Charlemagne was over 6ft tall, but those who stormed the Bastille were just 5ft on average, though well-bred officers were some 3in taller. In America, in the 18th century, life with respect to height seemed good - white colonists were around 5ft 9in, and even slaves were just 1in shorter.

While there was a small decrease in height at the time of the Civil War, the real change was observed at the time of the First World War, when the average American soldier was 2in taller than the average German. But this difference was reversed over the next 50 years, as male Europeans grew taller while Americans did not. Now, Northern Europeans are several inches taller than Americans, whose average height is 5ft 9.5in.

What could be the basis of this height reduction? Clues may be found in Holland, where the situation is the other way round. The Dutch are probably the world's tallest people - men average 6ft 1in. This growth spurt began in the 19th century, and seems linked to economic prosperity. The fall in height in America may be the result of the widening gap between rich and poor, together with fast-food diets. Studies have found that the loss of height by Americans compared with the Northern Europeans occurs in infancy and adolescence, so pointing a finger at inadequate postnatal care and teenage eating habits.

When one group of British children were fed on fast food such as chips and hamburgers, while another group was given wartime rations such as cabbage and corned beef, within eight weeks the ration group were taller and slimmer than the fast-fooders. Junk food may have more to answer for than obesity.

Professor Wolpert is professor of biology as applied to medicine at University College London