It is not for nothing that top politicians are known as political giants or "big beasts". Voters see tall politicians as better suited for leadership, according to a survey of how people visualise their leaders. Psychologists believe the bias may stem from an evolved preference for physically imposing chiefs who could dominate enemies.

The evolutionary throwback could prove bad news for the Labour party, assuming Ed Miliband (5ft 11ins) is still its leader and he faces David Cameron (6ft 1in) at the polls in 2015. And while Barack Obama (6ft 1in) saw off John McCain (5ft 8ins) in 2008, he may have a tougher fight on his hands if his opponent in the US presidential election next November is Republican front-runner Mitt Romney (6ft 2ins).

Dr Gregg Murray at Texas Tech University in Lubbock, Texas, was intrigued by the "presidential height index" – a previous finding that the taller of the Republican and Democrat candidates emerged victorious in 58 per cent of US presidential elections between 1789 and 2008.

When Murray and his colleagues asked volunteers to depict leaders and ordinary citizens, they drew the leaders taller.

"Our ancestors lived in groups that were constantly engaged in conflicts that were resolved through physical violence," said Dr Murray. "If you are in a group and the enemy hordes are coming over the hill, what you want them to see is the big person out front so they know they face a tough battle."

The psychologist, whose work is published in the journal Social Science Quarterly, asked 467 students at US universities to describe and draw their "ideal national leader" alongside a "typical citizen".

Almost two-thirds – 64% – of participants drew leaders who were taller than their average citizen. The leaders were on average 12% taller.

While most of those who took part in the study were American, students from Africa, Asia, Europe and Latin America were also involved. "It would be possible to argue that this effect might be cultural," said Dr Murray. "However, we found the results held across different cultures, suggesting an evolutionary cause."

"Some traits and instincts that may have been acquired through evolution continue to manifest themselves in modern life, seemingly irrationally. A near universal fear of snakes and a preference for unhealthy fatty foods likely evolved from when snakes were a common threat and caloric intake was uncertain. We believe similar traits exist in politics."

In a second part of the study, 238 of the same group of students were asked to assess their own suitability for a leadership position and for an elected post in an organisation.

The results showed taller men saw themselves as better leaders in both cases, but that height did not affect the women's perception of their own leadership potential.

Other studies suggest that tallness in others triggers a variety of subconscious positive associations, particularly for men. Most people seem to see tall men as more persuasive, impressive and capable than average.

One survey found that male Fortune 500 chief executive officers were almost 10 times more likely to be 6ft 2ins or taller compared with the average American man.

"Clearly there are some innate biological explanations for how we behave, but the evolutionary psychology perspective should not be overemphasised," said Richard Kwiatkowski, a senior lecturer in organisational psychology at Cranfield University in the UK. "At least post-Enlightenment one would hope that our ability to reason and actively evaluate arguments also plays at least as significant a role."