If you are physically strong, social science scholars believe they can predict whether or not you are more conservative than other men.

This might seem obvious. Fitness takes a lot of individual initiative, the government can do all of the outreach programs and legislate all of the soda cups they want, but it won't make people exercise. Super-fit people have to be conservative when it comes to their own exercise, even if they are liberal about money.

Michael Bang Petersen, associate professor in the Department of Political Science and Government at Aarhus University, and evolutionary psychology colleagues at UC Santa Barbara say the strength/politics connection is due to evolution, which is sure to annoy biologists.

Men's upper-body strength predicts their political opinions on economic redistribution, they write, and they believe that the link may reflect psychological traits that evolved in response to our early ancestral environments and continue to influence behavior today.

"While many think of politics as a modern phenomenon, it has — in a sense — always been with our species," says Petersen. Few people would argue that politics has not always been with us, and we have always evolved. They must be linked?

In the days of our early ancestors, they say, decisions about the distribution of resources weren't made in courthouses or legislative offices, but through shows of strength. With this in mind, the scholars hypothesized that upper-body strength — a proxy for the ability to physically defend or acquire resources — would predict men's opinions about economic redistribution.

So they surveyed hundred of people in America, Denmark and Argentina about bicep size, socioeconomic status, and support for economic redistribution. Their belief was that since bicep size as a proxy for upper body strength is irrelevant to payoffs from economic policies in modern mass democracies - might no longer makes right - anyone who wants to be strong is likely to have political decision making shaped by an evolved psychology designed for small-scale groups.

In line with their hypotheses, the data revealed that wealthy men with big biceps were less likely to support redistribution, while less wealthy men of the same strength were more likely to support it. In other words, richer men with big biceps supported lower taxes while poorer men with big biceps wanted higher taxes - on the rich. But men with tiny biceps were less adamant on both sides, they weren't as fanatical about socialism or capitalism.

"Despite the fact that the United States, Denmark and Argentina have very different welfare systems, we still see that — at the psychological level — individuals reason about welfare redistribution in the same way," says Petersen. "In all three countries, physically strong males consistently pursue the self-interested position on redistribution.

"Our results demonstrate that physically weak males are more reluctant than physically strong males to assert their self-interest — just as if disputes over national policies were a matter of direct physical confrontation among small numbers of individuals, rather than abstract electoral dynamics among millions."

No link was found between upper-body strength and redistribution opinions among women. Petersen argues that this is likely due to the fact that, over the course of evolutionary history, women had less to gain, and also more to lose, from engaging in direct physical aggression.

Whereas some biologists think nothing in biology has functions, evolutionary psychologists (and at least one political scientist and criminologist) believe everything in culture, psychology and decision-making is predetermined by inheritance. The psychology and political science scholars say the results indicate that an evolutionary perspective may help to illuminate political motivations, at least those of men.

"Many previous studies have shown that people's political views cannot be predicted by standard economic models," Petersen explains. "This is among the first studies to show that political views may be rational in another sense, in that they're designed by natural selection to function in the conditions recurrent over human evolutionary history."

So Republicans shouldn't be conducting voter registrations outside the IRS office, like they do now, they should be doing them outside the gym.

Petersen, M. B, Sznycer, D., Sell, A., Cosmides, L.,&Tooby, J. 'The ancestral logic of politics: Upper body strength regulates men’s assertion of self-interest over economic redistribution', Psychological Science doi: 10.1177/0956797612466415