How can the international community know it is election time in the United States? A whole raft of claims about science and why you should vote one way or the other will be produced. Some people have even claimed politics is hard-wired, which would mean that American Republicans and Democrats are distinct species, having branched off from the rest of the world in 1860.

While biologists laugh at the idea that voting preferences are biological, sociologists, psychologists and political scientists continue to match surveys to science and claim it might be true. What if only tall people voted Democrat and they only married other Democrats? Would that not shape evolution? Democrats would be tall and imposing and psychologists would say they will get their way more often.

Not in science, just like two pretty people getting married are not guaranteed to have an attractive child, it is actually less likely. But Pete Hatemi, associate professor of political science at Penn State, says that though the environment's influence on adaptation - survival of the fittest - and how it changes biology is better known, he and colleagues believe that there is an interaction between political and cultural forces and evolutionary results. Genes can shape culture and political institutions, which in turn can shape biology and physiology, passing on certain traits to future generations.

One obvious way to see how culture affects natural selection is politically inspired atrocities -- for example, Communist purges in China and the USSR and the Nazi Holocaust -- and the effects those had on genetic diversity, they write in Advances in Political Psychology. They have a point. When people in the late 20th century wondered why the French were so meek and obstructionist, it was noted that the French had lost their bravest and smartest by the millions in two World Wars, so the modern French were in large part the product of the timid and the unfit who did not fight.

Hitler killed off entire religions and ethnicities, but he was egalitarian about it. Stalin and Mao killed tens of millions more, but they were instead picked based on how much of a threat they could be to communism, and that would have had far greater evolutionary consequence. China can mass produce better than anyone in the world, but they can't do creative science, and they can blame Mao for that. 

Hatemi, who worked with Rose McDermott, the David and Marianna Fisher University Professor of International Relations, Brown University, said this interaction between culture and biology could explain why some troubled hot spots remain troubled. People who are born in aggressive environments may pass on traits that make it more likely that future generations react to certain situations violently.

"These changes, then, may have a long-range effect on children and on who those children become when they grow up," said Hatemi. "Those who grow up in a violent culture may have more of a tendency to respond with aggression in the future."

The American Revolution would never have ended if that were true, and the French would be more aggressive if that were true. But the authors also believe a similar dynamic may be at work in the creation of policies that guide health care and foreign affairs. Not all groups respond to diets in the same way, for example, and reproductive health varies across populations.

"We suggest that one of the reasons for the common failure of well-designed, well-intentioned social programs lies in the implicit 'one size fits all' assumptions, as well as the mismatch between modern intentions and older psychological drives and incentives," the researchers write.

While genetics is often seen by the humanities and the social sciences as a rigid blueprint for destiny, humans are extremely adaptable and capable of molding evolutionary forces for good and bad. Humans have managed their environment by developing everything from tools and weapons to medical technologies, from crutches to vaccines.

Why wouldn't that apply to politics? So marry a Democrat and, if that does not work, find a bunch of people and make them citizens so they will become Democrats, and you make humanity evolve so we all become Democrats.

"Evolution and genetic influence are, of course, important, but that doesn't mean it's fixed," Hatemi said. "We can shape policies that can shape evolution."