Scientists can tell who's conservative: They're the ones who blink and sweat a lot when startled.

According to a study that seems designed to get the maximum possible press coverage.

Don't you know it's your primal wussiness that's making you support capitalism, military power, and traditional values?

But let's take this seriously for a minute:

The researchers asked 46 volunteers about their views on a variety of political issues, including foreign aid, immigration policies, and gun control.

Two months later, they showed the volunteers a series of pictures, which included frightening images interspersed with pictures of a bunny, a bowl of fruit and a happy child while measuring the electrical conductance of the volunteers' skin, which signalled sweating, a characteristic used in polygraphs (lie tests).

They also played a series of sudden noises and monitored the volunteers' eye response, since harder blinks are a reflex response that signal heightened fear.

People who are physiologically highly responsive to threat are likely to advocate policies that protect against threats to the social unit: favouring defence spending, capital punishment, patriotism and the Iraq War.

In contrast, people who are less startled by sudden noises and threatening visual images are more likely to support foreign aid, liberal immigration policies, pacifism and gun control.

It's interesting, in this context, that gun control goes with the liberal ideas. It suggests that liberals support gun control not so much because they are afraid of gun violence, but because they are relaxed about the possibility that they may need to defend themselves.

I'm inclined to believe that there is something at a very basic physical level that makes a person tend toward conservatism or liberalism. And this study -- even assuming it's accurate -- doesn't necessarily mean that conservatives are more cowardly than liberals, only that they are more sharply tuned to perceptions of threat.

Perceiving and responding to threats had obvious survival value for human beings over the span of evolutionary time, beyond what makes sense in the modern world. But there is also value in remaining calm and steady in the face of threat and in accurately perceiving that a seeming threat is not real.

Who's to say what level of over- or under-reaction to threat would have been most useful to our distant ancestors as the human race evolved over the ages? But we've inherited variable tendencies, and it stands to reason that these feelings and capacities affect our political views.

Perhaps if we truly understood this, our political arguments would mellow.