New research suggests the tax office should expand the list of acceptable explanations for procrastinators' yearly extension requests and late tax filings. Two possibilities: "I was born this way" and "failure to evolve".

Procrastination, suggests a new study, is an evolved trait that likely served humans well in a time when finding food and water and fending off prey were job one. For man in the state of nature, pondering lofty goals for an indistinct future was sure to result in an early demise.

The inclination to defer unpleasant but necessary tasks appears to coexist intimately with the trait of impulsiveness. After all, before complex societies made a virtue of timely tax preparation, completed homework and avoidance of fattening foods, bold initiative was a good thing. Acting on impulse was more likely to get one fed and spread one's genetic material than was careful planning and an unwavering dedication to meeting deadlines and looking good at the next reunion.

Not surprisingly, then, psychologists have long noted that impulsive people are highly likely to be procrastinators, and that procrastinators are very likely to be impulsive.

These days, alas, acting on impulse is a behaviour that has lost its evolutionary cachet. In a world with rolling deadlines, goals that demand complex planning and execution, and many distractions, those who put off that which must be done and yield to temptations can pay a high price for their behaviour. Their credit scores suffer. They lose jobs and fail classes. They develop health problems and let them progress beyond the point of no return.

And yet, these traits survive - in some of us, very strongly. Try as we might, procrastinators tend to struggle throughout their lives with the impulse to put off the unpleasant and to lunge at more pleasurable pursuits instead.

That suggests that these once-adaptive traits must be enshrined in our genes, said a team of psychologists, neuroscientists and geneticists from the University of Colorado. In a report in the journal Psychological Science, the team set out to discover not only how much the tendency to procrastinate is determined by genetic inheritance, but whether procrastination and impulsiveness spring from the same genetic roots.

These days, whole genomes may be cheap and easy to sequence. But it remains a distant dream to precisely locate the chunk of code in 3 billion DNA base pairs that results in a behavioural trait such as procrastination. So the University of Colorado team explored the genetic underpinnings of procrastination the old-school way: by looking at identical and fraternal twins, sifting through their likenesses and dissimilarities to each other, and inferring the degrees to which their shared and not-shared traits are the result of shared DNA.

Twins can serve as a sort of genetic Rosetta stone because they share common genes, but to two different extents. Identical twins, which spring from a single embryo created by one egg and one sperm, are thought to share all of their DNA: they're virtual clones of each other. Since fraternal twins come from two separate embryos, created from two distinct sets of egg and sperm, they represent two separate rolls of the genetic dice. The overlap in these twins' genetic programs will be much less exact than that for identical twins.

So when, say, a behavioural trait is shared 100 per cent of the time by identical twins but less so by fraternal twins, it's reasonable to conclude - and it's possible to calculate statistically - that that trait springs from somewhere in the genetic code. When identical and fraternal twins are equally likely to share (or not share) a trait, it's a sure bet that environment and experience have shaped their behaviour. (And when identical twins have been separated at birth - believe it or not, it happens - researchers have a potential bonanza. When they see that despite different environments, the separated twins absolutely share certain traits, they can confidently infer that those traits are genetically determined. Where the same twins differ, it's a clear sign that their differing environments and experiences have played the larger role.)

The latest research delved into the behavioural tendencies of 347 same-sex twin pairs - 181 of them identical (or "monozygotic") and 166 fraternal ("dizygotic"). The average age of the twins was 22 years, and all had been recruited to participate in an ongoing study of twins in Colorado.

Study participants filled out a large battery of assessments on a computer. The measures asked them to rate their reliance on "external control" (think deadlines), their tendency toward goal neglect (say, abandoned resolutions) and effort avoidance (due date looming? How about a coffee run?). They asked about participants' inclination to speak before thinking, their ability to resist temptations, and whether they had a penchant for doing things on the spur of the moment. And they asked how often participants experienced "goal failures" - forgetting to return a borrowed item or pass on messages, failing to notice road signs, leaving a chore unfinished.

What they found was that, in a broad population of people, genetic inheritance substantially influenced whether the average person would be a procrastinator, accounting for 46 per cent of that probability. Genes were an even stronger driver of impulsivity, explaining the prevalence of impulsiveness in 49 per cent of cases. The genetic correlation between impulsiveness and procrastination was 100 per cent - meaning that where a person is impulsive but not procrastinating (or procrastinating but not impulsive), only an environmental difference could explain the mismatch.

Specifically, the researchers found that impulsive people who had learned to keep their eyes on a distant prize - a diploma, a promotion, a size 6 dress size - were more likely to resist the urge to procrastinate, suggesting "promising new ways to reduce procrastination."

Los Angeles Times