Over a decade ago, Chuansheng Chen (at university of California, Irvine) speculated that natural selection may have favoured a gene for risk-taking, to help our species radiate across the globe from our original home in Africa.
Nice idea: show me the proof
The idea is compelling, since we know that young men develop impulse control and the ability to unconsciously anticipate consequences at a later age than young women, which seems an adaptation to leaving home and setting out on their own. But it is only recently that evidence for such a gene has shown up.
DRD4 is a gene that codes for dopamine receptor D4 in the brain, which is associated with motivation and pleasure (also with addictions, eating disorders, bipolar disorder and schizophrenia). There are different versions (called alleles) of DRG4 that have been linked to different personality traits:
- Reflective and cautious people are more likely to have the version with 4 repeats (4R)
- Impulsive risk-takers are more likely to have the 7R or 2R version (and people with ADHD are twice as likely as the general population to have the 7R allele)
Luke Matthews (Harvard University) and Paul Butler (Boston University) looked at how these alleles are spread across the known migration routes that our early ancestors followed out of Africa and into Europe, Asia and the Americas.
Using statistical methods, they have found a “significant” link between the 7R and 2R alleles and migration in 18 indigenous populations.
I am not qualified to judge the strength of this evidence – which would require examining the statistics and interpreting “significant”. And let’s keep in mind that correlation does not necessarily imply causation. So, professionals in the area are treating the findings cautiously, but the evidence is consistent with other evidence that 7R and 2R alleles are relatively recent mutations.
The “so what?”
There is no so what – this is just interesting stuff. Don’t blame your genes for your attitude to risk. You have a conscious thinking brain, so take no short-cuts. Evaluate the evidence on its merits and make your decisions according to properly established priorities.