The Daily Mail published an article recently entitled “How long distance running makes men attractive: Those who run endurance races get more dates and have a higher sex drive.” Really? Wow, I run a lot of endurance races. Sounds great!
This article was derived from a research manuscript (Longman et al) that was published this month. Did the Daily Mail get it right? Well…
The research article is really an attempt to link anthropological research about hunting prowess and social status in our prehistoric forebears to reproductive potential. The authors discuss that much of successful prehistoric hunting involved tracking and hunting animals until they became exhausted. These exhausted animals were, therefore, vulnerable and relatively easy for prehistoric hunters to kill. To succeed in hunting, prehistoric humans had to be able to track and hunt over long distances. The authors stated that the 13.1 miles of a half-marathon would be representative of the distance that prehistoric hunters would have to track and hunt their prey.
Here is something extremely interesting that I did not know:
While humans are, obviously, slow over short distances compared to quadripeds like horses, because we cannot gallop, we are faster than almost all other mammals over longer distances. This is because galloping creates a lot of heat and quadripedal animals will overheat, typically after 10-15 minutes, if they continue to move this quickly. For this reason, the endurance-running gait of quadripedal animals is a trot, which is slower, in most mammals, than the speed of human endurance running. This advantage to humans is even more pronounced in hot weather. In some conditions, over distance, humans can even catch horses. Therefore, it makes sense to consider distance running as a proxy for hunting prowess if it is, indeed, true that the majority of prehistoric hunting was based upon exhausting the prey.
Does this sound like the headline of the Daily Mail article yet?
The next point that the authors made was that the ratio of the lengths of the fourth digit to the second digit has been shown to be a signal of testosterone exposure in the womb. In other words, if an individual, while a developing fetus, were exposed to more testosterone, then his or her fourth digits would be longer than his or her second digits.
Are you looking at your hands, yet?
Here is the next jump in the reasoning of the authors:
A greater 4D:2D ratio has been linked, in men, to higher testosterone levels and other measures associated with increased reproductive success. Furthermore, a greater 4D:2D ratio is correlated to physical prowess in a variety of sports including skiing and football. With regard to running, a study of cross-country races ranging in distance from 1 to 4 miles showed that the 4D:2D ratio explained about 25% of the variance in performances. The authors of the manuscript we are discussing today reasoned that since a greater digit ratio has been linked both to increased reproductive success and to improved athleticism, and since the half-marathon distance may be more representative of the distances our prehistoric ancestors had to run to hunt food, a study of the relationship between the 4D:2D ratio and half-marathon performance would show a strong correlation.
For this trial, 439 male participants of the Robin Hood Half Marathon in Nottinghamshire were recruited after having received an e-mail prior to the race (there were 103 female participants in the trial, as well, but this is beyond the scope of this review). Their hands were photocopied and the 4D:2D digit ratios were determined according to established techniques. These ratios were then matched to the participants’ finish times. The correlation between a greater 4D:2D ratio and faster finish times was striking. Unfortunately, the authors spent a lot more ink in their manuscript discussing anthropological theory than dissecting their data. They did report, however, to the Daily News, that the 10% of men with the greatest digit ratios finished an average of 24 minutes and 33 seconds faster than the 10% of men with the smallest (or negative) digit ratios. This is an enormous difference.
So, this really is the data. Quite simply, a greater 4D:2D ratio appeared to strongly correlate with faster running over the distance of a half-marathon. Perhaps this would mean that a greater 4D:2D ratio would lead to greater prehistoric hunting ability and, since this ratio is correlated with prenatal testosterone exposures, these greater testosterone exposures would, therefore, create better hunters. Since greater prenatal testosterone exposure is correlated with increased reproductive success, in general, the logical leap is that faster male runners are more attractive to women. These leaps of logic make sense to an extent, but also create fodder for the media to misrepresent the data with flashy headlines.
As a slightly-better-than-middle-of-the-pack runner, I am most intrigued by the new data that links the digit ratio to half-marathon times. I appear to have a pretty high 4D:2D ratio, but I’m not winning any races. Maybe it takes more than long ring fingers to be a fast runner…
Bramble DM and Lieberman DE. Endurance running and the evolution of Homo. Nature. 2004 Nov;423:345-352.
Lieberman DE and Bramble DM. The evolution of marathon running. Sports Med. 2007 Apr;37(4-5):288-290.
Longman D, Wells JCK, and Stock JT. Can persistence hunting signal male quality? A test considering digit ratio in endurance athletes. PLOS One 2015 Apr;DOI10.1371.
Manning JT, Morris L, and Caswell N. Endurance running and digit ratio (2D:4D): implications for fetal testosterone effects on running speed and vascular health. Am J Hum Biol. 2007 May-Jun;19(3):416-421.