Tuesday, May 22, 2012

Fingers Crossed: The 2D:4D Ratio and Football Success

Chris Anderson and Ramzi BenSaid

Now that the season is over, we thought we'd take a look at some of the more unusual football research we have come across during the year and that's piled up. Here's a first installment.

Genetics explain every physical aspect of a human being. But except for the occasional mention of Paul and Thomas Ince, Frank Lampard Sr. and Jr., or Brian and Nigel Clough, “genetics” and “football” rarely occur in the same sentence. Now, however, geneticists may have found a very simple indicator to keep in mind when looking to compete for the FIFA Golden Ball, or perhaps win a few more football matches.

The indicator is the so-called “2D:4D digit ratio” – the ratio between index and ring finger.* What does it have to do with genetics, and how does it relate to football? For some time, scientists have known that the length of these two fingers is associated with male competitiveness and athleticism. The 2D:4D ratio is a surprisingly good indicator of human exposure to various androgens during the fetal stage. One of these androgens in particular – testosterone – is strongly linked with competitiveness and athleticism. So your fingers don’t make you run faster, but they can tell us something about other physical characteristics of a human being.

Among the physical characteristics that have been linked to the 2D:4D ratio is prenatal exposure to testosterone, which promotes growth of the right hemisphere of the brain. And luckily for athletes (or traffic police), that part of the brain facilitates visuospatial ability – the brain’s capacity to process its surroundings. In addition, fetal exposure to these androgens can be indicative of vascular system stability and predisposition for coronary heart disease.

From there, it’s but a hop, skip, and jump to football. Obviously, without strong visuospatial abilities and a highly successful, working vascular system it would be hard to excel in football. Given the association between this specific physical attribute and such important abilities in sport, academics have taken a closer look at the connection. Professor John Manning of the University of Central Lancashire in particular has spent a fair mount of time studying the 2D:4D ratio among athletes of different sports, including hockey, rugby, martial arts, tennis, squash, swimming and running. While the results are interesting and worth reading about, the study we care the most about is the one he conducted on footballers (including 304 professional athletes from England and 99 from Brazil).

The results are fascinating. Among amateur footballers in England the 2D:4D ratio was 0.98, while professionals had a ratio of 0.95. International footballers had an even lower ratio with 0.94 and black footballers in England had a ratio of 0.93. Among the 99 Brazilian professional footballers he studied, the average ratio was 0.93, but when restricted to just first team players the average was 0.92.

At a minimum, these data support the idea that a lower 2D:4D ratio indicates athleticism. Other studies have delved deeper into this mysterious ratio, indicating that running speed is more strongly associated with the 2D:4D ratio on the right hand, while “football ability” correlates more strongly with the 2D:4D ratio on the left hand.**

The 2D:4D ratio has also been explored by examining some of the greatest footballers in the world – the Golden Ball winners crowned after each World Cup. But we must warn you: this part of the science is a bit more fun than hard science, if you ask us. But here are some of the results. 2006 Golden Ball winner, Frenchman Zinedine Zidane, for example, has a 2D:4D ratio of 0.90 on his right and 0.91 on his left hand. Brazilian winners of the1998, 1994 and 1970 Golden Ball also displayed this characteristic. 1998 winner Ronaldo has a 0.93 2D:4D ratio on his right hand, and a 0.94 2D:4D ratio on his left hand; 1994 winner Romario has a 0.93 2D:4D ratio on both hands; and 1970 Golden Ball winner Pele has a 0.94 2D:4D ratio on his right hand a 0.97 2D:4D ratio on his left hand. 1986 Golden Ball winner Diego Maradona has a 0.93 ratio on his right hand and a 0.91 ratio on his left hand. Of the 5 Golden Ball winners, Maradona and Zidane have the lowest 2D:4D ratios, and with a 0.97 on his left hand Pele has the highest.***

Now, before you get carried away and whip out the ruler to start measuring your team’s 2D:4D ratios, bear in mind that these are correlations, not proof of a causal link. That is, these studies lend further support to the connection between low 2D:4D ratios and athleticism. But they don’t mean that someone with a low 2D:4D ratio will necessarily be a successful athlete, let alone footballer. In particular, the stronger correlation between the right hand 2D:4D ratio and running speed  and the stronger association of the left hand ratio with “football ability” made us wonder. Think about Zinedine Zidane for a moment. To most observers, Zidane’s strength was his vision, passing ability, technique and touch rather than his running speed – of course, exactly the opposite of what the research would predict.

In the end, we remain skeptical but intrigued. If refined further, this could be a very cheap way to measure a player’s very general characteristics. But absent further research on a broader set of players, and a better definition and measurement of “football ability”, these results are mostly suggestive. Sure, top-level football is a high-testosterone world – we don’t need science to confirm that - and there is more to selecting the best players than measuring their hands. At the same time, a little more hand holding (for the purpose of measuring) wouldn’t kill even the most manly of men, would it?!

* The 2D:4D digit ratio is specifically the length from the crease where the finger connects to the palm to the tip of the finger.
** For more, see http://www.handresearch.com/diagnostics/digit-ratio-fifa-world-cup-football-finger-length.htm.
*** These measurements come from http://www.handresearch.com/diagnostics/digit-ratio-fifa-world-cup-football-finger-length.htm.