THIS year will mark 50 years since Jamaica became an independent nation. It is also anticipated that it will be an outstanding year for Jamaica as it prepares to participate in the upcoming summer Olympics in London.

Jamaica's athletic sprinting prowess has become legendary and expectations are high that the 2012 Olympics will be one of the best ever in Jamaica's athletic history. But what accounts for Jamaica's outstanding track record in sprinting and how does a small country such as Jamaica with limited resources produce such awe-inspiring athletic performances?

Apart from its legendary sprinting prowess Jamaica is also characterised by having a high prostate cancer incidence and mortality rate. Prostate cancer is in fact the number one cancer affecting Jamaican men and the leading cause of male cancer-related deaths. Indeed, one study performed in 1998 by Johns Hopkins University in collaboration with Jamaican urologists found that Jamaica had the highest prostate cancer incidence in the world at 304/100,000/year.

Since that study, Jamaica's cancer registry has documented more conservative rates, the latest being 78.1/100,000/year in 2010. Interestingly other Caribbean territories such as Guadeloupe and Barbados have since documented much higher rates such as 168/100,000/year and the Caribbean region is recognised as having the highest prostate cancer mortality rate in the world at 26.3/100,000/year.

Of course, sprinting talent is not unique to Jamaica but is distributed throughout the Caribbean. Could these two seemingly unrelated phenomena be related in any way whatsoever? Could there be underlying causal factors that are common to both phenomena?

There in fact exists overwhelming similarities between the geographic and demographic distributions of athletic sprinting prowess and prostate cancer. Both phenomena are clustered among African Americans and Afro-Caribbean peoples. African-Americans as an ethnic group has the highest established prostate cancer incidence in the world while the Caribbean region has the highest established prostate cancer mortality rate worldwide.

The incidence of prostate cancer is 60 per cent greater and the probability of death almost three times higher from prostate cancer among African-Americans compared to Caucasian Americans. In most Caribbean Islands prostate cancer is not only the most common male cancer but it is also the most common cause of male cancer-related deaths.

In Guadeloupe (birthplace of Marie-Jose Perec and Christine Aaron) for instance, the incidence of prostate cancer is 168/100,000/year as noted above. Of course, the sprinting accomplishments of African-Americans and Afro-Caribbean peoples in general and Jamaicans in particular are legendary. Is the clustering of these two phenomena due to chance, the admixture of European and African ancestry or are there some causative underlying sociocultural or biological factors which are common to both? Could history perhaps have intersected with biology to create reasons for this clustering?

Talent and Tradition are Intertwined

Looking at sprinting prowess in isolation, possible reasons for the skewed distribution (especially in Jamaica's case) include a strong athletic sprinting tradition, excellent coaches and outstanding sports administration, including regular development meets and national schools' championships which serves to efficiently identify and nurture athletic talent from an early age. Without the requisite talent however, no amount of development meets and championships along with outstanding coaches can compensate for this to engender the types of stellar performances we have grown accustomed to see and indeed almost now take for granted.

How many of us really believe that if we were able to transplant our tradition, coaches and athletics administration with all its allied support systems to say India or even Kenya, that we would be able to replicate our athletic sprinting success? The fact is tradition and talents are intimately intertwined: we do what we are good at and we establish tradition when we do outstandingly well repeatedly!

Is it in the eating of yams?

But where does the outstanding athletic talent come from and could it be that the same underlying factors which account for our athletic sprinting talent also account for our high incidence and death rates from prostate cancer?

Professor Morrison from the University of Technology believes that athletic prowess is partly due to the eating of yams, which are high in phytates and other substances thought to boost athletic performance. However, Nigeria, by far the world's largest per capita consumer (and producer) of yams with a population of 150 million people and an athletic sprinting tradition, does not even come close to the sprinting accomplishments of the almost 500,000 Afro-Trinidadians who eat little if any yams, not to mention Jamaicans! Food for thought, but perhaps not yams!

Regarding the Trinidadians, it is interesting commentary that all their outstanding sprinters are of African descent. Again, is this primarily due to sociocultural/environmental factors or could racial/ethnic differences in innate talent explain this? Could the way society is structured, and the power relationships within it, as well as the avenues and opportunities for social mobility and economic advancement available to people of African descent who have historically been exploited and marginalised be part of the reason for the differences seen in athletic prowess?

The incidence and mortality rates from prostate cancer are three times higher among Afro-Trinidadians than among Indo-Trinidadians although these two racial groups share more or less the same environment!

Synthesis of Hypothesis

In advancing a hypothesis of a common link between sprinting prowess and prostate cancer the following have been noted and an attempt made to synthesise them:

1. Both these phenomena are dependent on the male hormone, testosterone. Lean muscle mass and muscular strength are necessary for sprinting ability and both are highly dependent on testosterone. There is some evidence that testosterone can influence the ratio of fast to slow twitch muscle fibres, the former being necessary for sprinting ability. The testes, the source of 95 per cent of the testosterone in the male, if removed by castration during young adulthood can prevent prostate cancer from ever developing and indeed castration has been used as a means of treating advanced prostate cancer since Huggins and Hodges first discovered this effect in the early 20th century.

2. Anabolic steroids taken by athletes enhance athletic sprinting ability (Remember Ben Johnson and many others?)

3. The skewed racial distribution with respect to sprinting prowess and prostate cancer in Trinidad and Tobago already alluded to.

4. Testosterone blood concentrations does not differ markedly between different races and populations.

5. The testosterone receptor, which mediates the effects of testosterone, is generally more responsive in people of African descent and this is correlated with the number of cytosine, adenine and guanine (CAG) repeat sequences in one end of the gene that codes for the receptor. The lower the number of CAG repeats, the more responsive the receptor.

6. The ratio between the index finger (2nd digit) and the ring finger (4th digit) of the right hand in men (2D:4D ratio) is related to the level of antenatal exposure to testosterone in utero. The lower the ratio the higher the antenatal testosterone exposure. Studies suggest that Jamaicans have among the lowest 2D:4D ratios in the world.

7. Persons of African descent are generally known to have a narrower and deeper bony pelvis compared to Caucasians (a fact every pelvic surgeon who operates on different races is aware of) resulting in the typical 'cock bottom' and this is believed to be due to the differential influence of testosterone in Blacks compared to Whites.

8. Prostate cancer incidence and mortality in men of African descent in the Americas is higher than in urban West African centres.

Hypothesis linking Sprinting Prowess and Prostate Cancer

Briefly, the hypothesis is that persons of African descent in the Americas (New World), who are descendants of African slaves who survived the Middle Passage, experienced a population shift in favour of greater testosterone responsiveness compared to Africans living in Africa and this was created by the inhumane conditions under which the slaves were transported.

The specific conditions (slaves packed tightly in the hull of the slave ship in stifling, hot, humid conditions with little convection of air and in body fluids such as urine, faeces, vomit and menstrual effluent) created a tremendous selection pressure in which many slaves succumbed. Some ship logs indicate that as many as 90 per cent of the slaves perished during the average three-month-long journey!

Those who survived did so not because of luck or chance but because they had specific attributes which allowed them to withstand the adverse effects of the inhumane conditions.

It is hypothesised that the slaves who survived had greater lean muscle mass and therefore higher skin surface area to body volume ratios and were consequently able to dissipate heat more efficiently and keep relatively cool in the hull of the slave ship; those with greater haemoglobin concentrations were able to enjoy better oxygen-carrying capacity and therefore greater tissue oxygen delivery in the stifling conditions; those with thicker, hardier skin and greater sebum production were able to resist the macerating effect of lying in urine, faeces, vomit and blood for hours without getting skin infections and sores; those with thicker and more robust bones resisted bone fractures which, should they have occurred, would have meant being tossed overboard, and finally, those with the mental toughness, vitality and aggressive will to survive would have experienced a survival advantage.

These attributes are all expressions of testosterone's influence on the human mind and body. Among the slaves surviving the journey there would be a much higher proportion exhibiting these features than among those who originally began the transatlantic voyage because of the severe selection pressure. Those without these attributes would have more easily succumbed and died.

Multiply this scenario many times over for a total period of four centuries and voila! A shift in the population distribution of testosterone responsiveness in favour of greater responsiveness when comparing descendants of African slaves in the New World to West Africans in Africa.

This would partly explain why relatively small countries like Jamaica and Trinidad have done better than Nigeria, the seventh largest country in the world and by far the world's largest consumer of yams, when it comes to sprinting prowess; it would also explain the much higher incidence and mortality from prostate cancer in the Americas compared to urban West Africa.

The observation that Australia (as a country) currently has the highest documented prostate cancer incidence in the world fits nicely into this hypothesis. Australia, by virtue of being originally a prison colony for British prisoners, historically would have been constituted by persons on the more aggressive end of the population spectrum. The Australians would have experienced a population shift in favour of testosterone responsiveness when compared to the British population of origin.

Moreover, the long and perilous, though not as inhumane, journey from Britain to Australia would have created some selection pressure for only the very fittest to survive. I predict, partly based on the above hypothesis, that if Australia were to develop a tradition of sprinting they would do well at it compared to their European Caucasian counterparts!

Sprinting prowess and prostate cancer are phenomena which both have multiple causative factors. This article has served to offer a hypothesis which accounts for the very similar skewed racial and geographic distribution of these two seemingly unrelated phenomena. Perhaps the population shift in testosterone responsiveness explained above may be interacting with dietary (perhaps yams?) and other environmental/sociocultural factors such as excellent coaching to produce the current picture.

Dr William Aiken is a lecturer in surgery (urology) and consultant urologist at the Faculty of Medical Sciences at the University of the West Indies, Mona

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