The Kenyan success genetic controversy

Kenyan success: Genes, method and controversies

Earlier today, I tweeted two articles of interest tackling the question of whether Kenya's incredible distance running success is genetic or training-related.

The first article, from the Atlantic, takes the genetic view, while the response from a Kenyan paper is quite offended at the suggestion, and attributes their success to method, which includes the usual combination of training, altitude, system, etc.  I won't summarize the articles here, but would encourage you to have a read on what is quite a controversial topic.

I recall this controversy from a year or two ago, when I wrote some articles about innate ability.  Then, my specific purpose was to address the fallacy that anyone could become a champion with 10,000 hours of practice, and the discussion moved into one of genetic factors that predispose individuals to success in sport (or activities like chess and darts, for that matter).

I received some fairly angry emails, I think from Kenyan readers, who take offense at the suggestion that their runners may have some genetic advantage as long-distance runners.  I think much of this controversy comes from the all too typical error that people make when they polarize a debate into an "either/or" situation, and fail to recognize how complex factors must interact with one another.  In my opinion, the issue is pretty straight-forward, and I've not really fully understood why it evokes such hostile responses.  My brief take on this issue is below.

Upcoming review - more on the science of the genes and why studies have thus far failed to find "the gene"

While I'm on the subject, I will soon have a review article published in the British Journal of Sports Medicine on this very subject.  It was invited by the journal as a follow up to a review I had published last year, called "What makes champions? A review of the relative contribution of genes and training to sporting success".

On that occasion, I co-wrote with Prof Malcolm Collins, a geneticist, and we tried to explain the essential role of BOTH genes and training on ultimate sporting success.  The 10,000 hour concept holds little water when evaluated scientifically, but is a nice way to get people fired up to train more.  Similarly, genetics cannot explain sporting success entirely.  To disregard either is to provide a false explanation and the ultimate conclusion is that training should be defined as the realization of genetic potential.  Alone, each is insufficient, and it is the right training applied to the optimal genotype  that produces world champion caliber performance.

For this latest review article, I was asked to delve more deeply into the issue, and the question of Kenyan running is just too intriguing to pass up.  So, I teamed up with Prof Collins again, and this time added another colleague, Dr Jordan Santos, who did his PhD studying North African and Spanish elite runners, and is now looking into East African running physiology.

We wrote a paper that has just been accepted, and once it is available, I will certainly describe it in more detail and send out links for those who are interested.  The paper describes the current science of the genes in East Africans, and we explain why those studies have thus far failed to find the performance gene.  It is a technical and conceptual failure, one where the research has, in our opinion, looked in the wrong place for the wrong thing.  We propose a theory for Kenyan success that IS genetic, but which is not unique to Kenya, and which does not in any way exclude the method and system they can rightly credit with their success.  More on that soon.

Today, briefly, and since it is topical thanks to the above-linked articles, this is a summary of that review paper, which represents our thinking based on where the science of this matter stands today:

Unlikely a unique gene

• First, and perhaps most important, if you are looking for a specific gene or gene variant that Kenyans possess, and which no other athletes have, then you may be be looking for a long, long time.  It is improbable that a) a single gene variant will explain something as complex as running physiology, and b) only one population in group in the world will possess this unique variant.  That said, until the entire genome is understood, it remains possible that a variant or combination of gene variants unique to a population in East Africa is the 1% difference between a 2:04 marathon and the 2:06 we see from elsewhere.  But it is unlikely, in my estimation.
  
  
  
• Instead, if there is a genetic basis for performance, it will be polygenic (think hundreds, if not thousands of genes), which exist in the optimal combination for an individual to be predisposed for sporting success.  Crucial to realize is that this individual could be found anywhere in the world.  Among the billions of people in it, there will be individuals with this 'endurance favored genotype' in every population.  There may be more in some populations than others, but chances are that a genetic advantage is NOT unique to one population only.  Therefore, Kenyans are not likely to be unique or possess unique genes.  This does not mean there is not genetic advantage, however.
  
  For instance, if we take the very simplified view that Kenyans are great runners because they have longer legs, shorter torsos and skinny calf muscles (this is part of the explanation put forward), then I guarantee that there are thousands of adults in the USA, UK and here in South Africa with that same structure and hence advantage.  It is not unique to Kenya.  However, this does not mean that genes do not contribute, as I shall explain shortly.
  
  
  
• Once a collection of factors are identified, they must be exposed to the optimal environment in order to be "expressed".  And I'm not talking gene expression here (though this is part of it, literally).  I'm talking more about the ability to identify, nurture and then develop whatever innate ability is there.  In the absence of the right environment - the coach, the competition, the system, the culture - any genetic advantages will never be identified or realized.  Therefore, a method or a system is just as crucial as genes

It may be about prevalence, not presence

• Now, where this leaves one is with a combination model, that says that genes ARE important, but so is the application of training and hard work to them.  If now one looks at the Kenyan population, there are only two possible theories available:
• Kenyans have exactly the same probability as the rest of the world's athletes of becoming elite, but the difference is in the system.  This is the theory of the second article I linked to earlier.
• Kenyans have the same types of genes, nothing unique sets Kenya apart, but...the prevalence of these favorable genetic factors is greater in this population.  The result is that the same system applied to 100 people in Kenya and 100 people in say, the UK, will produce a different result, because the "raw material" is different in the different populations.  There may be a greater probability of discovering champions in Kenya, not because of the presence of a gene variant, but rather its prevalence among the population
  
  
  
• Differentiating between these options requires large scale genome wide association studies on huge numbers of the respective populations.  It comes with many strings attached - the interpretation of genetic differences across ethnic groups is fraught with difficulty.  It is impossible at this stage to conclusively link a particular gene variants, or even a panel of gene variants, to performance, though some breakthroughs have been made.  For instance, it was recently found that individuals who had 19 or more of a panel of 21 SNP (single nucleotide polymorphisms) were high responders to training, wherease individuals who had 9 or fewer of these 21 SNPs were poor responders.  I think it's fair to say that Olympic champion runners would come from the first group, and thus possess 19 or more of these identified SNPs.
  
  That's the approach that will further unlock understanding of the genetic basis for performance.  If I had to commit to a hypothesis, it would be this:  
• Within the Kenyan population, and specifically, the Nandi sub-tribe of the Kalenjin tribe (this group, incidentally, makes up 3% of the Kenyan population, but make up almost half of their great international runners), there will be a higher prevalence of favorable gene variants or genotypes than in a population from another country.
• The result is that the application of the same training stimuli, plus the environmental factors and culture, will result is a greater emergence of international caliber runners from this population.  For every 100 people, there exists a greater probability that an elite athlete will emerge from the Kenyan population than a similarly aged population in say, Australia or America
• On top of this, add the fact that the environment in Kenya (and East Africa) is uniquely suited to distance running.  The people, the culture of running, the history of success, the altitude, diet, economic factors and 'system' ensure that in Kenya, the training environment is unlike any other in the world.  This is why so many athletes go to Kenya to train - their system is 'best of breed'
  
  
  
• So, when you combine this training environment to a theorized prevalence model for genetic advantage, it is not difficult to see the origin of statistics that are so often quoted to support the Kenyan dominance - 20 of 25 Boston champions, 7 of 8 London champions and the top 25 times in the marathon world two years ago.  These are the result of BOTH genetic and training related factors, but it is unlikely to be a unique gene that is found only in Kenya.  The rest of the world therefore is not destined to be beaten (as Galen Rupp and a number of Americans have shown), but they have to work a lot harder on a system-wide level to identify those athletes with the potential to be competitive, and to expose them to the right environment (without a host of other distractions, which arguably compromise the success of runners).
  
  Think of the mining analogy - there are some places in the world where you can pick valuable metals off the ground.  In others, you have to prospect, consult geologists, and invest heavily to dig deep into the earth's crust to extract those valuable materials.  Kenya may just be, genetically speaking, the richest natural source of talent.  But they also mine it more effectively, and that combination is the secret to success.
  
  
  
• Finally, I do not see any genetic argument in any way undermining the achievement of a nation like Kenya.  To suggest that they have some advantage is not to say that they have done any less to earn their champions and medals.  I think this is the root of the controversy, and it's a pity because it comes from a polarization attitude that seems to believe that if you have one, you don't need the other.  When I am watching Boston, or Rotterdam, or London, over the next week, I will be in awe of men running 2:05 and women running 2:20, not because they are genetically superior in any way, and not because they train hard, but because they have it all, and they're maximizing natural and hard earned talent.  That's worth celebrating.  And understanding.

Of course, this is all just hypothesis generating thought.  The studies will come in time, and perhaps we will one day discover a unique gene in East Africans, and another in West Africans or Jamaicans that makes them such amazing sprinters.  Or perhaps we'll discover no differences at all.  Regardless, I can't see how either extreme position (it's all genes, or it's all training) is defendable.  It must be, as I've now written often, the realization of genetic potential through training that produces those great performances.

Thoughts welcome!

Ross

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Ditulis oleh reyhan iki pada tanggal Sabtu, 13 April 2013