Hui Zhou raised some interesting points in the comments to my 15 mile race results post. He even when on to write about some of our very divergent views on this issue. I made a comment about not having natural aptitude for running. The crux of Hui’s argument was this “So, when you say “natural aptitude”, do you recognize the snowball effects of pure experience? How much in us are real natural? or is it just experience difference matters?” For me, the answer is a bit of both.
I run a genetics research lab and am firmly convinced by the data I see daily that genes (nature) have a huge impact on physical and behavioral phenotypes. However, even genetically identical individuals can have significant variation both behaviorally and physically that is typically written off as either environmental (nurture) or stochastic effects. In general, I tend to view most traits as continuums (tall–short; fat–thin; strong–weak; smarter–dumber). Some of these we can change with training and practice, whereas others we cannot. I would love to be taller but it simply is not something I can change. I used to have a martial arts teacher that tried to teach us to fight strategically rather than with brute force. Just about every class he would remind us that “there will always be someone who is faster, smarter, stronger and better looking.”
So when I say I have “no natural aptitude” for running it is because genetically I am more endomorphic than ectomorphic like “natural runners.” The skeletal structure of my hips is wider than most great female runners. Sure, I have legs and can train. So, I do have some innate capacity for running but I don’t think this will get me to the front of the pack, even if I keep striving at it. Conversely, I may end up being able to run faster and further than someone with a natural aptitude for running who never trained to run. But I think that the point where the training will plateau is largely driven by “natural aptitude.”
So Hui, we may not come to agreement on this but I thank you for an interesting discussion.
Edit to address Hui’s comment below:
Hui, I’m not sure that I agree that running fast and far was one of the essential characteristics of our survival and evolution. I might instead say that using our brains to hide and avoid having to run fast and far might have provided an even greater advantage. But lets stick with running for now.
Human beings have about 20,000 to 30,000 genes encoded by our 3 billion DNA base pairs. On average, every 1000 base pairs there is a polymophism or variation between just about every person on the planet. This is a significant amount of variation between individuals. I’m not sure how many genes are involved in running performance but let’s assume that this number is between 10 and 100. There are 1000’s of different proteins needed to make up our muscles and bones so this is a very low estimate. Now let’s assume that most of the variants work pretty well (not a disease state) with differences in function for a single gene/protein being between 0.5 and 10 percent. That is, each one is between 90 and 99.5% as good as another. The real variation happens when individuals get all of the optimal or suboptimal versions. I’ve put together a very quick table that shows the impact of this effect depending on how much variation there is between each version and how many genes play a role in the trait of interest.
|number of genes|
So if the genes variants are substantially similar, and very few genes are involved I should be 95% as good as olympic runners. If there are more genes involved, you can see how, just by the random chance of gene assortment, I can very quickly become an innately bad runner.
Obviously, the chance of getting all of the bad genes is quite remote (it requires your parents carry them and transmit them, etc.). Let’s assume that there are only 2 versions of each gene and that each gene is equally common in the population. Now let’s assume I had average parents who had one good copy and one less good copy of each of the genes. If I use the example where only 10 genes are involved in running performance, the chance of inheriting both bad copies (the less good copy from each parent) is (0.25)^10 or 1 in 1,048,576. The chances of inheriting all of the good copies is identical. Thus, in my opinion, elite atheletes will be rare. Most of us can do OK. And some group of people will have utterly no capacity for athletic performance.
Here ends my lovely lesson in genetics for the day. Hope this clarifies a bit where I am coming from.