If you were asked to pick two people on opposing sides of the nature/nurture debate, you might pick myself and David Epstein, author of the new book The Sports Gene: Inside the Science of Extraordinary Athletic Performance. If you haven’t bought it already, you should: it’s a fascinating, thought-provoking look at the leading edge of sports performance, written by a guy who knows the territory. David, besides being a senior writer for Sports Illustrated, was  a collegiate runner for Columbia University. More to the point, he’s a terrific researcher and a fine, thoughtful writer.

Last week David and I had a wide-ranging barroom-style chat that covered Jamaican sprinters, the 10,000-hour rule, and the secret role of David’s mother in his new book. You might think we would spend the entire time hurling barstools at each other. You would be wrong. Partly because David is an incredibly nice guy, and mostly because science is shining new light on this area: when it comes to raw athletic skills (endurance, speed, leaping ability) genes are a difference-maker, particularly at the world-class level. With complex athletic skills (basically everything else), it’s far more about environment (quality practice, coaching, motivation, etc.).

Here’s how our chat went:

DC: David, let me start by saying how much I admire the book, your work, and how it made me appreciate physical talent in a different way. I can only presume that the skill you show in writing this book is mostly genetic.

DE: It’s funny — my friends think of me as a guy who thinks that training is a miracle, because it can totally transform someone. But the questions I get on TV are mostly, “What’s the gene for this, what’s the gene for that?”  Like this TV show I went on yesterday tweeted “David Epstein thinks that there’s an actual sports gene that separates athletes from the rest of us.” I totally don’t think that.

DC: I’m especially interested in this notion of trainability you write about — how when some people exercise, they get a lot more fit, and other people who follow the exact same regimen don’t improve at all, and it seems controlled by genes. I wonder if you found any evidence whether these same sorts of variances apply to the brain and the process of learning skills.

DE: Yeah, I didn’t get into skills as wide ranging as you have, but I did look at twin studies, fraternal and identical twins, heritability and things like that. Experimenters would have them doing skills like balancing on a plank that has a ball under it, and the identical twins would usually progress in a way that was similar to each other and different from the fraternal twins, and sometimes significantly different. But it depended on the tasks. For tasks that were really simple, everyone would get better at the same rate, fraternal and identical, and everybody would end up in a pretty similar state. But if the tasks were pretty complex, sometimes people would actually get more different from one another with practice. Identical twins would move together, and they would move away from the fraternal twins. So it seems, even though we don’t know the genes for all that, that in complex tasks there was usually a trainability phenomenon, or almost always a trainability phenomenon.

I had to cut 40,000 words from the manuscript, and some of the material I cut involved some studies like this. One of the genes was the BDNF gene, which stands for “brain-derived neurotrophic factor.” There’s studies with versions of BDNF called val and met, and they’d have people do a driving simulation and people with a certain version would tend not to repeat their mistakes as much, so when they would bring them back, a day or month later, they’d remember the course better. The same thing happened with putting pegs in holes.

In one specific case, in a motor-learning task, there were suggestions that one version of the BDNF gene coordinates the reorganization of the brain that happens when skills are learned. I remember one 2006 study where people practiced motor skills with their right hand, like putting pegs in holes as quickly as they could, and the activated area of the brain that represented the right hand increased in size with practice only in people who didn’t have the met version of that gene. So all the subjects started with similar-size motor maps, but only the non-met carriers experienced a significant change with practice. So there was some sort of proof of concept there, but not so much repeated work that when it came down to what I had to cut from the book, it had to get cut.

I think there was one other study… can I read you a paragraph?

In 2010 a group of scientists led by neurologist Steven C. Cramer set out explicitly to test whether the BDNF gene impacts the kind of memory involved in motor skill learning, and their findings suggest that it does. In that study, people drove a car along a digital track 15 separate times in one day. All of the drivers improved as they learned the course, but the met carriers did not improve as much. And when all the drivers were asked back four days hence and made to drive the course once more, the met carriers made more mistakes. When scientists used fMRI to look at the drivers’ brains as they practiced simple motor skills, they found different patterns of activation in the people who had a met version of the BDNF gene.

So I think there’s some proof of concept. And also the fact that competitive table-tennis players with mental handicaps actually failed to learn the anticipatory cues to effectively return shots. I found the fMRI literature to be so, sometimes all over the place and contradictory, so it suggests to me that there’s more to look at there, but I didn’t feel like it was nailed down. It feels to me that it might work on a skill by skill basis, because individual skills are so different. I ended up actually cutting all of that because I think there needs to be more done. Sorry, that’s a long-winded, wishy-washy answer to your question.

DC: Backing up for a second. When we first started talking, we talked about the response to your book, and the fact that people are reacting to the idea of this sports gene, and how you’re put in the position of pointing out that things are a bit more complicated. Are you surprised at the reaction to your book?

DE: Totally surprised. I was really leaning on family members to buy copies. When I pitched the book, a lot of publishers lost interest when there wasn’t a takeaway message. The first question was always, is this another Born to Run? That was the first. Next, was where are you going to come down on nature versus nurture? My answer was, I don’t know where I’m going to come down, but I can tell you that it will be nature/nurture-plus. I guess I thought the complexity of the book would deter other media from covering it at all, and that would in turn deter people from reading it, and I guess that’s turned out not to be the case, though it’s been difficult because some of the coverage will take one side or the other. I hope people read the book. Some of the coverage has made it seem like I believe there’s some specific sports gene that separates great athletes from the rest of us, but I definitely don’t believe that.

DC:  Although some companies out there would love parents to believe that that sports gene is out there and can be tested for.

DE: Some of the direct-to-consumer marketing is total rubbish. Sometimes the genes that the companies market do have scientific principles behind them, like they do impact capillary growth when you train, but they’ll say, “We’re gonna test you for these three genes, for cardiovascular response to training so we can tell you whether your kid is going to be an endurance athlete.” Those three genes might explain just two percent of the variance. Even though, for research purposes, that’s an interesting number, for parents or athletes it’s completely useless.

DC: I was fascinated by was the chapter on the Jamaican sprinters. Because if there was a part of the world where you could say, yes, there’s a gene  for speed and the Jamaicans seem to have it, that would be the story. But that’s not the story you found.

DE: One of the ways I got curious about this, other than the fact that there were a lot of Jamaicans on my track team who were really fast, was that a demographer told me that there were more people of Jamaican descent in America than there are in Jamaica, so if it were just down to Jamaican genetics, American should be winning — and we’re not.  And so, when I went to Jamaica and I kept hearing this story of how this group called the Maroons, these warrior slaves who beat back the British army and cloistered themselves in the northwest corner of the island where all the great runners come from, Ben Johnson and Usain Bolt and all the others, that these warriors had given rise to the great track and field athletes, but so far the genetic data doesn’t really support that.

So Jamaicans are a very mixed group of West Africans, and Maroons look genetically pretty much like other Jamaicans, which is to say like West Africans so all the studies that have been done to date show that people from that part of the world tend to have a higher-than-average proportion of fast-twitch muscle fibers, and every 100-meter male Olympica finalist since the boycott in 1980, no matter what country they’re running for, they’ve all been from that tiny area of West Africa, and they all have proportionally longer limbs, for cooling purposes.

That said, I like to think of the Usain Bolt example. In what other country in the world would a six-foot-four 15-year-old end up in track? I think the answer is the Bahamas, Trinidad, and maybe Barbados and Jamaica, and that’s it. So while you can think of Usain Bolt as a genetic freak, I think he does have physical gifts that are pretty rare, and his mentality allows him to capitalize on those gifts in a certain way, but I absolutely think there are other Usain Bolts out there. I think Randy Moss might be another Usain Bolt. But you’re not going to find them outside Jamaica, because they’ve forced everyone to sprint. I mean, the chances of a great sprinter slipping through the cracks in Jamaica is like the chance of a great high-school football player slipping through the cracks in America.

DC: You say forced to sprint, but is it forced, or something else? The scene you describe in that stadium… I mean, if I went to that stadium as a ten-year-old kid, it would light me up, I’d start dreaming of being a great sprinter. The way that culture sends out this clear shared signal that creates this motivational response is the interesting part to me.

DE: Right. Forced is the wrong word, because it starts with sports day at school when kids are five years old, and of course they want to take part in that because it’s fun and everybody gets a pat on the back and everyone takes a crack at sprinting from the time they’re little. The kids start to get to know who’s fast. As they get older, all the enthusiasm in Jamaica is for youth track. Prior to Usain Bolt and Asafa Powell facing off before the 2008 Olympics at the Jamaican national trials, [Jamaica] didn’t care about pro track at all. The sportswriters there were telling me that they had empty stadiums for pro track.

And so all the emphasis is on youth track, which is amazing. So kids get recruited… I remember going around the track at the high-school national championships and asking coaches how recruiting worked, and they’d tell me without me asking, “Well, we’re not allowed to give refrigerators to parents anymore.” It was like their version of shady boosterism, they’d give fridges to parents to try to get their kids to come to a certain school. So kids are looking at high school as a place where they can gain local renown and compete in a stadium where there is a World Cup atmosphere. The atmosphere was like being at the Olympic final in London. There weren’t quite as many people because the stadium isn’t that big, but it was more energetic. I was sitting next to former Olympian Sandie Richards, and her high school was catching up in a relay, and she’s digging her nails into my leg.  This is an Olympian on the edge of her chair watching her high-school team! So it’s really cool, and the alums are still part of the program, it’s something that anybody in sports would want to be a part of.

DC: That’s amazing. That brings us to the idea of motivation and how that happens. As an Alaskan, I like the chapter on the sled dogs and the idea that it’s possible to breed dogs for motivation. Which makes me wonder: what’s more powerful, to have a gene to help your motivation along, or to have an environment — like being in that stadium?

DE: That’s a good question, and I don’t totally know the answer, and I’m sure it’d a different answer for different people, but we know intuitively that we respond differently when we’re in different training groups, with different partners. Some people require a heck of a lot more management to get them to train the way they should, and other people who you have to manage in order to get them to stop training. So I think it’s a sliding scale. The less innate it is for someone… and I hope that chapter doesn’t come off so that people read it and say, “Oh, I’ve got coach-potato genes, I’m just not going to exercise.” When I’ve been interviewed about it, I say, “No, that means you might have to work harder to form your environment in such a way as to make it more conducive to exercise.” I know that about myself. I know I can get really lazy really easily, so I look for training groups because I know that’s something that works for me. I tell you, if you don’t get excited by being at National Stadium in Kingston during Champs, check your pulse.

DC: Another thing in the oxygen these days is the 10,000-hour rule. It’s clear, though your work in the book and the work of others,  that this number represents an ideal, not some kind of magical scientific threshold. Did you find anybody who defied the 10,000 hour completely, either as a raw athlete or as one with more complex skills?

DE: I think the more complex a skill is, the more unlikely that is to occur, for a variety of reasons that you cover in your book. But from a raw athletic standpoint, I think, yeah, I think I saw it quite a bit with guys like [high jumper] Donald Thomas, for example, as compared to a guy like Stefan Holm. Stefan Holm estimated his own training at 20,000 hours, and Donald Thomas was close to zero, so those guys average 10,000 hours. If somebody had done what Donald Thomas did at the high school level, my eyeballs would have popped out of my head. But to see someone do it at the world-championship level, just like knocked my socks off. I think the lower the level you go to, the more you see that, like the study at York University on aerobic capacity.  They kicked people with even a light training background out of the study, and six people out of the 1,900 in the study had aerobic capacities in the sixties without any training history whatsoever.  So that’s where I think you look for these people, when they haven’t achieved anything, people who have had no training whatsoever, so you can catch them when they don’t know they have it, or haven’t practiced. Mid-sixties is really high aerobic capacity for people who haven’t trained at all. I think those people are out there.

Right now we’re watching the world championships and  Ashton Eaton, world-record holder in the decathlon, I think he didn’t have a deep athletic history when he won, but he was able to do the decathlon because he was small. Or Bolt, who won the world junior championships I believe when he was 15, and that’s an under-19 competition, which is crazy when you think of the developmental differences there. In the book there’s the story of [world-champion triathlete] Chrissie Wellington didn’t sit on a road bike until she was 27 years old. So those people are out there.

DC: Most of those examples and those in the book involve speed, endurance, and aerobic capacity — you’re talking about primal qualities of the human body. Are there any that jump out at you that were succeeding in that way with what we might call more complex skills?

DE: Not really, not in more complex skills. I don’t think that anyone’s born knowing complex skills. I make the case in the book that in tennis, general athleticism seems to speed the learning curve for sports-specific skills, but even those players who were tracked from the time they were youth, even Steffi Graf and Boris Becker had to put in a ton of time in order to learn those sports-specific skills. They were superior on tests of raw athleticism, but they were also superior on tests of focus and concentration, and they were tied for the highest in ambition with some other players. So no, I don’t think… the idea that someone knows how to hit a tennis ball or a baseball when they are dropped on earth, and I don’t think the most deterministic geneticist would think so.

DC: You mention ambition, and you’ve spent time around some top performers through your day job at Sports Illustrated and through this book. The self-narratives of these top performers is really interesting, which leads me to a question: with a great performer, do you want them to know the scientific truth about what’s happening? We’re obviously in the barroom portion of this conversation now, but I often think that they function better when they don’t know the truth, when they’re immersed in some other narrative, which gives them more power than just the scientific facts.

DE: I’d agree with that on a number of levels. One principle I have for sportswriting is, “Just because you’re a bird doesn’t mean you’re an ornithologist.” When I see sportswriters, they often ask athletes how they do what they do, because they think the athlete is the expert. And the athletes don’t know. Albert Pujols really thought he was going to hit the ball off [softball pitcher] Jennie Finch.

DC: They don’t know! They’re in the worst position.

DE: Exactly. They’ve automated it. They have no idea what’s really going on. So they’ll naturally find the narrative that’s best for them, and they should be allowed to embrace it. Jonathan Edwards, the triple jumper, is a really interesting example. He was sort of, and maybe this crosses lines that I shouldn’t get into, but he was extremely religious and saw triple jumping as a way to give him a platform to spread certain religious values, and when he retired he had a crisis of personality, and ultimately looked back on it and said, “Oh, I think that believing that just helped me stay focused on my training. “ Now, he’s not religious at all. So it’s a very strange thing, and I think those narratives can be important. Where I think knowing some of the science could help is in knowing and figuring out the best kind of practice to do, in terms of helping people know that skills develop in certain ways and you do need to put in this time to let those skills develop.

A college friend of mine was world-ranked in the 800 meters and just picked up cycling recently.  He’s really good for a beginner, but he’s  getting mad because he’s not winning the race. I’m like, come on, man, you don’t pick it up overnight! With respect to genetics, the danger is that we tell people, “You have these genes, you have to do this.” I hope that it leads to more options. Where we say, “You have these genes, you can do whatever you want, but your machinery might be really adept at improving at this other thing, so if that training over here isn’t working for you, and you aren’t getting the joy and progress you want, don’t be afraid to try this other thing.” So I hope it leads to more options.

DC: It’s interesting that people really, really want there to be a sports gene, that this sense of pre-destination is almost built into our culture. That there’s a magic thing out there that I was born to do. And that probably is the case with a tiny percentage of extraordinary athletes. But for most of us it’s about exploring and tweaking things this way and that to optimize.

DE: Exactly. That tweaking thing. I love this quote I came across for the book by a guy named J. M. Tanner who was a world-class hurdler the world expert in body development and growth. His quote was something like, “We all have an absolutely unique genome, so for optimal development we would want a completely unique environment.” There are certain principles that apply across all sorts of training. But I also think great coaches know that different people respond to things in different way.

I have a friend who was in special forces, and when he got to a certain level of training, every guy had a one-on-one coach. Every guy, so their training was tailored to them. Obviously that requires a lot of resources, but I hope people take sort of a trial-and-error approach to their training. I know that I was a better cross-country runner on 30 miles a week of targeted training in college than I was on 80 or 85 miles a week in high school.

DC: With that in mind, let’s go to the lightning round portion of this, where I ask you to rank the relative impact of several factors on performance, for a few hypothetical athletes. For the purposes of this experiment, I want you to picture them as average Joes and Josephines. No Usain Bolts allowed.

Here are the four qualities I want you to rank, from most important to least important:

• Genes
• Quality of Coaching
• Motivation/Mindset
• Quality of Practice

DE: OK, ready.

DC: First, for an average high-school soccer player — which factors matter most, and least?

DE: I’m gonna say, I’d put quality of practice first. Quality of coaching second, genes third, and motivation/mindset last.

DC: Okay, now for a world-class golfer — same question. Which factors matter most, and least?

DE: This one I’m going to say, quality of practice, genes, then motivation/mindset, and last, quality of coaching.

DC: Okay, how about a weekend tennis player — someone like you and me, in his thirties or forties, trying to get better, to do well in club tournaments.

DE: In this case, I think quality of coaching would go first. Then I think quality of practice and genes tied for second, then motivation/mindset last. Man, I’m really sticking it to motivation/mindset, aren’t I?

DC: It must be your coach-potato gene speaking. Okay, how about an Olympic marathoner?

DE: Genes first, quality of coaching last — because most of the Kenyans don’t even have coaches —  quality of practice, motivation/mindset, and quality of coaching.

DC: Lastly, how about for the author of a new book called The Sports Gene. How do you rank those factors for your own skills, your own performance in writing the book.

DE: This one, I think motivation/mindset is really important. I’m gonna put it on top of this one. Then I’m gonna say quality of coaching last. Then I’ll put genes second, and quality of practice third — wait, no, no let me switch those. Can I tie genes and quality of practice or is that lame?

DC: You can have a tie. That’s definitely permitted.

DE: I did notice, when I was digging through some stuff for my acknowledgments I recently found a letter from my mother and though she’s never done any writing, she’s really quite good

DC: That’s awesome. So we can thank her for making today possible, then.

DE: I read somewhere that the point of all this science is so that we can figure out whether to blame our genes or our parents [laughs]. I don’t know if we settled anything, but it’s been fun.