I commend Slate for putting the genetic results presented here in their proper context, which is sadly unusual in media coverage of this issue.

Athletic performance is determined by a complex mixture of multiple genes and many interacting environmental factors (diet, training, culture, etc.). Although genes are certainly important, ACTN3 alone is not the explanation: this gene predicts only around 2% of the variation in muscle strength and sprint performance in the general European population (see here and here), and is likely just one of dozens or even hundreds of genes that contribute to athletic prowess.

The ACTN3 gene certainly can't explain the unusual success rates of Jamaican sprinters: very similar frequencies of this genetic variant are found in populations throughout Africa (including, for instance, in Kenyan marathon runners), and yet sprinting performance is highly unevenly distributed across this continent and its diaspora. This indicates that many factors beyond ACTN3 - likely both genetic and environmental - affect variation in sprinting success between populations.

The science of performance genetics is still very much in its infancy, with most "athlete genes" yet to be discovered, let alone validated and studied. Readers should bear this in mind when they hear the hype about ACTN3 or any other "sporting gene".

But wouldn't the "cultural importance" placed on sprinting be a result of that culture's genetic superiority in these events? I find it curious that the writer would bring up culture, without asking *why* the culture is that way.

al campanis and jimmy the greek got canned for saying similar things.

irvingchang:

al campanis and jimmy the greek got canned for saying similar things.

No, they didn't. Jimmy the Greek got fired for positing that blacks were good athletes because of a breeding program by white slave masters. Campanis lost his job because he opined that black people weren't intelligent enough to handle management positions. Neither comment had any scientific or historical evidence to back it up.

This is why subjects like this are so dicey in America - issue of genetics and biology always seem to veer off into eugenics and bigotry.

The whole "Jimmy the Greek" fiasco is also why this whole article if flawed. What is this topic even doing in Slate? Why is the scientific community always looking for reasons why Black athletes win? Why not an Explainer on Phelp's 8 medals?

And, as one poster pointed out, Jimmy the Greek had no scientific basis, but I challenge even the basis of this so-called study. For too long the conventional wisdom has been that Black West Indians have their origins in West Africa, but historical records (and now, since we're talking science, DNA testing) show that more people have their origins in present-day Angola. Which has never won an Olympic medal. In anything.

And in any case, this topic always degenerates into eugenics because, with the exception of Hitler's "science", it's always focussed on trying to explain Africans' "natural" prowess. Why not study white and Asian swimmers? Does this mean that the WHITE French guy who came second in the 3,000 meter steeplechase is somehow more talented than the Kenyan who won it because he's working with less of a genetic advantage?

'Why not study white and Asian swimmers?'

negroes bones are denser which makes them sink. just kidding! they don't get to the beach or pool much and the only water sports they have is opening up a hydrant on a hot day.

i remember my boot camp days. being in the navy, they want you to know how to swim. you should have seen the black guys struggling! they had a special company called 4999 for people who couldn't swim and it was 95% black.

Irvingchang: Black people live all over the world, not just in the housing project down the block from you.

But another question for the Explainer: if this is the case, why haven't people from Antigua, Barbados, Bermuda etc dominated the sprints too? They should have the same "genetic stock," shouldn't they?

That would make a pretty compelling case for "culture" - and not a "culture" influenced by genetic predisposition, as one poster suggested, since that would mean the entire Caribbean would be egging on their naturally gifted populations, right?

As the original poster said the gene only explains 2% of the variation. That is essentially nothing, and the ACTN3 hypothesis should be discarded immediately. Also if the West vs East African theory was true then why hasn't West Africa produced champion sprinters? Tomorrow if Jamaican decides to place more resources into developing a swimming program then it will also produce star swimmers. The type of athlete produced by a country is dictated more by socio-economics and cultural values more than genetics.

And irvingchang's comments about swimming abilities among blacks underscores the major and pervasive role that socio-economics plays in even the realm of sports. It dictates health care, education, career and stereotypes.

The same reason why Michael Phelps is able to swim so rapidly is the same reason why Usain Bolt can run so rapidly. Same type of muscles, but different appendages are involved.

Overall I found this article awkward and utterly absurd. I suppose gymnists have a genetic advantage because of their height and low body mass as well as incredible coordination.

The British have been dominating the cycling, 10 years ago they were nowhere. Must be the latent cycling gene suddenly expressing itself. Either that or all the money and training they put into it recently.

Most Jamacians are of mixed heritage especially with the

Irish & Scottish peoples. So There. The origins of the people of the Caribbean vary from island to island to country. Before you make blanket statements do your research. I am not suprised by the ENVY protrayed in this blog.

Jamacians, besides being talented worked hard because they cannot afford the skilled pharamicists from the US and elsewhere. (Get acquainted with the Dublin Inquiry)

Congratulations Jamacia!!!!!!

There is a eugenics experiment that goes on every year at high schools, colleges and the NFL, who gets to be running back.

Every tailback in the NFL is black, every back-up tailback in the NFL (currently) is black. Blacks make-up about 12-13% of the US population. Across America White dudes are star running backs in high schools where there are large White populations. Some of these guys rise up and even make it to the collegiate level, but for some reason when it comes time to pay these athletes none are acceptable at this position. Despite an overwhelming number of White guys spending considerable energy to succeed in this field they can't cut it not even an odd representative at the highest level. Why is this? The explanation is superior genetics for explosive speed. Arguing against genetics here in my opinion is like arguing for Intelligent Design or a flat-earth. What cultural phenomenon could overcome this overwhelming statistical evidence?

Why is it surprising that natural selection wouldn't favor one of the races in this aspect.

It's like if you had a thousand Clydesdales and 5 thoroughbreds what would be surprising about the 5 thourouhbreds finishing 1-2-3-4-5. Nothing. They are all horses, but one is built to separate itself from the others.

The NFL runningback experiment is awesome data that year after year despite an overwhelming number of white kids wanting to play runningback, only black kids get the spot. Are white coaches in the NFL secretly conspiring to make this spot all black? No, they would put your grandma at tailback if she could get 1,500 yards on the ground for a season in the NFL. It is money driven and to get the most for your money, you pay for genes that (for now) seem to be more widely expressed in black athletes. This isn't to say that skin color and the "athletic" genes are locked together. I would guess that the "athletic" genes could be expressed in a variety of skin colors, but due to some natural selection reasons are for now found overwhelmingly in people with black skin color.

To me the 100 M race is this same experiment, bunch of people of different color (the vast majority not black) from around the world dedicate their lives to running fast, but come Olympic 100M final time...its a monochrome sweep.

dgmacarthur makes some excellent points,

If what the author says is true, ACTN3 is a terrible explanation for Jamaica's sprinting dominace.

1) 70 percent of Jamaicans have the "strong" form of ACTN3 versus 60 percent of American (blacks?). Presumably, the author means 70 percent "are homozygous for the gene". Given Jamaica's population of ~2.8 million compared to the ~40 million US black population, that would give Jamaica a pool of 1.9 million potentially fast people versus 24 million in the US and many, many, more in West Africa, the Caribbean, South America, etc. The numbers don't add up.

2) If ACTN3 really had such a magical effect, Jamaicans would be competing against others with the same gene variant at the top level (it is very common after all), essentially nullifying the genetic advantage. Of the tens of millions of people worldwide with the "strong" variant, you'd think that at least a few could keep up with Usain Bolt's casual jog.

3) The ACTN3 variant is probably an ancient polymorphism. Jamaicans have traditionally been fast runners but they really only started blowing away the competition this year. How does one explain the sudden change?

I do agree with nurture as an important reason for all that speed; Namely that the the Jamaican team has been "nurtured" with massive doses of performance enhancing drugs. The Jamaican anti-doping agency has never, to my knowledge, even tested an athlete. Even if they did, they'd be very likely to look the other was for a National hero. With all the scrutiny, it's becoming harder for Americans to get away with doping (which they obviously did a lot of in the past), so it's only natural that Jamaica is filling the void.

The obvious explanation for why Jamaican's like Bolt set world records with no real genetic difference from Africans in the US, other islands or Africa is culture. Specifically a culture of PEDs (performance enhancing illegal drugs). Same reason the Canadian sprinter Ben Johnson won medals (oh and he was born in Jamaica too). Jamaica has no international drug testing.