Autism in the News

Autism is coming off a big week in the news. The New York Times covered a recent study, which suggested that the risk of autism in children is linked to paternal age since older fathers pass on more mutations to their children. In another New York Times piece, this time an Op-Ed, Moises Velasquez-Manoff offers up the possibility that autism might be an autoimmune disorder. This is an idea with roots in the hygiene hypothesiswhich proposes that conditions like asthma and allergies are the result of a “bored” immune system, no longer burdened with fending off parasites (hence the hygiene), mounting an inappropriate response against the body or otherwise, unharmful, environmental substances (e.g. pollen). Lastly, there was the announcement of an FDA-approved trial using stem cells as a therapy for autism. In a week when headlines were dominated by autism, here were my favorite reads that offered some balance and insight:

On the Paternal Age and Autism linkVirginia Hughes gives us the “Top 3 Reasons to Stop Fretting About Being an Old Dad,” while Seth Mnookin writes about an overlooked implication of this study–“that the genetic health of the species is now facing a serious threat.” With regard to the stem cell trial for autism, Youssef Rizk explores how the design of the trial sidesteps ethical complications by using the patient’s own cord blood stem cell, and Kathleen Raven, rather than simply calling the trial a “cure,” explains the hypothesis being tested in the trial and the, “study’s primary goal…assessing changes in patients’ speaking and understanding of vocabulary.” As for Velaquez Manoff’s Op-Ed piece on autism as an autoimmune disease, Jonathan Eisen laments the “lack of a discussion of the distinction between correlation and causation.” And finally, Emily Willingham, in her critique, isn’t quite buying what Velaquez-Manoff is selling:

“From the headline to the final paragraphs focused on using parasitic worms to treat or even prevent autism, the science as Velasquez-Manoff presents it is limited at best, and frequently unsourced and unreferenced. Where a source is given or traceable, the conclusions are overstated or cherry-picked.”

Experimental Ethics

by Youssef Rizk, Esq.

While doing some reading online during the work day, I came across an article about a recently FDA approved experiment that would attempt to develop a treatment for autism using stem cells collected from the child’s umbilical cord blood (“cord blood”) at birth. Quickly summarized, the experiment intends to locate children with autism that do not exhibit any obvious genetic pre-disposition for the disease, such as a hereditary history.  The experiment also attempts to rule out people with head injuries or other trauma that may have caused autism.  The study intends to focus on children with autism that developed the disease from factors like the environment or exposure to infection (perhaps easier said than done when it comes to filtering out candidates, but that’s their problem to figure out).

What really interested me about the article was one particular paragraph that read:

“Using the child’s own cord blood will make the study safe and ethical – plus, the cells are younger and have not been exposed to environmental factors, like viruses or chemicals, which can alter the cell’s function and structure. By using the children’s own stem cells, their bodies cannot reject them.”

The article suggests that using the children’s cord blood to gather stem cells is ethically sound in light of how divisive stem cell research is in society. The objections are mainly against human embryonic stem cells and the research performed using them, which is an objection closely linked to the abortion debate (and I am conveniently going to steer clear of that debate). Objections, which prompted President Bush to limit embryonic research and which President Obama reversed during his presidency. Nonetheless, using one’s own cord blood for stem cell research arguably avoids any ethical issues. It is simply blood kept for the original host’s use at a later time and does not rely on stem cells from other sources.

Intentional or not (and I’m assuming intentional), this experiment is designed in a way that avoids the stem cell research controversy. The decision to use the cord blood of the patients themselves is an admittedly smart way of going about obtaining stem cells because that also ensures that the patient will not reject those cells. It also happens to avoid the ethical debate, thus rendering the experiment with less opposition (if any) and easier to approve by the FDA.

One could argue that true/pure science should not be at the mercy of public opinion and that an experiment should remain unbiased by such opinions. The idea that allowing public opinion into science, corrupts pure scientific research could in fact have some truth (see the old “Cigarettes are good for you” ads like this one:  

Nonetheless, we don’t live in a world where scientists can do whatever they want. Politics are everywhere from the highest reaches of the government to the struggle between competing lab-mates working on similar experiments. Scientists that seek to excel have no choice, but to play society’s games in order to keep progressing in their fields. Scientists often need to be liked as well as distinguished, especially when much of the funding for scientific fields comes from non-scientific sources. David H. Guston of Rutgers University calls it the principal-agent theory.

I thought about political influence on science when I read about the FDA approved autism experiment. Did the scientists consider potential societal objections to their work in such a controversial field? Did that consideration have a factor in the design of their experiment and in seeking FDA approval? Taking into account the fact that the laws of a nation can severely limit or open up scientific research, a good scientist would seem to have to take political factors into considerations for not only experiments, but for grants, and reputation. A scientist that knows how to “play the game” may be the scientist that has the best chance of advancing science.

I find this type of balancing act fascinating because unless a scientist goes off into international waters and funds his/her own research, there is always an influence of public opinion weighing in on the advancement goals of science. Does that influence merely dictate what fields scientists pursue or does it in fact dictate the course of experiments as well? The brief point made in the article about the experiment with autism and stem cells seems to illustrate just one example of where science as well as law/politics meet to discuss ethics.

Maybe we should just not eat anything

It seems like every week the news runs a story, based on some new study, that either touts the health benefits or demonizes the hazards of a particular food. One week, it’s eat walnuts if you want healthy spermies. Other weeks, it’s eating red meat could raise the risk of bowel cancer. Unfortunately, many of these stories lack, well, journalistic vigor, which can often lead to a regurgitation of the study’s press release, sensationalization of the studies claims, or worse, outright distortion of its conclusions. Other times, it overlooks just plain, old bad science. And to add to the confusion, this week’s story might contradict the findings of past nutrition research–leaving many of us wondering, “What CAN I eat, then?”

Luckily, capable science writers and communicators often step in to fill in the gap. Take for instance, Cassandra Willyard’s dissection of the actual study that many news outlets declared demonstrated eating eggs was almost as bad for your arteries as smoking cigarettes.

Or biochembelle’s breakdown of the link between Alzheimer’s and exposure to diacetyl, an ingredient in popcorn butter flavoring–pointing out that most of the articles failed to mention who was really at risk (industry workers) and also, that the “two major manufacturers, ConAgra and PopWeaver, removed diacetyl from their microwave popcorn.” Lastly, for a longer read, Gary Taubes writes on the limits of observational epidemiology, after reports that “meat-eating apparently causes premature death and disease” and “that chocolate is a food we should all be eating to lose weight” were published earlier this year.

These science writers provide insight and perspective into the science involved in food research by pointing out the limitations of these studies, illustrating what the news simply got wrong, or even  reminding us that sometimes we need to take these studies…with a grain of salt. And maybe, that’s why some of these journalists take the easy road. They know that someone else will come in later and do the hard work.

Related Reading:

Pink Slime: My beef with Jamie Oliver and Food Blogs

Is Sugar Really Sugar?

Image credits:

Walnuts courtesy of Marco Bernardini

Egg and Cigarette courtesy of Benjamin Maubach

Popcorn courtesy of  Jeff Baxter 


Olympics Recap: Race, Gender, & Genetics

Barr bodies used to bar men from competing as women

Last week, I discussed the inadequacies of genetic-based gender verification. What I failed to mention was that at the 1968 Olympic games in Mexico,

“Barr body detection was introduced and was widely proclaimed to be the solution to gender misrepresentation in sport. This reportedly ‘simpler, objective and more dignified’ test involved the cytological analysis of a buccal smear. The Barr body was first detected by Murray Barr in 1948 during research on the nervous system of cats – cells were analysed following electrical stimulation and a dark staining body was found in the nucleus of some animals and not others. The distinction was found to be related to sex and a similar finding was noted in human autopsies. The findings were published in Nature in 1949 and the nuclear marking became known as the Barr Body.“1

As it turns out the Barr body is actually an inactivated X chromosome found only in the cells of females. The genetic imbalance of having two X chromosomes in females and only one X chromosome in males means that the expression of X-linked genes in females can potentially be twice as high as that in males. A process called X-inactivation ensures that expression of X-linked genes are equal between sexes by “silencing” the gene expression from one copy of the X chromosome in every cell of the female body. As a result of this silencing, the inactivated X chromosome appears as a clump attached to the edge of cell nucleus.

Barr bodies appear as a darkly-staining bodies attached to the nuclear membrane (arrows)

In marsupials (kangaroos and other weirdo mammals) it’s always the paternal X chromosome that is silenced, whereas in placental mammals (us and most other normal mammals) the X chromosome that gets inactivated is selected randomly. This random inactivation means that not every cell in the female body is genetically equivalent–some cells are expressing genes from only the paternal X chromosome, while others are expressing genes from only the maternal X chromosome. A visual consequence of this random inactivation can be seen in tortoiseshell and calico cats since one of the genes responsible for coat color is found on the X chromosome.

Using Barr body detection to verify female gender in athletes, however, raised more issues than it solved. Barr bodies, although normally present in only female cells, can also be found in males with Klinefelter’s syndrome, who have an XXY sex karyotype. Using Barr body detection, alone, would have qualified these males to compete as females in the Olympics.

1) Ritchie R, Reynard J, Lewis T. Intersex and the Olympic Games. J R Soc Med. 2008 Aug;101(8):395-9. PubMed PMID: 18687862; PubMed Central PMCID: PMC2500237.

Maybe all Asians DO look alike?

The combination of Twitter, sports, and race generally makes for some cringe-worthy moments. Take for example, comments about Jeremy Lin made by Floyd Mayweather or the racist aftermath of Joel Ward’s winning goal that eliminated (my beloved) Boston Bruins. Unfortunately, this year’s Olympics was no exception:

Switzerland Olympic footballer expelled for alleged Twitter racism

Greece expels Olympic athlete over racist tweets

Japan’s Olympic soccer loss brings out the Twitter racism

North Korean Women’s National Soccer Team

One particular episode of Twitteracism during the Olympics that caught my attention was when some really observant people tweeted about how all the women on the North Korean National Soccer team had “the same face.” The old “you all look alike” stereotype is familiar to many Asians, and this made me consider if there were an ounce of truth to it. Maybe Asians are more homogeneous with respect to their physical features than other races/ethnicities. Admittedly, when I saw the North Korean team photo, even to my discriminating Asian eyes, I thought they all looked uncannily alike (you know, except for the one in orange). But, then again, so did the women on the Swedish team:

Sweden women’s national soccer team

The inability to distinguish, or discriminate, individuals of another race/ethnicity is a well-documented phenomenon called the “cross-race” or “other-race” effect. Current explanations for why the cross-race effect exists lie largely outside of my specialty and in the realm of sociology and evolutionary psychology. It’s often related to a concept known as in-group advantage or bias, where individuals within a group (in this case race or ethnicity) are viewed favorably over individuals from outside the group.

It is known that the cross-race effect is a general phenomenon observed in all races. That is to say that whites have just as much difficulty identifying Asians from other Asians, as Asians do in distinguishing whites from other whites. To help explain this, it has been suggested that certain races/ethnicities use different standards for discrimination. For example, one group might place more weight on hair color and eye color, whereas another group will rely more on shapes of facial features. Furthermore, psychologists recently identified a potential neurological basis for the cross-race effect. In a study published in PNAS, the researchers found that when study participants were shown “faces of people of a different race to their own, their neurons responded as if they were the same person, whether they were or not. The results were the same whether Caucasian volunteers were looking at East Asian faces or vice versa.” These findings that the cross-race effect is a phenomenon common to all races argue against my initial instinct that the effect could be simply explained by racial differences in the variability of physical features.

Let me be clear here, that the cross-race effect exists doesn’t absolve people of the racist crap they pull. Having difficulty distinguishing Asians in a group is one thing, but calling them all shemales is just offensive. And for the record, starting a statement with the “I’m not being racist, but” disclaimer immediately signals that whatever follows the “but” is going to be racist. Denying individuality to people of other races only contributes to racism. Not to mention that cross-race effects introduce bias in eyewitness testimonies that can lead to wrongful incarceration of people like Ronald Cotton, who was convicted of rape but was later exonerated by DNA tests. Lastly, as Bruce Reyes-Chow writes, “Sure, everyone is mistaken for someone at some point in time, but I simply do not think this happens to white folks as much as it does for people of color.” I suppose that explains why there were no tweets about the Swedish women’s soccer team.

The taboo of race and genetics in sports.

Ever wonder why it seems that East African runners dominate long distance races while runners of West African descent are the kings of sprinting? Jon Entine, writer of Taboo, argues that it mainly comes down to the genetic makeup of these two distinct populations that churn out elite, albeit different style, runners. This is not a new idea, in fact his articles in The Daily Beast and Forbes seem to be rehashes of his earlier writing. But this provocative idea, which invariably touches “the third rail of race,” will surely ruffle some feathers (for proof, see the comments section for each article).

Kenyan long distance runners

At the heart of his argument is that East Africans and West Africans have different physical packages that are favorable for particular styles of running. He then infers that the physical characteristics specific to each population are genetic, heritable traits. In The Daily Beast he writes, “Kenyans simply don’t seem to have the genetic package to make them world-class sprinters. But East Africans do tend to excel at long-distance running, and many suggest that’s due to an increased natural lung capacity and a preponderance of slow-twitch muscles.” That both populations are black, he would argue, are correlative coincidences–their black skin is indicative of shared ancestry but their success in different styles of running represents their genetic divergence. The fact that both populations are black and that they are the focus of his argument, however, cannot be escaped. (Although, later in the article he does discuss the traits that might lend specific athletic advantages to whites and Asians). Understandably, his arguments can appear like justifications for existing stereotypes, such as the stereotype of the naturally superior, black athlete or the slavery-bred black athlete, dressed up in genetics and science. The nuance of his premise is further muddled when he has to rely on racially-charged descriptors such as black and white.

Entine runs into a bit of scientific trouble as well. He cites little genetic evidence in support of his argument and, in fact, concedes the paucity of data. Instead, to bolster his claim, he points to the genetics of skin color–an analogy that is tenuous at best. “Do we yet know the specific genes that contribute to on-the-field success? No, but that’s not an argument against the powerful role of genetics in sports. We do not yet know all the factors that determine skin color, but we know that genetics determines it.” Except, we know a lot about the genetics of skin color, enough to safely conclude that genetics is a main determinant. And while many genes contribute to skin color, the major environmental factor that impacts skin color outcome is sun exposure. When considering athletic ability, however, Entine cites a host of physical characteristics that contribute to success: skeletal structure, muscle fiber types, reflex capabilities, metabolic efficiency, and lung capacity, for each of which it can be assumed is controlled by a whole set of genes. Entine is only able to cite one gene, ACTN3, a variant of which has been dubbed the sprint gene and “is more common in those of West African descent than in Europeans.” But as Dr. Daniel Macarthur, one of the discoverers of ACTN3, explains in his blog, “an excessive emphasis on ACTN3 as a major explanation for Jamaican success does a grave disservice to the complex interplay of genetic and environmental factors required for top-level athletic performance.” This is a notion that is seconded by evolutionary biologist Dr. Joseph Graves in an interview with PBS, “all of those genetic factors have to be tempered in terms of the environment in which individuals train.” So, in the absence of such genetic data, what Entine has is a collection of observations and only a hypothesis to explain them.

Usain Bolt
Usain Bolt

But would it be surprising if, in the end, geneticists did “link human performance, including sports skills, to our DNA and more specifically to our ancestral roots—populations?” Not to me, and probably not for most geneticists. I might not have put it in such certain terms as Entine did, preferring instead, Steven Ross’s measured, hedging-his-bets quote, “There are…probably genetic as well as environmental reasons why Ethiopians make good marathon runners whereas Nigerians on the whole do not” [emphasis mine]. The problem again is not whether science will find the population genetics that underpin athletic skill, but the blurred line between what is meant by population and race (read the PBS interview of Dr. Graves for a discussion on this topic). At the end of Entine’s piece, he declares, “There’s no need to make consideration of race in sports a taboo.” But what I really think he means is that we shouldn’t let the social construct of race stop us from having a discussion of how the genetics of populations, which are genetically divergent or geographically-confined groups, might give individuals of that population a “leg up” in certain types of athletic competitions. The focus shouldn’t be that East and West Africans are black, but that their geographic separation might point to real genetic differences that account for their differing athletic skill sets. This discussion might be made easier, or be bolstered, if there were also such stark examples in “white” populations or in “Asian” populations.

Lastly, Entine does a fairly inadequate job of framing the taboo of race in sports: ‘every defeat encouraged simplistic, racist beliefs that blacks were an inferior “race,” too frail to handle extreme physical challenges and not smart enough to plan a race strategy. Even winning didn’t shatter the stereotype; racist whites just created a new one… black athletes succeed because of their “natural” athleticism.’ Although he points out the stereotypes that surround black athletes, he does little to explain why it’s taboo. Perhaps that’s because he’s written a book on the topic–which he amusingly plugs several times in the comments section (disclaimer: I have not read it). 

Compare that to Max Fisher’s treatment of the subject in the Atlantic:

Talking about the greatness of African athletes can be fraught in the Western world. Generations of American slavery were justified in part by arguments that Africans were “specialized” for physical labor, and whites for mental work, ideas that have persisted in American paternalism and racism through today. For a white writer like myself (or a white researcher or a white anthropologist) to talk about the physical attributes of black men and women can echo some of the worst moments in modern history. And there is something distasteful about reducing Africans to the prowess of their best athletes. After all, Kenya’s contributions to the world include, for example, great writers,environmentalists, and politicians.

It’s hard to talk about the subject without revealing some bias, or giving the impression of trying to explain away their success, or hitting on some still-fresh cultural wound from centuries of exploitation. This may be why definitive answers seem so hard to find, and why we tend to embrace theories that downplay legitimate biological distinctions and emphasize the idea that Kenyans simply work harder. But this kind of thinking, though clearly well intentioned, is a kind of condescension in itself. We’re so afraid of reducing Africans to their physical attributes that we’ve ended up reducing them to an outdated stereotype: Cool Runnings, the barefoot village boy who overcame.

Without properly discussing why it’s taboo, I imagine that Entine does little to engender his view with black readers. And if he’s unable to do that, then how does he expect to remove the taboo of discussing race from sports?

Related Reading:

Gender Verification at the 2012 Olympics: New IOC Regulations for Female Athletes

Sports, race, and the taboo…

The problem with gender verification in the Olympics.

At the London 2012 Olympics Opening Ceremony, Caster Semenya had the honor of carrying South Africa’s flag. This week, she makes her Olympic debut (qualifier preliminary heat spoiler alert) representing her country in the 800m and 1500m events. This is in stark contrast to 3 years ago, when Semenya was banned from competition by the IAAF after cruising her way to gold in the 800m at the World Athletic Championships in Berlin. Combined with her physical appearance, Semenya’s dominating performance came at a price, fueling speculations that she was not, in fact, a woman. After her victory, Semenya was barred from competing until her gender was verified by genetic testing. As you will see, this can be subjective and unreliable (You can try for yourself using the HHMI’s biointeractive gender test).

Humans have two sex chromosomes designated as X and Y chromosomes. Females have two X chromosomes (XX) while males have one X and one Y chromosome (XY). One of the major factors that initiates male sex determination is a protein called Testis-determining factor, which is encoded by the SRY (Sex-determining region Y) gene normally found only on the Y chromosome. So, at first glance it would appear that a simple sex chromosome test would suffice to verify sex. 

In humans, females have two X chromosomes and males have one X and one Y chromosome. The Sex-determining region Y (SRY) gene drives male sex determination and is found on the Y chromosome.

However, the  line delineating sex is not so rigid– disorders of sex development (DSD) can complicate reconciling genetics with gender and sex. For instance, in Swyer syndrome, individuals appear outwardly female and have a normal uterus and Fallopian tubes, despite having the  male sex chromosome karyotype (number and appearance of chromosomes in the cell): XY. This condition arises when the SRY gene on the Y chromosome has either been lost or mutated and, as a result, male sex determination cannot be initiated. Instead, these individuals develop physically as females. 

Male sex determination cannot be initiated because the SRY gene is either mutated or lost.

On the other hand, an individual with an XX karyotype can develop as male is if one of the X (X*) chromosomes abnormally carries the SRY gene. The SRY gene can find its way from the Y to the X chromosome through chromosomal crossover, a phenomenon where corresponding chromosomes exchange parts with each other to generate new, unique chromosomes. This usually occurs during meiosis, a specialized form of cell division that gives rise to either sperm or egg. Crossovers ensure that different combinations of paternal genes are packaged into sperm and different combinations of maternal genes are packaged into eggs. This recombination of chromosomes is the reason why we look different from our siblings (exception: identical twins) and is generally good because it increases genetic diversity.

Recombination between the X and Y chromosomes normally occurs only at the tips of the chromosomes, beyond the region that encompasses the SRY gene. However, sometimes recombination can go awry and crossing over occurs such that the SRY gene is moved to the X chromosome. Since the SRY gene is located on the Y chromosome, the abnormal recombination event that results in an X* chromosome must occur in the father of an XX individual. The presence of the SRY gene, even in the absence of a Y chromosome, is sufficient to initiate male sex determination.

Abnormal recombination in the father of XX males, results in an X chromosome that carries the SRY gene (designated X*). Reproduction involving sperm that carry the X* results in XX* males since the presence of the SRY gene, even in the absence of a Y chromosome, can initiate male sex determination.

Given the importance of the SRY gene in male sex determination, one might expect a test that detected the presence of SRY would be adequate to verify gender. But even this test has it’s problems. For one, the test is subject to false positives since it can detect the presence of a mutated, non-functional SRY gene. There are also conditions which can override male development, even when the SRY gene is present. Such was the case for “8 of 3,387 female athletes” who tested positive for the SRY gene, but were allowed to compete at the 1996 Atlanta Olympics. In addition to carrying SRY, these 8 athletes also had a condition known as androgen insensitivity syndrome (AIS), which rendered them insensitive to the effects of male hormones such as testosterone.

Now, the International Olympics Committee (IOC) is pivoting away from gender verification to what they consider testing female “eligibility” by measuring levels of naturally occurring testosterone, a hormone classically associated with masculinity. This is not to be confused with tests that detect synthetic testosterone used for dopingUnder the IOC’s new rules, “women with levels of testosterone that reach a man’s [emphasis mine] normal level will be barred from competing with other women if it is found that the athlete’s body is responsive to androgens.” Still sounds like a gender verification test to me.


Unfortunately, testosterone is also an unreliable standard. For one, some women have abnormally high levels of testosterone, a condition known as hyperandrogenism. Secondly, as Rebeeca Jordan-Young and Katrina Karkazis write in the New York Times, “Testosterone is one of the most slippery markers that sports authorities have come up with yet. Yes, average testosterone levels are markedly different for men and women. But levels vary widely depending on time of day, time of life, social status and — crucially — one’s history of athletic training. Moreover, cellular responses range so widely that testosterone level alone is meaningless.” It’s also unclear whether higher levels of testosterone is a key factor in athleticism in women. Lastly, androgen insensitivity syndrome (AIS), or the inability to respond to male hormones such as testosterone, is overrepresented in women athletes. 

Testosterone testing, and gender verification in general, also reeks of sexism and discrimination, reinforcing not only perceptions of what a women should look like but also placing limits on what women can physically achieve**. Jesse Ellison of the Daily Beast writes,

“It all highlights a cruel injustice: the policy—and the testing, treatment, and humiliation that can come with it—only applies to female athletes. Men who excel at, say, ice dancing or synchronized swimming, where success has more to do with grace and rhythm than brute strength or speed, simply aren’t questioned in the same way women are. In 2010, after two French-Canadian sports commentators snickered over the flamboyant skating champion Johnny Weir and suggested that he should compete with the women, they were immediately and vociferously condemned for what was widely perceived as homophobic, despicable language. (This was, keep in mind, precisely the moment that Semenya was living in virtual exile after the subject of her gender had made international news.) Similarly, there is no upper—or lower, for that matter—limit to the amount of testosterone their bodies naturally produce.”

All of which raises the question: If the IOC feels that high levels of natural testosterone offer an unfair advantage, then will they apply an eligibility policy to men as well?

China’s Ye Shiwen after winning gold in the women’s 200 IM.
Photo by Adam Pretty/Getty Images

Note: On the use of gender, Wood and Stanton: “Unfortunately, ‘gender verification’ is a misnomer that confuses the distinction between sex and gender. Sex is a biologic definition that distinguishes male and female; gender is the sense of one’s own self as a man or woman.”

** While the speculations surrounding Chinese Olympic swimmer, Ye Shiwen, is the suspicion of doping and not gender, it should be noted that it has been framed within the context of gender since in the “final 50 meters of the IM’s freestyle leg, she swam faster than Ryan Lochte did in that portion of his gold-medal-winning 400-meter IM.”

1) Eggers S, Sinclair A. Mammalian sex determination—insights from humans and mice. Chromosome Res. 2012 Jan;20(1):215-38. Review. PubMed PMID: 22290220; PubMed Central PMCID: PMC3279640.

2) Wood RI, Stanton SJ. Testosterone and sport: current perspectives. Horm Behav.2012 Jan;61(1):147-55. Epub 2011 Oct 1. Review. PubMed PMID: 21983229; PubMed Central PMCID: PMC3264812.

Related Reading:

Olympic inequality: Studies show Olympics commentary differs based on gender, race and nationality

Sex Hormones! The Chemistry Behind Testosterone Doping


by Viet Le