This article is an excerpt from the Shortform book guide to "The Sports Gene" by David Epstein. Shortform has the world's best summaries and analyses of books you should be reading.
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What is the SRY gene? What role does the SRY gene play in sports performance?
According to David Epstein, the author of The Sports Gene, no single gene has as much of an impact on an athlete’s performance as the SRY gene found on the Y chromosome. The SRY gene also accounts for the predictable and significant differences in sports performance between men and women.
Learn about the SRY gene’s function and its implications for atheltic ability.
The SRY Gene Explained
What is the SRY gene? The Sex Determining Region Y (SRY) gene accounts for most sexual variation between men and women. It is found on the Y chromosome. (Most women have two X chromosomes, and most men have an X and a Y chromosome.) At six weeks gestation, the SRY gene causes the formation of testicles, which release the testosterone that produces male characteristics in developing fetuses.
(Shortform note: Testosterone is a steroid hormone that is produced in both men and women, although men generally have much higher levels. In men, the testes produce testosterone, and in women, it is produced in the ovaries. In men, testosterone regulates sperm production, sex drive, fat distribution, bone mass, muscle size, and red blood cell production. In women, testosterone impacts sex drive, muscle strength, and bone density.)
Testosterone levels may be one of the most powerful factors in athletic performance. Epstein explains that performance differences between boys and girls are almost non-existent in many sports before puberty. Once boys hit puberty their bodies produce extra testosterone and the athletic gap widens quickly. (This is one reason why it makes sense to have co-ed sports teams for young children). Testosterone has such a defining impact on athletic performance that in 2012 the Olympic Committee decided that an athlete’s sex should be determined by how much testosterone their body is able to use.
- Women typically produce under 75 nanograms of testosterone per deciliter of blood, while men produce between 240 and 1,200 nanograms per deciliter.
- Anecdotes from runners who have transitioned from male to female add compelling evidence of the influence of testosterone levels on performance. A small sample of transitioning runners consistently shared that, while their running times have gotten slower, they have remained equally as competitive against women as they were against men.
- The NCAA mandates that a male athlete who transitions to female must wait for a year while her testosterone levels fall before she can resume competition as a woman.
- One study of elite female athletes showed that across sports, the elite female athletes have twice as much testosterone in their blood as non-elite female athletes.
| Sex-Linked Traits Traits that are produced by genes found only on the X or Y chromosome are called sex-linked traits. Off the field, genes found on one chromosome or another can help explain why some diseases are more common in men than in women. Women have a greater degree of protection from diseases known as X-linked recessive diseases. These diseases are caused by a recessive gene on the X chromosome. Since women have two X chromosomes they can have the recessive version of the gene on one chromosome and the dominant version on the other and be carriers of the disease. Since men only have one X chromosome, if they inherit a disease-causing version of a gene on their X chromosome, they will have the disease. Sex-linked traits also explain why red-green color blindness is more common in men than in women. The gene that causes red-green color blindness is located on the X chromosome. Women can carry one “faulty” gene but still see color normally, but if a man inherits that single “faulty” gene, he will be color blind. |
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Like what you just read? Read the rest of the world's best book summary and analysis of David Epstein's "The Sports Gene" at Shortform .
Here's what you'll find in our full The Sports Gene summary :
- A look at how our genes play a determining role in our success in sports
- Why practice doesn't always guarantee success
- The fortuitous gene pairings that can lead to elite athleticism
