As the national election draws near, observers have commented on every aspect of the candidates' appearance, including raising questions regarding their testosterone (T) levels. One of the more humorous comments circulating is that Sarah Palin, Republican candidate for Vice-President and Governor of Alaska, has more testosterone than any of the other candidates, based on her self-description as a "pit-bull with lipstick," and her attacks on the Democratic ticket. And on Salon.com an article written after the Vice-Presidential debate was titled, "Joe Biden is made of testosterone and strong verbs."
So what is the story with men and testosterone? And for that matter, women and T? Do virility, strength, or aggressiveness really correlate with T levels? Sexuality and sex appeal? Did the fondness of women for the late Paul Newman have anything to do with his T levels, or could it have been his baby blue eyes? And is there any truth to the notion that Sarah Palin, or Hillary Clinton, or any other powerful woman must have higher than normal T levels in order to achieve their success in a man's world?
As is often the case, biological aspects of T and its effects on masculinity have been overly simplified in the press and elsewhere in order to try to explain social behavior. Testosterone is a hormone produced by the testicles that is responsible for development of the male genitalia during fetal life, is the major hormone involved in male puberty, and maintains male appearance (eg, shaving, muscularity). Major changes in T certainly produce easily observable results. Centuries ago, domestic farmers figured out that castration (removing the testicles) caused males to be more docile, less apt to engage in mating behaviors, and sterile.
But what about males of the human species? Do T levels vary much between normal men, and if so, can this translate into behavioral differences?
The answers are yes, and yes.
Blood concentrations of T may vary normally from about 300 ng/dl to 1000 ng/dl, meaning that a man at the upper end of normal may have 3 times the T concentration as another "normal" man with T at the low end of normal. In general, T concentrations decline as we age, with a gentle decline in the total testosterone and a much more rapid decline in bioavailable T. Based on age and population-based statistics alone, Barack Obama at 47 years is likely to have bioavailable T levels that are approximately 33% higher than John McCain at 72 years.
In general, though, variations in T levels within the normal range are not associated with behavioral or medical changes. Once an adequate level of T is achieved, additional T acts primarily as an excess. So, for example, if we take a man with normal T and normal sex drive, raising his T further will not transform him into a howling sex addict. An important exception, however, is the response of muscle to T, since there appears to be no upper limit to the ability of ever-greater T levels to stimulate more rapid muscle growth and strength. Hence the doping scandals in sports related to testosterone and testosterone-like substances.
On the other hand, there are clear changes that happen to men when T levels drop below normal. Testosterone deficiency becomes increasingly common in men as they age, affecting as many as 10-20% of men over the age of 45 years. Symptoms include reduced energy, vigor, and libido, erectile dysfunction, depressed mood, and irritability, and difficulty concentrating. Men with low T may also sustain fractures and lose height due to osteoporosis, and they are at increased risk of developing diabetes. These are important issues for men, and for this reason I believe it is important for men over 40 years to have a baseline T level obtained, whether or not they have symptoms.
Of course, I have no idea what are the T levels of John McCain or Barack Obama. And observers of the debates can make their own determination as to who appeared more vigorous or virile. But the fun story has to do with Sarah Palin. Women, after all, lack a key part of the male anatomy that manufactures testosterone in large amounts, but they do make small amounts via the ovaries. As a rule, though, women have only a small fraction of the T levels seen in men, even T-deficient men. Regardless of what one thinks of her politics, one has to be impressed with Governor Palin's willingness to step into the national spotlight and mix it up with the big boys. Which leads to this biologically and politically incorrect conclusion- The absence of testosterone does not necessarily indicate the absence of "balls."