Heroes, Rogues, & Lovers: Testosterone and Behavior Read Online Free Page A

large numbers of people would volunteer for our studies. Occasionally we did have to reassure them that we were looking only for testosterone, because saliva tests can also indicate whether a person has been using alcohol, tobacco, or drugs.
Using salivary measures, my students and I set up procedures and began collecting data. Over the years we analyzed saliva samples from more than three thousand college students, prison inmates, trial lawyers, athletes, heroes, construction workers, sex offenders, strippers, actors, wrestlers, and various others. We measured people several times each, to examine changes across the day and around important events. We also examined data on blood levels of testosterone from government records of about five thousand military veterans.
People often ask me what a high testosterone score is. When Mike Roseberry said he'd "spit a ten," that meant the concentration oftestosterone in his saliva sample measured ten nanograms (ng) oftestosterone per deciliter (dl) of saliva. That was a high score in his particular assay batch. In our lab, we run assays in batches that range from thirty to fifty samples each. In another lab run, Mike's score might have been a little different, but still high in his particular assay. Radioimmunoassays often take two days to complete, and there is normal analytic variability in every lab that performs them. Variability in results from assay to assay are due to slight differences in chemicals, procedures, and lab personnel. Because of this variation, we include a high control and a low control sample in each assay. The comparison with known values tells us more about the testosterone level of a particular individual than his or her "number." That is why when I describe individuals, I say they are "high," "medium,'' or "low," rather than they scored a "two," "six," or "ten." Scores from blood samples are about a hundred times higher than scores from saliva samples, but the numbers are highly correlated with each other, which means that one measure is as accurate as the other.
Although testosterone is not visible to the naked eye, and there is no single marker to reveal its presence, we learned during the course of

 

Page 8
our research that testosterone is related to traits that are readily observed. For example, high-testosterone men, on average, are leaner, balder, more self-confident, more rambunctious, less likely to have friendly smiles, and more likely to favor tattoos than other men. That is not to say that we can look at a particular individual and know with certainty what his or her testosterone level is. Many characteristics and behaviors that are related to high testosterone levels are also related to social, cultural, and other biological factors. Nevertheless, my students who are familiar with testosterone research can often look at pictures of experimental subjects and tell which subjects are high or low in testosterone. As my students and I become more familiar with what high-and low-testosterone people are like, we get better at predicting which research projects will be productive.
Testosterone is a hormone, and understanding it requires a general understanding of hormones and how they work. Hormones are molecules, tightly bound clusters of atoms, that carry messages from one part of the body to another. Hormone molecules can be small, because all they do is carry simple messages, but they must be numerous enough to spread throughout the body. Each person, man or woman, produces just a few milligrams of testosterone every day, but each milligram contains a million trillion molecules.
Endocrinologists, who study hormones, group hormones into families, in which members of the same family have similar origins and do similar jobs. 7 For example, in the brain there is a family of hormones called endorphins that spreads feelings of pleasure and blocks feelings of pain. Elsewhere in the body there are families of hormones that control growth, metabolism,