Dabbs studied testosterone levels in men and women in a wide variety of professions. In his investigation of the military, he found that generals had the lowest testosterone levels and combat soldiers the highest. In the heat of a battle, in a life or death situation, acting fast is often more important than thinking about options; one needs to shoot first and (perhaps) think later.

But to win wars on a larger scale -- or better still, to avoid them in the first place -- one needs to be a strategist able to envision both sides when conflicts are looming and to avoid letting situations escalate out of hand. Being low in testosterone helps one to think before reacting, to consider options and to envision outcomes. These skills are impeded by high testosterone and it thus benefits senior strategists in both military and non-military situations to have low, or even castrate levels, of testosterone.

To do their tasks well and to maintain government stability, the eunuchs needed to be both agreeable and conscientious. Although the data are not as statistically significant as on agreeableness, studies on the personality of testosterone-deprived adult males also suggest that lowering testosterone may, in fact, enhance conscientiousness.

As diplomats, eunuchs had to negotiate peace with neighbors to avoid dangerous conflicts. That is what is meant by good diplomacy, which is a product of agreeability and to some extent, a by-product of low testosterone. Diplomatic solutions are hard to achieve when one is high on testosterone and roaring for a fight.

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In the modern world the most empowered negotiator on the planet is the U.S. Secretary of State. It may be more than a coincidence that three of the four most recent individuals to occupy that role have been women: Madeleine Albright; Condoleeza Rice; and Hillary Clinton. These women have filled a post that would have commonly been held by eunuchs in the Byzantine, Ottoman, and Chinese empires.

As secretaries of state, women are now key players in keeping peace on earth at a time when confrontations between Christians and Muslims have been intensifying. Women have thus filled the diplomatic roles that eunuchs filled when the Christian and Islamic worlds -- the Byzantine and Ottoman empires -- first came into conflict centuries ago in what is now the Middle East. Back then, many of the military leaders on both sides were eunuchs.

The similarity between modern women and eunuchs also shows up in data on life expectancy. Men don't live as long as women and the difference in longevity has been linked to testosterone. Recently historians studying court records from Korea have confirmed that eunuchs of the past also lived longer than their male contemporaries of similar socioeconomic status.

Still another way that empowered women appear to be converging on the eunuchs of history relates to reproduction. Before the development of the contraceptive pill, the fertility of women often trapped them in traditional patriarchal families. Empowered women today have far fewer pregnancies than they would have had in the past. The most powerful women in the world -- the top 20 percent on the Forbes' list -- have on average 1.65 children. The collective fertility of Hillary Clinton, Condoleeza Rice, and Madeleine Albright is four children between the three of them; 1.33 kids per person. This is admittedly more children than a eunuch in Constantinople would have had, but it is still below the replacement level of two children per generation.