Understanding Asexuality

Did you know that there are sexual-orientation “tests” in male sheep (rams)? And no, I do not mean measures of genital responding while the rams view pictures of sheep, or even a “drunk test” (see chapter 2). In the United States Sheep Experiment Station in Dubois, Idaho, researchers test the erotic inclinations of their animals by allowing rams to have access to two “stimulus” females (ewes) in estrus or to two “stimulus” rams. These sexual-orientation tests occur in specialized pens, over repeated time periods (e.g., three thirty-minute exposures). The stimulus animals are restrained, so the test rams have easy access to them. The rams’ sexual interest is measured by observing various mating behaviors characteristic of these animals: sniffs, kicks, mounting attempts, and “flehmans” (i.e., head raisings with curling of the upper lip) (Roselli, Larkin, Schrunk, & Stormshak, 2004).

But why would researchers test rams for their erotic inclinations in the first place? They do so to understand and ultimately increase the productivity of rams for sheep farmers, who want, as you might expect, stud rams to produce lots of little lambs.

If the rams are sexually attracted to ewes, they are called FORs (female-oriented rams); if they are attracted to other rams, they are called MORs (male-oriented rams). If they are attracted to neither, they are called NORs (no-oriented rams), or asexuals.

A surprisingly high percentage are MORs, but equally surprising is that a high percentage are evidently NORs (i.e., asexual). For example, here is a quote by researchers Charles Roselli and colleagues in a paper summarizing their results: “Over the past 2 years, 584 rams were tested. Of these 12.5% were asexual, 55.6% mounted and attained ejaculation with ewes, 9.5% mounted other rams, and 22% interacted sexually with both males and females” (Roselli et al., 2004, p. 235).

As in rodents, there does not seem to be strong evidence that sexual variation among the rams is related to circulating testosterone. For example, asexual rams (NORs) do not have lower levels of testosterone than the FORS or the MORs (Perkins, Fitzgerald, & Price, 1992), also suggesting that asexual rams may develop their sexual orientation because of prenatal factors organizing the brain in a certain way.

Rams may be especially relevant to understanding human sexuality; indeed, they provide a better animal comparison to human sexual orientation than male rodents, because rams show similar patterns of sexual behavior to human males. For example, MORs actively pursue other males for sexual liaisons, as do human men sexually interested in other men. Thus, sexual orientation patterns in both species, perhaps including asexuality, may emerge because of similar prenatal mechanisms, such as exposure to prenatal hormones organizing sites of the brain (see chapter 13). Indeed, research suggests that structural differences in a site of the lower brain, the SDN-POA (sexually dimorphic nucleus of the preoptic area) of the hypothalamus, is relevant to ram sexual orientation, just as a similar site is likely relevant to men’s sexual orientation (Roselli, Stormshak, Stellflug, & Resko, 2002; LeVay, 1991). However, the researchers have not as yet examined the brains of NORs to determine if this site is related to asexual rams’ sexual orientation.

A final note on these animal studies: They are interesting and well worth considering as they relate to human asexuality, but recall the caution about animal behavior being an imperfect model of underlying attractions, particularly as they apply to human sexual attractions (see also chapter 2 on the attraction/behavior distinction).

Let’s move from natural history to human history. Many humans throughout history have lived their lives without sex.[12] A reality of human life, from the emergence of human beings to their existence in the present day, is that some people, even when motivated, do not find mates. These people may have had certain traits—very low physical attractiveness, extreme shyness, or other factors—that made finding a partner difficult. So, a lack of (partnered) sexual behavior is sometimes not a matter of choice.