Terror-management theory (TMT) postulates that denying personal mortality is a primary human motive (Greenberg, Solomon, & Arndt, 2008). Humans, uniquely among all animals, are intelligent enough to have a sense of self and also to understand that they as agents are certain to eventually stop existing. Thus they create and endorse ideals, philosophies, and social structures that imbue life with symbolic meaning, providing a kind of symbolic immortality. This broad idea is originally due to Ernest Becker, an anthropologist who was inspired by Otto Rank and hence by Freud, but it was first examined experimentally by Jeff Greenberg, Tom Pyszczynski, and Sheldon Solomon.

Basic TMT experiments take the form of making mortality salient to subjects assigned to the experimental group, while making some other topic salient to subjects in the control group. Possible mortality cues include having subjects describe in writing "the emotions that the thought of your own death arouses in you" or subliminally presenting the word "dead". Control cues may prime a totally innocuous concept, such as television, or an aversive but nonlethal concept, such as dental pain or flunking a test. Then the researchers measure subjects' adherence to or defensiveness about supposedly death-denying constructs, such as social groups or religions. Sure enough, mortality salience makes people more clannish: death-primed Christians view Christians more favorably and Jews more negatively (Greenberg et al., 1990), death-primed whites express more positive attitudes towards white racists (Greenberg, Schimel, Martens, Solomon, & Pyszcznyski, 2001), and death-primed Scots judge the English more negatively (Castano, 2004). An example of a subtler mortality-salience effect is provided by Taylor (2012), who found that mortality salience increased preference for TV shows with themes of law and justice, like Law & Order. Furthermore, among Taylor's death-primed subjects, watching an episode of Law & Order ameliorated a self-enhancing bias observed in subjects who saw no episode or an edited version of the episode in which justice was thwarted. Thus, seeing justice being done seems to comfort death anxiety, and people choose what media to consume accordingly.

So where do sex and the body come in? You would expect that mortality salience could increase defensiveness about sexual norms just as for any other social norm, as in Rosenblatt, Greenberg, Solomon, Pyszczynski, and Lyon (1989), in which death-primed municipal court judges recommended higher bonds for indicted prostitutes. The thing about the body, though, is that it is itself a reminder of mortality. The fact that our minds are so tightly bound to bodies undermines the symbolic immortality we strive for. We may then be threatened not just by illness and injury but also by pleasures of the flesh like food and sex. And the picture is further complicated by how bodies and sex can themselves take on symbolic and therefore terror-management value: think of athletes who strive for an ideal physique, or men who boast of their sexual conquests.

The complex relationship between death and sex in the human mind has been examined primarily by Jamie Goldenberg. To begin with, Study 1 of Goldenberg et al. (1999) found that mortality salience made the "physical aspects" of sex less appealing, in that death-primed subjects gave lower appeal ratings to experiences during sex such as "Having an orgasm" and "Feeling my partner's sweat on my body". Ratings for the "romantic aspects" of sex, like "Blending of selves" and "Expressing love for my partner", were unchanged. Conversely, in Study 2, priming subjects with physical but not romantic aspects increased the accessibility of death (i.e., how readily death-related knowledge was brought to mind), as measured by how subjects filled in word fragments such as "C O F F _ _" that had death-related and non–death-related solutions ("coffin" versus "coffee"). So it appears that we associate sex with death, and this association is what makes sex potentially unsettling. The significance of the romanticization of sex was best demonstrated by Study 3, which showed that additionally priming subjects with the concept of romantic love removes the increase in death accessibility brought about by a sex prime. So romance can act as a means of whitewashing sexuality: as Goldenberg et al. put it (p. 1,176), "Romantic love transforms sex from an animal act to a symbolic human experience, thereby making it a highly meaningful part of one's cultural worldview and obscuring its threatening link to mortality."

A catch of the effects just described is that they were found only in people relatively high in neuroticism, one of the Big Five personality traits. There are plausible theoretical reasons for this, such as neuroticism either causing or being caused by difficulty with terror management. But the plausibility of TMT as an explanation for large-scale features of human society suffers, since we'd expect that low-neuroticism people have a lot of influence on social norms, too. Fortunately, Goldenberg, Cox, Pyszczynski, Greenberg, and Solomon (2002) were able to find a reduction of the appeal of the physical aspects of sex that wasn't influenced by neuroticism, with the help of an additional manipulation: having subjects read an essay that emphasized the similarity of humans to other animals (by saying things like "the boundary between humans and animals is not as great as most people think"). The idea is that maintaining an ideological distinction between humans and animals is another way to defend against the mortality salience of corporeality. When this defense is undermined, even low-neuroticism people can be intimidated by the connection between lust and death.

To extend this thinking to bodily things other than sex, consider Goldenberg et al. (2006). Again, the effects of interest were found only in high-neuroticism people. In Study 2, death-primed subjects spent less time using a foot massager. In Study 1, death-primed subjects lasted for a shorter time in the cold-pressor task, that is, the keeping-your-hand-in-ice-water task, which has a long history of use in experimental psychology as a pain stimulus; in this study, however, subjects "were told that different individuals find the experience 'exhilarating, uncomfortable, pleasurable, or unpleasant.'". The value of this paper is that the dependent measures concern tactile sensations, one pleasurable and one painful, that aren't related to sex and to which few social norms apply.

As an example of how even the physical aspects of sex can manage terror, consider Study 2 of Goldenberg, McCoy, Pyszczynski, Greenberg, and Solomon (2000). Subjects high on a measure of "body esteem" (how positively they viewed their appearance, strength, sensations, etc.) found the physical aspects of sex more appealing after a death prime. (Neuroticism wasn't measured.)

Finally, McCallum and McGlone (2011) examined a perhaps more down-to-earth dependent variable: euphemism. Subjects had to write descriptions of nine photographs, supposedly for another subject who would try to answer questions about each image using only the description. Between subjects, the seventh image was randomly assigned to be a picture of dogs urinating, defecating, or copulating. Death-primed subjects were more likely to describe these actions euphemistically.