Sexual interaction, potentially leading to sperm deposit, is impossible at a distance. Two or more individuals need to be in close proximity before sperm transfer can occur. The establishment of the required proximity must inevitably precede the activation of copulatory behavior. The ways in which humans and other animals succeed in establishing this proximity is extremely variable. In fact, it is safe to propose that proximity is established by a series of entirely arbitrary behaviors as already pointed out in the previous section. Whereas copulatory behavior is very stereotyped in all mammals, with the exception of the human, behaviors leading to proximity are extremely varied. They are determined by an interplay between the specific context and individual experience. The importance of proximity as a requisite for copulation cannot be overestimated. For many animals, and perhaps particularly for the human, copulation is a far lesser problem than finding with whom to copulate. Despite this rather obvious fact, the stereotyped copulatory behavior has attracted (more…)

I will present the fundamental elements of sexual behavior in reverse order. First we will examine copulatory behavior, the series of reflexes or fixed action patterns that usually are activated or executed in association with sperm deposit in the female’s vagina or uterus. Please note that this statement refers to copulatory behaviors in non-human mammals. We have already learned that human sexual interactions do not necessarily end in intravaginal sperm deposit. We have also, at least implicitly, noted that human sexual behaviors are far less stereotyped than those found in other mammals. The discussion beginning here and continuing over the next several pages refers, consequently, mainly to non-human copulatory behavior. In fact, due to the rather important difference between human and non-human copulatory activities with regard to variability and flexibility of behavior patterns, I have found it convenient to analyze human behavior in a separate section.

In the male mammal, the reflexes or fixed action patterns executed during copulation ultimately lead to vaginal (more…)

Sexual motivation is not activated by endogenous events but by an external stimulus. This is not the whole story, though. The external stimulus must initiate some processes within the central nervous system and these internal processes must sooner or later translate themselves into observable behavior, which means activity in skeletal muscles. This overt activity may or may not be associated with responses in the autonomous nervous system. In order to understand the mechanisms of motivation, it is essential to have some basic knowledge of the interactions between certain kinds of stimuli, central nervous activities and behavior. To that end, the incentive motivation theory elaborated by Dalbir Bindra (Bindra, 1969, 1974, 1976, 1978) is most useful. I will start this article with an introduction to that theory.

Environmental stimuli can be divided into three classes. Those that have no effect on an organism’s behavior are neutral. The vast majority of stimuli belong to this class. Some stimuli may activate approach behaviors and (more…)

Sex is normally included on the list of primary needs or drives. Likewise, sex is frequently considered a primary reward and reinforcer. However, it is not evident that sex should be lumped together with food, drink, need for oxygen, adequate temperature, defecation, micturition and avoidance of pain. The lack of food or drink for a prolonged period of time eventually becomes incompatible with the survival of the organism. An organismic need is being built up and the individual will feel clear manifestations of the need in the form of a sensation of hunger or thirst. This sensation of need is called the drive stimulus in Hullian theory (Hull, 1943) and simply motivation in many other contexts. Afundamental feature of this motivation is that it increases with increasing deprivation. It is generally so that the amount eaten or the latency to start eating are directly and inversely, respectively, related to the length of deprivation and hence to the intensity of motivation. After a very long deprivation, the individual is weakened because of the organismic need and the motivation may fail to manifest (more…)

Most of those interested in human sexual behavior realize that biological mechanisms are important. At the same time, it is accepted that the expression of sexual activities is socially rather than biologically determined. This applies to the choice of partner, to the place and time chosen for the performance of sexual behaviors, as well as for the specific behaviors displayed. Considering that procreation for a long time has been regarded as the only legitimate reason for engaging in sexual behaviors, it becomes immediately evident that the only socially acceptable sexual activity is penile–vaginal intercourse. Any other activity leading to genitally induced positive affect is sinful, anti-natural, asocial and possibly also criminal. Such activities include masturbation (solitary or mutual), fellatio, cunnilingus, anal sex, and whatever other way the human mind can figure out for obtaining sexual reward. Sex between individuals of the same sex can never lead to procreation and is, therefore, by definition sinful, anti-natural, asocial and frequently also criminal. (more…)