Comparisons of the Ejaculatory Response in Men and Animals

Abstract

Observations and experiments relating to the causes and results of ejaculation in male mammals of several species reveal that in a number of different mammals, erection and emission can be mediated by purely spinal mechanisms. In intact males, emission is possible without genital stimulation, and the occurrence of emission is not automatically associated with orgasm in men or with the normal behavior sequelae to ejaculation produced in animals by copulation. These and other similarities between sexual reflexes in primates, carnivores, and rodents are taken to indicate the potential values of a broadly comparative approach to human sexual functions.A FUNDAMENTAL REACTION included in the copulatory behavior of all male mammals is the ejaculatory response which results in delivery of sperm into the female reproductive tract and therefore constitutes an essential link in the behavior chain leading to reproduction and perpetuation of the species. An indispensable element in the total pattern is, of course, the expulsion of seminal fluid comprising secretions from the prostate and seminal vesicles as well as sperm. However, seminal emission normally occurs in conjunction with several other reactions which are equally necessary for insemination of the female. These ancillary responses include penile erec-

The Psychobiology of Consciousness

“…This effect is hypothesized to result from failure of closure of the internal bladder sphincter (Shader, 1972), a necessary part of the sympathetically controlled series of smooth muscle contractions in emission. That loss of arousability is not apparently affected by these drugs in men-or in rats (Beach et al, 1966)-is consistent with the hypothesis of a separate, centripetal neural mechanism for this effect, which need not be disturbed simply because the path of semen expulsion has been misdirected by a peripheral mechanism. Beach et al (1966) related several such situations in men to observations of animals where seminal emission is separated from the behavioral sequelae of ejaculation.…”

“…That loss of arousability is not apparently affected by these drugs in men-or in rats (Beach et al, 1966)-is consistent with the hypothesis of a separate, centripetal neural mechanism for this effect, which need not be disturbed simply because the path of semen expulsion has been misdirected by a peripheral mechanism. Beach et al (1966) related several such situations in men to observations of animals where seminal emission is separated from the behavioral sequelae of ejaculation. They commented (p. 759) that "the simple discharge of seminal fluid does not, in and of itself, account for all of the behavioral changes which normally follow an ejaculation resulting from genital stimulation."…”

Spontaneous Ejaculation in a Wild Indo-Pacific Bottlenose Dolphin (Tursiops aduncus)

“…Spontaneous ejaculation, which is defined as the release of seminal fluids in the absence of apparent sexual stimulation, has been reported in several male land mammals, including Rodentia (rats [1], hamsters [2], guinea pigs [3], mice [4]), Cetartiodactyla (mountain sheep, warthogs (reviewed in [5]), tsessebes [6]), Carnivora (domestic cats [7], spotted hyenas (reviewed in [5])), Perissodactyla (horses [8]), and Primates (chimpanzees [9], (reviewed in [10]), humans (reviewed in [11])). Spontaneous ejaculation could possibly be widespread in various animals, including humans, but has passed unrecognized because it is an unpredictable and rare behavior that lasts only a few seconds, making it difficult to observe.…”

“…Three (not mutually exclusive) possible “functions” of animal spontaneous ejaculation have been discussed in previous publications: (1) a type of “masturbation” as a sexual outlet and/or for the removal of surplus (or abnormal) spermatozoa [5], [10], [12]–[16]; (2) an element of sexual display [6]; (3) no clear function, or misuse of inhibitory neural control system during drowsiness and sleep [8], [11], [17]–[20].…”

Plug fate in the copulatory behavior of rats

“…The discovery that spontaneously emitted plugs could be recovered beneath wire-mesh cages if rats were muzzled or girdled led to much interest in the fate of such plugs. It was found that, unless restrained from doing so, male rats consume most spontaneously emitted plugs (Orbach, 1961;Beach, Westbrook, & Clemens, 1966;Orbach, Miller, Billimoria, & Solhkhah, 1967).…”