Frank A. Beach

Sexual attractivity, proceptivity, and receptivity in female mammals

Abstract Special definitions are proposed for three concepts representing characteristics of female mammals when they are in estrus. Attractivity refers to the females stimulus value in evoking sexual responses by the male. Proceptivity connotes various reactions by the female toward the male which constitute her assumption of initiative in establishing or maintaining sexual interaction. Receptivity is defined in terms of female responses necessary and sufficient for the males success in achieving intravaginal ejaculation. Attempts are made to measure each variable in the S-R paradigm and to identify the causal agents determining each aspect of the estrous females behavioral characteristics.

Sexual exhaustion and recovery in the male rat

Twelve male rats were left with receptive females and allowed to copulate and ejaculate until they reached a criterion of “sexual exhaustion” They were then retested after 1, 3, 6 and 15 days of sexual inactivity. Following these observations males were tested once each day or once every other day and allowed to achieve a single ejaculation. In the course of a period of unlimited access to the receptive female males usually need approximately 10 intromissions to produce the initial ejaculation, but successive ejaculations are produced by fewer and fewer intromissions. The time to recover from the effects of an ejaculation increases progressively as exhaustion is approached. Very few animals copulate when tested 24 hours after sexual exhaustion. Considerably more recovery is evident in tests conducted after a 3-day rest, but it is not complete and rats are not capable of achieving as many ejaculations as they tend to achieve after longer periods of inactivity. As measured by ejaculation-frequency, the curve of sexual recovery is negatively accelerated and probably reaches asymptote after 7 to 10 days of rest. Various other measures in addition to ejaculation-frequency support this conclusion. Males allowed to ejaculate once each day or every other day are somewhat less responsive than fully rested animals, but do not show any progressive loss in sexual excitability or capacity. A working hypothesis is proposed to explain most of the findings. It postulates the existence of an Arousal Mechanism which is distinct from a Copulatory Mechanism. The ways in which these hypothetical mechanisms are affected by sexual performance and sexual rest arc discussed.

Importance of Progesterone to Induction of Sexual Receptivity in Spayed Female Rats.

Young and his co-workers1-3 have reported that although estrogen may induce heat behavior in spayed female rats, the administration of progesterone to estrogen-treated animals markedly increases sexual receptivity. Ball 4 , 5 was unable to confirm these results. She was of the opinion that her failure may have been due to peculiarities in the strain of rats used. In all of the studies listed the behavior of females has been recorded as nonreceptive, slightly receptive or receptive. In the course of a longer experiment we have collected some data which tend to resolve some of the differences between the findings of Ball and those of Young and his co-workers. Further, our results include complete and sensitive records of different degrees of receptivity in treated females. Procedure. Virgin female rats were raised in segregation and ovariectomized at 3 or 4 months of age. Hormone injections and mating tests were initiated approximately 3 weeks after castration. The effects of 3 types of injections upon sexual receptivity were tested. Seven spayed females were injected with 500 R.U. of estrogen∗ and tested for sexual receptivity 66-68 hr later. Eight days after the first estrogen treatment the same 7 animals were injected with 500 R.U. of estrogen followed 48 hr later by 0.5 mg of progesterone.† Sex tests were conducted 16-18 hr after the progesterone treatment. The second injection schedule was repeated 3 times at weekintervals, and mating tests were carried out in each instance. Six spayed females were injected with 100 R.U. of estrogen followed 48 hr later by 0.5 mg of progesterone, Sex tests were conducted 16-18 hr after the progesterone injection. jection. Two weeks later these same 6 females were injected with 500 R.U. of estrogen followed 48 hr later by 1 mg of progesterone, and mating tests occurred 16-18 hr after the injection of progesterone. After

Studies of Maternal Retrieving in Rats. Iii. Sensory Cues Involved in the Lactating Female's Response To Her Young 1)

Twenty-six lactating female rats were observed in a series of tests designed to identify the sensory cues involved in the retrieving of young to the nest. In some instances females were surgically deprived of one or more sensory receptors. In other cases the females were unoperated and the sensory qualities of the young were modified. The types of desensitization employed were enucleation of the eyes, cauterization of the olfactory bulbs, and transection of the sensory nerves serving the anterior portion of the head, including the snout and lips. Modification of sensory qualities of the young was achieved in different instances by spraying living young with oil of lavender, coating young with vasoline or collodion, killing the young just before the test by separation of the brain and spinal cord, and chilling freshly killed young in a refrigerator. In some tests living young were enclosed in glass vials so that they were visually accessible to the female but could not be smelled or touched. In other tests normal young were confined inside a small, wire-mesh cage so that the female could smell them but could not establish physical contact. In addition to normal or artificially modified young, other retrievable objects were offered to the experimental females. These included young mice and rabbits, and pieces of fresh meat cut to the size of a newborn rat. The results of these various procedures led to the conclusion that the retrieving response is ordinarily governed by a combination of sensory cues. When they are available, visual, chemical, tactile and thermal sensations all contribute to the females tendency to approach, pick up and retrieve her offspring. No single type of sensation is indispensable. It appears that the females retrieving behavior, like the sexual behavior of the male rat or like the maze-learning performance of both sexes, normally involves multisensory controls. This finding is believed to be related to the fact that the cerebral cortex plays an important role in the males copulatory behavior, the females maternal performance and in maze learning. It is probably the intervention of a cortical component which makes the rats maternal behavior different from analogous reactions in lower vertebrates. In the latter, much of the reproductive activity seems to be controlled by relatively simple, unisensory forms of stimulation. This could be due to the fact that in these lower forms a higher nervous mechanism such as the cortex is lacking.

Studies of Maternal Retrieving in Rats I: Recognition of Young

Many naturalistic reports indicate that lactating females of many mammalian species are capable of discriminating between their own offspring and other young of the same age. “Recognition behavior” of this sort has been reported to occur in the Alaskan fur seal (Bonnot, 1929; Preble, 1923), elephant seals (Hamilton, 1934), domestic sheep (Fraser, 1937; Scott, 1945), Dall sheep of Mt. McKinley (Murie, 1944), red deer of Scotland (Darling, 1937), American elk (Altmann, 1926), and mule deer (Linsdale and Tomich, 1953). The most extensive investigation of maternal behavior in the laboratory rat lead Wiesner and Sheard (1933) to conclude that similar discrimination does not occur in this species. In studies of maternal activity in the rat ( Rattus norvegicus ), the senior author became convinced that some female rats do react selectively to their own young. The present study was conducted to determine whether or not discrimination does occur, and to discover if possible the nature of the cues involved. This study is part of a larger investigation conducted in the Department of Animal Behavior at the American Museum of Natural History and supported by a grant from the Committee for Research in Problems of Sex, National Research Council. Subjects and methods .—Ten primiparous and six multiparous female rats of a strain derived from Wistar stock served as experimental subjects. No differences were found between the maternal reaction of multiparous and primiparous individuals, and the results of their tests have therefore been combined. Approximately five days prepartum each pregnant female was placed in an observation cage …

Hormonal modification of sexually dimorphic behavior

Abstract 1. Female animals exposed to stimulation by testosterone in utero or very soon after birth may exhibit changes in adult mating behavior which are indicative of two independent types of modification. One is defeminization, and another quite different one is masculinization. The behavioral modifications are believed to represent changes in separate neural mechanisms, either of which can be altered without changing the other. The implication is, of course, that the CNS is originally bisexual with respect to its behavioral potential. 2. Independent changes which can be produced in males by eliminating the effects of endogenous testosterone during early development are demasculinization and/or defeminization. Here again, separate neural mechanisms are postulated. 3. In rodents and carnivores there are at least two types of behavior which are normally dimorphic in adulthood and are subject to modification by manipulation of androgenic stimulation during very early development. One type, represented by mating behavior, depends heavily upon concurrent hormonal stimulation in adulthood during the time it is being manifested. The other, represented by urination behavior in female dogs, is hormonally modifiable in utero but independent of gonadal hormones in adulthood. Female dogs genitally masculinized by testosterone pre- and neonatally exhibit male mounting responses as adults but only if they are injected with testosterone propionate before and during the time of testing. The same females display the male urination pattern as adults, but this behavior occurs without any concurrent androgenic stimulation and is in fact unaffected by testosterone injections. It would appear that certain sex differences in behavior which normally appear at the time of puberty are dependent upon both prenatal and pubertal hormonal action, whereas other differences may depend only upon hormonal action during development and emerge at the normal age of puberty without any additional endocrine facilitation.

Effects of gonadal hormones on urinary behavior in dogs

Abstract The effects of testicular and ovarian hormones on urinary frequency and posture were studied in 8 groups of dogs. Three of the 4 female groups had been exposed to androgenic stimulation in utero, neonatally, or both in utero and in infancy. The fourth group of females consisted of ovariectomized controls. Males were intact or castrated as adults, as juveniles, or as neonates. Frequency of urination was increased in all groups by estrogen and by testosterone. Urinary posture was unaffected in males by castration in the adult or juvenile stages. Neonatal castration of males resulted in periodic regression from the adult male posture to the immature male posture. Control and prenatally androgenized females urinated in the feminine position. Females treated with large amounts of testosterone in infancy showed a limited degree of masculinization of urinary posture. Females exposed to testosterone before and immediately after birth urinated as females about 50% of the time and as adult males for approximately half of their urinations. Exogenous estrogen or androgen administered in adulthood had no effect on posture assumed for urination.

Human sexuality and evolution.

My first experiment on reproductive behavior was published in 1937, and since that time most of my research has dealt with the neural, hormonal, and experiential control of sexual activity in various species of birds and mammals. In the course of nearly four decades I have authored, coauthored, or edited three books dealing with sexual behavior. Two years ago I decided to capitalize upon my experience as an experimentalist and author by teaching a new undergraduate course entitled “Human Sexuality.” The result was very nearly a total disaster.

Coital behavior in dogs. X. Effects of androgenic stimulation during development on feminine mating responses in females and males

Abstract Female beagles were exposed to androgenic stimulation prenatally, neonatally, or both. A fourth group was ovariohysterectomized in adulthood and never given androgen. Male beagles were castrated at birth, just before puberty, or in adulthood. All males and females were injected with estrogen and progesterone during maturity and tested with experienced stud males for the display of sexually receptive behavior. Females spayed as adults exhibited the most complete and intense mating responses and were the most stimulating to stud males. Females exposed to androgen before but not after birth ranked second in both of these respects. Females treated with androgen during infancy were much less receptive than those treated prenatally but exhibited some responsiveness to ovarian hormones. Females receiving androgen both pre- and postnatally did not differ from males castrated in adulthood. Neither group showed any clear-cut behavioral response to estrogen and progesterone. Neonatally and prepuberally castrated males were noticeably influenced by the hormones on some behavioral measures, with the former group being somewhat more responsive than the latter.

Coital behaviour in dogs. I. Preferential mating in the bitch

Abstract Five male and five female beagles were raised together from puppyhood in a large field and were tested for copulatory behaviour when the females came into oestrus. Mating tests were repeated 8 to 13 months later during a second oestrous period. Females exhibited clear-cut preferences for particular males as sexual partners. Feminine rejection behaviour ranged from simple avoidance to active attack. Some females were more selective than others, but all showed discriminatory responses. Some males were rarely rejected by any bitch, whereas others were generally unpopular. It is suggested that any concept of sexual receptivity as an endogenously controlled condition leading to indiscriminated acceptance of all conspecific masculine partners must be evaluated separately for each species. The absence of preferential responsiveness on the part of the females should not be assumed a priori. Its existence or nonexistence can be established only by direct investigation.