Experimental homosexual behavior in male albino rats

Abstract

Summary 1. A method for giving rats electric shocks in an apparatus the entire floor of which is made of wires, is described. 2. In order to see if male rats given a shock each time they tried to mate with a female, would attempt to copulate with an introduced male, there has during 351 separate tests been administered a total number of 986 shocks. 3. A total number of 740 attempts at coitus with another male has been recorded. Among the 62 animals tested, 27 showed behavior definitely homosexual in character (from 19 to 55 attempts at coitus with another male in the 2nd, 3rd and 4th series of tests, from 4 to 9 in the first). 3 of these 27 animals achieved ejaculation on the back of the other male. Eleven males displayed behavior which cannot be regarded as unmistakably homo- sexual — while 24 animals had below 4 attempts (in the first series below 2 attempts) at coitus with another male. As a male must be allowed to mount another animal a few times in order to ascertain whether the object is a receptive female, none of these 24 animals can be said to have displayed homosexual behavior. 4. Disregarding the 15 males in the 3rd series of tests, which were given no op- portunity to demonstrate their heterosexuality after they had received shocks, 14 of the remaining animals showed exclusively homosexual behavior, 8 exclusively hetero- sexual behavior, 21 both homo and heterosexual behavior and 4 no sexual activity. 5. There were 4 separate series of tests with different experimental procedures. The procedures used in the 2nd and 3rd test series demonstrate that homosexual behavior is less readily provoked in animals with a strong sex drive (receiving many shocks). They strive for a heterosexual relaxation (17) of the drive as long as pos- sible. Successfully defying the inhibition, they finally copulate with the female and achieve ejaculation (2nd test series). The sex drive does therefore not need to seek relaxation through homosexual behavior. But the procedure used in the first series of tests seems to demonstrate that when the inhibition has once been firmly established in animals with a strong drive, they will engage more actively in homosexual behavior than animals with a low sex drive (having received relatively few shocks). Mention is made of experimental investigations to be found elsewhere (15) showing that the strength of the sex drive depends on genetic factors. 6. The great difficulties in drawing conclusions concerning man from experiments with animals are discussed. From a comparative point of view the homosexual behavior in the human being seems to be the result of an interaction of at least two of the following factors: a) strength of sexual drive, hereditarily determined. b) inhibitions (established by the environment) with regard to individuals of the op- posite sex. The psychological factor. c) lack of sufficient opportunity to obtain a relaxation of the sexual need with in- dividuals of the opposite sex, adequate to the individual hereditary demand for such relaxation. The sociological factor. d) hormonal imbalance, of importance first and foremost in those cases in which there is a reversal of the sexual pattern of behavior and whole personality. The imbalance may be hereditarily determined or the result of a disease e. g. tumors in any of the glands of internal secretion. 7. We have in this paper shown experimentally that it is possible to provoke homosexual behavior in the male albino rat by punishing the animal when it tries to copulate with a female. In spite of the fact that receptive females are later present, many males will repeatedly and vigorously try to execute the act of copulation with other males after such a procedure. The biological foundation of the above psychological factor in humans, mentioned under 6 b), has thus been demonstrated. Until more experiments with animals have been performed and more data for humans secured by the taxonomic method (Kinsey), it is difficult to have a justified opinion as to the relative importance of the above factors.