Lee Ellis

Dominance and reproductive success among nonhuman animals: A cross-species comparison

Abstract This paper updates and extends Dewsburys (1982) review of the literature on dominance and reproductive success (RS). The findings from approximately 700 studies are included, over two thirds of which were unavailable to Dewsbury. In order to give a highly condensed and yet meaningful overview, the main findings are represented in four tables, one for male nonprimates, one for female nonprimates, one for male primates, and one for female primates. In the tables for males, findings are analyzed in terms of six different indicators of RS, and in the tables for females, in terms of eight RS indicators. Outside the primate order, evidence largely supported the hypothesis that high-ranking males enjoy greater RS than do subordinate males. For females, studies are more evenly divided between those supporting the hypothesis that high rank and RS are positively correlated and those indicating no significant rank-RS relationship. This may reflect both the lower saliency of hierarchical relationships among females, as well as the lower variability in RS among females, relative to males. Among primates, a complex picture has emerged, especially in the case of males. Much of the complexity appears due to the importance of age and seniority in affecting dominance rank. Also, in some primate species, female preferences for sex partners seem to have little to do with the males dominance rank, at least at the time mating takes place. Nevertheless, the majority of studies suggest that high- to middle-ranking males have at least a slight lifetime reproductive advantage over the lowest ranking males.

Neurohormonal functioning and sexual orientation: A theory of homosexuality–heterosexuality.

Following a historical sketch of attempts to explain homosexuality, we review evidence indicating that the process of determining human sexual orientation is fundamentally the same in all mammals. In this process, four phenotypic dimensions of sexuality develop from two more or less distinct sex genotypes. Studies are reviewed that indicate how phenotypic deviations from these two genotypes (called sexual inversions) can occur. The causes of sexual inversions are categorized as genetic-hormonal, pharmacological, maternal stress, immunological, and social experiential. From this evidence, we propose a theory of how the entire spectrum of human sexual orientation (vs. simply homosexuality) is determined. A consistent preference for sexual relations with ones own sex (homosexuality), the opposite sex (heterosexuality), or varying degrees of ambivalence about the partners sex (bisexuality) may be called sexual orientation. Homosexuality should not be confused with occasional homosexual experiences. Homosexual experiences are fairly common, especially early in adolescence (Chilman, 1983, p. 18; Kinsey, 1941) or in the absence of alternative sexual outlets (Aldridge, 1983; Groth & Burgess, 1980) and are no more indicative of homosexuality than occasional heterosexual experiences are indicative of heterosexuality. An individuals sexual orientation refers to distinct preferences consistently made after puberty in the presence of clear alternatives, whereas isolated instances of sexual behavior may or may not reflect ones sexual orientation (Gadpaille, 1972, p. 193).

Racial/ethnic variations in male testosterone levels: A probable contributor to group differences in health

Racial and ethnic variations in serum testosterone levels were investigated among a large sample of male Vietnam era veterans. Based on geometric means, significant average differences were found between 3,654 non-Hispanic white and 525 black individuals. The geometric mean for testosterone levels among 200 Hispanic individuals was similar to that of non-Hispanic white individuals. Regarding two other racial/ethnic groups (Asian/Pacific Islanders and Native Americans), no significant differences were found, due perhaps to small sample sizes. Results were interpreted as having considerable potential for explaining some of the race differences in the incidences of cardiovascular diseases, hypertension, and prostate cancer.

Theories of rape : inquiries into the causes of sexual aggression

The nature and extent of rape three contemporary theories of rape the feminist theory - hypotheses and evidence the social learning theory - hypotheses and evidence the evolutionary theory - hypothoses and evidence a synthesized theory of rape a model and general discussion of the synthesized theory.

Religiosity and Criminality Evidence and Explanations of Complex Relationships

Assertions about the relationship (or, sometimes, the lack of a relationship) between religiosity and criminality are examined in light of over 50 research studies, paying special attention to how criminality and particularly religiosity were operationalized in each study. These studies reveal that three religiosity-criminality relationships have been established. The best documented relationship is between church attendance and crime rates. At least among church members, the evidence consistently indicates that frequent church attenders have lower crime rates than infrequent attenders, especially regarding victimless offenses. Second, among the main Western religions, membership in the Jewish religion is associated with lower crime rates, compared to Christian religious membership as a whole; and, among Christians, Protestants as a whole have lower crime rates than Catholics. Third, belief in an afterlife with divine punishment possible, at least among persons who consider themselves members of an organized religion, is associated with lower crime rates. Four conventional explanations of these associations are assessed.

Interaction of fraternal birth order and handedness in the development of male homosexuality

The present study investigated evidence for an interaction between two of the best established etiologic factors, or markers of etiologic factors, in the literature on male homosexuality: fraternal birth order and hand preference. By combining five samples, the authors produced study groups of 1774 right-handed heterosexuals, 287 non-right-handed heterosexuals, 928 right-handed homosexuals, and 157 non-right-handed homosexuals. The results showed a significant (P = 0.004) handedness by older brothers interaction, such that (a) the typical positive correlation between homosexuality and greater numbers of older brothers holds only for right-handed males, (b) among men with no older brothers, homosexuals are more likely to be non-right-handed than heterosexuals; among men with one or more older brothers, homosexuals are less likely to be non-right-handed than heterosexuals, and (c) the odds of homosexuality are higher for men who have a non-right hand preference or who have older brothers, relative to men with neither of these features, but the odds for men with both features are similar to the odds for men with neither. These findings have at least two possible explanations: (a) the etiologic factors associated with non-right-handedness and older brothers-hypothesized to be hyperandrogenization and anti-male antibodies, respectively-counteract each other, yielding the functional equivalent of typical masculinization, and (b) the number of non-right-handed homosexuals with older brothers is smaller than expected because the combination of the older brothers factor with the non-right-handedness factor is toxic enough to lower the probability that the affected fetus will survive.

Evidence of neuroandrogenic etiology of sex roles from a combined analysis of human, nonhuman primate and nonprimate mammalian studies

Abstract To explore the question of whether or not androgenic influences upon brain functioning constitute significant causes of sex differences in human behavior, the present report compares research based upon studies of humans, nonhuman primates and nonprimate mammals. The major assumption underlying the approach was as follows: if similar average sex differences in behavior existed for humans and nonhumans alike, and could be shown to be due to the effects of neuroandrogenic factors in nonhumans, one could infer that neuroandrogenic factors are a likely cause of human sex differences in such behavior as well. Twelve behavior patterns were found to exhibit similar average sex differences in humans as in a number of nonhuman species. Evidence surrounding the causes of these behavior patterns lead to the conclusion that neuroandrogenic factors were all but certainly responsible for much of the average sex differences in (a) assertive erotic sexual behavior and (b) status-related aggressive behavior, both in humans in most other mammals. In addition, neuroandrogenic etiology has been demonstrated among several nonhuman species for (c) the acquisition and recall of spatial environmental perception, (d) spacing behavior, (e) pain tolerance and (f) retarded acquisition of aversive conditioning, although for humans, the evidence is only fairly suggestive of neuroandrogenic influence. For six more behavior patterns, most of the evidence was consistent with a neuroandrogenic etiological hypothesis, both in humans and in other mammalian species, but fell far short of justifying definite conclusions. These were (g) diminished fearful emotional responses to threats, (h) task control-oriented tenacity, (i) transient bonding tendencies, (j) peripheralization, (k) sensation seeking and (l) predatory behaviour.

The effects of prenatal stress, and of prenatal alcohol and nicotine exposure, on human sexual orientation

BACKGROUND Studies of rats have shown that mothers who are subjected to stress during pregnancy are more likely than mothers who are not stressed during pregnancy to have male offspring who exhibit female-typical sexual receptivity postures (lordosis) in the presence of other males following the onset of puberty. More recent animal experiments have indicated that prenatal exposure to alcohol affects the sexual preferences of male offspring in ways that are similar to the effects of prenatal stress. Research with human subjects have thus far yielded inconsistent findings regarding the effects of prenatal stress on male sexual orientation, and no research has yet addressed the possible involvement of prenatal exposure to alcohol or other widely used recreational drugs, such as nicotine. PURPOSE The present study was undertaken to determine if prenatal stress could be one of the causes of variations in sexual orientation in humans, both singularly and in conjunction with prenatal exposure to alcohol and nicotine. METHODS Over 7500 offspring and their mothers provided information regarding the offsprings sexual orientation and the mothers stressful experiences and use of alcohol and nicotine during pregnancy. RESULTS Findings indicate that prenatal stress has a modest but significant effect on the sexual orientation of male offspring, particularly when the stress occurred during the first trimester of pregnancy. Regarding prenatal exposure to alcohol, no evidence was found to suggest that it impacted offspring sexual orientation of either males or females. Prenatal nicotine exposure, however, appears to significantly increase the probability of lesbianism among female offspring, especially if the exposure occurred in the first trimester along with prenatal stress in the second trimester. CONCLUSION The present study is consistent with animal models suggesting that prenatal stress disrupts the typical sex hormonal milieu within which male fetal brains are sexed, thereby feminizing/demasculinizing the males sexual orientation. However, little support was found for similar effects of prenatal alcohol exposure. In the case of prenatal nicotine, this study is the first to suggest that this drug has masculinizing/defeminizing effects on the sexual orientation of female offspring.

Crime in biological, social, and moral contexts

The Concept of Pro/Antisociality and the Biosocial Perspective Introduction Conceptualizing Criminal Behavior from a Biosocial Perspective Universal Behavioral and Demographic Correlates of Criminal behavior Contemporary Criminologists on Causes and Theories of Crime Evolutionary and Genetic Aspects of Criminality The Evolution of Violent Criminal Behavior and its Nonlegal Equivalent The Evolution of Collective Counterstrategies to Crime Courtship Disorder: Voyeurism, Exhibitionism, Tocheurism, and the Preferential Rape Pattern International Crime Rates and Evolutionary Theory Inherited Dispositions Toward Learning Delinquent and Criminal Behavior On Possible Genetic Bases of Race Differences in Criminality Neurochemical Aspects of Pro/Antisociality Hormonal Correlates of Sexual Aggression Androgens, Brain Functioning, and Criminality Neurological Bases of Crime, Psychopathy, and Aggression The Role of Sensory Stimulation in Criminal Behavior Neurological Links Between Substance Abuse and Crime Biosocial Theorizing in the Area of Pro/Antisociality Evolutionary and Neurological Roots of Prosocial Behavior Risk, Crime, and Neurophysiologic Highs Index

Sexual orientation of human offspring may be altered by severe maternal stress during pregnancy

To test the hypotheses that maternal stress during pregnancy may alter the sexual orientation of offspring, 285 women with offspring 19 years of age and older provided retrospective accounts of stressful experiences they had, beginning 12 months prior to pregnancy up to the point of giving birth, and indicated how severe they recalled each event being. When weighted according to severity, stressful experiences helped to predict sexual orientation of male offspring. While most of the variance in sexual orientation remained unexplained, the data suggest that the most critical time in gestation for influencing human sexual orientation of male offspring is during the second trimester, although the first and possibly the third trimesters may be of secondary importance. For female offspring, no significant relationships between maternal stress and sexual orientation were found, although mothers of lesbians did report slightly higher average levels of stress throughout gestation than mothers of female heterosexuals.