Collaer ML, Hines M. Human behavioral sex differences: a role for gonadal hormones during early development? Psychol Bull 118: 55-107

Department of Psychology, University of California, Los Angeles, USA.
Psychological Bulletin (Impact Factor: 14.39). 08/1995; 118(1):55-107. DOI: 10.1037/0033-2909.118.1.55
Source: PubMed

ABSTRACT Evidence that gonadal hormones during prenatal and neonatal development influence behavior is reviewed. Several theoretical models of hormonal influences, derived from research in other species, are described. These models are evaluated on the basis of data from humans with either normal or abnormal hormonal exposure. It is concluded that the evidence is insufficient to determine which model best explains the data. Sexual differentiation may involve several dimensions, and different models may apply to different behaviors. Gonadal hormones appear to influence development of some human behaviors that show sex differences. The evidence is strongest for childhood play behavior and is relatively strong for sexual orientation and tendencies toward aggression. Also, high levels of hormones do not enhance intelligence, although a minimum level may be needed for optimal development of some cognitive processes. Directions for future research are proposed.

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    • "The process of puberty results in the release of some specific hormones which are primarily responsible for the development of secondary sex characteristics and for the emergence of reproductive capabilities in boys [2]. During this stage an increase in testosterone causes an increase in the sex drive (libido), enlargement of the reproductive organs such as the penis and testes, the production of sperm, increase of muscle mass and lowering of the voice, increased frequency of erection, and the growth of facial, chest, nipple and pubic hair among boys [3]. "
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    ABSTRACT: The use of crude kerosene as a dietary supplement in boarding schools has been a common practice in east Africa and other countries for many years, with the belief of it reducing the sex drive (libido) at the pubertal stage. There is however no scientific basis for this belief. The present study aimed at using a rat animal model to investigate the effects of crude kerosene on serum testosterone levels, aggression and its possible toxic effects. Fifteen male albino rats of approximately similar age and average weights were put into three groups of five animals each; the control group (placebo), low kerosene dose (10 μl/day) group and high kerosene dose (300 μl/day) group. ELISA was used to determine the serum testosterone levels. During treatment, changes in aggression were observed and noted. Liver toxicity was determined using enzyme assays, total protein and albumin while renal toxicity was monitored using serum creatinine levels. A full hemogram was conducted to determine hematological effects. Various tissue biopsies were obtained and examined using histopathological techniques for evidence of toxicity. Contrary to the common belief, our findings showed an overall increase of serum testosterone levels of up to 66% in the low dose and 75% in the high dose groups, with an increasing trend by the end of the study. The high dose group showed significantly increased levels of white blood cells (WBC) (p = 0.036), red blood cells (RBC) (p = 0.025), hematocrit (HCT) (p = 0.03), red cell distribution width (p = 0.028) and platelets (p = 0.017). The histological results of the stomach indicated chronic gastritis.
    Toxicology Reports 12/2015; 2:175-183. DOI:10.1016/j.toxrep.2014.11.017
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    • "Deleterious mutations in AR can result in syndromes ranging from mild abnormalities to total failure of normal male phenotypic development (McPhaul, 2002a,b). AR also has associations with disease states (such as prostate cancer) and behavior in humans (Collaer and Hines, 1995; Wyce et al., 2010; Zitzmann and Nieschlag, 2003). Androgen receptors (AR) are DNA-binding transcription factors, the main regulators of androgen signaling in the cell, activated mostly by testosterone and 5α-dihydrotestosterone. "
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    ABSTRACT: Androgen receptor genes (AR) have been found to have associations with reproductive development, behavioral traits, and disorders in humans. However, the influence of similar genetic effects on the behavior of other animals is scarce. We examined the loci AR glutamine repeat (ARQ) in 44 Grevy's zebras, 23 plains zebras, and three mountain zebras, and compared them with those of domesticated horses. We observed polymorphism among zebra species and between zebra and horse. As androgens such as testosterone influence aggressiveness, AR polymorphism among equid species may be associated with differences in levels of aggression and tameness. Our findings indicate that it would be useful to conduct further studies focusing on the potential association between AR and personality traits, and to understand domestication of equid species.
    09/2015; 5:120-123. DOI:10.1016/j.mgene.2015.06.006
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    • "A second NIH-sponsored report published in 2007, the Chapel Hill Consensus Statement, indicated that extensive data in rodents identified the potential for adverse outcomes in humans due to exposure during critical periods of development, and that the changes would likely be irreversible (vom Saal et al., 2007). Ethical considerations, however, make any study of potential vulnerabilities in children to BPA limited to epidemiological approaches that reveal correlations but not causation (Collaer and Hines, 1995; Rochester, 2013; Trasande et al., 2012). Another environmental estrogen that is prevalent globally is 17a-ethinyl estradiol (EE2), the active estrogen in birth control pills (Caldwell et al., 2012; Hinteman et al., 2006; Kostich et al., 2013; Lu et al., 2011; Pojana et al., 2004; Zhou et al., 2012). "
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