Human evolution theory utilizing concepts of neoteny & female sexual selection
An etiology of neuropsychological disorders such as autism and dyslexia, and the origin of left handedness.
"Table 2 shows a clear and highly significant estrone, estradiol, and androstenedione dose-response relationship according to the number of cigarettes smoked by current smokers. No such association was seen for testosterone or sex hormone binding globulin. Additional data were available for 198 of these men who had also participated in Visit II. Smokers had significantly higher age-adjusted 24-hour caffeine intake than nonsmokers (634 vs. 427 mg; p less or equal to 0.01). ... In this population, men without cardiovascular disease who were current cigarette smokers had significantly higher estradiol, estrone, and androstenedione levels than past and never smokers, but did not differ significantly with regard to testosterone or sex hormone binding globulin. ... Interestingly, other previous reports of increased estrogen levels in cigarette smokers (13,14) were those in which cardiovascular disease or cardiovascular risk factors were not selection criteria. Studies which found the reverse, i.e., lower estrogen levels in smokers, generally were studies of men with known or suspected cardiovascular disease (5, 12)." (Barrett-Connor E. & Khaw, K.T. (1987) Cigarette smoking and increased endogenous estrogen levels in men. American Journal Epidemiology 126: pp. 190-91)