A number of nonsteroidal estrogens, which are common naturally occurring substances in human foods, were examined for competitive binding to estrogen receptor proteins. These compounds bound competitively to estrogen receptor proteins in rat uterine cytosol, in tissue from 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat mammary tumors, and in human mammary tumor tissue. The relative affinity of these estrogens for rat uterine cytosol receptors paralleled closely the affinities reported for other receptors. Oral administration of coumestrol did not appear to support the growth of DMBA-induced rat mammary tumors, nor did coumestrol act as an antiestrogen when administered orally in combination with 17 beta-estradiol. Coumestrol administered sc might, however, be able to support the growth of these tumors.
Left-handedness is a costly, sexually dimorphic trait found at low frequencies in all human populations. How the handedness polymorphism is maintained is unclear. The fighting hypothesis argues that left-handed men have a negative frequency-dependent advantage in violent intrasexual competition giving them a selective advantage. In support of this, many studies have found that left-handed men are overrepresented among modern professional fighters, but studies typically find no difference in fighting success between left and right-handed fighters. We studied over 13,800 professional boxers and mixed martial artists of varying abilities in three of the largest samples to test this hypothesis to date, finding robust evidence that left-handed fighters have greater fighting success. This held for both male and female fighters, and for both percentage of fights won and an objective measure of fighting ability. We replicated previous results showing that left-handed fighters are strongly overrepresented in professional combat sports, but left-handed fighters did not show greater variance in fighting ability, a hypothesis suggested in previous studies. Overall we find strong evidence consistent with the fighting hypothesis.
14Left-handedness is a costly, sexually dimorphic trait found in all human populations. How the 15 handedness polymorphism is maintained is unclear. The fighting hypothesis argues that left-16 handed men have a negative frequency-dependent advantage in fighting giving them a selective 17 advantage. In support of this, many studies have found that left-handed men are overrepresented 18 in combat sports, but studies typically find no difference in fighting success between left and right-19 handed fighters. We studied over 9800 professional boxers and mixed martial arts fighters of 20 varying abilities in three of the largest samples to test this hypothesis to date, finding robust 21 evidence that left-handed fighters have greater fighting success. This held for both male and 22 female fighters and when considering percentage of fights won, and objective measures of fighting 23 ability. We replicated previous results showing the left-handed fighters are strongly 24 overrepresented in professional combat sports, but left-handed fighters did not show greater 25 variance in fighting ability, a hypothesis suggested in previous studies. Overall we find strong 26 evidence consistent with the fighting hypothesis. 27 30 population is left-handed [6] and though exact numbers vary with culture, [7] left-handers are 31 always a minority. Since left-handedness is under direct negative selection, its persistence in 32 humans is an evolutionary puzzle. 34One explanation for the persistence of left-handedness is the fighting hypothesis [8]. This argues 35 that the polymorphism in human handedness is maintained due to a negative frequency-dependent 36 advantage that left-handedness confers to males in combat (see [9] for theoretical support, and [10] 37 for a review of empirical evidence as well as alternatives). According to this theory right-handed 38 males often lack experience fighting rare left-handed males, while left-handed males accumulate 39 plenty of experience fighting right-handed males, putting them at a selective advantage. Combined 40 with the intrinsic fitness costs of left-handedness, this would explain the universal pattern of low but 41 stable levels of left-handers in all studied populations. There is mounting evidence that intrasexual 42 contest competition such as fighting has been a key component of sexual selection on human 43 males [11]. Modern males may possess adaptations to assist them in fighting and assessing 44 opponents' fighting ability [12]. Handedness could therefore be considered a sexually selected trait 45 in males, and may be expressed in females a by-product [9].48 overrepresented in combat sports. Sports are particularly relevant systems for testing theories 49 based on intrasexual competition, as they are thought to have evolved culturally as a display for 50 males to advertise fighting and competitive ability [13]. Overrepresentation of left-handers has 51 been seen in boxing (where is it referred to among coaches and fans as 'Southpaw Advantage': 52 [14-16], mixed martial arts or MMA ...
This paper describes the application of the sulphonated 2,4-dichlorophenol/glucose oxidase method of Barham and Trinder for the estimation of blood glucose to the AutoAnalyzer I and AutoAnalyzer II. Use has been made of the increased sensitivity achieved with this reagent to (1) increase sampling rates, with concomitant reduction in sample volume, (2) reduce the consumption of enzymes required, and (3) reduce carryover, all without significant loss of precision.
Growing evidence suggests that human males have been sexually selected for violent contest competition. I propose the hypothesis that increased arm length is an intrasexually selected adaptation for fighting in males. Longer arms may have provided several advantages to our male ancestors during conflict. However previous research on the effects of arm span on fighting success have shown mixed results and may not have fully accounted for allometric scaling of arm span with size. In a sample of 1,660 modern mixed martial arts fighters, I find that arm span is sexually dimorphic and associated with fighting success, even when controlling for body size. However, effects of arm span on fighting success were very small, suggesting that selection may have been weak. I review evidence for alternative explanations for men’s longer arm span and propose future directions to further test this hypothesis.
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