Oncogenic BRCA1,2 Mutations in the Human Lineage-A By-Product of Sexual Selection?

In this review, we discuss the long-known problem of tissue-specific carcinogenesis in BRCA1 and BRCA2 mutation carriers: while the genes are expressed ubiquitously, increased cancer risk is observed mostly in the breast and ovaries, and to a much lesser extent, in some other tissues such as the prostate or pancreas. We reevaluate hypotheses on the evolutionary origin of these mutations in humans. Also, we align together the reports that at least some great apes have much lower risks of epithelial cancers in general and breast cancer in particular with the fact that humans have more voluminous breast tissue as compared to their closest extant relatives, particularly chimpanzees and bonobos. We conjecture that this disparity may be a consequence of sexual selection, augmented via selection for enhanced lactation. Further, we argue that there is an organ-specific enigma similar to the Peto paradox: breast cancer risk in humans is only minimally correlated with breast size. These considerations lead to the hypothesis that, along with the evolutionary development of larger breasts in humans, additional changes have played a balancing role in suppressing breast cancer. These yet-to-be-discovered mechanisms, while purely speculative, may be valuable to understanding human breast cancer, though they may not be exclusive to the mammary gland epithelial cells. Combining these themes, we review some anti-carcinogenesis preventive strategies and prospects of new interventions against breast cancer.

Definitions of Abnormal Breast Size and Asymmetry: A Cohort Study of 400 Women

BACKGROUND

Macromastia, micromastia and breast asymmetry have an impact on health and quality of life. However, there is scarce information addressing breast size and asymmetry frequency distribution in reference populations.

OBJECTIVE

The current study aims to identify factors that influence breast size and symmetry and classifies abnormal breast sizes and breast asymmetries in an adult German population.

METHODS

Breast base dimensions, breast volume, symmetry, and other breast anthropometric parameters of 400 German female patients were determined in a retrospective review of the MRI archives at our institution. Professional medical MRI-segmentation software was used for volume measurement.

RESULTS

A total of 400 Patients were retrospectively enrolled. The patients had a mean age of 50 ± 12 years (min: 24; max: 82), mean BMI of 25.0 ± 5.0 (min: 14.7, max: 45.6), and a mean total breast volume of 976 ml (right: 973 ml, min: 64, max: 4777; left: 979 ml, min: 55, max: 4670). The strongest correlation of breast volume was observed with BMI (r = 0.834, p < 0.001), followed by breast base width (r = 0.799, p < 0.001). Smaller breasts have higher breast volume asymmetry ratios (r = - 0.124, p < 0.014). For a BMI between 18.5 and 24.9 kg/m2, micromastia is defined by breast volumes below 250 ml (5th percentile) and macromastia by volumes above 1250 ml (95th percentile). Abnormal breast volume asymmetry (< 5th and > 95th percentile) is equivalent to an absolute difference of approximately 25% relative to the smallest side (bidirectional asymmetry ratio 5th percentile - 19%; 95th percentile 26%).

CONCLUSION

This study provides normative data of German women, as well as selected size-for-BMI percentiles and asymmetry ratio percentiles. The normative data may help to establish transparent and objective coverage criteria for health insurances.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Are Beards Honest Signals of Male Dominance and Testosterone?

The male beard is one of the most visually salient and sexually dimorphic traits and a hypothesized potential marker of other traits, such as dominance, masculinity, social status, and self-confidence. However, as men can easily alter their facial hair, beards may provide unreliable information about the beard owner's characteristics. Here, we examined whether beards are honest signals of biological (testosterone levels) and psychological (self-reported dominance) traits. Young (M = 21.29, SD = 1.54) and healthy men (N = 97) participated in the study. Their beards were measured directly (using digital calipers) and by self-report. Participants provided saliva samples before and after acute exercise (to assess their testosterone and cortisol levels) and reported their dominance on a 5-item scale. The results showed that beard length (directly measured and self-reported) was not related to testosterone levels or dominance; thus, no evidence was found to support the hypothesis that beards are honest (or dishonest) signals of the beard owners' testosterone levels and dominance.

Bigger Bust No Longer on Trend: Malaysians Prefer Moderation in Ideal Female Breast Augmentation

Background It is important to correctly determine the ideal female breast anatomy and aesthetic proportions in order to prepare for surgery and establish its goals. Leaving the preference to the operating surgeons alone might leave unsatisfactory results, which especially leads to reoperation, quite often in the aspect of breast dimension.

Methods This study was conducted using an online graphic questionnaire. We attempted to seek male and female perspectives toward their preferred ideal female breast size for breast augmentation, in order to provide up-to-date data to assist breast surgeons in attaining satisfactory surgical results.

Results Sixty males and 67 females participated in the study comprising Asian major ethnicities of Malay, Chinese, and Indian. Universally, 46.6% of men and 53.5% of women preferred 30 mm diameter for the most ideal nipple-areola complex (NAC) size. For the perfect bust, they generally favored size C and D cup (37.8% and 38.5%, respectively).

Conclusion The majority of women seek natural breast beauty and the longing for an oversized look appears to have infiltrated practice but these assumptions have finally been challenged by these findings.

The evolution of perennially enlarged breasts in women: a critical review and a novel hypothesis

The possession of permanent, adipose breasts in women is a uniquely human trait that develops during puberty, well in advance of the first pregnancy. The adaptive role and developmental pattern of this breast morphology, unusual among primates, remains an unresolved conundrum. The evolutionary origins of this trait have been the focus of many hypotheses, which variously suggest that breasts are a product of sexual selection or of natural selection due to their putative role in assisting in nursing or as a thermoregulatory organ. Alternative hypotheses assume that permanent breasts are a by-product of other evolutionary changes. We review and evaluate these hypotheses in the light of recent literature on breast morphology, physiology, phylogeny, ontogeny, sex differences, and genetics in order to highlight their strengths and flaws and to propose a coherent perspective and a new hypothesis on the evolutionary origins of perennially enlarged breasts in women. We propose that breasts appeared as early as Homo ergaster, originally as a by-product of other coincident evolutionary processes of adaptive significance. These included an increase in subcutaneous fat tissue (SFT) in response to the demands of thermoregulatory and energy storage, and of the ontogenetic development of the evolving brain. An increase in SFT triggered an increase in oestradiol levels (E2). An increase in meat in the diet of early Homo allowed for further hormonal changes, such as greater dehydroepiandrosterone (DHEA/S) synthesis, which were crucial for brain evolution. DHEA/S is also easily converted to E2 in E2-sensitive body parts, such as breasts and gluteofemoral regions, causing fat accumulation in these regions, enabling the evolution of perennially enlarged breasts. Furthermore, it is also plausible that after enlarged breasts appeared, they were co-opted for other functions, such as attracting mates and indicating biological condition. Finally, we argue that the multifold adaptive benefits of SFT increase and hormonal changes outweighed the possible costs of perennially enlarged breasts, enabling their further development.

Perception of the most perfect female breast shape among Malays, Chinese, and Indians community

Researchers have long tried to search for the 'perfect' aesthetic outcome of breast surgery. Although lots of anthropometric studies have been done, there is no consensus when dealing with harmony, abstract, and proportion that make up for its ideal shape. This study was convened via a survey to find the most perfect breast shape by assessing the upper pole contour and upper pole to lower pole ratio (UP:LP) preference among the Malays, Chinese, and Indians races. Hundred thirty-five individuals partook in this survey. Most of the participants generally preferred a more convex shape of upper pole contour with the Malay (50%) and Indian (35.7%) favored a more convex shape while the Chinese preferred it to be just slightly convex (42.8%). Single unmarried individuals (64.7%) significantly preferred a more convex upper pole contour (p = 0.018). The UP:LP ratio of 45:55 (p = 0.002) was the most significantly preferred proportion (37.8%) which largely comprised of the Chinese (51%), followed by Indian (21.6%) and Malay (19.6%). With these findings, using a controlled perception-preference method is a more preferred choice when describing an ideal breast shape as compare to an anthropometric measurement that might be less accurate. Therefore, breast and plastic surgeons alike need to look beyond the anthropometric numbers and should consider the other 'abstract' aesthetic shape which difficult to measure including the upper pole breast that has more convexity and the UP:LP ratio of 45:55 which showed to be the most aesthetically perfect form as agreed in the current works of literature.

Stereotypical and Actual Associations of Breast Size with Mating-Relevant Traits

Breast size varies substantially among women and influences perception of the woman by other people with regard to her attractiveness and other characteristics that are important in social contexts, including mating. The theory of sexual selection predicts that physical criteria of partner selection should be markers of the candidate's desirable properties, mainly biological quality. Few studies, however, have examined whether breast size really signals biological quality or its components and whether observers accurately interpret these signals. Our first study encompassed 163 young women and aimed to establish actual correlates of breast size. The aim of the second study was to determine preferences and stereotypes related to breast size: 252-265 women and men evaluated female digital figures varying in, among other characteristics, breast size. Breast size (breast circumference minus chest circumference) was negatively associated with body asymmetry and positively associated with infections of the respiratory system, but did not correlate with infections of the digestive system, openness to casual sex, and testosterone and estradiol level. Women and men perceived breasts in a similar way to each other: the bigger the breasts the higher the reproductive efficiency, lactational efficiency, sexual desire, and promiscuity attributed to the woman. Nevertheless, large breasts were not regarded more attractive than average ones, though small breasts were the least attractive. In addition, big-breasted women were perceived as less faithful and less intelligent than women with average or small breasts. We discuss our results from the perspectives of evolutionary psychology, perceptual biases, and social stereotypes.

Breast firmness is of greater importance for women's attractiveness than breast size

OBJECTIVES

Male preferences are believed to have played a role in the evolution of permanently enlarged breasts in human females. Although breast size and shape are proven to affect women's attractiveness, their relative importance has not been investigated thus far. We aime to address this gap.

METHODS

We prepared two sets of stimuli, each comprising 49 high-quality color images of a topless woman in a three-quarter view that varied in breast size (from 1 to 7) and firmness (from 1 to 7). Set A depicted the glandular ptosis (ie, breast shape being manipulated but the nipple always directed forward), while Set B depicted true ptosis (both breast shape and nipple position being manipulated). Participants (aged 18-45) were assigned to Set A (62 women, 60 men) or Set B (76 women, 52 men). First, each participant indicated the most attractive woman in the set of images. Next, the participant chose the more attractive woman from pairs in which one female deviated from the participant's ideal in breast size and the other in breast firmness.

RESULTS

Both men and women preferred breasts of average or slightly above-average size and high or extreme firmness. Glandular ptosis was as important for attractiveness as breast size, but true ptosis was of much greater importance. Men preferred slightly bigger breasts than women.

CONCLUSIONS

Further attempts to explain evolution of permanent breasts in human females should give greater attention to breast shape than has previously been the case.