Gender bias in the attribution of creativity

Slightly edited abstract from Proudfoot et al., who provide further examples of gender discrimination:

We propose that the propensity to think creatively tends to be associated with independence and self-direction—qualities generally ascribed to men—so that men are often perceived to be more creative than women. In a first study, we found that “outside the box” creativity is more strongly associated with stereotypically masculine characteristics (e.g., daring and self-reliance) than with stereotypically feminine characteristics (e.g., cooperativeness and supportiveness.) A second study found that a man is ascribed more creativity than a woman when they produce identical output. A third study analyzed archival data, and found that men’s ideas are evaluated as more ingenious than women’s ideas. Study four found that female executives are stereotyped as less innovative than their male counterparts when evaluated by their supervisors. Finally, we observed that stereotypically masculine behavior enhances a man’s perceived creativity, whereas identical behavior does not enhance a woman’s perceived creativity. This boost in men’s perceived creativity is mediated by attributions of agency, not competence, and predicts perceptions of reward deservingness.

Wielding power increases testosterone in women.

Anders et al. provide evidence for a gender→testosterone pathway:

Significance

Human biology is typically studied within the framework of sex (evolved, innate factors) rather than gender (sociocultural factors), despite some attention to nature/nurture interactions. Testosterone is an exemplar of biology studied as natural difference: men’s higher testosterone is typically seen as an innate “sex” difference. However, our experiment demonstrates that gender-related social factors also matter, even for biological measures. Gender socialization may affect testosterone by encouraging men but not women toward behaviors that increase testosterone. This shows that research on human sex biology needs to account for gender socialization and that nurture, as well as nature, is salient to hormone physiology. Our paper provides a demonstration of a novel gender→testosterone pathway, opening up new avenues for studying gender biology.

Abstract

Testosterone is typically understood to contribute to maleness and masculinity, although it also responds to behaviors such as competition. Competition is crucial to evolution and may increase testosterone but also is selectively discouraged for women and encouraged for men via gender norms. We conducted an experiment to test how gender norms might modulate testosterone as mediated by two possible gender→testosterone pathways. Using a novel experimental design, participants (trained actors) performed a specific type of competition (wielding power) in stereotypically masculine vs. feminine ways. We hypothesized in H1 (stereotyped behavior) that wielding power increases testosterone regardless of how it is performed, vs. H2 (stereotyped performance), that wielding power performed in masculine but not feminine ways increases testosterone. We found that wielding power increased testosterone in women compared with a control, regardless of whether it was performed in gender-stereotyped masculine or feminine ways. Results supported H1 over H2: stereotyped behavior but not performance modulated testosterone. These results also supported theory that competition modulates testosterone over masculinity. Our findings thus support a gender→testosterone pathway mediated by competitive behavior. Accordingly, cultural pushes for men to wield power and women to avoid doing so may partially explain, in addition to heritable factors, why testosterone levels tend to be higher in men than in women: A lifetime of gender socialization could contribute to “sex differences” in testosterone. Our experiment opens up new questions of gender→testosterone pathways, highlighting the potential of examining nature/nurture interactions and effects of socialization on human biology.

Can epigenetics explain homosexuality?

Michael Balter notes work presented by Vilain's UCLA laboratory at this year's American Society of Human Genetics meeting. His abstract, followed by some clips of his text:

(added note: an alert reader, see comment below, just added this critique of the following work from The Atlantic)

A new study suggests that epigenetic effects—chemical modifications of the human genome that alter gene activity without changing the DNA sequence—may sometimes influence sexual orientation. Researchers studied methylation, the attachment of a methyl group to specific regions of DNA, in 37 pairs of male identical twins who were discordant—meaning that one was gay and the other straight—and 10 pairs who were both gay. Their search yielded five genome regions where the methylation pattern appears very closely linked to sexual orientation. A model that predicted sexual orientation based on these patterns was almost 70% accurate within this group—although that predictive ability does not necessarily apply to the general population.

Researchers thought they were hot on the trail of “gay genes” in 1993, when a team led by geneticist Dean Hamer of the National Cancer Institute reported that one or more genes for homosexuality had to reside on Xq28, a large region on the X chromosome...but some teams were unable to replicate the findings and the actual genes have not been found...Twin studies suggested, moreover, that gene sequences can't be the full explanation. For example, the identical twin of a gay man, despite having the same genome, only has a 20% to 50% chance of being gay himself.

That's why some have suggested that epigenetics—instead of or in addition to traditional genetics—might be involved. During development, chromosomes are subject to chemical changes that don't affect the nucleotide sequence but can turn genes on or off; the best known example is methylation, in which a methyl group is attached to specific DNA regions. Such “epi-marks” can remain in place for a lifetime, but most are erased when eggs and sperm are produced, so that a fetus starts with a blank slate. Recent studies, however, have shown that some marks are passed on to the next generation.

In a 2012 paper, Rice and his colleagues suggested that such unerased epi-marks might cause homosexuality when they are passed on from father to daughter or from mother to son...Such ideas inspired Tuck Ngun, a postdoc in Vilain's lab, to study the methylation patterns at 140,000 regions in the DNA of 37 pairs of male identical twins who were discordant—meaning that one was gay and the other straight—and 10 pairs who were both gay...the team identified five regions in the genome where the methylation pattern appears very closely linked to sexual orientation...Just why identical twins sometimes end up with different methylation patterns isn't clear. If Rice's hypothesis is right, their mothers' epi-marks might have been erased in one son, but not the other; or perhaps neither inherited any marks but one of them picked them up in the womb...In an earlier review, Ngun and Vilain cited evidence that methylation may be determined by subtle differences in the environment each fetus experiences during gestation, such as their exact locations within the womb and how much of the maternal blood supply each receives.

Is "gaydar" a myth?

Cox et al. contest work by Rule et al. that I mentioned in a previous post and suggest that the idea of "gaydar" is a myth. (Use gaydar as a search term in the search box in the left column for other posts on this topic.)

In the present work, we investigate the pop cultural idea that people have a sixth sense, called “gaydar,” to detect who is gay. We propose that “gaydar” is an alternate label for using stereotypes to infer orientation (e.g., inferring that fashionable men are gay). Another account, however, argues that people possess a facial perception process that enables them to identify sexual orientation from facial structure (Rule et al., 2008). We report five experiments testing these accounts. Participants made gay-or-straight judgments about fictional targets that were constructed using experimentally-manipulated stereotypic cues and real gay/straight people’s face cues. These studies revealed that orientation is not visible from the face—purportedly “face- based” gaydar arises from a third-variable confound. People do, however, readily infer orientation from stereotypic attributes (e.g., fashion, career). Furthermore, the folk concept of gaydar serves as a legitimizing myth: Compared to a control group, people stereotyped more when led to believe in gaydar, whereas people stereotyped less when told gaydar is an alternate label for stereotyping. Discussion focuses on the implications of the gaydar myth and why, contrary to some prior claims, stereotyping is highly unlikely to result in accurate judgments about orientation.

Hormones and clothing choices.

Here is an interesting and curious bit from Eisenbruch et al.:

Recent evidence supports the idea that women use red clothing as a courtship tactic, and results from one study further suggested that women were more likely to wear red on days of high fertility in their menstrual cycles. Subsequent studies provided mixed support for the cycle-phase effect, although all such studies relied on counting methods of cycle-phase estimation and used between-subjects designs. By comparison, in the study reported here, we employed frequent hormone sampling to more accurately assess ovulatory timing and used a within-subjects design. We found that women were more likely to wear red during the fertile window than on other cycle days. Furthermore, within-subjects fluctuations in the ratio of estradiol to progesterone statistically mediated the within-subjects shifts in red-clothing choices. Our results appear to represent the first direct demonstration of specific hormone measurements predicting observable changes in women’s courtship-related behaviors. We also demonstrate the advantages of hormonal determination of ovulatory timing for tests of cycle-phase shifts in psychology or behavior.

Speaking out in a group correlates with gender.

The effectiveness of group decision-making depends on whether the best informed members actually contribute to the discussion. Coffman does a laboratory experiment to examine factors that influence an individual's propensity to contribute, finding that in general undergraduate women contribute less than men, but show the least reluctance for more female-stereotyped subject areas such as art and the most for male-stereotyped subject such as sports:

We use a lab experiment to explore the factors that predict an individual's decision to contribute her idea to a group. We find that contribution decisions depend upon the interaction of gender and the gender stereotype associated with the decision-making domain: conditional on measured ability, individuals are less willing to contribute ideas in areas that are stereotypically outside of their gender's domain. Importantly, these decisions are largely driven by self-assessments, rather than fear of discrimination. Individuals are less confident in gender incongruent areas and are thus less willing to contribute their ideas. Because even very knowledgeable group members under-contribute in gender incongruent categories, group performance suffers and, ex post, groups have difficulty recognizing who their most talented members are. Our results show that even in an environment where other group members show no bias, women in male-typed areas and men in female-typed areas may be less influential. An intervention that provides feedback about a woman's (man's) strength in a male-typed (female-typed) area does not significantly increase the probability that she contributes her ideas to the group. A back-of-the-envelope calculation reveals that a “lean in” style policy that increases contribution by women would significantly improve group performance in male-typed domains.

And, a related bit of work from Eddy et al. shows that although females outnumber males in biology, does a study of 23 different introductory biology classrooms that reveals systematic gender disparities in student performance on exams and student participation when instructors ask students to volunteer answers to instructor-posed questions.

Is it love or lust? Look at eye gaze.

Bolmont et al. ask:

When you are on a date with a person you barely know, how do you evaluate that person’s goals and intentions regarding a long-term relationship with you? Love is not a prerequisite for sexual desire, and sexual desire does not necessarily lead to love. Love and lust can exist by themselves or in combination, and to any degree.

Using the usual collection of heterosexual college students as subjects, the authors tracked eye movements as subjects viewed a series of photographs of persons they had never met before. In a separate session the subjects were asked whether the same photographs elicited feelings (yes or no) of sexual desire or romantic love. The results of a lot of fancy eye tracking analysis?

...subjects were more likely to fixate on the face when making decisions about romantic love than when making decisions about sexual desire, and the same subjects were more likely to look at the body when making decisions about sexual desire than when making decisions about romantic love

Duh........anyway, here is their abstract, which inexplicably doesn't include the above bottom line:

"Reading other people’s eyes is a valuable skill during interpersonal interaction. Although a number of studies have investigated visual patterns in relation to the perceiver’s interest, intentions, and goals, little is known about eye gaze when it comes to differentiating intentions to love from intentions to lust (sexual desire). To address this question, we conducted two experiments: one testing whether the visual pattern related to the perception of love differs from that related to lust and one testing whether the visual pattern related to the expression of love differs from that related to lust. Our results show that a person’s eye gaze shifts as a function of his or her goal (love vs. lust) when looking at a visual stimulus. Such identification of distinct visual patterns for love and lust could have theoretical and clinical importance in couples therapy when these two phenomena are difficult to disentangle from one another on the basis of patients’ self-reports."

Female hurricanes are deadlier than male hurricanes

The fact that I am driving away from Madison Wisconsin tomorrow, to my cold weather nest in Fort Lauderdale Florida, made me recall this interesting bit on hurricanes, which are still a possibility for a month or two after my arrival in Florida.

Meteorologists and geoscientists have called for greater consideration of social science factors that predict responses to natural hazards. We answer this call by highlighting the influence of an unexplored social factor, gender-based expectations, on the human toll of hurricanes that are assigned gendered names. Feminine-named hurricanes (vs. masculine-named hurricanes) cause significantly more deaths, apparently because they lead to lower perceived risk and consequently less preparedness. Using names such as Eloise or Charlie for referencing hurricanes has been thought by meteorologists to enhance the clarity and recall of storm information. We show that this practice also taps into well-developed and widely held gender stereotypes, with potentially deadly consequences. Implications are discussed for understanding and shaping human responses to natural hazard warnings.

Parenting rewires men's brains.

From Abraham et al., interesting material on a global "parental caregiving" neural network in our brains:

Although contemporary socio-cultural changes dramatically increased fathers' involvement in childrearing, little is known about the brain basis of human fatherhood, its comparability with the maternal brain, and its sensitivity to caregiving experiences. We measured parental brain response to infant stimuli using functional MRI, oxytocin, and parenting behavior in three groups of parents (n = 89) raising their firstborn infant: heterosexual primary-caregiving mothers (PC-Mothers), heterosexual secondary-caregiving fathers (SC-Fathers), and primary-caregiving homosexual fathers (PC-Fathers) rearing infants without maternal involvement. Results revealed that parenting implemented a global “parental caregiving” neural network, mainly consistent across parents, which integrated functioning of two systems: the emotional processing network including subcortical and paralimbic structures associated with vigilance, salience, reward, and motivation, and mentalizing network involving frontopolar-medial-prefrontal and temporo-parietal circuits implicated in social understanding and cognitive empathy. These networks work in concert to imbue infant care with emotional salience, attune with the infant state, and plan adequate parenting. PC-Mothers showed greater activation in emotion processing structures, correlated with oxytocin and parent-infant synchrony, whereas SC-Fathers displayed greater activation in cortical circuits, associated with oxytocin and parenting. PC-Fathers exhibited high amygdala activation similar to PC-Mothers, alongside high activation of superior temporal sulcus (STS) comparable to SC-Fathers, and functional connectivity between amygdala and STS. Among all fathers, time spent in direct childcare was linked with the degree of amygdala-STS connectivity. Findings underscore the common neural basis of maternal and paternal care, chart brain–hormone–behavior pathways that support parenthood, and specify mechanisms of brain malleability with caregiving experiences in human fathers.

First direct evidence for human sex pheromones.

Here is a clever experiment by Zhou et al., who digitally morph the gender of moving point light displays of walking from male to female while subjects are exposed to two human steroids that they can not discriminate. Here is their summary and abstract:

•Human steroid androstadienone conveys masculinity to straight women and gay men
•Human steroid estratetraenol conveys femininity to straight men
•The effects take place in the absence of awareness
•Human gender perception draws on subconscious chemosensory biological cues

Recent studies have suggested the existence of human sex pheromones, with particular interest in two human steroids: androstadienone (androsta-4,16,-dien-3-one) and estratetraenol (estra-1,3,5(10),16-tetraen-3-ol). The current study takes a critical step to test the qualification of the two steroids as sex pheromones by examining whether they communicate gender information in a sex-specific manner. By using dynamic point-light displays that portray the gaits of walkers whose gender is digitally morphed from male to female, we show that smelling androstadienone systematically biases heterosexual females, but not males, toward perceiving the walkers as more masculine. By contrast, smelling estratetraenol systematically biases heterosexual males, but not females, toward perceiving the walkers as more feminine. Homosexual males exhibit a response pattern akin to that of heterosexual females, whereas bisexual or homosexual females fall in between heterosexual males and females. These effects are obtained despite that the olfactory stimuli are not explicitly discriminable. The results provide the first direct evidence that the two human steroids communicate opposite gender information that is differentially effective to the two sex groups based on their sexual orientation. Moreover, they demonstrate that human visual gender perception draws on subconscious chemosensory biological cues, an effect that has been hitherto unsuspected.

Judging a man by the width of his face.

Valentine et al. make interesting observations in a speed-dating context. The effect of higher facial width-to-height ratio on short-term but not long-term relationships is compatible with the idea that more dominant men who are selected for mating because of their good health and prowess may also more likely to be less faithful and less investing as fathers:

Previous research has shown that men with higher facial width-to-height ratios (fWHRs) have higher testosterone and are more aggressive, more powerful, and more financially successful. We tested whether they are also more attractive to women in the ecologically valid mating context of speed dating. Men’s fWHR was positively associated with their perceived dominance, likelihood of being chosen for a second date, and attractiveness to women for short-term, but not long-term, relationships. Perceived dominance (by itself and through physical attractiveness) mediated the relationship between fWHR and attractiveness to women for short-term relationships. Furthermore, men’s perceptions of their own dominance showed patterns of association with mating desirability similar to those of fWHR. These results support the idea that fWHR is a physical marker of dominance. This is the first study to show that male dominance and higher fWHRs are attractive to women for short-term relationships in a controlled and interactive situation that could actually lead to mating and dating.

Another demonstration of the gender gap.

The observations of Brooks et al. are quite clear-cut:

We identify a profound and consistent gender gap in entrepreneurship, a central path to job creation, economic growth, and prosperity. Across a field setting (three entrepreneurial pitch competitions in the United States) and two controlled experiments, we find that investors prefer entrepreneurial pitches presented by male entrepreneurs compared with pitches presented by female entrepreneurs, even when the content of the pitch is the same. This effect is moderated by male physical attractiveness: attractive males are particularly persuasive, whereas physical attractiveness does not matter among female entrepreneurs. These findings fundamentally advance the science related to gender, physical attractiveness, psychological persuasion, bias, role expectations, and entrepreneurship.

Meditation and brain imaging of two kinds of love.

Judson Brewer and collaborators perform fMRI scans of experienced practitioners of loving kindness meditation, which fosters feelings of selfless love for others. Their abstract (below) notes their observations (but doesn't emphasize one of their more interesting findings: that the tranquility of selfless love without expectation of reward lowers activation of the areas activated by romantic love - which are the same reward areas activated by cocaine.)

Loving kindness is a form of meditation involving directed well-wishing, typically supported by the silent repetition of phrases such as “may all beings be happy,” to foster a feeling of selfless love. Here we used functional magnetic resonance imaging to assess the neural substrate of loving kindness meditation in experienced meditators and novices. We first assessed group differences in blood oxygen level-dependent (BOLD) signal during loving kindness meditation. We next used a relatively novel approach, the intrinsic connectivity distribution of functional connectivity, to identify regions that differ in intrinsic connectivity between groups, and then used a data-driven approach to seed-based connectivity analysis to identify which connections differ between groups. Our findings suggest group differences in brain regions involved in self-related processing and mind wandering, emotional processing, inner speech, and memory. Meditators showed overall reduced BOLD signal and intrinsic connectivity during loving kindness as compared to novices, more specifically in the posterior cingulate cortex/precuneus (PCC/PCu), a finding that is consistent with our prior work and other recent neuroimaging studies of meditation. Furthermore, meditators showed greater functional connectivity during loving kindness between the PCC/PCu and the left inferior frontal gyrus, whereas novices showed greater functional connectivity during loving kindness between the PCC/PCu and other cortical midline regions of the default mode network, the bilateral posterior insula lobe, and the bilateral parahippocampus/hippocampus. These novel findings suggest that loving kindness meditation involves a present-centered, selfless focus for meditators as compared to novices.

The Kerfuffle over whether men and women's brains are different.

Nothing kicks up a firestorm in the Neuroscience blogosphere like talk of sex differences in brain architecture. Within days of PNAS's early December 2013 publication of what may be a landmark paper on the differing 'connectomes' (nerve fiber tracts connecting different brain areas) of 428 male and 521 female 8-22 year old humans, a storm of criticism of the work was bouncing around the internet, along with accusations of 'neurosexism'. (see, for example, here, here, here, and here.)

The critics make many points - 1. Men have bigger brains on average than women, possibly conflating results; 2. Maybe men and women move their heads differently while in the MRI machine; 3. The structural differences don't necessarily correlate with behavioral differences, and there are varying results on whether the structural results correlate with cognitive function tests. It is unfortunate that the authors of the study were spouting gender stereotypes...but...it seems to me that the objections are mainly nit-picking, the data are rather compelling on fundamental differences in sexual connectivity that arise from genetic/environmental/cultural factors during brain development. (There is no such thing as 'hard wiring'.):

The results establish that male brains are optimized for intrahemispheric and female brains for interhemispheric communication. The developmental trajectories of males and females separate at a young age, demonstrating wide differences during adolescence and adulthood...The brains of men exhibit a far smaller degree of interconnectedness, both within and across the hemispheres, than do those of women.

I decided to wait for the dust to settle a bit, and let the final publication appear, and sure enough in the same issue there is an essay commentary by Larry Cahill that argues essentially that the politically correct view in brain research has been to assume no significant difference between male and female brain, and to assume results obtained (mainly for male brains) apply also to female brains.  Mouse studies in particular have shown that this is not the case.

...we now know that sex influences—small to medium to large—are extremely widespread on brain function. The validity of the assumption that the sex of subjects cannot powerfully alter, negate, and even reverse findings (hence, conclusions) has been crushed under the weight of evidence proving that it can and regularly does and at every level of investigation down to genes, single neurons, and even ion channels...For neuroscientists cognizant of this striking development, the main challenge now is to better understand the dizzying plethora of sex influences being uncovered. Males and females appear to be two complex mosaics, similar in some respects, mildly to highly different in others

Here is Cahill's summary comment:

A comedian discussing men and women once described the male brain as a bunch of boxes that don’t touch one another and the female brain as a complex ball of interconnected wires. Amusing as the bit was, the analogies may be more apt than he could have known. The findings of Ingahalikar et al. do indeed point to a greater degree of modular function in the physical architecture of the male brain and of interconnectedness in physical architecture of the female brain. Given the size of the study, the consistency of the conclusions across various analytic approaches, and the seeming concordance of key findings with well-established literature addressing brain function, one cannot fairly accuse Ingalhalikar et al. of hyperbole when they claim that their findings “reveal fundamental sex differences in the architecture of the human brain.” Theirs is a landmark paper that should accelerate acceptance of the notion that, for those who want to understand how brains function, sex matters.

And here, finally, is the Ingalhalikar et al. abstract:

Sex differences in human behavior show adaptive complementarity: Males have better motor and spatial abilities, whereas females have superior memory and social cognition skills. Studies also show sex differences in human brains but do not explain this complementarity. In this work, we modeled the structural connectome using diffusion tensor imaging in a sample of 949 youths (aged 8–22 y, 428 males and 521 females) and discovered unique sex differences in brain connectivity during the course of development. Connection-wise statistical analysis, as well as analysis of regional and global network measures, presented a comprehensive description of network characteristics. In all supratentorial regions, males had greater within-hemispheric connectivity, as well as enhanced modularity and transitivity, whereas between-hemispheric connectivity and cross-module participation predominated in females. However, this effect was reversed in the cerebellar connections. Analysis of these changes developmentally demonstrated differences in trajectory between males and females mainly in adolescence and in adulthood. Overall, the results suggest that male brains are structured to facilitate connectivity between perception and coordinated action, whereas female brains are designed to facilitate communication between analytical and intuitive processing modes.

Oxytocin and the strength of romantic bonds in men.

Here is an interesting bit from Scheele et al.:

Significance:

Sexual monogamy is potentially costly for males, and few mammalian species along with humans exhibit it. The hypothalamic peptide oxytocin (OXT) has been implicated in mediating pair bonds in various species, but as yet, we know little about neurobiological factors that might act to promote fidelity, especially in men. Here we provide evidence for a mechanism by which OXT may contribute to romantic bonds in men by enhancing their partner's attractiveness and reward value compared with other women.

Abstract:

The biological mechanisms underlying long-term partner bonds in humans are unclear. The evolutionarily conserved neuropeptide oxytocin (OXT) is associated with the formation of partner bonds in some species via interactions with brain dopamine reward systems. However, whether it plays a similar role in humans has as yet not been established. Here, we report the results of a discovery and a replication study, each involving a double-blind, placebo-controlled, within-subject, pharmaco-functional MRI experiment with 20 heterosexual pair-bonded male volunteers. In both experiments, intranasal OXT treatment (24 IU) made subjects perceive their female partner's face as more attractive compared with unfamiliar women but had no effect on the attractiveness of other familiar women. This enhanced positive partner bias was paralleled by an increased response to partner stimuli compared with unfamiliar women in brain reward regions including the ventral tegmental area and the nucleus accumbens (NAcc). In the left NAcc, OXT even augmented the neural response to the partner compared with a familiar woman, indicating that this finding is partner-bond specific rather than due to familiarity. Taken together, our results suggest that OXT could contribute to romantic bonds in men by enhancing their partner's attractiveness and reward value compared with other women.

Penis size and male attractiveness - the most read article in The Proceedings of the National Academy!

I finally had to pass this on.... When I check out the table of contents for new issues of the Proceedings of the National Academy of Science, the right hand column of the page lists most read and most cited articles. For weeks I've been noting that the most read article is "Penis size interacts with body shape and height to influence male attractiveness." I've been trying to avoid it, assuming another evolutionary psychology fairy tale...but, I did have a look. To not deprive MindBlog readers of this gem, I pass on the abstract and one illustration:

Compelling evidence from many animal taxa indicates that male genitalia are often under postcopulatory sexual selection for characteristics that increase a male’s relative fertilization success. There could, however, also be direct precopulatory female mate choice based on male genital traits. Before clothing, the nonretractable human penis would have been conspicuous to potential mates. This observation has generated suggestions that human penis size partly evolved because of female choice. Here we show, based upon female assessment of digitally projected life-size, computer-generated images, that penis size interacts with body shape and height to determine male sexual attractiveness. Positive linear selection was detected for penis size, but the marginal increase in attractiveness eventually declined with greater penis size (i.e., quadratic selection). Penis size had a stronger effect on attractiveness in taller men than in shorter men. There was a similar increase in the positive effect of penis size on attractiveness with a more masculine body shape (i.e., greater shoulder-to-hip ratio). Surprisingly, larger penis size and greater height had almost equivalent positive effects on male attractiveness. Our results support the hypothesis that female mate choice could have driven the evolution of larger penises in humans. More broadly, our results show that precopulatory sexual selection can play a role in the evolution of genital traits.

Figures representing the most extreme height, shoulder-to-hip ratio, and penis size (±2 SD) (Right and Left) in comparison with the average (Center figure) trait values.

How to dress to say it is wrong to be gay!

I had to pass this on.....

FABULOUS! The Pope Emeritus, wearing a fabulous vintage chiffon-lined Dior gold lame gown
over a silk Vera Wang empire waist tulle cocktail dress,
accessorized with a three-foot House of Whoville hat
and the ruby slippers Judy Garland wore in the Wizard of Oz,
on his way to tell us it's wrong to be gay.

Stay plain and simple, Francis! Stay plain and simple!

How do alligators get errections?

I couldn't resist passing on this Discoblog pointer to Kelly's article. Most birds, reptiles, and mammals have penises that become erect by filling with fluid, but the alligator penis does not change shape or stiffness before sex. Kelly suggests it is popped out of the cloaca by muscles evolved for this purpose:

The intromittent organs of most amniotes contain variable-volume hydrostatic skeletons that are stored in a flexible state and inflate with fluid before or during copulation. However, the penis in male crocodilians is notable because its shaft does not seem to change either its shape or bending stiffness as blood enters its vascular spaces before copulation. Here I report that crocodilians may have evolved a mechanism for penile shaft erection that does not require inflation and detumescence. Dissections of the cloaca in sexually mature male American alligators (Alligator mississippiensis) show that the cross section of the proximal shaft of the alligator penis contains dense collagenous tissues that do not significantly change shape when fluid is added to the central vascular space. The large amount of collagen in the wall and central space of the alligator penis stiffen the structure so it can be simply everted for copulation and rapidly retracted at its completion. Because no muscles insert directly onto the penis, eversion and retraction must be produced indirectly. My results suggest that the contraction of paired levator cloacae muscles around the anterior end of the cloaca rotates the penis out of the cloacal opening and strains the ligamentum rami that connect the base of the penis to the ischia. When the cloacal muscles relax, the elastic recoil of the ligamentum rami can return the penis to its original position inside the cloaca.

Can the Catholic Church evolve?

Maureen Dowd discusses gay author Colin Toibin’s “The Testament of Mary,” a one-woman show with Fiona Shaw previewing later this month on Broadway, and I pass on this fascinating clip on Toibin’s thoughts about the Church and homosexuality (I was fascinated to learn about Benedict's “Gorgeous Georg”, who he takes with him into retirement.):

Benedict may have given up his flashy red loafers, downgrading to brown ones made for him in Mexico, but he is taking “Gorgeous Georg,” as the younger German is known, to live in his new home, a monastery in the Vatican. Some cardinals are worried about the arrangement of having Gänswein serve two pontiffs, by day as prefect of the new pope’s household and at night as secretary to the emeritus pope.

“An 85-year-old man having such a beautiful companion with him morning and night to talk to and walk with,” Toibin said. “It’s like the end of a novel. It’s what all of us want for ourselves, straight or gay. It’s better than sex.”

I ask him whether he thinks the church will evolve under a new pope.

“Everyone is hoping for some change,” he said. “If you could see nuns making sermons. Clerical celibacy has to be abolished and soon. And we must quickly begin the process of allowing women into the priesthood.

“They need to think very carefully about not recognizing that gay people, like all other people, are made in God’s image. It’s just possible that they have more gay priests than they know. I think most gay priests are very good people in the priesthood for very good reasons, and actually faithful to the vows of celibacy. On the issue of gays, Benedict made things even worse.”

As Cardinal Ratzinger, Benedict called homosexuality a “more or less strong tendency ordered towards an intrinsic moral evil.” As pope, he reiterated the church view that homosexuals were “objectively disordered” and that men who had such tendencies could not be allowed into seminaries. He called gay marriage a threat to “the future of humanity itself.”

Toibin says that the church must have tolerance, and that its leaders have lost any sense of how their sanctimonious denunciations clash with their scandals and imagery, causing nothing but pain.

“I remember being at the Vatican at Easter 1994,” he recalled, “and watching all the cardinals and bishops, wonderfully powerful old men with great chins, sitting nobly with a long row of extraordinarily beautiful young seminarians standing behind, shading them with different colored sun umbrellas, some of which were pink."

“It was remarkable that none of them seemed to know what it looked like, and I watched it thinking, somebody must tell them.”

Big brains decrease fertility.

More intelligent mammals, such as humans, whales, and dolphins, have decreased fertility. One ideas has been that the energetic cost of increased brain power has been meet by decreasing the size of the gut and decreasing reproductive function. Kotrschal et al. have tested this idea by selecting for brain size in guppies and obtaining populations of fish whose brains were larger or smaller than normal and differed from one another by about 10%. The cost of the increased brain power was a decrease in the size of the gut and a decrease in reproductive function. Here is their abstract:

The large variation in brain size that exists in the animal kingdom has been suggested to have evolved through the balance between selective advantages of greater cognitive ability and the prohibitively high energy demands of a larger brain (the “expensive-tissue hypothesis”). Despite over a century of research on the evolution of brain size, empirical support for the trade-off between cognitive ability and energetic costs is based exclusively on correlative evidence, and the theory remains controversial. Here we provide experimental evidence for costs and benefits of increased brain size. We used artificial selection for large and small brain size relative to body size in a live-bearing fish, the guppy (Poecilia reticulata), and found that relative brain size evolved rapidly in response to divergent selection in both sexes. Large-brained females outperformed small-brained females in a numerical learning assay designed to test cognitive ability. Moreover, large-brained lines, especially males, developed smaller guts, as predicted by the expensive-tissue hypothesis, and produced fewer offspring. We propose that the evolution of brain size is mediated by a functional trade-off between increased cognitive ability and reproductive performance and discuss the implications of these findings for vertebrate brain evolution.