hormones

Now, baby, Cissy Caffrey said. Say out big, big. I want a drink of water. And baby prattled after her: A jink a jink a jawbo.

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Recent studies have shown that women are more sensitive than men to subtle cuteness differences in infant faces. It has been suggested that raised levels in estradiol and progesterone may be responsible for this advantage. […]

Thirty-six women were tested once during ovulation and once during the luteal phase of their menstrual cycle. In a two alternative forced-choice experiment, participants chose the baby which they thought was cuter (Task 1), younger (Task 2), or the baby that they would prefer to babysit (Task 3). […]

During ovulation, women were more likely to choose the cuter baby than during the luteal phase, in all three tasks. These results suggest that cuteness discrimination may be driven by cyclic hormonal shifts.

{ Hormones and Behavior | Continue reading }

art { Henri Chopin, La crevette amoureuse, 1967-1975 }

Your reputation precedes you

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The idea of two sexes is simplistic. Biologists now think there is a wider spectrum than that.

The presence or absence of a Y chromosome is what counts: with it, you are male, and without it, you are female. But doctors have long known that some people straddle the boundary — their sex chromosomes say one thing, but their gonads (ovaries or testes) or sexual anatomy say another. Parents of children with these kinds of conditions — known as intersex conditions, or differences or disorders of sex development (DSDs) — often face difficult decisions about whether to bring up their child as a boy or a girl. Some researchers now say that as many as 1 person in 100 has some form of DSD. […]

That the two sexes are physically different is obvious, but at the start of life, it is not. Five weeks into development, a human embryo has the potential to form both male and female anatomy. Next to the developing kidneys, two bulges known as the gonadal ridges emerge alongside two pairs of ducts, one of which can form the uterus and Fallopian tubes, and the other the male internal genital plumbing: the epididymes, vas deferentia and seminal vesicles. At six weeks, the gonad switches on the developmental pathway to become an ovary or a testis. If a testis develops, it secretes testosterone, which supports the development of the male ducts. It also makes other hormones that force the presumptive uterus and Fallopian tubes to shrink away. If the gonad becomes an ovary, it makes oestrogen, and the lack of testosterone causes the male plumbing to wither. The sex hormones also dictate the development of the external genitalia, and they come into play once more at puberty, triggering the development of secondary sexual characteristics such as breasts or facial hair. […]

For many years, scientists believed that female development was the default programme, and that male development was actively switched on by the presence of a particular gene on the Y chromosome. In 1990, researchers made headlines when they uncovered the identity of this gene, which they called SRY. Just by itself, this gene can switch the gonad from ovarian to testicular development. For example, XX individuals who carry a fragment of the Y chromosome that contains SRY develop as males.

{ Nature | Continue reading }

49 days, surely I should be feeling a whole lot better

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Does morality depend on the time of the day? The study “The Morning Morality Effect: The Influence of Time of Day on Unethical Behavior” published in October of 2013 by Maryam Kouchaki and Isaac Smith suggested that people are more honest in the mornings, and that their ability to resist the temptation of lying and cheating wears off as the day progresses. […]

One question not addressed by Kouchaki and Smith was whether the propensity to become dishonest in the afternoons or evenings could be generalized to all subjects or whether the internal time in the subjects was also a factor.

All humans have an internal body clock — the circadian clock — which runs with a period of approximately 24 hours. The circadian clock controls a wide variety of physical and mental functions such as our body temperature, the release of hormones or our levels of alertness. The internal clock can vary between individuals, but external cues such as sunlight or the social constraints of our society force our internal clocks to be synchronized to a pre-defined external time which may be quite distinct from what our internal clock would choose if it were to “run free”. Free-running internal clocks of individuals can differ in terms of their period (for example 23.5 hours versus 24.4 hours) as well as the phases of when individuals would preferably engage in certain behaviors. […]

Some people like to go to bed early, wake up at 5 am or 6 am on their own even without an alarm clock and they experience peak levels of alertness and energy before noon. In contrast to such “larks”, there are “owls” among us who prefer to go to bed late at night, wake up at 11 am, experience their peak energy levels and alertness in the evening hours and like to stay up way past midnight. […]

The researchers Brian Gunia, Christopher Barnes and Sunita Sah therefore decided to replicate the Kouchaki and Smith study with one major modification: They not only assessed the propensity to cheat at different times of the day, they also measured the chronotypes of the study participants. Their recent paper “”The Morality of Larks and Owls: Unethical Behavior Depends on Chronotype as Well as Time of Day” confirms that Kouchaki and Smith findings that the time of the day influences honesty, but the observed effects differ among chronotypes. […]

[M]orning morality effect and the idea of “moral exhaustion” towards the end of the day cannot be generalized to all. In fact, evening people (”owls”) are more honest in the evenings. […]

Gunia and colleagues only included morning and evening people in their analysis and excluded the participants who reported an intermediate chronotype, i.e. not quite early morning “larks” and not true “owls”. This is a valid criticism because newer research on chronotypes has shown that there is a Gaussian distribution of chronotypes. Few of us are extreme larks or extreme owls, most of us lie on a continuum.

{ Fragments of Truth | Continue reading }

photo { Steven Meisel }

I eat cannibals

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Campion was an ophthalmologist […] He became a testosterone doctor. […] The initial session costs $5,000, and the monthly charges are over $1,000. Clients get their blood work done every three months, so that Campion can keep tabs on how their “hormonal balancing” is going. Most patients lock into a permanent testosterone regimen, as Campion has. “I will take testosterone for the rest of my life,” he says. […]

Testosterone can be manufactured cheaply in large quantities, and the risks seem manageable for most people. Users report increased energy, more muscle mass, decreased body fat, greater sex drive, and a general sense of well-being. In short, it’s one of the most transformative substances a human can take. […]

According to a study by University of Texas epidemiologist Jacques Baillargeon, nearly four percent of men in their 60s are taking testosterone. The number of men between 40 and 64 went up 77 percent from 2010 to 2013 to 1.5 million men.

{ Fusion | Continue reading }

art { Andy Warhol, Eight Elvises, 1963 | The current owner and location of the painting, which has not been seen publicly since the 1960s, are unknown }

Baby baby baby, look to the sky, seeking to find, the third eye

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Impending fatherhood can lower two hormones–testosterone and estradiol–for men, even before their babies are born, a new University of Michigan study found.

Other studies indicate that men’s hormones change once they become fathers, and there is some evidence that this is a function of a decline after the child’s birth. […]

Expectant mothers experience significant hormone changes throughout the transition to parenthood, but less has been known about the prenatal hormone changes among soon-to-be fathers.

Women showed large prenatal increases in all four hormones, while men saw declines in testosterone (which is associated with aggression and parental care) and estradiol (which is associated with caregiving and bonding). No changes were found in men’s cortisol (a stress hormone) or progesterone (which is associated with social closeness and maternal behavior).

{ EurekAlert | Continue reading }

sculpture { Duane Hanson, Old Man Playing Solitaire, 1973 }

‘Let’s break shit.’ –Guy Vidra

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The Male Idiotic Theory (MIT) stipulates that the reason men are more prone to injury and death is simply because they “are idiots and idiots do stupid things“. Despite tons of anecdotal evidence confirming MIT, there’s never been a systematic analysis on sex differences in idiotic risk taking behaviour. Until now.

In a new study published in BMJ, researchers obtained 20 years worth of data from the Darwin Awards to tally up the sex of each year’s winner. For those not in the know, the Darwin Awards are given to people who die in such astonishingly stupid ways that “their action ensures the long-term survival of the species, by selectively allowing one less idiot to survive”. […]

Men made up a staggering 88.7 % of Darwin Award winners in 318 examined cases.

{ Neurorexia | Continue reading }

related { Males are more likely to die than females while in the womb }

In the morning signorina we’ll go walking

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Although many studies have reported that women’s preferences for masculine physical characteristics in men change systematically during the menstrual cycle, the hormonal mechanisms underpinning these changes are currently poorly understood. Previous studies investigating the relationships between measured hormone levels and women’s masculinity preferences tested only judgments of men’s facial attractiveness. Results of these studies suggested that preferences for masculine characteristics in men’s faces were related to either women’s estradiol or testosterone levels.

To investigate the hormonal correlates of within-woman variation in masculinity preferences further, here we measured 62 women’s salivary estradiol, progesterone, and testosterone levels and their preferences for masculine characteristics in men’s voices in five weekly test sessions. Multilevel modeling of these data showed that changes in salivary estradiol were the best predictor of changes in women’s preferences for vocal masculinity.

These results complement other recent research implicating estradiol in women’s mate preferences, attention to courtship signals, sexual motivation, and sexual strategies, and are the first to link women’s voice preferences directly to measured hormone levels.

{ Hormones and Behavior }

related { Evidence to Suggest that Women’s Sexual Behavior is Influenced by Hip Width Rather than Waist-to-Hip Ratio }

Le paradigme de l’art contemporain

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In his groundbreaking research, Geoffrey Miller (1999) suggests that artistic and creative displays are male-predominant behaviors and can be considered to be the result of an evolutionary advantage. The outcomes of several surveys conducted on jazz and rock musicians, contemporary painters, English writers (Miller, 1999), and scientists (Kanazawa, 2000) seem to be consistent with the Millerian hypothesis, showing a predominance of men carrying out these activities, with an output peak corresponding to the most fertile male period and a progressive decline in late maturity.

One way to evaluate the sex-related hypothesis of artistic and cultural displays, considered as sexual indicators of male fitness, is to focus on sexually dimorphic traits. One of them, within our species, is the 2nd to 4th digit length (2D:4D), which is a marker for prenatal testosterone levels.

This study combines the Millerian theories on sexual dimorphism in cultural displays with the digit ratio, using it as an indicator of androgen exposure in utero. If androgenic levels are positively correlated with artistic exhibition, both female and male artists should show low 2D:4D ratios. In this experiment we tested the association between 2D:4D and artistic ability by comparing the digit ratios of 50 artists (25 men and 25 women) to the digit ratios of 50 non-artists (25 men and 25 women).

Both male and female artists had significantly lower 2D:4D ratios (indicating high testosterone) than male and female controls. These results support the hypothesis that art may represent a sexually selected, typically masculine behavior that advertises the carrier’s good genes within a courtship context.

{ Evolutionary Psychology | PDF }

previously { Contrary to decades of archaeological dogma, many of the first artists were women }

Muro de incomprensión

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Each month many women experience an ovulatory cycle that regulates fertility. Whereas research finds that this cycle influences women’s mating preferences, we propose that it might also change women’s political and religious views. Building on theory suggesting that political and religious orientation are linked to reproductive goals, we tested how fertility influenced women’s politics, religiosity, and voting in the 2012 U.S. presidential election. In two studies with large and diverse samples, ovulation had drastically different effects on single versus married women. Ovulation led single women to become more liberal, less religious, and more likely to vote for Barack Obama. In contrast, ovulation led married women to become more conservative, more religious, and more likely to vote for Mitt Romney. In addition, ovulatory- induced changes in political orientation mediated women’s voting behavior. Overall, the ovulatory cycle not only influences women’s politics, but appears to do so differently for single versus married women.

{ Psychological Science | PDF }

The human mind does not involve an adequate knowledge of the parts composing the human body

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The microbiome — the kilogram of microbes that each of us carries around — has been shown to be involved in everything from obesity and type 2 diabetes to behaviour and sexual preferences. The composition and effects of the microbiome are very active areas of research, producing results which have challenged the way we think about the evolution and interactions of organisms, including ourselves. In a paper recently published in the journal Science, researchers showed for the first time that the make up of the microbiome differs between the sexes, linking these differences to changes in hormone levels and disease resistance. […]

When female mice were given a testosterone inhibitor along with the bacteria from male mice, the rate of diabetes returned to normal.

“It was completely unexpected to find that the sex of an animal determines aspects of their gut microbe composition, that these microbes affect sex hormone levels, and that the hormones in turn regulate an immune-mediated disease,” said Dr. Danska.

{ Inspiring Science | Continue reading }

photo { Jackie Hardt }

Resist. Your efforts will be rewarded.

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Recent experimental psychology […] suggests that the best leaders — both male and female — seem to have relatively high testosterone, which is linked to decreased fear and increased tolerance for risk and desire to compete, and low cortisol, which is linked to decreased anxiety. Effective leadership is associated with hormone levels, and with this hormone profile, leaders are confident and willing to take risks, but not overly threatened or reactive to stressors. [..]

It turns out these two hormones, testosterone and cortisol, are very touchy, sensitive to social and physical cues and fluctuating a great deal over the course of a single day. As Sandberg mentioned in her book, our research shows that people can change their own hormone levels and behaviors, by “faking it” — by “power posing,” or adopting expansive, open nonverbal postures that are strongly associated with power and dominance across the animal kingdom (imagine standing with hands on hips and feet spread, like Wonder Woman). By holding these postures for just two minutes before entering a high-stress situation, people (both men and women) can increase their testosterone by about 20% and decrease their cortisol by about 25%.

{ Harvard Business Review | Continue reading | Thanks Tim }

In blue dungarees, stands up in the gallery, holding in each hand an orange citron

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The researchers also found that men require a slightly longer wavelength to see the same hue as women; an object that women experience as orange will look slightly more yellowish to men, while green will look more blue-green to men.

This last part doesn’t confer an advantage on either sex, but it does demonstrate, Abramov says, that “the nervous system that deals with color cannot be wired in the exact same way in males as in females.” He believes the answer lies in testosterone and other androgens.

{ Smithsonian | Continue reading }

photo { Nicholas Nixon }