How hormones make us choose a life partner
Slaves of Biochemistry
Daria Rybina, Copper News
We all want to think that in our lives we act rationally and make an informed choice. But very often our preferences do not depend on the mind, but on the most subtle biochemical changes occurring in the body.
MedNovosti found out how sex hormones affect the behavior, choices and preferences of women and men.
Brutal macho and gentle fathersPsychologist Kelly Cobey and her colleagues – biologists and psychologists from the School of Natural Sciences in Stirling (UK) – have shown that in the postpartum period, women's preferences in choosing men temporarily change.
Newly-made moms do not find brutal macho men attractive, but men with softer facial features.
The study, published in the journal Biological Psychology, involved more than a hundred women.
During pregnancy and six weeks after giving birth, they were asked to evaluate the degree of attractiveness of male and female faces. "We already know from earlier studies that men with less pronounced masculine qualities become more caring fathers," comments Kelly Cobey. "Perhaps that's why women after childbirth are more attracted to those men whose appearance shows that they will help take care of the baby, and not those who seem more sexy."
"It's not me, it's all pills" Having studied 365 couples, an international group of scientists led by social psychologist Craig Roberts from the same School of Natural Sciences concluded: if a woman who is already in a relationship starts or, conversely, stops taking hormonal contraceptives, this can affect the perception of a partner and satisfaction with sex.
"Previous studies have shown that oral contraceptives change women's sexual preferences and perceptions of male attractiveness," says Craig Roberts. This change of tastes is similar to what happens to recently born mothers: in general, women taking hormonal pills like less masculine men (this, for example, is evidenced by a recent work by Italian psychologists published in The Journal of Sexual Medicine).
Therefore, if a woman chose a partner by taking pills, then, having refused hormonal contraception, she can see him with different eyes, and he suddenly turns out to be not such a handsome prince. "The same thing happens in the opposite situation – when a woman starts taking oral contraceptives while in a relationship," Roberts emphasizes.
At the same time, in general, the degree of sexual satisfaction does not differ between women taking oral contraceptives and those choosing other methods of protection – only "fidelity" to the chosen method of contraception affects the quality of sex and the perception of a partner.
Women in "ovulation glasses"Psychologist Kristina Durante from the University of Texas at San Antonio studies how ovulation affects women's behavior and their choices in a variety of areas of life.
For example, when women were asked to choose the men best suited for the role of future fathers from photos and questionnaires on dating sites, the answers directly depended on the phase of the menstrual cycle. "During ovulation, when the probability of conception is highest, ladies are attracted to brutal machos, boors, impudents and hooligans," says Durante.
At the peak of fertility, women instinctively choose the most genetically healthy males to give birth to healthy offspring. It is surprising that during the surge of hormones, women sincerely deceive themselves, claiming that aggressive boors are more suitable for the role of fathers than calm, caring, attentive men. At the same time, Durante says, ladies at this moment naively believe that their love will help a rude man who starts fights in a bar and looks at every skirt to become an affectionate dad and a respectable family man.
In another study on how women make shopping decisions and spend money depending on the phase of the cycle, Durante and her colleagues invited the participants of the experiment to play economic games and choose the goods they would like to buy. It turned out that during the week around ovulation, women are tougher towards other women, but demonstrate humility and generosity towards men.
In addition, during the period of maximum fertility, women are willing to spend money on more expensive things that will increase their social status compared to "rivals". So, the participants of the experiment were asked to choose what they wanted more: a car for 25 thousand dollars, provided that other women would have cars for 40 thousand (option A) or a car for 20 thousand dollars, provided that others would have cars for 12 thousand (option B). At the peak of fertility , women chose B.
Finally, ovulation affects even political and religious views! During the 2012 American presidential election, Christina Durante's team discovered that everything depends not only on the phase of the cycle, but also on whether a woman is in a long-term relationship. Single women during ovulation tended to liberal values, were less religious and preferred to vote for Democrat Barack Obama. Ladies in a relationship were more conservative, more religious during ovulation and chose Republican Mitt Romney.
"We are pregnant"A study by scientists from the University of Michigan, published in the American Journal of Human Biology, showed that not only women experience hormonal fluctuations during pregnancy.
A team led by psychologist Robin Edelstein examined 29 couples expecting their first child. At 12, 20, 28 and 36 weeks of pregnancy, the level of sex hormones was measured in expectant mothers and fathers: testosterone, cortisol, estradiol and progesterone. In women, as expected, the levels of all four substances increased markedly. Men were found to have changes in only two hormones: a small but significant decrease in testosterone and estradiol levels.
The authors suggest that a drop in the level of testosterone – the main male hormone responsible for sexual attraction and aggression – makes future fathers more "domestic" and caring, promotes the formation of attachment of the father to the child, protects the family from male infidelity. By the way, this group of scientists also studied couples who do not have children yet, and found that where both partners are satisfied with the relationship and plan to live together happily ever after, testosterone levels are low for both.
But why the level of the female sex hormone estradiol falls in men, the authors cannot explain yet. Estradiol is responsible for the care and formation of attachment between mother and baby, so it is not surprising that its level increases in women during pregnancy. Perhaps the fact is that in the body of men, estradiol is produced from testosterone, so if the latter becomes less, then the amount of estradiol decreases. Animal studies have shown that in some species, for example, in steppe voles, estradiol inhibits paternal behavior. So science does not know everything about this hormone yet.
Earlier studies had shown a slight drop in testosterone levels in men who had recently become fathers, but the Michigan team measured hormone levels in "pregnant" dads for the first time. However, the sample is too small – there is not enough data on 29 pairs to make far-reaching conclusions.
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These works clearly demonstrate that so far we know very little about how our body works, and what forces actually control our behavior. So, when you once again make a "reasonable and balanced" decision about your relationship, think again.
Portal "Eternal youth" http://vechnayamolodost.ru13.01.2015