Thema Liebe

Verliebtheit, Liebe und die Hormone

Eine Freundin hat die Theorie, dass casual Sex bei Frauen dazu führen kann, dass sie sich in den Mann, der zufällig bei ihnen im Bett liegt, verlieben, obwohl er eigentlich wirklich nicht ihr Typ ist. Sie hat ein psychologische Erklärung dafür (wenn schon die Möglichkeitkeit besteht, dass eine Frau von diesem Mann schwanger wird, dann ist es besser, wenn sie ihn liebt und dadurch auch an sich binden kann).

Hier ein TED Talk, in dem die Biologin Helen Fisher erkärt, "Why we love, why we cheat", nämlich chemisch, hormonell.

    Anthropologist Helen Fisher takes on a tricky topic – love – and explains its evolution, its biochemical foundations and its social importance.

Titelbild des Buchs von Helen Fisher: why we love

H. Fischer in an artikel from 2004: ...... These three brain systems -- the sex drive, romantic love and attachment -- are connected, particularly the romantic love and sex drive. When you fall in love you want to start hopping in bed with the person, in part because the elevated levels of dopamine associated with romantic love can trigger testosterone, the hormone of desire, of sex craving. But the reverse can happen -- testosterone can elevate the activity of dopamine and you can fall madly in love with someone that you hadn't intended to. And so a lot of people, the very young especially, they do a lot of sleeping around, and some can fall in love with people they don't want to take home, don't want to marry, could never have kids with, and boom! -- they spend the next five years with this person and spend the rest of their lives wondering why they did that.

Q: So the idea that one could always keep having sexual adventures without real emotional consequences, that's a fairy tale we've been telling ourselves?

H. Fischer: It's not gonna happen. With orgasm, levels of oxytocin go up in women and vasopressin in men -- they call these the satisfaction hormones because they do give a sense of calm and peace and security and often a cosmic sense of union. If you have enough of them with somebody you're going to feel attached to them.

From a male's perspective, seminal fluid has dopamine and norepinephrine in it, as well as serotonin and testosterone and estrogen -- all kinds of things they've now shown have an antidepressant effect. When a man doesn't deposit them in the vaginal canal, [he's not able to influence a woman's mood positively, and therefore not able to] trick a woman chemically into liking him.


Q: Was zeigt ein Brain-scan von Verliebten

H. Fischer: What we discovered is that the parts of the brain that lit up and became active when someone falls in love are part of the reward system in the brain. And one of them is the ventral tegmental area, a tiny part in the midbrain, quite far down, that makes dopamine and sprinkles it around the brain.

On average, men tended to show more activity in two regions in the brain: One was associated with the integration of visual stimuli and the second was with penile erection. This really shouldn't come as a surprise. Everybody knows that men are highly visual -- men spend their lives commenting on women, looking at porn, and the like. I believe these visual networks evolved 1 or 2 million years ago because men needed to look at a woman and size up her ability to give him healthy babies. If he saw that she was young and healthy and happy, it would be adaptive for him to become aroused to start the mating process. Men definitely fall in love faster than women -- there's good psychological data on that. And I think that's because they are more visual.

Q: And women?

H. Fischer: Several regions associated with memory recall became active. And I couldn't figure out why at first, and then I thought to myself, my goodness -- for millions of years women have been looking for someone to help them raise their babies, and in order to do that you really can't look at someone and know whether they're honest or trustworthy or whether they can hit the buffalo in the head and share the meat with you. You've got to remember what they said yesterday, what they said three weeks ago, what they gave your mother two months ago at the midwinter festival. For millions of years women have had the hardest job on earth -- raising tiny helpless babies for as long as 20 years. That is an enormous job. There's no other animal on earth for whom motherhood is so complex.

Women remember. It drives both sexes crazy. If women could forget a few things, it might be better for them. Men complain about their marriages much less than women do; they remarry faster than women do. Throughout their lives women have many more complaints during the marriage. But if men could remember a few things, it would probably be better for them too!


Q: Wie definiert Helen Fisher "verliebt"?

H. Fischer: So here are the basic characteristics: You lose a sense of self, your edges become porous -- this person almost invades, but it's a very pleasant invasion. Then there are mood swings -- real giddiness and ecstasy when things are going well, but if you don't hear from him via e-mail or phone, there's despair. But the main characteristic for me is obsessively thinking about the person. When I was interviewing people to put into the fMRI machine, the question I asked was, what percentage of the day or evening do you think about this person? And I was looking for those who said 85, 90 percent -- as in, I can't stop, she's never out of my mind.


Q: Was sagt sie zur lebenslangen Ehe?

H. Fischer: Americans come out of a farming tradition, as all Westerners do. The whole concept of "till death do us part," that is our idea, because we have so much property. But we are probably built to be restless in long relationships. And now, when we break up -- well, it's not like the grasslands of Africa where you pick up your spear and walk off. You've got cars and houses and college educations to pay for. But for most of human evolution there was a lot of serial pair-bonding. You would form a pair bond for a while, have a child, break up, fall in love again, have another marriage, another child, break up again, and then somewhere in middle age probably form another long-term relationship -- and maybe were adulterous on the side.

We live a long time, and we're nicely wired to fall in love several times in our lives. So this trend we have now of a long period of extended practice [with having different partners] before beginning a long attachment is a good one. A woman learns a great deal about a man in bed -- is he patient, is he kind, does he persevere until she has her orgasm? The female orgasm is what they call fickle -- it doesn't always happen. That used to be regarded as a maladaptive trait, but evolutionary psychologists now think it's a very adaptive one because it allows a woman to distinguish between Mr. Right and Mr. Wrong.

Because we weren't built to be happy; we were built to reproduce. Lust, romantic love, attachment, these three different systems, we all have them to various degrees, and some people find it easier to form a long-term attachment than other people do. And I do think that there's a chemical basis to that. Divorce does run in families. Some people need thrills all the time -- and if they do have a marriage they're almost always adulterous within a couple years of that marriage.


Q: Selbstmord nach einer Trennung?

H. Fischer: Three out of four people who kill themselves after a love relationship has ended are men, not women. Men are much more likely because they have fewer friends -- so they put more into relationships than women. They're not as expressive as women.


Q: So how can we control love?

H. Fischer:The only one way I really know of to kick in that dopamine system and to help spark love, particularly in a long-term relationship, is to do novel things together. Novelty is associated with elevated activity of dopamine and norepinephrine -- those are the same stimulants associated with cocaine and amphetamines. Novelty can step up that system. Some people can just go to a different restaurant. You don't have to go skydiving. Other people, maybe they should.




Liebe im Gehirn


Grundlage dieses Abschnitts ist ein Artikel der New York Times vom 31.5.2005. Dort wird von Versuchen mit MRI (Magnet Resonanz Imaging) berichtet. Es geht um mehr oder weniger frisch Verliebte. Die Forscher finden im Gehirn eine große Aktivität im Bereich des Caudate Nucleus wenn die Versuchspersonen Bilder des Objektes ihrer Liebe betrachten. Caudate Nucleus kam in der letzten Zeit in die Presse, weil MRI-Scans auch starke Aktiviäten ergaben, wenn eine Person einer anderen vertraut. "Past studies have shown the caudate nucleus is connected to the brain's reward pathways and that it goes into overdrive when a reward is expected". D.h. der Anblick der frisch entdeckten Objekts der Liebe erzeugt ein starkes positives Erleben, weit entfernt von bewussten Vorgängen. Der Bereich ist auch weit entfernt von den Bereichen, die beim Betrachten von attraktiven Personen aktiv werden. "This distinction, between finding someone attractive and desiring him or her, between liking and wanting, is all happening in an area of the mammalian brain that takes care of most basic functions, like eating, drinking, eye movements, all at an unconscious level".

Eine frühere Studie (2000) hat die Gehirn-Aktivitäten von Paaren untersucht, die sich bereits 2 Jahre kannten. Dabei hat sich gezeigt, dass nun diese Bereiche viel weniger aktiv waren, dafür aber andere, die mit "langfristiger Bindung" verbunden sind. Auch in der aktuellen Studie hat sich mit der Dauer der Partnerschaft eine Verschiebung vom Bereich der "ersten Verliebtheit" in den Bereich der "längeren Partnerschaft" gezeigt.

Und noch ein Ergebnis: In einem Nachfolgeexperiment ging es um Trennung. Dabei wurden die Fotos des Ex-Partners gezeigt Menschen gezeigt, die sich gerade von einem Partner getrennt hatten. Ergebnis war, dass wiederum die gleichen Bereiche aufleuchteten, das heißt, die Trennung tut der Verliebtheit erst mal keinen Abbruch.


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