Prairie Voles, early stress and sexual behavior

Not going to start where the title suggests. First, I want to highlight another quote from the Carol Tavris article Mind Games. David Blakeslee noted this in a comment recently and it is an appropriate beginning for this post:

The scientific method is designed to help investigators overcome the most entrenched human cognitive habit: the confirmation bias, the tendency to notice and remember evidence that confirms our beliefs or decisions, and to ignore, dismiss, or forget evidence that is discrepant. That’s why we are all inclined to stick to a hypothesis we believe in. Science is one way of forcing us, kicking and screaming if necessary, to modify our views.

Live by the sword…

It is no secret that I believe research does not support a reparative drive formulation as a general theory for same-sex attraction. On the other hand, I need to practice what I preach about confirmation bias so I am looking for any evidence that could support the notion. As a consequence, I am reviewing the literature in the area of hormones, early brain organization, attachment and sexual behavior. A 2003 article by C. Sue Carter, using prairie voles as a model, reported the following:

Another example of the consequences of perinatal exposure to stress hormones comes from work with prairie voles; in this species, corticosterone treatment during the perinatal period altered both social and reproductive behaviors. In female prairie voles, postnatal treatment with corticosterone was associated with an increased preference for unfamiliar partners versus siblings, lower levels of alloparenting and increased masculinization of sexual behavior (indexed by mounting behavior in females). A more stressful early life, including possibly the absence of the father, also inhibited alloparenting in female prairie voles from a population captured in Illinois [92–94]. In nature, a lack of preference familiar animals or unwillingess to engage in alloparenting behavior might be associated with less tendency to remain with the natal family, further undermining communal breeding and monogamous social systems [20].

Note that stress hormones introduced around the time of birth effected adult parenting and sexual behavior, including same-sex behavior in females. This is the kind of evidence one would need to make a link between high levels of stress and later sexual behavior. There is nothing here that provides direct support for the developmental scheme of reparative drive theory. However, the notion that attachment stress might act to organize the developing brain structures involved in sexual behavior is plausible. Several lines of research suggest that hormones at critical periods may impact sexual behavior. However, what human experiences would lead to comparable hormone changes is not at all clear. We know that many people experience neglect, abuse, disappointment, etc., during early development and demonstrate no same-sex sexual interest. Individual genetics may play a role as may cognitive mediation and the individual experiences which shape self awareness.

One thing is clear. Whatever shapes sexual attraction leads to clear brain responses out of the awareness of the person. What is in awareness is most often experienced as intrinsic. As opposed to prairie voles, however, what we do is mediated by cognitive and social concerns that often are of greater importance than impulse.

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  • Drowssap

    Is it possible that prenatal or early life stress could contribute to something that might lead to SSA? From a natural selection point of view the answer is yes.

    Severe Stressful Events Early In Pregnancy May Be Associated With Schizophrenia Among Offspring

  • David Blakeslee

    I look up to you, Warren.

    Integrity is an amazing thing.

  • David Blakeslee

    NO AXE TO GRIND…

    just facts to find.

  • Mary

    However, what human experiences would lead to comparable hormone changes is not at all clear. We know that many people experience neglect, abuse, disappointment, etc., during early development and demonstrate no same-sex sexual interest. Individual genetics may play a role as may cognitive mediation and the individual experiences which shape self awareness

    I am more inclined to follow this kind of thinking.

  • Ann

    Individual genetics may play a role as may cognitive mediation and the individual experiences which shape self awareness

    if there is vulnerability in one area, including the germ theory, can’t one or all of these factors build on and strengthen each other in varying degrees?

  • @David Blakeslee: Thanks David. I might have an axe to grind but that is a different story. What I like about talking about biases is that it makes me aware of my own. Then I have to do something about them. If I step away from the matter (defuse) then I really don’t care where the data lead.

  • Ann

    What I like about talking about biases is that it makes me aware of my own. Then I have to do something about them.

    this is a very good example for me to aspire to – thanks – found myself sitting up straighter in my chair reading it 🙂

  • From Drowssap’s link to the Danish study on stress and schizophrenia:

    During the study period, mothers of 21,987 children were exposed to the death of a relative during pregnancy, 14,206 were exposed to a relatives’ serious illness during pregnancy and 7,331 of the offspring developed schizophrenia.

    The risk of schizophrenia and related disorders was approximately 67 percent greater among the offspring of women who were exposed to the death of a relative during the first trimester. However, death of a relative up to six months before or any other time during pregnancy was not related to risk for schizophrenia in the child, nor was exposure to serious illness in a relative. The association between a family death and risk of schizophrenia appeared to be significant only for individuals without a family history (parents, grandparents or siblings) of mental illness.

    Wow. This sentence in particular is striking:

    The risk of schizophrenia and related disorders was approximately 67 percent greater among the offspring of women who were exposed to the death of a relative during the first trimester.

    Gotta love those Danes for their long-term studies. 67% greater? Quite a stat. We have researchers coming at the topic of schiz from both directions–from the molecular level and from the level of correlations. This article speaks of “related disorders.” I wonder what those disorders are?

    Yes, all the things tossed around might come into play, even germs, as the mother’s immune system is tested when she is under stress. (I’d like it better if the researchers had determined if the relatives who died were close to the mothers, however.)

    While our blood brain barrier seems to still be a wonder of evolution, it’s not as perfect as we thought, particularly since we now realize that the germs themselves are masters of evolution themselves. A virus can evolve in weeks. We can’t.

    That having been said, I realize my own bias here. I have become so awe-struck by what I have read about our recent discoveries about the pathogenic causes of diseases that I too have to temper myself sometimes. However, stress, germs–they could all be related. Think of the number of times we have been under stress because of a life event, even something fairly innocuous like final exams: we skip meals: we lose hours of sleep; then, we get a cold! Related? Sometimes yes–two of our bodies’ sources of energy, food and sleep, have been compromised, and the immune system can’t operate at its best.

    The rate of spontaneous abortions should tell us that a heck of a lot is going on in the first few days and weeks of a pregnancy that we just don’t understand. A lot of babies are strong enough to make it to birth and beyond, but maybe we are just beginning to see what kinds of problems those babies encountered in the womb and the long-term effects of those problems.

  • Drowssap

    Carole

    Sometimes yes–two of our bodies’ sources of energy, food and sleep, have been compromised, and the immune system can’t operate at its best.

    Exactly correct. For example when sleep gets messed up the immune system drops, germs sneak in and a disease can develop.

    Study: Night light raises cancer risk

    They found that the breast cancer rate in neighborhoods with average night lighting was 37 percent higher than in those with the darkest streets, while the rate was an additional 27% higher in areas with the highest amount of light.

    Even small amounts of light at night disrupt the bodies production of melatonin. This wasn’t a problem until the 20th century and our bodies don’t have a defense mechanism.

    Having less than seven hours’ sleep a night almost triples risk of catching a cold

  • Eddy

    LOL. Don’t let this be cause for a detour but it kinda fits. Story on the news tonight said that cows that are named produce more milk than those that aren’t. It doesn’t seem to be the naming, of course. Stress seems to be the culprit that inhibits the milk-producing hormone.

  • Drowssap

    Eddy

    LOL. Don’t let this be cause for a detour but it kinda fits. Story on the news tonight said that cows that are named produce more milk than those that aren’t. It doesn’t seem to be the naming, of course. Stress seems to be the culprit that inhibits the milk-producing hormone.

    That is actually an awesome example of how stress can work in the real world.

    increased stress = less milk production makes a lot of sense

    However increased stress = no milk production wouldn’t work in the natural world because most animals are under stress and they still need milk for their babies.

    By comparison:

    increased stress = less attraction to women could easily be true.

    But increased stress = lifelong SSA makes no evolutionary sense at all.

  • Drowssap

    Warren

    Here is my 2 cents on SSA and hormones.

    SSA can’t be triggered by a normal level of hormones for the same reason that SSA can’t be triggered by a normal childhood. If it’s normal it’s also common and if it’s common you can bet our bodies and minds are optimized to handle it. It’s the rare or unexpected event (biological or otherwise) that humans or any other species have a hard time with.

    So IMHO if it’s hormones it has to be an odd level of hormones or maybe just bad timing of hormones. But even in that case why would this happen in 3% of male births? That is staggeringly common, way to common to be a normal part of human biology. It would need an outside triggering mechanism. This mechanism could be anything but since SSA has been around forever pathogens would have to be at the top of the short list.

    Or one last possibility, normal hormones + common genes = lifelong SSA. It would be an amazing, one of a kind exception but I suppose until we know the truth anything is possible.

  • For a long time, I have wondered if there are more consequences of high and low blood sugar levels in all of us than we have previously thought.

    Mothers-to-be who get quality pre-natal care are monitored for gestational diabetes, and we do know many of the birth defects caused by gestational diabetes; however, what about the effects we don’t know? Each and every day, we realize just how much we don’t understand about our glucose levels.

    Even a non-diabetic has times when his or her blood sugar plummets to unacceptable levels and when it rises to unacceptable levels. I can’t help thinking that blood sugar levels, even in those who aren’t tagged as “diabetic,” during pregnancy, have effects we’ve not yet discovered.

    I looked up “stress hormones” and discovered the primary one is cortisol, a hormone which regulates blood sugar. When we are under stress, the hypothalamus sends signals to the endocrine system and one of the most important stress hormones, cortisol, kicks in. Cortisol’s job is to increase the glucose in our blood stream.

    Those of you with friends or family members with diabetes…you know what neuropathy is. The nerve cells are damaged by spikes in blood sugar levels over a long period of time. Diabetics often lose feeling in their fingers, toes, and even up their legs. Neuropathy affects their internal organs as well. This happens over a long period of time, as far as we know, even in those who were not thought to have been diabetic. By the time they are diagnosed, damage has been done.

    What if brain cells in the fetus (or in an infant or in a toddler) were zapped by bad blood sugar levels? What if the fetus, the infant, or the child didn’t have to be a diabetic for this to happen? As I said, there are many times when the blood sugar levels of even non-diabetics is out of kilter. Who knows what damage is done?

    I decided to mention this because cortisol is a stress hormone and because I have never seen a study that eliminated the possibility that blood sugar levels during pregnancy or in early life could be related to SSA.

    While diet varies from culture to culture and always has, and while there are indeed some cultures in which diabetes is not a problem, I am talking here of bad blood sugar levels that are transitory in nature. When you don’t eat or sleep properly, even a so-called “healthy” person has bad blood sugar levels.

    Just food for thought, that’s all.

  • Drowssap

    Carole

    For a long time, I have wondered if there are more consequences of high and low blood sugar levels in all of us than we have previously thought.

    It definitely could be that or something just like that. But if prenatal blood sugar caused SSA it would have to be outside the normal range one way or the other. And that leads to the question of why is this out of whack during a critical time like pregnancy?

    The other problem is that for identical twins if one is gay the other is straight 3 out of 4 times. That’s doesn’t sound prenatal or at least not entirely prenatal.

  • Drowssap

    Hormones absolutely do have an impact on behavior regardless of what might theoretically push them up or down in the womb. Obviously genes and socialization have an impact on behavior as well.

    What else can impact behavior? Well…. as weird as it might sound parasites can. Although Greg Cochran has mentioned that this might be how SSA works I don’t think he is right. Nevertheless the fact this is not only possible but happens ALL THE TIME is pretty amazing.

    NatGeoVideo: Parasites take control of ants brains and direct their behavior, AMAZING!

  • Drowssap

    Video: Hairworms infect grasshoppers and manipulate their behavior

    “It is one of the most spectacular instances known of behavioral manipulation of a host by a parasite”

    “It is the parasites genes that are being expressed in the behavioral phenotype of the infected host that instruct it to jump”

    This one is awesome… unless you happen to be a cricket, grasshopper or spider.

  • Wow, the hairworms and the grasshoppers I hadn’t heard about.

    As for twins–blood sugar levels are affected by all kinds of things so I can see how one twin could be affected and not the other. After all, even monozygotic twins are often quite different in birth weight and not even MZ twins develop at the exact same rate.

    Just to take guesses at a few variables among many: the blood glucose levels themselves; the stage of brain cell development; the relative strength or weakness of the mother’s immune system. etc. Often it’s the confluence of several biological occurrences that causes something–happenstance. Even whether you and I come down with symptoms of a common rhinovirus is often determined by several chance factors, including the state of our immune system at the time the virus makes contact with us and of course, the relative virulence or benignity of the virus.

  • Eddy

    If it does follow through that stress can impact sexual behavior is that impact irreversible? Is the area of the brain and/or nervous system that was impacted permanently impacted? (Like the ‘grooves’ that ongoing depression leaves in the brain.) Would the absence of stress only stop reinforcement or would it also begin to diminish the present impact?

    With the cows and the milk, I surmised that that particular impact wasn’t permanent. Take away the stress…add to sense of contentment…production enhanced.

  • Eddy, we don’t know. I will post another paper perhaps later today that debunks the maternal stress theory for men so on that point, some work has already been done.

    See the paper on child abuse and herpes in children. Some early stressors apparently leave their mark on the immune system, although we do not know for how long.