Yesterday, in How Birds Are Like Humans, I wrote this about testosterone levels in males, both avian and human -
Too high means too much risky behavior, which leads to health-endangering fights and predation, etc. Too little means poorer territory (which includes poorer access to food and less desirable/safe nesting sites) as well as poorer reproductive success.
This morning I encountered this article: Research shows personality can predict fertility. And this finding -
In the study of men, individuals with above average levels of extraversion, prone to be sociable and outgoing, had 14% more children than men with below average extraversion.
I suspected that testosterone and extraversion may be associated. And so I entered the two terms into a Google Scholar search, just out of curiosity. And yes, as many studies suggest, there does seem to be a link. Makes sense. Males that more ease-ily venture into novel social situations will encounter more females and show greater confidence in talking to them. In making the sale to mate.
But just because something makes sense doesn’t mean it is fully true, of course. Until I see good evidence supporting the links I make, I tend to refrain from putting full confidence in an idea. At least I try to.
In many ways, birds are like humans. Or maybe humans are like birds. No, that’s not right. Maybe both are animals and, as distantly related animals, share some attributes.
For instance, the behavior of both male humans and male birds is influenced by testosterone levels. While male birds don’t have external testes (can you imagine flying with those? — running upright is bad enough!) they do have internal testosterone-producing gonads. And new research has found that male birds with intermediate blood levels tend to do better.
In Costs and Benefits of Testosterone in Birds we learn that having high enough testosterone is good for a male bird’s mating success and survival. Testosterone gives a guy bird the starch in its spine (not the technical language) to acquire and defend a territory as well as the sexual drive to find/attract mates and . . . mate with them.
But while “enough” is good, “even more” is not better. In fact, it’s worse. The experimenters found that of the birds with their levels experimentally manipulated, those with levels near the wild average did the best. Too high means too much risky behavior, which leads to health-endangering fights and predation, etc. Too little means poorer territory (which includes poorer access to food and less desirable/safe nesting sites)as well as poorer reproductive success.
In another bird study, scientists found Wild Birds Opt for Conventional Food Over Organic, Study Shows.
Lead researcher Dr Ailsa McKenzie:
“We showed that when given free choice, wild birds opt for the conventional food over the organic, and the most likely explanation is its higher protein content.”
It may simply be an unfounded stereotype, but many human males, and a fair share of females, too, seem to prefer a fat and protein laden steak dinner over high-vegetable-content alternatives. For dessert: a calorie-rich but nutrition-poor piece of pie. Why? It’s elemental: our evolutionary history placed a premium on what was then higher value foods: protein and calories. Green leafies — a belly full of that would give you the energy to last a day at best. And for building muscles salad alone gets a failing grade.
While animals — birds and humans and thousands of other types — live in a present environment, their body plans and functioning physiology was shaped years ago, in one past. How well do they fit their immediate environments? Only time will tell.
For those uncomfortable with change, you might want to start your own self-sustaining community. Call it 1950′s-Ville. Or 60s or 90s-Ville, or even 2010 Town.
Our world and what we understand about it is in flux. There are very few absolutes to tether your mind to. That’s probably why many people will simply make some up.
What follows are two science “quick hits.” One demonstrating how scientific knowledge is rapidly progressing. Which is change. The other providing me the opportunity to speculate about a change in the making.
1. In Mirror neuron system functions normally in autism we learn:
New research suggests that a brain system called the mirror neuron system, previously implicated as being dysfunctional in autism appears to function normally in individuals with autism spectrum disorder (ASD). [bolds mine]
Some may wonder, is this progress? Well, yes it is. Science very frequently advances by subtraction. Hypotheses are made, then tested. And when we see one is incorrect Eureka! some uncertainty has been eliminated. Besides knowing of “what is” knowledge includes an understanding of “what is not.” Null results ain’t sexy, but they help us advance toward the true by subtracting the false. Of course, an important word in the above quote is “appears.”
The article also included this:
The study, published by Cell Press in the May 13 issue of the journal Neuron, argues that difficulties in social communication experienced by individuals with ASD are caused by neural abnormalities other than a mirror neuron system dysfunction.
Time to find those other neural abnormalities by setting a course of action, testing it, and then changing course if it proves to be a dead end.
2. In It Was Brawn Over Beauty in Human Mating Competition, Anthropologist Says we encounter these . . . facts?:
“On average men are not all that much bigger than women, only about 15 percent larger[. . . .] But, the average guy is stronger than 99.9 percent of women.”
[W]omen tend to store more body fat, while men have 60 percent more muscle mass than women.
Here’s my speculation. While the above numbers may have been true for one/all human populations past and perhaps present, the numbers are likely to change significantly in the future. Why? Exercise builds muscle and burns fat-building calories. Males, on average, are getting less of it in their daily lives (keyboard operating finger muscles don’t count), while females are becoming more active, at least in terms of athletics.
How much will those numbers change (if they haven’t already, which I suspect they have)? I don’t know. Gender hormone differences will likely prevent perfect parity — it’s much easier to grow muscles when the tissue is fertilized with high levels of testosterone. Still, there is more to behavior and even physiology than hormones.
The world is changing. While the kitchen was “the place” for females in decades past (or so the stereotype goes), today it may be the basketball court. And elsewhere. This will influence all sorts of things. I, for one, am curious to see what develops, and have no attachment to past gender roles perceived as being the ones nature and/or a god intended. And so I won’t be moving into 70′s-Ville. I’ll keep rolling into an unfolding future. Fortunately, my home has wheels.
Dudes! We’ve got the hormone prolactin circulating through our muscled bodies (perhaps formerly or potentially muscled). Recent research told me so. How will science emasculate us next?
In case you are unfamiliar, prolactin is a girly hormone if there ever was one. Think “lactation.” Here’s a snippet from Wikipedia:
In breastfeeding, the act of an infant sucking the nipple stimulates the production of prolactin, which fills the breast with milk via a process called lactogenesis, in preparation for the next feed.
Holy smokes. We’ve known that Victoria has a secret. Now it seems Victor does too. What’s his?
First, let it be noted that prolactin plays other roles in the human body, including in sexual activity, particularly orgasm. So maybe we shouldn’t be rushing off to have this hormone with a pink reputation removed from the visually protruding veins in our forearms.
And yes, manly men can have a sensitive side. For instance, is there anything more he-man than a mass of toughness cradling an infant? He will obviously protect his little precious to the death.
So here’s the secret: It seems that prolactin plays a role in that, too. Experiments on rodents have revealed:
In normal mice, the hormone prolactin is produced in adult males in response to physical interaction with their offspring. This research illustrates that prolactin is essential to the generation of new brain cells and memory. Paternal mice without prolactin signaling fail to generate more neurons when they physically interact with their offspring and, therefore, cannot recognize those babies when they become adults. [source, bold mine]
Okay, we men aren’t mice. Maybe rats some times. . . . However, it is likely that the above finding pertains to our kind. Which means that whether or not you’ve got a hairy chest, prolactin will play a role in how good a mommy or daddy you are.
Interesting. Maybe men and women aren’t from separate planets. Maybe we just sleep on different sides of the bed.
Chemicals are bad, right? Chemicals . . . you don’t want those in your morning cereal!
Oh wait. Chemicals are just molecules of elements that occur in nature.
Okay, so natural chemicals are good. Like cyanide. Which is a simple molecule consisting of carbon and nitrogen. It is found in the seeds of apples and mangos, among other things. But cyanide can kill you, which isn’t good. Hmm.
What about the chemical oxytocin? To those unfamiliar with it, it certainly can sound unnatural. And the chemical is a relatively massive clot of a laundry list of elements. And yet the human body naturally produces this hormone. So it’s good, right?
What about the synthetic form? Produced in a laboratory. Some would say this is bad, or not-as-good, because, once again, it is not natural. It wasn’t produced by Nature herself. Rather, John Q. Safety Goggles produced it by combining refined elements.
It seems to me that that the naturalistic fallacy is akin to believing in homeopathy: somehow the chemicals retain the memory of something no longer present but retain a good vibe. Or something.
Back to oxytocin. New research, conducted in a laboratory by Susan P. Clipboard, no doubt, has discovered that delivered as a spray, the hormone can improve male sensitivity. No, not sensitivity “down under,” but social sensitivity.
Here’s a particularly information paragraph from the news release:
In summary, Dr. René Hurlemann of Bonn University´s Clinic for Psychiatry was able to state that “significantly higher emotional empathy levels were recorded for the oxytocin group than for the placebo group“, despite the fact that the participants in the placebo group were perfectly able to provide rational interpretations of the facial expressions displayed. The administration of oxytocin simply had the effect of enhancing the ability to experience fellow-feeling. The males under test achieved levels which would normally only be expected in women. [bolds mine]
In-ter-est-ing.
I wonder, do more sensitive guys “naturally” have higher levels of oxytocin, or more receptors for the molecular substance?
Chemicals, man. Without them, we’d be . . . cold nothings.
I’m sure lawyers have tried, and maybe even some succeeded, in making the “PMS defense.” My client couldn’t help taking an axe to her husband, she was under the influence of PMS. Certainly it is a running stand-up routine and sitcom gag. But is there any truth to it?
PMS, and the degree to which the symptoms are psychogenic (learned/cultural . . . unconsciously “amplified”?) is actually a contentious, and fascinating, topic. During my decade teaching psychology, even the textbooks I used differed widely in their portrayal of it. While the developmental psychology texts seemed to accept it at face value, the introductory/general psychology texts cast great doubt upon its prevalence and typical severity. It sited significant cross-cultural differences (some don’t even recognize it) and a number of studies that found no evidence of significant emotional/social/work impairment during “that time” of the month for women, when such things as anecdotal reports and hindsight bias were eliminated.
Hmm.
Yet I can see how there could be something physiological going on. Hormones can exert a significant influence on many aspects of human psychology. An extreme example includes this recent, somewhat tangential, research finding:
Brain estrogen shows promise as schizophrenia treatment
Huh?
A study has found that Raloxifene – a synthetic estrogen currently used to treat osteoporosis – has beneficial effects on postmenopausal women with schizophrenia, with a test group experiencing a more rapid recovery from psychotic and other symptoms compared to control groups.
Research project leader and Director of the Monash Alfred Psychiatry Research Centre (MAPrc) Professor Jayashri Kulkarni said women in the trial who were given 120mg a day of the unique selective estrogen receptor modulator had a significantly greater improvement in psychosis symptoms compared with those on placebos and lower doses.
“The results were very promising. Under daily treatment with this ‘brain estrogen’, the women in the study had improvement in their key psychosis symptoms and also experienced enhanced memory and higher learning capacity,” Professor Kulkarni said. [bold mine]
Yes, hormones can and do influence human psychology in many, complex ways. Yet so can social/cultural dynamics. My own verdict is that our culture is likely guilty of exaggerating (and encouraging by fostering preconceptions and directing attention to) the PMS-defense.
Of course, there is a great deal of individual variation in how much a woman’s estrogen and progesterone levels fall and rise over the course of her cycle. As there is likely individual variation in how these fluctuations influence her brain. But influence they certainly can.
