That is probably true sometimes. But we have sequenced the entire human genome, so shouldn’t we know about all the genes? Well, yes and no. We may have a list of genes found in a sample of humans, but “The Human Genome” can consist of a single individual (though it does not) and miss variation between individuals, i.e., it may not be a record of all of the possible alleles (variants) of each gene. Also, beyond the scope of this discussion but worth mentioning, a “gene” is not a simple concept. Whether or not a gene is expressed, where, when, and exactly what product it produces is not entirely encoded in the gene itself, but rather, elsewhere in the genome, or not encoded at all, but rather, dependent on external, non-genetic factors. So that complicates things too. So, if there is a trait that you think must be genetic, but years of research have failed to find it, the existence of a human genome and the prior acquisition of a lot of genetic data does not necessarily mean that the genetic information that determines the trait in question is not there. You can continue to believe that the genetic code for the trait will eventually be found

Except when you can’t.

There are two separate ways in which people sort out which traits are assumed to be genetic from those that are assumed to be not genetic. Both are heuristic, one is valid, and one is not. Let’s start with the one that is valid.

Suppose, as before, there is a trait that is seemingly inherited in families in such a way that a genetic trait would be, in the time tested manner that with respect this trait “offspring resemble their parents” as Darwin noted. The next question you can ask is this: Is it biologically sensible that this trait is inherited genetically, or is there a better, obvious, non-genetic mode of inheritance? If the trait is a physical feature such as eye color, then we have a sensible biological explanation for the trait having to do with developmental process we know something about and a set of metabolic pathways that produce various molecules such as pigments. The idea that this trait is genetic is biologically sensible, so even if you can’t find any, or all, of the genetic determinants of this trait, you can figure they are out there somewhere. Suppose, though, that the trait is a behavioral one that we see people in real life learning. For example, what language a person speaks generally follows the same kind of inheritance pattern many clearly genetic traits follow. With respect to spoken language, most of the time, offspring resemble their parents. But, rather than there being a sensible biological explanation for this trait, there is a sensible cultural explanation for this trait, so we don’t even look for the genetic variants for “French” vs. “Mandarin” vs. “English.” We simply assume this is not genetic.

The second method, the incorrect one, is to work with an article of faith. Broadly speaking, and I oversimplify greatly here, there are two primary articles of faith that often inform people’s thinking, shaping their assumptions, about genetics. Both usually have to do with behavioral traits in humans, but this can apply to physical traits as well. One article of faith asserts that humans are born as a blank slate, and all of their behavioral characteristics, such as their personality, intelligence by one measure or another, and so on, are added by experience. The other is the inheritance assumption, that some or much of an individual’s personality, intelligence, etc is determined by genes. There is not necessarily a consistent logic behind either of these assumptions, though various schools of thinking will include, often, a logical framework. However, this method of coming to a conclusion about the genetics or lack thereof behind various traits relies on one important element regarding genetic systems: Ignorance. If you are a blank slatist, then the absence of a clear pathway from genes to behavior means that your hypothesis can’t be falsified. If you are a genetic determinist, then the lack of such a pathway can be attributed to ongoing ignorance about the genes. The former might then be expected to live in fear that a gene will be found for their favorite learned behavior, and the latter might be expected to to live in a state of hubris, firmly knowing and asserting a truth that is not yet known but someday will be.

My impression is that over time there are fewer and fewer pure genetic determinists out there, and few and fewer blank slatists. I think the reasons for that shift have little to do with increasing knowledge, and more to do with changes in how one plays the academic game of argument, but that is discussion for another time. There is a danger in that shift, though. In the absence of any useful research results, if blank slatists start to admit that there could be some sort of genetics behind behavior, and determinists start to admit that experience and learning can also play a role, then we are converging on an increasingly simplified view of what is really a very complicated process. We should be gaining more complex, nuanced, and better informed views of how behavior arises, not simpler ones. Probably.

Over the last few decades, there have been a few important changes in how we should view human behavior over generational time and variation in those behaviors within and across categories (gender, ethnicity, geography, etc.). In short, certain behavioral traits have shown, synchronically (lacking the perspective of change over time) patterns that look genetic. For example, some families seem to be extra smart. Some have suggested that some “races” are smarter than others (at another time we can discuss why there really are no races, but let’s use “race” here as a potentially valid sampling strategy, which it can be even if the underlying races are fictions). We also see assertions of behavioral differences between the primary sexes (male vs female).

These observations are really statements about variance. Two groups are different, but vary within. There is overlap in the trait (i.e., IQ) but the means vary. We can statistically test the validity of the asserted differences in means by examining the variance in each sample and seeing if the mean of one sample fall within the predicted range of the central tendency of the others. In other words, asserting that there is a statistical difference between two groups is a process that involves understanding the variance of the underlying population(s) and samples. So, the questions can all be reframed in this manner:

Is the variation we see in trait X across certain groups best explained by underlying corresponding variation in the genetic system, or by the variation found in some other cause?

People fight vigorously over the underlying cause of IQ differences between groups. Some say it is primarily genetic, some say it is primarily not genetic, but rather, related somehow to what has become known as “lived experience.” Over the last couple of decades, there have been many attempts to explain observed variation in IQ using socioeconomic status, diet, education, issues having to do with test making or testing procedures. All of these factors have been shown to explain differences between groups to a modest to large degree in several studies. In other words, if you want to explain variation in IQ using non-genetic explanations, you can have some real success.

The genetic explanation of variation in IQ has had success in one main area which is irrelevant. This is the fact that genetically determined developmental differences between people that affect function that are generally classified as disorders predict large IQ differences. But this set of effects is not related to the question being asked.

The strongest evidence for a genetic underpinning of IQ is probably the large scale racial model solidified years ago by J. Philippe Rushton. He demonstrated that there is a grouping of brain sizes by race, with Asians having the largest brains, Caucasians the second larges, and Blacks the smallest (these race terms are his). He then showed that these brain sizes correlated with IQ difference. The modern psychometric literature assumes a racial difference in IQs, and asserts that this difference is real, but does to by citing sources that then site sources that ultimately cite Rushton. Rushtons all the way down, as it were.

The problem with this is that Rushton’s analysis was bogus. The brain sizes were taken from such sources at hat sizes for army conscripts classified by race, with the hat sizes used to estimate brain size. The Black (African) brain got smaller because Rushton subtracted a factor from that estimate of brain size, using an archaic thick skulled African fossil to assume that Africans have very very thick skulls. Correspondingly, the Asians were assumed to have thin skulls, and thus, got larger brains. The IQ data is similarly adulterated. In one part of the study, Rushton needed an “African” (native) IQ value, so he used the results of a test administered by racist anthropologists commissioned by the Apartheid government of South Africa to prove the inferiority of Blacks. And so on. The bottom turtle in this edifice is a fake.

The range of variation across “racial” groups (or other groups) in modern IQ data is very small compared to the change in IQ measured or estimated over decades of time through the 20th century within a single large and diverse population (Americans). If IQ is genetically determined and a stable feature of behavior, then there has been more evolution of these genes over less than 100 years of time in the US than we see across any two groups of modern humans. That is impossible. Again, IQ does not behave nicely as a genetic trait.

The discovery of a gene or set of genes that would underly IQ has not happened. In some recent studies, IQ is assumed to be very complex and the result of many different genes, and there is some statistical evidence for this. But, there is a big problem there too. Any trait can be linked to a set of genetic variants if the set of genes is large enough. That is a statistical effect and it is not really a link. More like a party trick, or a con game. (In fact this method is a con you may have heard of. I send 10,000 people an email predicting that a certain stock will go up, another 10,000 people an email predicting it will go down. One or the other happens. I then send 5,000 of the people who got the “correct” prediction another prediction, and 5,000 of them the opposite prediction. Now, 2,500 people have gotten two correct predictions from me. I keep doing that until I’ve got several dozen people convinced I am a stock market genius, and I take their money.)

Generally speaking, many behavioral traits have been explained, in part and sometimes in large part, by factors that are not genetic, while at the same time, the hunt for the presumed underlying genes have come up empty. There was great optimism up through the 1990s that genetic underpinning of human behavior … genetic variation corresponding to behavioral variation … would be found. But even as early as 1993 this was being questioned. Here is a sidebar, reproduced in full, from a Scientific American article by John Horgan summarizing the work up to that time:

Behavioral Genetics: A lack of progress report (1993)

CRIME: Family, twin and adoption studies have suggested a heritability of 0 to more than 50 percent for predisposition to crime. … In the 1960s researchers reported an association between an extra Y chromosome and vio-lent crime in males. Follow-up studies found that association to be spurious. MANIC DEPRESSION: Twin and family studies indicate heritability of 60 to 80 percent for susceptibility to manic depression. In 1987 two groups reported locating different genes linked to manic depression, one in Amish families and the other in Israeli families. Both reports have been retracted. SCHIZOPHRENIA: Twin studies show heritability of 40 to 90 percent. In 1988 a group reported finding a gene linked to schizophrenia in British and Icelandic families. Other studies documented no linkage, and the initial claim has now been retracted. ALCOHOLISM: Twin and adoption studies suggest heritability ranging from 0 to 60 percent. In 1990 a group claimed to link a gene—one that produces a receptor for the neurotransmitter dopamine—with alcoholism. A recent re-view of the evidence concluded it does not support a link. INTELLIGENCE: Twin and adoption studies show a heritability of performance on intelligence tests of 20 to 80 percent. One group recently unveiled preliminary evidence for genetic markers for high intelligence (an IQ of 130 or higher). The study is unpublished. HOMOSEXUALITY: In 1991 a researcher cited anatomic differences be-tween the brains of heterosexual and homosexual males. Two recent twinstudies have found a heritability of roughly 50 percent for predisposition to male or female homosexuality. These reports have been disputed. Another group claims to have preliminary evidence fo genes linked to male homosexualty. The data have not been published.

This is from a study by Jay Joseph on the “Classical Twin Method in the Social and Behavioral Sciences”

The classical twin method assesses differences in behavioral trait resemblance between reared-together monozygotic and same-sex dizygotic twin pairs. Twin method proponents argue that the greater behavioral trait resemblance of the former supports an important role for genetic factors in causing the trait. Many critics, on the other hand, argue that non-genetic factors plausibly explain these results…. In 2012, a team of researchers in political science using behavioral genetic methods performed a study based on twin data in an attempt to test the critics’ position, and concluded in favor of the validity of the twin method and its underlying monozygotic–dizygotic “equal environment assumption.” The author argues that this conclusion is not supported, because the investigators (1) framed their study in a way that guaranteed validation of the twin method, (2) put forward untenable redefinitions of the equal environment assumption, (3) used inadequate methods to assess twin environmental similarity and political ideology, (4) reached several conclusions that argue against the twin method’s validity, (5) overlooked previous evidence showing that monozygotic twin pairs experience strong levels of identify confusion and attachment, (6) mistakenly counted environmental effects on twins’ behavioral resemblance as genetic effects, and (7) conflated the potential yet differing roles of biological and genetic influences on twin resemblance. The author concludes that the study failed to support the equal environment assumption, and that genetic interpretations of twin method data in political science and the behavioral science fields should be rejected outright.

With respect to psychiatric disorders, from the same author:

The psychiatric genetics ?eld is currently undergoing a crisis due to the decades-long failure to uncover the genes believed to cause the major psychiatric disorders. Since 2009, leading researchers have explained these negative results on the basis of the ‘‘missing heritability’’ argument, which holds that more effective research methods must be developed to uncover presumed missing genes. According to the author, problems with the missing heritability argument include genetic determinist beliefs, a reliance on twin research, the use of heritability estimates, and the failure to seriously consider the possibility that presumed genes do not exist. The author concludes that decades of negative results support a ?nding that genes for the major psychiatric disorders do not appear to exist, and that research attention should be directed away from attempts to uncover ‘‘missing heritability’’ and toward environmental factors and a reassessment of previous genetic interpretations of psychiatric family, twin, and adoption studies.

And from researcher Tim Crow:

A substantial body of research literature, identified by nine out of ten papers on genetics in the recent ISI research front on schizophrenia, claims to have established associations between aspects of the disease and sequence variation in specific candidate genes. These candidatures have proven unreplicated in large sibling pair linkage surveys and a targeted association study. Even if the case for an association be regarded as a lucky guess (assuming one gene in 30 000 was guessed right) the large linkage and association studies provide no evidence of sequence variation relating to psychosis at any of these gene loci. Thus this body of work must be regarded as an indicator of the extent to which the ‘eye of faith’ is able to discern meaning in complex data when none is present.

I could go on. There have been further criticisms of the twin studies, for example. The most interesting, potentially, of these studies was on twins reared apart, more or less separated at birth. Commonalities among such individuals would be strong evidence for a genetic underpinning, because these individuals were raised in completely different environments so there would be no chance of a learned or cultural component other than a general background effect of having been raised n the same planet, or in the same country. Right? Well, no. Twins separated at birth were mostly twins that were not all that separated. After all, where do researchers actually find twins truly and distantly separated at birth, especially in the days when people seeking birth parents had hardly become a thing yet? Many of these twins, probably the vast majority, were separated only in the sense that they were raised by different members of the same family, or separately by divorced parents. Many were raised in the same neighborhood or often, the same house. My brother and I are not twins, but we were “raised apart” by the criteria of the twin studies because my family was distributed among the rooms of a two family residence, so technically he and I had bedrooms at different addresses.

In sum, it is easier to find sociological, cultural, or environmental explanations for variation in human abilities, intelligence, or personality traits. The seeming inheritance by family of some of these traits may well be a combination of something genetic and something experiential or cultural, but when looking for the actual underlying causes, genetics has repeatedly come up wanting while environmental explanations do a good job of addressing a fairly large part of the variation we see. Models of race based differences are so poorly done, and are often highly politically motivated, that they should never be trusted. That scientific ship sailed a long time ago.

Maybe the blank slate theory isn’t so bad after all. It does not imply that just anything can happen when making a human being out of a sperm and an egg. After all, it is a blank slate and not a blank whatever. But it is probably not true that some people’s lived experiences are written on slate, while others on white boards, and still others on smart boards, even if there are some people who I’m sure assume that they were.

Selected references:

Horgan, John. 1992. Eugenics Revisited. Scientific American. June.
Joseph, J. (2011). The Crumbling Pillars of Behavioral Genetics. GeneWatch, 24 (6),4–7. Web page
Joseph, J. (2012). The “Missing Heritability” of Psychiatric Disorders: Elusive Genes or Non-Existent Genes? Applied Developmental Science, 16(2), 65–83. doi:10.1080/10888691.2012.667343
Joseph, J. (2013). The Use of the Classical Twin Method in the Social and Behavioral Sciences : The Fallacy Continues, 34(1), 1–40.
Lewontin, R. Human Diversity. 2000, Scientific American Library.
Marks, J. (2008) Race: Past, Present, and Future. In: Revisiting Race in a Genomic Age, edited by B. Koenig, S. Lee, and S. Richardson. New Brunswick, NJ: Rutgers University Press, pp. 21–38. PDF
Marks, J. (2008) Race across the physical-cultural divide in American anthropology. In: A New History of Anthropology, edited by H. Kuklick. New York: Blackwell, pp. 242–258. PDF
Tizard, B. (1974). IQ and Race. Nature, 247, (5349), 316.

Other posts of interest:

• How to get rid of spiders in your house
• Why is your poop green?
• How many cells are there in the human body?
• Is there really a plot hole in Harry Potter Goblet of Fire?
• How long is a human generation?
• Is blog ever really blue?
• How to not get caught plagiarizing
• The origin of the domestic chicken
• What are the three necessary and sufficient conditions of Natural Selection?
• How do I get rid of foot fungus?
• Which is better, Tap Water or Bottled Water?
• Has Global Warming stopped?

Also of interest: In Search of Sungudogo: A novel of adventure and mystery, which is also an alternative history of the Skeptics Movement.

On Friday, June 24, President Obama designated the Stonewall National Monument – the first national monument dedicated to telling the story of the lesbian, gay, bisexual and transgender community’s struggle for equal rights.

Listen for the Ken Burns tribute near the end.

Here’s the press release for the paper:

Scientists know that temperature determines sex in certain reptiles—alligators, lizards, turtles, and possibly dinosaurs. In many turtles, warm temperatures during incubation create females. Cold temperatures, males. But no one understands why.

A recent study sheds further light on this question. The findings of researchers Kayla Bieser, assistant professor at Northland College, and Thane Wibbels, professor of reproductive biology at the University of Alabama at Birmingham, will be published this month in the primary research journal “Sexual Development,” and is now available online.

This study represents the most comprehensive, simultaneous evaluation of the chronology of how sex-determining genes express themselves during embryonic development and and looks at the impacts of estrogen.

Bieser and Wibbels followed five different genes and what was going on in the exact same turtle. To date, scientists have looked at a number of turtles and pooled the data but Bieser is the first to follow individual turtles. She wanted to know when and how they “express” themselves. For an example, Bieser describes expression as the physical manifestation of those genes such as blue or brown eye color.

She looked at turtle eggs incubated at male and female temperatures and documented what the genes were doing while sex is being determined. “Which genes ‘turn on’ and when, could be an indication of what is triggering sex,” Bieser said.

According to Bieser, temperature-dependent sex determination species may be unable to evolve rapidly enough to offset the increases in temperature, which may ultimately result in their extinction.

“It’s critical that we understand the genetic mechanisms for which temperature acts and incorporate this knowledge into management plans for the conservation of these vulnerable species.”

Secondly, Bieser applied estrogen to eggs at a male-producing temperature. The purpose she said is to help determine the triggers for sex determination and how hormones, such as estrogen, can override the temperature signal.

In other words, would temperature or estrogen win out in deciding sex? The answer: in short, neither. What she found — and this is new information — is when estrogen is applied to eggs incubating at a male temperature, gonads—or sexual parts—do not develop. Or, if they do, they barely develop.

Why? “We don’t know yet,” Bieser said.

Scientists have been doing this experiment for some time but never reported these results. She suspects the reason is because scientists did not dissect the gonadal area specifically and that they took the general area but may have not analyzed the gonads to the same detailed level. In fact, this was a sticking point for one of the reviewers of this study—so Bieser provided photos of her findings.

“This research provides a critical understanding of how temperature acts on and above the genes in species where temperature determines sex—this is particularly critical in light of global climate change,” Bieser said.

Here’s the video:

The original paper:
Bieser K.L. · Wibbels T. 2014. Chronology, Magnitude and Duration of Expression of Putative Sex-Determining/Differentiation Genes in a Turtle with Temperature-Dependent Sex Determination. Sexual Development 8(6).

No, seriously. In a certain archaeological culture known from the vicinity of Prague, male and female burials are distinguished by the mode of burial and the artifacts. The males tend to be buried with their heads towards the west and along with various weapons. Females, on the other hand, tend to be buried with their heads towards the east and surrounded by domestic jugs.

This is interesting for many reasons (to an archaeologist, at least) but even more interesting is the possible discovery of a transgendered person’s burial. This is a male skelton buried in female style. (This story was first reported in 2011, but is being talked about again lately. Which is OK because we really don’t need to ignore or devalue everything that happened more than 72 hours ago, right?)

I quickly add the following caveats:

1) I’ve never seen an archaeological culture where the artifacts matched with the burial practices perfectly. For a number of reasons, what ends up happening under ground is not culture-normative. So, the generalization I provided above is only a generalization; and

2) The skeleton is presumably sexed (that’s the word we use for assigning sex… if you are dead, and a bone, an archaeologist or physical anthropologist will sex you) using the usual techniques of identifying several markers on the skull and pelvis, and a few other measurements, and overall robusticity. This can be wrong. It works, but it can be wrong a lot.

Also, this is not terribly uncommon. Well, it’s uncommon, but it happens. I think it is more common to find probable females in male settings, though.

The story is reported here.

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BIC Cristal For Her has an elegant design – just for Her! It features a thin barrel designed to fit a women’s hand. It has a diamond engraved barrel for an elegant and unique feminine style.

Bic actually makes several feminine pens:

• BIC Cristal For Her Ball Pen
• BIC For Her Retractable Ball Pen
• BIC For Her Fashion Retractable Ball Pen, Fashion Ink
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I recommend getting the assorted pack, and they you can try them all out and see how each one feels, and then if you settle on one that works really well for you, order that one on line in bulk to save money. Always carry a couple of the with you in case you want to write something.

Oh, and just in case you did’t know, the reviews on these products are a blast! Its a new internet meme.

Someone has answered my gentle prayers and FINALLY designed a pen that I can use all month long!…

Finally! For years I’ve had to rely on pencils, or at worst, a twig and some drops of my feminine blood to write down recipes …

I don’t know why they didn’t put a clearer warning on the label, they really should have because if you are a boy and use this pen you put yourself at great risk. My little brother turned into a unicorn…

See also Menz with Penz

[doesn’t] rule out the existence of very small biological difference, but, by comparing test scores across cultures, [does] indict local social factors as the likely primary culprit. Gender gaps vary from place to place, showing that cultural factors swamp biological ones.

Read about the study here.

Speaking of time, this was one of those days when it got to 3:30 in the afternoon when I decided I should get a second cup of coffee and have some breakfast. In the end, combining breakfast with dinner is more efficient, but I probably would have been less edgy, oversensitive and easily traumatized earlier in the day had I eaten properly in the morning. (For which I apologize. To “you know who you are.” Not that you read my blog or anything, but in case you do… 🙂

There are several items I do wish to point out to you today. First, don’t forget to listen in to the upcoming podcast of Skeptically Speaking, which features the insectiphilia of Bug Girl herself as well as a side trip through the anthropology of Arthropodiphagia by yours truly. And while we are on the subject of me, if you’ve not see them yet, please check out this blog post about birds — What happened with Archaeopteryx? as well as this blog post also about birds — The Dove of Peace Has Not Always Been Safe. Also, although I have a long list of birdy topics I plan to address at 10,000 Birds, I’d be happy to take your suggestions as well. Are there topics concerning bird evolutionary biology that you’d like to see addressed? Let me know in the comments or via email.

Enough about me. There are also some things I’d like to point out happening out there on the intertubes. Speaking of Trauma, please have a look at This Blog Post at Traumatized By Truth, in which DuWayne Brayton makes a small request for help. I sent a chemistry book. If you are a FOD, please go help him out.

And I want to spend a moment discussing This Post about scientific literacy and sex by Sheril Kirshenbaum over at her new blog (which is great fun, add it to your RSS reader). Sheril shows a bunch of graphs from a study comparing males and females in the degree to which they are smart about science. Or not.

55% of males know that it takes one year for the Earth to go around the Sun, while a mere 42 percent of females know this. A similar result is found for knowing the relative size of atoms and electrons. A sex reversed result obtains regarding the idea that it is the father’s gene that decides whether the baby is a boy or a girl: More females get that right than males.

Interestingly, all three assumptions can be questioned. The Earth does not go around the sun in one year. It takes longer (thus leap year and the occasionally leap second). Electrons might be small, but they take up more space than the nuclei of atoms. It is not universally true in mammals that the male’s “gene” determines sex of offspring. Yes, sex of zygote, but to get an offspring you must not selectively abort it. In Red Deer, females determine the sex of their offspring using some sort of biological magic, and this is true in many other mammals. Prolly not in humans, though.

But seriously, these data obviously reflect two things: 1) Everybody is poorly educated in science but to varying degrees and 2) how bad this is may be sex-biased in the expected ways, with males being less misinformed about the physical sciences and females being less misinformed about the life sciences. Why that sex bias exists is, of course interesting and important.

Which brings us full circle (back to me!) When I was working as an administrative assistant (putting myself through graduate school) at the Kennedy School of government, this thing went around that was rather annoying and related to this. This was male economists (faculty and graduate students, and yes, if I listed the names you’d have heard of some of them). It’s a small experiment you can carry out on your own. You ask a person a question and see what the answer is, and each of the economists claimed that when they asked their female significant other, she did not know the answer, but if they asked a randomly chosen male, he did.

Here’s the question. The speed of light is 186 thousand miles a second, and the speed of sound is a slow 700 feet a second. When I sit in my home in Cambridge and turn on WGBH, and that tower is across the Charles River, I get the sound and video at the same time, synced. If I drive north several hundred miles to Concord New Hampshire, and turn on WGBH I get the same thing… sound and light are synced. If sound and light travel at different speeds, how can this be????

So, I took this question and asked my female wife. Then I asked five or six female colleagues over in the Anthro department. They all knew the answer. (“The question is absurd. The signal for both video and sound that is decoded in your TV is a radio signal, essentially light, and the sound is not transmitted from the tower to your house, duh.” … or words to that effect.)

So, while high profile economists who write books about human behavior, race, and sometimes get jobs in the White House were convincing themselves that males are smarter than females, I was busy discovering that high profile economists that write books about human behavior, race, and sometimes get jobs in the White House choose compliant girlfriends and spouses who tell them what they want to hear. Apparently.

Prior to birth there are a number of factors than can influence things like gender or sexuality in a human. You have probably heard of the finger-index (not the index-finger … actually called the 2D:4D ratio). The ratio of length of two of your fingers seems to be associated with certain trends; Men with a certain ratio tend to be more athletic or more gay, for instance. The mechanism for the finger ratio variation is probably straight forward but has not been nailed down yet. Likely, a surge of steroid hormones enhances growth rate of whatever bones are forming at that time (I simplify somewhat) and if such a surge occurs at a certain time, a slight shift in bone length ratio affecting fingers occurs and because of the timing, a slight change in something else also occurs, something having to do with what will eventually be adult behavior.¹ I am not arguing here for the strength of this association or its meaning, but available evidence shows that there is something going on. To the extent that this particular relationship is true, we see an adult outcome (related to gender, sexuality, or other behavior) being the result of something that is biological and prenatal, but not likely genetic. While the overall pattern of the hormonal environment of a fetus may be broadly determined by genes, variations in the details are just as likely determined by other things. In many contexts, one steroid hormone looks a lot like another, or can convert into another as they float around in the blood supply, so any large surge of steroids could act like sex hormones or growth hormones even if they are merely stress hormones, and there is an exchange of hormones between the mother’s blood supply and that of the fetus. Since the mother’s hormonal environment is heavily influenced by her environment (especially stress hormones), the ultimate cause of steroid hormone-mediated developmental variations in a human is very likely to be strongly environmental, if not entirely environmental, even though it all happens before birth.

Then there is the stuff that happens after birth. One study carried out in Australia seems to show that adults in a specific culture (Australian middle class) treated infants very differently depending on their knowledge of the infant’s sex.² For instance, a boy would be moved around more, tossed about a bit, handed boy-specific toys, and so on, while a girl would be held more calmly, not tossed about, hugged more, and handed girl-specific toys. In that study, the “sex” of the infant (boy vs. girl) was “known” to the adult on the basis of obvious clothing choices and pronoun use, and in fact, the infant was always a boy. After months of treatment as one sex or the other, depending on what that treatment consisted of, one could potentially get a gendered difference. Movement, touch, voice, etc. all form part of the environment in which the infant’s neural system, including the infant’s brain, develops. This would make a difference.

And so it goes throughout development; At numerous stages along the way, a human is affected by hormones, bathed in gendered behavior, and eventually, starts to observe her or his own environment and act accordingly. One study seemed to show that at about Kindergarten age, boys were more conscious of how they would fit into a group than girls, paying special attention to what other boys were doing before making certain choices. If this was a general pattern in a particular group of people, one might see girls engage in a wider range of available stereotypes while boys restricted themselves to a narrower range.

While it is possible that there is some hidden Jungian subconscious difference between nominal boys and girls resulting in different thematic tropes in their behavior (i.e., girls like circles and boys like lines or some such thing), the degree to which kids past a certain age … say six or so … gravitate towards gender specific toys or other objects, or engage in gender specific behaviors, is way too finely tuned to be the product of anything other than high cognitive function. While we know that across cultures, different colors are associated with different genders, within a culture most boys and girls know what the boy vs. girl colors are and to varying degrees express this knowledge as strong preferences, perhaps with boys expressing a narrower range of preferences than girls. Most likely, culturally specific gender preferences for things like toys and clothing are learned early, become deeply ingrained, are unlikely to be genetically determined at any level of detail (if at all) but may be attended to by boys more than girls.

There are many factors that would determine a person’s gender over a lifetime. The above mentioned inter-uterine hormonal conditioning is probably fairly complex, with multiple moments in time when one or another thing might happen, and where one version of the developmental scenario would lead towards one gender orientation than another. After birth, more of the same but less hormonal and more cultural, and later on, with puberty, the hormones kicking in again, but with a twist: Early conditioning may determine the nature of later hormonal activity by setting up differences in receptor sites or sensitivity, or other aspects of hormone feedback systems.

In speaking of humans it is easy to assume that other animals, who lack the complex and often costly (and therefore presumably ‘important’ in some way) trappings of prolonged development and culture have simpler systems for determining gender. For the most part, I would argue that rodents do in fact have simpler systems of gender than do humans, with the caveat that I’ve just compared an entire order of mammals (and a rather speciose and diverse one at that) with a single species. But what would you make of a gender-shaping system in rodents that was actually very complex, in which ‘culture’ was the main determinant of adult male-ness?

In rats, males get to be males in large part because they have testes that secrete testosterone, which in turn causes other changes. But according to at least one study, the degree to which testes will secrete testosterone is determined by anogentital licking behavior of the mother. This behavior is, in turn, brought on by some sort of cue produced by the newborn male. Without this licking, the testes do not produce much testosterone and andorgenization of the rat does not take place.³

OK, so I was exaggerating slightly when I said that rat “culture” determines adult gender, but prior to hearing this you probably assumed that there was a gene or set of genes that simply coded for which sex the rat would be when it grew up. And yes, you can get some interesting results when the mother rat is replaced with a lab tech and various different variations of the licking thing are tried out. (Using tiny wet paintbrushes.)

And I could go on. But I want to make two points about development and behavior, especially gender. One is that whatever genetic component is working, most aspects of adult behavior and orientation are shaped by non-genetic factors and those genetic factors that may exist come in the form of basic species-specific (but almost certainly gender-differentiated) “drives.” I’ve discussed the importance of drives here, and if you want to read a whole book about the link between drives and everything you do in your life check out Mean Genes: From Sex to Money to Food: Taming Our Primal Instincts (See all Self-Help Books)

The second point is that as something complex (and both personal and social) as gender orientation emerges in a person it must be true that it comes to whatever point it comes to after a series of many turning points. If every single factor is thought of as a simple binary choice (and I use the word “choice” with no reference to human decision making) between two cannalized options, then the number of possible outcomes could be thought of as 2ⁿ where ‘n’ is the number of times a binary choice is encountered. So, if there are, say, three hormonal moments in utero, and one more after birth (puberty) and, say, three life stages that have major influences on gender (and I oversimplify) then the number of possible routes a person may take from conception to adulthood would be 2⁷. That is 128. If these different paths lead to mostly different outcomes, wouldn’t there be over 100 “genders” among humans?

The interesting thing about this is that a cursory examination of potential human gender diversity from a purely biological point of view suggests that there are at least dozens of “genders” but the vast majority of cultures define (or even allow) only a few. Perhaps culture, in this case, is more restrictive than biology. Which, to a behavioral biologist, is not much of a shock, though it might be if considered from a broader social science perspective.

So, the next time you are in charge of making a form to collect personal information from people, when you are designing the “gender” question, you might consider something other than a couple of checkboxes. Perhaps a drop-down list. Or, best of all, just have people write a short essay. Make ’em think, that will.

¹Be careful with this idea: While I’m sure there are several aspects of 2D:4D research that are valid and interesting, it is often somewhat over-reported. Also, the numbers are tricky. The measurement is often done on fleshed and living fingers, but should really be done on the bones directly (using X-ray technology, not sacrificing the subject and defleshing them!). And the meaning of this trait is somewhat open to interpretation. I’d be comfortable sorting out males from females in a skeletal population with good preservation of hands but no pelvic remains, but more reluctant to use this for sorting out ethnic groups, gender orientations, or assertiveness levels. For a recent review see Bailey and Hurd, 2005. Finger length ratio (2D:4D) correlates with physical aggression in men but not in women. Biological Psychology. Volume 68, Issue 3, March 2005, Pages 215-222.)

²The specific research to which I refer was shown on a documentary about sex differences; For an exemplar published study on this work see Frisch 1977. Sex Stereotypes and Adult-Infant Play. Society for Research in Child Development. Vol. 48, No. 4 (Dec., 1977), pp. 1671-1675

³See this study and references therein: Moore and Morelli, 1979. Mother rats interact differently with male amd female offspring. Journal of Comparative and Physiological Psychology, Vol 93(4), Aug 1979, 677-684. doi: 10.1037/h0077599.

Moore, C., & Morelli, G. (1979). Mother rats interact differently with male amd female offspring. Journal of Comparative and Physiological Psychology, 93 (4), 677-684 DOI: 10.1037/h0077599

Personally, I think that most biological drives, maybe all, produce extreme or pathological behavior if unchecked, and that therefore all drives are repressed to some degree in almost all individual humans. There is considerable evidence that things like anger, thirst, or fear (to use highly generalizable terms) are manifest as a balance between limbic circuits that are excitatory or inhibitory; Experimental interference with one or the other circuit produces extreme results such as a rat that will not stop eating or a cat that will maintain an arch-backed bristle-haired stance until it falls over in exhaustion.

Also, I think that what I’m calling drives (again, as a convenience … you won’t find what I am thinking on Wikipedia) are a basic mammalian trait. Therefore, it is reasonable to ask if some of the evolutionary events related to the rise of new species of mammals are related to changes in drives, or more interestingly (and more commonly, I suspect) changes in how drives are on one hand repressed and on the other hand re-configured to work with each other.

Thus, one could say that since humans are behaviorally derived with respect to many traits in comparison to African apes in general, a major feature of the human brain must be mechanisms telling the rest of the brain, to some extent every minute of the day, “Don’t be a chimp …. Don’t be a chimp. Seriously, dood … don’t be a chimp.”

At the individual level, and I’m oversimplifying a great deal here, one might imagine drives being enhanced or repressed to a degree that makes an individual very different from others. The fictional character “Brennan” on the TV series Bones comes to mind. She seems most of the time to have no drives at all, or to be intellectually in denial of them. Social and psychological pathologies may often be associated with drives that are inappropriately strong or weak.

So, is it really true that behaviors are not “caused by genes” if there are these drives? Yes, and I say this because the average person who is thinking that behaviors are caused by genes is not thinking at all about intermediate mechanisms, and if they are, they are assuming that the intermediate mechanisms are little more than a transparent ether through which genes operate on the behavioral phenotypes we observe. Also, “genetic determinism” is not about whether or not one or more genes are involved in a trait, but rather (and this is very important so if you’ve got a yellow highlighter uncap it now) “genetic determinism” is about the close correspondence between variation across individuals in the genetic code they carry and the ensuing variation across individuals in the phenotype they express. Moreover, “genetic determinism” as usually conceived is presumed to average out within categories such as “race” or “sex” with very little variation within, but enough variation between these categories to be measurable. Which is why the concept is almost always racist or sexist or both.

But in reality, variation in the way limbic and other brain functions as well as closely related endocrine systems are manifest in humans and probably many other mammals is only to a small extent a function of genes, and is otherwise a function of what we may loosely call development. This relationship is not a post-hoc observation, or a liberal excuse, or a politically motivated bit of rhetoric. It is, rather, the explanation for why we have large brains that mostly develop, in detail, on the basis of experience rather than genetic coding for how they are hooked up. (And, while this applies mainly to mammals, something like it might be going on in some birds.)

Consider long term habituation. When endocrinologists (those who study hormones) measure hormone levels, they generally adjust the numbers to account for individual baselines, because while two individuals may have very different baselines they can have the same range of behaviors and responses. Two men may have androgen hormone levels that vary between them by a factor of 2X or 3X, but have the same basic behavioral repertoire. This is because of two things: First, the number of receptor sites and their sensitivity matters as much as, if not more than, the serum hormone levels; and second, most hormone systems are some sort of feedback loop that relies on changes in concentration against set points that are individually established, not species-specific. Putting it another way, if a hormone system is like a thermostat in your house (a homeostatic equilibrium system) then each individual has a personally established and potentially unique “room temperature.” This variation between individuals could be genetic, but is it just as likely, or even more likely, to be developmental. A related example is the mechanism by which we become “cold” or “warm” (with respect to comfort). This is not innate, but rather, a function of exposure to environmental conditions in early life (thigh there are body-shape related variations that probably are genetic that matter to thermoregulation in a non-industrial population).

Given huge piles of evidence for individual variation in behavior as a function of context, conditioning, and development and relatively little evidence that has not been made up, cooked up, or otherwise tainted or damaged for straight forward genetic determination of behavior, I’m going to go with the model that humans vary mostly on the basis of their biological and cultural experiences post-conception. For example, the single largest factor in variation in human intelligence in a given population can easily be prenatal alcohol exposure, or variation in folic acid in the maternal diet. Given the amount of post-conception stuff the brain does in development, and how much of that depends on experience, it is very unlikely that brain function varies across individuals on the basis of genes (other than individuals with genetic disorders, but we need not count broken individuals in considering normative development).

From what we know about “drives” and from what we know about brains and development, it is very reasonable to hypothesize that variation across individual human males in something like violence levels, likelihood to carry out rape, or other widespread and usually male-associated behavior is environmental. Yet, these behaviors at the base, the systemic potential for these behaviors, is a mammalian feature or a primate feature or a great-ape feature, depending on level of analysis.

This is not the place to discuss this in detail, but a quick digression regarding comparison among mammals is probably useful at this point in order to stem unnecessary direct comparisons that may come up in discussion. Maybe mammalian males in general have certain traits leading them towards violent or icky behavior, but the details are important. The fact that big horn sheep butt heads in contests sometimes to the death, taken as an extreme male-male competitive trait, can not be linked to similar behavior among human males (and such behavior does seem to happen in humans). The basal bovid-type organisms from which the big horn sheep derive was probably a small bodied monogamous forest dwelling animal in which males probably did not have a much greater tendency to butt heads than females, though both males and females would likely have employed some sort of “violence” in defending young or territories. Among primates, Old World Monkeys include a lot more examples of violent male behavior than do New World Monkeys. The latter group, in fact, have many cases of distinctly non-violent males as typical of the species. We don’t know the nature of the basal primate, but we cannot assume that it was like a baboon, which is the primate often taken as prototypical in thinking about primate social behavior. In fact, we can guess that it was probably NOT like a baboon for a number of reasons. Therefore, what might be thought of as “over the top” male behavior (butting heads to the death) is NOT a basal mammalian trait that may be found in humans because we are mammals. The phylogenetic link between big horn sheep and human football players is non-existent. (This is why many of us cringe with the latest “evolutionary psychology” finding!) Rather, violence in human males is either derived in our species or in a set of species closely related, including perhaps the great apes, or apes in general, or some other subset of Old World primates.

And, this would be a matter of evolution of drives in a very general sense which are then shaped in a maturing individual by other developmental tendencies and in social beings with large brains, buy culture.

Which brings us to the famous YanSan comparison.

There is an intellectual and pedagogic tradition that comes from people working out of a handful of American Universities (originally, Berkeley, Chicago and Harvard, but then other places such as Madison) having to do with the study of both primates and human foragers. The details are interesting but this is not the place for them. What is important is this: A lot of us (and I’m part of that tradition) learned some of our best metaphors, for doing both research and teaching, from Irv DeVore, who either came up with them himself or consolidated them from people with whom he overlapped or worked, such as Sherwood Washburn, George Gaylord Simpson, and others. And one of those tidbits, which is a comparison and a set of stories much larger than your average metaphor, is the YanSan comparison.

It runs like this. Imagine a Yanomamo village in the Amazon. The Yan (short for Yanomamo) live in a society that for various reasons incorporates a fair amount of violence among men. Men who have killed other men are given a special name of respect, tend to have more children than other men, and often have two wives (in a society in which while polygyny is allowed, it is rare). Then, in contrast, imagine a “San” (Busheman) community in southern Africa. The San live in a society of hunter-gatherers where variation in status among men, for any reason at all, is discouraged, and interpersonal violence is frowned upon. Among the Yan, disputes are settled with chest pounding duels or axe fights, while among the San, disputes are settled by endless discussion during which there might even be hugging.

That’s the background. The YanSan comparison itself goes like this:
In the day to day course of events, a Yan child may become upset or agitated as children occasionally do, perhaps in relation to another child. The good Yan father steps in. He brings his son to the center of the community courtyard and calls over the other child with whom the conflict has arisen, and that child’s’ father tags along. The two Yan dads equip the children with poles about the length of their bodies and set them up to whack at each other until one of them succumbs to injury. Or perhaps, instead of using the poles (because that can be dangerous … you can poke your eye out with one of those things) the dads teach the 6 year olds the rudimentary form of the chest pounding duel, in which each participant gets one free shot at the other’s chest, and you can use one fist or two to pound on your opponent. The participants go back and forth taking fee shots at each other’s chest until one falls to the ground. The one still standing wins.

Meanwhile, over in the San society which is entirely different, a perturbed child is treated differently. If a toddler or youngster is very upset, yelling, having a tantrum, any nearby adult who knows the child, often but not always a relative, will hold the child in both arms until he calms down (this can take considerable time), and then spend some time soothing the boy and telling him thoughtful thoughts.

In both cases, there is a set of drives typical for men, and there is a society in which there is expected, normative male behavior. But since the expected behavior is very different between the two societies the developmental process has a lot of work to do. Boys will not on their own grow up to be Yanomamo warriors with the proper kind of fierceness, and boys will not on their own grow up to be San hunters with a proper cooperative attitude, unless a great deal of cultural energy is expended.

And this is facilitated by the existence of childhood, which may well be Homo sapiens most important adaptation. The YanSan comparison exemplifies how humans transit from blastosphere to adult with respect to behavior, and demonstrates that there is a great deal of potential variation in what the result is, and thus, there is great potential variation in the sorts of societies that Homo sapiens can come up with.

But males are still demonic.

What I mean by that is this: Across all human societies, even when there is relative equality between males and females in power or other measures, males are the more violent sex on average. When human societies range into more violent normative behavior, it is males who are in the vanguard virtually all the time. There are plenty of cases where females are also violent, but they are comparatively rare and less extreme.

And, there are patterns to this behavior seen across society, and interestingly, there are even patterns of male behavior when males are viewed across species, as per the above discussion, among the great apes and in particular comparing chimps and humans. Those patterns may be accidental, they may be nothing more than basic mammalian behavior (or the behavior of an internally fertilizing lactating creature, on whatever planet it is found) and thus almost too basic to be meaningful, or they could be patterns around the specific nature of ape social systems, of which chimpanzees and humans have their own similar yet different versions.

Some years ago, Richard Wrangham, emerging as a leading primatologist, was woo’ed away from his home in Michigan by Harvard to do research and teach interesting courses. One of the courses he developed in his new milieu and taught to advanced undergrads in bioanthropology was about male behavior in apes, looking at the behavioral biology and culture of this behavior, seeking patterns, similarities, contrasts, etc. Over a short period of time this course became very popular. Knee-jerk feminists responded to the course with great disdain because it seemed to be biological determinism, but then some went ahead and took it anyway and found out that it was not. And eventually the course became a book: Demonic Males: Apes and the Origins of Human Violence

Many have criticized Wrangham’s book for suggesting that simple underlying genetic systems determine things like gang violence in humans, but few who have read the book have come away thinking that. It may well be that Wrangham’s view is somewhat deterministic, but that is hardly the point of the study. And, if you bring to the discussion, as Wrangham does, the concept of “drives” or similar psychological phenomena as I’ve described above, the genetic determinism that might be inherent in many comparisons between species’ behavior rather fades away. More interesting, though, may be the political nature of the problem of determinism, and this relates to the ongoing discussion of male privilege as well as to a previous discussion we’ve had on this blog about rape. Is it possible to attain the ideal feminist society (towards which we all strive) if male and female drives are somewhat different, and male drives are (or at least some of them are) so … dickish?

… a new philosophy has emerged in the last decades, an evolutionary brand of feminism that sees the emergence of patriarchy as an intimate part of human biology. Evolutionary feminists, writers like Patricia Gowaty, Sarah Hrdy, Meredith Small, and Barbara Smuts, agree with traditional feminists about the evils of patriarchy, but they do not disconnect humans from their biological past. The logic of evolutionary feminists appreciates the rich details of patriarchal history as recounted by historian Gerda Lerner, but it simultaneously rejects the notion of plumbing the human condition through reading merely the last 6,000 years of history.

Evolutionary feminists … would insist that people can think about the evolutionary pressures that elicit rape, for example or other forms of violence, without necessitating any absurd pronouncement that because rape is “natural” it is in any way forgivable. After all, no one considers the case of the black widow spider, who kills and eats her male counterpart after mating, to mean that murder and cannibalism are okay. …

Patriarchy is worldwide and history-wide, and its origins are detectable in the social lives of chimpanzees. It serves the reproductive purposes of the men who maintain the system. Patriarchy comes from biology in the sense that it emerges from men’s temperaments, out of their evolutionarily derived efforts to control women and at the same time have solidarity with fellow men in competition against outsiders.

(Wrangham 1996 pp 124-125)

It is interesting to consider the commentary emerging (mainly in comments but also in a few blog posts) around Rebeccapocalypse in light of this discussion. Most commenters are either on board with giving women the right to set their own level of concern about potentially dangerous men (those are the feminists) or they re busy making excuses or denying the demonic nature of male Homo sapiens. While many of the former are men (it might be about 50:50 men:women) the vast majority of the latter are men.

Just sayin’

In homage to an inspiration of this post, I provide this link to the secret, generally unseen obituary of Professor Irven Boyd DeVore.