One of the key points I’ve tried to stress on this blog is that micro-scale population structure – that is, fine genetic variation across populations can have a substantial impact on societal characteristics. We aren’t just talking about continental racial variation. We aren’t even talking just about ethnic variation. Sorting within an ethnic groups can produce distinct regional differences. Founder effects are powerful, as is the converse effect, boiling off.
This means that regional differences across countries like the United States reflect genetic differences between people. Even of those who accept that genes impact behavior, many like to blame these local variations on local “culture” (as if culture was some otherworldly force itself without cause). But our discoveries render that view untenable. These include many newer behavioral genetic studies using nationally representative U.S. samples. These studies find no shared environment influence, which would turn up if local cultural effects existed (see the following: on victimization, Boutwell et al 2013; on domestic violence, Barnes et al 2012; on criminality in adoptees, Beaver et al 2015a; on football participation and violence, Beaver et al 2013; on enlisting in the military, Beaver et al 2015b; on peers and academic performance, Barnes et al 2014; on peers and delinquency, Boisvert et al 2013; on handgun ownership, Barnes, Boutwell, and Beaver, 2014). In addition, there are large extended twin studies looking at politics, religiosity, and marriage that find nothing attributable to local environment (Hatemi et al 2010; Coventry & Keller, 2005; and Zietsch et al 2011, respectively). (These are in addition to the many population-wide Scandinavian studies that generally find an absence of neighborhood effects – future post). These behavioral genetic studies along with quantitative genetics methods (which inform us about rates of selection) demonstrate to us that this…
…results from the genetic variation that exists within it (see my page American Nation Series for a review).
Now a new piece of evidence has emerged, one that speaks to the other myth, of “assimilation”. This evidence will explain other fine-scale variation we see, like on this map of income per capita by county (from here):
Different regions of the United States perform differently on various social indicators. A great many of these indicators were featured in my post More Maps of the American Nations (as well as in the earlier post Maps of the American Nations). The pattern we see above (and many other patterns) – while clearly partially the result of (continental) racial variation, isn’t solely due to such, since we see variation within the White population as well, as can be seen with White poverty rates (from here)…
…and with White teen birth rates (from the CDC)…
…in addition to many other aspects as discussed and mapped in my previous posts. One can’t help but notice that these follow a pattern, one that generally follows the American Nations lines. But what drives the American Nations divide, and is that the only factor at work here? Here now I tackle another persistent myth: the myth of assimilation
While the founding colonial stock was the base for the subsequent differences that would take shape across North America, as argued by David Hackett Fisher and Colin Woodard (see Maps of the American Nations), it isn’t solely responsible for what we see today, because British Americans are not a majority even among White Americans. Subsequent immigrants have greatly altered the American landscape.
The United States received many immigrants – who have largely come in two major pulses. The first was after the Civil War and was mostly European. The second came after the 1965 immigration act and was mostly Asian, Latin American, and Caribbean in origin:
These immigrants reshaped the nation in their image. Many of the differences across different parts of North America owes more to these immigrants than to the original settlers.
The immigrants settled unevenly. The Scandinavians, Germans, and Eastern Europeans mostly settled into northern areas in the western reaches of Yankeedom and the Midlands. The (Catholic) Irish, the French Canadians, and (especially) the Italians stayed closer to the industrial centers in New England and New York. All immigrants generally avoided the nations that make up the South:
Now a new study has made strides in tracking the legacy of these immigrants, and in so doing, laying the rest the matter of assimilation.
A key problem with tying socioeconomic outcomes to ethnic ancestry has been the difficulty of getting reliable measures of present-day ancestry (see Being the Dutch | West Hunter). Genomic data has helped somewhat, but isn’t yet fine-grained enough to examine matter very well (see More Maps of the American Nations). However, Fulford, Petkov, and Schiantarelli (2015) have come up with a novel way to solve this problem.
Using longitudinal data from the U.S. Census, they were able to track the movement of people across the country. This allowed them to estimate the actual ethnic ancestry in each U.S. county, rather than rely purely on self-report (which they show to be highly inaccurate). Here are the actual ancestry fractions across the country:
(Unfortunately, due to the limitations of their data, the “English” category does not break down the “Four British Folkways” of David Hackett Fischer’s Albion’s Seed but includes them all. This makes comparison of the original American Nations difficult here.)
With a reliable measure of the ancestral make-up of each county, analyzing each county’s characteristics and comparing these characteristics with those of the ancestral nations was a fairly straightforward endeavor:
We see that (with a few exceptions), the performance of the different ancestry groups conforms closely to what we’d expect (given the average IQ of the source country, with selective migration considered). They were able to correlate ethnic ancestry in each county with both characteristics in the source countries and with GDP per capita in each county:
These clearly show the positive relationship between immigrant characteristics and county level characteristics. One drawback of their analysis is that they compare everything against only their determined ancestry coefficient. We already that IQ is associated with all sorts of positive social outcomes. What may have been more useful is to compare these national characteristics with the same characteristics in each county. While many US counties probably lack the appropriate measures, it would have been a far more of a solid statement if they were able to do so.
Nonetheless, this paper confirms the importance of genetic stock to social outcomes, and weakens any case for “assimilation.” Areas across the northern Plains with exceptionally good outcomes have such because they are heavily Scandinavian in origin. The poorer outcomes of the South can be traced to its Scots-Irish heritage. Even more recently, the independent-minded nature of the Far West and the introverted but cosmopolitan nature of the Left Coast can be traced to the traits of the people who founded (and continue to relocate to) these nations. These patterns follow each of these groups even after more than century. As Fulford et al put it:
Every form of the estimation strongly rejects that ancestry does not matter. All estimates include county group fixed effects, so the fixed characteristics of the place of settlement is controlled for. We can also ask whether regional trends—which might reflect evolving factors, such as industrial structure, that may be related both to county GDP and ancestry composition—may affect our answer. However, the inclusion of state specific period effects or county group specific trends, leaves the significance of the ancestry composition intact. Our conclusion that ancestry matters are also robust to the adding county income in the previous period … as a regressor. One might be concerned that ancestry matters only because it reacts to current shocks, yet ancestry matters even when we include it only at a decade lag. The last several columns include other possible explanatory variables including county level education, population density, and fractionalization constructed using our ancestry vector … All of these may be a result of ancestry, for example, if some groups put more emphasis on education than others. Similarly, an increase in density may reflect a higher level of urbanization of the county, resulting in a differential attraction for different immigrant groups. Ancestry continues to matters even after including these controls, and so ancestry matters beyond its relationship to education or urbanization.
This finding serves to complete the case for heritable human differences as a source societal variation. This goes past the well-known (at least in the HBD-sphere) relationship between average IQ (derived from Lynn & Vanhanen, 2006) and national wealth and economic development:
And beyond intraracial variation such as intra-Euro differences:
The evidence should show that even the rich regional flavor across North America has genetic roots. This also means that the persistent regional conflicts that trouble us here in America are in good measure intractable, as Colin Woodard discusses in a recent Politico piece.
Woodard touches on another key point in his article: the regional differences are amplified by assortative migration. See the following:
All these facts should makes clear how key demography is to societal outcomes. The people make the society. If you want a better society, you must (in one way or another) get better people. This has obvious consequences for immigration and for many other matters as well. Only time will tell if these facts come to be appreciated for what they are.
Happy Independence Day to my American readers! (And a slightly belated Happy Canada Day to my Canadian readers!) I hope you enjoy your holiday. (Note: the following is NOT an endorsement of Hillsdale College or of their views.)
Unlike many commenters in this space, I don’t particularly lament the secular rise of “universalism” that has occurred in Northwestern European societies (and their derivatives). Indeed, as a Black man, this is especially important to me. Without universalism, slavery may never have ended in the West. Without universalism, my family may never have been able to come to the United States from Jamaica, and I would likely not exist. Without universalism, laws banning interracial marriage might still be on the books, and my marriage to my wife would not be recognized throughout much of the country, and quite possibly my son would not exist.
“Universalism” is, broadly, the belief that all humans deserve the rights and recognition that historically people would only reserve for their own clan, own tribe, or at best, own countrymen. The idea of “universal human rights” is a very foreign concept to most of the world (even if many pay lip service to the idea today). As we saw in my previous post (200 Blog Posts – Everything You Need to Know (To Start): section Intraracial group variation and HBD Chick’s theory), this is the purview of Northwestern Europeans, a group of people who are distinct from all others in the world.
Many Northwestern Europeans unfamiliar with this fact assume that values found in WEIRDO societies are found across the globe. This has led some like Steven Pinker to conclude that all humanity is imbued with an “expanding moral circle.” That is, we posses an adjustable circle of morality, that can be expanded when we gain familiarity with those outside. If one confines oneself to NW European societies, it sure does look that way: we no longer keep people as slaves; we feel all have a right to participate in democracy; we don’t allow child labor; we feel that the disabled and the mentally ill deserve to live with dignity; Jim Crow has ended. We have enshrined a Universal Declaration of Human Rights as adopted by the United Nations (a NW European invention). We even extend some of these ideas beyond the human species with certain segments pushing for animal rights.
The idea of a universal “expanding moral circle” was mocked by Staffan in his post The Myth of the Expanding Circle or You Can’t Learn How to Be an English Vegetarian:
if width of empathy is so large in most people, does it really matter if it’s a behavioral trait or not? Doesn’t growing awareness and the empathic inclusion that follows amount to the same thing as an expansion of our circle of empathy? Yes, you might say this is all semantics, weren’t it for one important thing: width of empathy is only large in Northwest Europeans and their descendants. People sometimes referred to as WEIRD (Western, Educated, Industrialized, Rich, Democratic). This trait is intimately (inversely) linked to ingroup loyalty which is weaker among the WEIRD populations as well as among liberal/progressive people, as Haidt’s research has shown.
The rest of the world is not very impressed by Enlightenment ideals and it never was. To this day most of the world is not very into human rights. It’s something you do to make rich Western friends. And now with the rise of China many are abandoning this pretense altogether.
In fact, present day China makes an excellent example of how awareness and reason (this is a highly intelligent people) in no way has expanded the circle of empathy. The internet is full of videos from China illustrating cruelty and lack of concern for both humans and animals. This is a glaring contradiction that Pinker and Goldstein fail to address. Another friend of the expanding circle (who even wrote a book with that name), Australian philosopher Peter Singer has made an attempt to resolve this problem in his own TED talk. In it he shows very disturbing film clip (so click at your own peril) in which a 2-year-old Chinese girl is run over by a car and then left lying in the street. Other people look at her but walk by without helping in any way. He then goes on to compare this behavior with Westerners who can prevent child mortality by supporting UNICEF but fail to do so, at least sufficiently to eradicate the problem
Indeed, China is rife with awful tales, such animals being routinely skinned alive (WARNING: extremely graphic video – click here to view). Pakistan is known for “bear baiting” (where a declawed and detoothed bear is tied up left to be attacked by dogs), as well as the recent case of a married couple who were burned alive for blasphemy. Face-disfiguring acid attacks against women are common occurrences across South Asia. Human rights abuses abound in much of the non-Western world; the idea of a universal morality is clearly untenable.
Peter Frost discussed a trait that plays a significant role in universalism: affective empathy. From his post Feeling the Other’s Pain:
We like to think that all people feel empathy to the same degree. In reality, it varies a lot from one person to the next, like most mental traits. We are half-aware of this when we distinguish between “normal people” and “psychopaths,” the latter having an abnormally low capacity for empathy. The distinction is arbitrary, like the one between “tall” and “short.” As with stature, empathy varies continuously among the individuals of a population, with psychopaths being the ones we find beyond an arbitrary cut-off point and who probably have many other things wrong with them. By focusing on the normal/abnormal dichotomy, we lose sight of the variation that occurs among so-called normal individuals. We probably meet people every day who have a low capacity for empathy and who nonetheless look and act normal. Because they seem normal, we assume they are as empathetic as we are. They aren’t.
Like most mental traits, empathy is heritable, its heritability being estimated at 68% (Chakrabarti and Baron-Cohen, 2013). It has two distinct components: cognitive empathy and affective empathy. Some researchers identify a third component, pro-social behavior, but its relationship to the other two seems tangential.
Cognitive empathy appears to be the evolutionarily older component of the two. It is the capacity to understand how another person is feeling and then predict how different actions will affect that person’s emotional state. But this capacity can be used for selfish purposes. Examples are legion: the con artist; many telemarketers; the rapist who knows how to charm his victims …
Affective empathy is the younger component, having developed out of cognitive empathy. It is the capacity not just to understand another person’s emotional state but also to identify with it. A person with high affective empathy will try to help someone in distress not because such help is personally advantageous or legally required, but because he or she is actually feeling the same distress.
Is it possible, then, that this capacity varies among human populations, just as it varies among individuals? … I have also argued that this evolutionary change has gone the farthest in Europeans north and west of the Hajnal Line (Frost, 2014a). In these populations, kinship has been a weaker force in organizing social relations, at least since the early Middle Ages and perhaps since prehistoric times. There has thus been selection for mechanisms, like affective empathy, that can regulate social interaction between unrelated individuals.
In child labor laws (from here):
With where slavery remains:
With vegetarianism (in Europe):
And of course (relevant to current events), in this (now a bit outdated) map of the legal standing of homosexuality across the world:
The countries closest to the upper right corner of the plot embrace universalistic values the strongest, and those furthest away are more clannish and kin-centric.
So why this rapid change in NW European societies? Indeed, it seems many of these changes have happened in an eye-blink. Nationally recognized same-sex marriage in the U.S. was unfathomable 25 years ago:
Now it’s the reality. But this shift in attitudes is only one such “secular change” we have witnessed in just the last few decades. Others include the rise in individuals claiming not to embrace a religion…
Much has changed in a pretty short period of time. Now, as we saw previously, views and attitudes are highly heritable. So how could they have changed so quickly? This brings me to an on-going point of confusion that I encounter on this topic. Such rapid changes couldn’t reflect genetic changes, since evolution doesn’t proceed that quickly. Nor can this be attributed to demographic changes. So what then? This illustrates that sometimes a change in the gross environment can lead to considerable changes in the expression of highly heritable phenotypes.
The nature of these changes are almost always poorly understood, since they’re incredibly difficult to research. I previously discussed this topic in my post Why HBD:
Rapid change can result when an idea receives widespread appeal among the people. Both components of this – the origin of the idea itself (a reflection of the heritable temperament of its progenitors) – and its reception among the masses (a reflection of the heritable temperament of adherents) are influenced by genes. In a way then, social revolutions can reflect pent-up genetic “potential” in a population, which may express itself when enough people accept that the idea is “OK” and hence can successfully overturn the established order. This is the essence of HBD Chick’s ideas, and Staffan’s remark on needing to “account” for the “history of communism” when looking at the current state of Eastern European societies (“We can’t adjust for their entire history”). The sexual revolution wasn’t the only revolution of consequence in relatively recent history. The American Revolution itself, the Protestant Reformation, the abolition of slavery in the U.S., the rise of communism in Russia, etc are as well. Historical revolutions are in essence, in many respects, a “changing of the genetic guard”, where the genetic dam “bursts” so to speak. More loosely attached individuals may convert if the idea attains a critical mass (see how much longer? | hbd* chick).
To be clear: this is not to say that “genetic potential” is the only factor. As mentioned, other realities, such as technology and the geographic/climatic landscape affect the viability of new ideas/behaviors, and facilitate or quench their dispersal.
However, I believe sometimes the environmental change that precipitates this behavioral change is the previous behavioral change. In other words, the secular change could be a rapid move towards realizing genetic potential. To illustrate what I mean, I’ll point out that Charles Darwin foresaw a good bit of this nearly 150 years ago!
Here’s a passage from his 1871 The Descent of Man, and Selection in Relation to Sex (Vol. 1, pp 101-102):
As man advances in civilisation, and small tribes are united into larger communities, the simplest reason would tell each individual that he ought to extend his social instincts and sympathies to all the members of the same nation, though personally unknown to him. This point being once reached, there is only an artificial barrier to prevent his sympathies extending to the men of all nations and races. If, indeed, such men are separated from him by great differences in appearance or habits, experience unfortunately shews us how long it is before we look at them as our fellow-creatures. Sympathy beyond the confines of man, that is humanity to the lower animals, seems to be one of the latest moral acquisitions. It is apparently unfelt by savages, except towards their pets. How little the old Romans knew of it is shewn by their abhorrent gladiatorial exhibitions. The very idea of humanity, as far as I could observe, was new to most of the Gauchos of the Pampas. This virtue, one of the noblest with which man is endowed, seems to arise incidentally from our sympathies becoming more tender and more widely diffused, until they are extended to all sentient beings. As soon as this virtue is honoured and practised by some few men, it spreads through instruction and example to the young, and eventually through public opinion.
In short, the idea appears to be this: once sympathy (and hence rights) are extended to one group, what’s to stop it from being extended further? If it is wrong to enslave poor Englishmen, then why is it OK to enslave Blacks or Native Americans? If the wealthy are deserving of living decent, healthy lives, why not the poor? If men can have the right to vote and earn a living, why can’t women? If Whites can marry other Whites, and Blacks can marry other Blacks, why can’t Blacks marry Whites? If straights can get married, why not gays? If “cis-gendered” can have their own bathrooms, why shouldn’t transgendered?
The progress has carried us from the abolition of slavery all the way up to the “safe spaces” and “microaggressions” of today. NW Euro society aims to be more inclusive, as the expanding moral circle identifies more targets worthy of human regard. This means the process isn’t over, as it will likely continue to expand.
How could this happen? The ultimate reason is the nature of NW European regard for others. In most societies across the world (i.e., clannish ones), there are weak and highly conditional attitudes towards reciprocity. The primary targets of altruism are kin. Prosociality is maintained through various forms of social honor and shame or at worst, fear of reprisal from the aggrieved or by the state. Dealings between non-kin typically take place warily and with many measures to ensure honesty by all participants. Trust is very low and is not given freely.
By contrast, NW Europeans have evolved a sense of reciprocal altruism and can deal much more readily with non-related individuals. Trust is extended. The other party is presumed to act honestly. Indeed, favors will be extended to others because the recipient may one day return the favor (or at the very least, the helping individual may earn a reputation for generosity that may parlay into favors from others).
In clannish societies, there is typically low regard for those outside the clan, let alone those from social outgroups. Regard for outgroups comes through expediency or through fear. With little outgroup regard or sense of reciprocal altruism, little by way of universalism can appear. We can see this in measures of civic engagement, particular the kind directly involved in helping others:
As Misdreavus put it in his debunking of “ethnic genetic interests” (emphasis in original):
1) It is impossible for such a thing as a “race altruist gene” to evolve, because sacrificing yourself on behalf of strangers does nothing to increase the frequency of the gene under any set of circumstances. It doesn’t matter if the frequency of a such a gene “magically” originated with a frequency of 4 in 10 Chinese people. The Chinese who don’t have the gene, on average, would have a higher fitness, resulting in the frequency decreasing monotonically over time.
2) On the other hand, it is entirely possible for complex social arrangements to evolve between completely unrelated people — and the more that strangers have in common culturally (e.g. speaking a common language, sharing a common religion, etc.) the stronger such ties will be. But that has absolutely nothing to do with “altruism”, in the strict evolutionary sense. All participants in the social network either have something to gain (e.g. the help of one’s neighbours during a famine), or at least something terrible to lose (e.g. being sent to a prison camp for insulting Kim Jong Un). And all societies, virtually everywhere, have social mechanisms in place that penalize shirkers, cheaters, moochers, and all other people who do not uphold their end of the social bargain.
Once any such social bargains erode away, there is absolutely stopping individuals from betraying their “racial interests” [sic] to enrich themselves and their close kin, or any other people with whom they have arranged better social bargains.
When there are no natural seams (kin interests) in conferring human regard to others – as is the case with NW European societies – the social boundaries of who deserves regard are wholly “artificial.” Having a sense of reciprocal altruism (which actively seeks targets with which to trade favors) – along with a suite of other traits that co-evolved with this (such as a sense of fairness and a belief in the equality of all in-group members) – there is little to prevent extending the (soft) cognitive barrier those presently in an outgroup when new information serves to humanize this outgroup (by appealing to affective empathy). And since no outgroup is really any different from any other (being effectively equally unrelated), there’s nothing to stop this process from repeating once new outgroups become humanized. Runaway universalism was thus inevitable.
The conservatives (typically being more clannish) who lament the rise of same-sex marriage like to point out that redefining marriage such that individuals of the same sex may marry establishes a slippery slope. After all, if those of the same-sex may marry, why not more than two individuals, for example. On this, they do have a point. The nature of the expanding moral circle, bereft of inherent boundaries, makes the slippery slope argument somewhat valid in this case. (Indeed, there are now calls to legalize polygamy.)
(For those curious about my own view on these things, I don’t have a problem with same-sex marriage. I don’t see it causing any particular harm, even if it likely confers little benefit. Live and let live. For that matter, I have a similar view towards polygamy. I have said before that the main issue arises in only if the polygamy rate gets too high, which it’s unlikely to in the West. Society can – contra Peter Frost – easily tolerate low levels of polygamy, since indeed, it essentially already does. Though it will be interesting to see how attitudes towards homosexuality will be affected by knowledge of its pathogenic origin. I expect it will not be well.)
Many commenters on this matter like to blame Jewish influence for these shifts in social attitudes, and it is true that Ashkenazi Jews commonly hold and have promoted progressive agendas. But what these commenters ignore is this: why do people listen? Or more to the point, why have some people (and peoples) embraced these views and not others? A promoted agenda is only as good as the traction it gains. Clearly, the trend towards universalism has been the purview of Northwestern European societies almost exclusively. If Jewish influence has had any role, it is only in the form of a rush in a much larger prevailing current.
Indeed, Jews are a vanishingly small portion of the population in many of the most progressive countries, such as the Scandinavian ones. Sweden for example is known for being a foremost champion of progressive causes:
The Swedes … “are extremely liberal toward immigration, but they have a very authoritarian attitude toward debate about it. In Norway the idea is, open discussion is basically good. If there’s hostility, better to get it out.”
In America, there’s clear variation in enthusiasm for universalistic causes by regional population. This variation follows the American Nations lines (see here and here), and many examples of such were featured in my post More Maps of the American Nations.
Some of these include women’s suffrage:
The most recent example, the Supreme Court decision establishing same-sex marriage across the country, is the culmination of a process that spread unevenly (though predictably) across the country:
We can see the clear American Nations lines by following the pattern of rates of adoption of the red equal sign on Facebook profiles:
Throughout history, certain peoples in certain American nations ave resisted progressive goals, most notably those in the Deep South, the Tidewater, and Greater Appalachia. The populations in these regions are more clannish – and hence less universalistic than those in other parts of the country (see A Tentative Ranking of the Clannishness of the “Founding Fathers” and the The Cavaliers). To these peoples, there are is a natural division of and natural hierarchies and (and in this respect they are quite like most the peoples of the world) that run diametrically opposed to universalism and many progressive causes. Hence they are always pulled along for the ride (often reluctantly) rather than spearheading the charge when the more “core” European-derived populations in the rest of the country proceed down their genetically ordained path of universalism.
The problem however is that temperaments do not change. No amount of “progress” is going to completely rid American Southerners of their non-progressive views about the world. Rather, the residents of the South continue to feel slighted as they see their “proper” society perverted by the universalist northerners (click to play animated GIF):
Tensions between the various American nations have recently been running high as of late, and may only continue to intensify. This was predicted by Peter Turchin, and discussed in my earlier post Mapping the Road to American Disunion. In short, in many societies, unrest seems to follow cyclical patterns (likely due to underlying generational negative feedback loops). Violence in particular follows a roughly 50 year cycle, and following the pattern, we are due for a peak in violence and unrest. Recent events have not been encouraging.
Despite certain key problem presented by it, there is no question that NW European universalism has been an enormous positive force for humanity. It has ended institutional exploitation, oppression, and marginalization. It has improved the quality of life for millions, or even has made those lives possible. I personally have benefited from it and continue to do so. Some may argue that progressive causes have run their course. Having achieved as much as they could hope to achieve, they now reach a point of diminishing returns – and there’s certainly some truth to that…
…but let us not throw out the baby with the bath water (if such were even possible), and remember the great gift to humanity that universalism is.
An enduring mystery (among many mysteries) is the existence of women exhibiting sexual attraction to other women. Unlike male homosexuality, where a likely explanation has been put forth (see Greg Cochran’s “Gay Germ” Hypothesis – An Exercise in the Power of Germs), female same-sex attraction remains the realm of speculation. My previous foray into the matter, The Evolution of Female Bisexuality, contains much of that speculation. I’ve learned quite a bit since then, so the time has come to revisit the matter. This time I will make use of one of the most powerful exploratory methods in social science, behavioral genetics.
The first thing to look at is the heritability. An analysis of large twin registry studies pegs the heritability of female same-sex attraction (SSA) as 33% (Whitehead, 2011). This is in contrast to the very low heritability of male SSA, 22%, as reported in the same study. However, these heritabilities were not significantly different.
Unfortunately, a key weakness here (as with virtually all sex research) is that this relies entirely on self-report – worse, with no form of corroboration from any other measurement. Hence, measurement error can be expected to be large.
Looking at the various studies examined by Whitehead, heritabilities were quite variable. A lot of this stems from the relative rarity of SSA, making samples of SSA individuals small even in large studies. (Another problem with that non-response was generally high in these studies, which may have biased heritabitlity estimates.) Only the largest population-based studies with good compliance can firmly pin down the heritability of SSA.
The low heritability and evolutionary contradiction of male homosexuality necessitates the pathogenic explanation. But, assuming the 0.33 heritability of female SSA is reliable, is an evolutionary explanation workable? It is quite possibly is.
A big component is the fitness impact of female SSA. It appears to be much more common than male non-heterosexuality (again, assuming self-reports are to be believed). A British survey (Mercer et al, 2013) finds that among the youngest cohorts of women (ages 16-34), as much as 19% claim to have sexual contact with another woman (the fraction maxes out at around 9-10% for men).
However, the racial composition of the sample changes considerably across age, going from 92% to only 82% White from the oldest to the youngest cohort. Hence it’s unclear how much demographic changes are driving this apparent generational change (more on that shortly).
Nonetheless, female SSA is quite common. Its historic fitness impact then would appear to be – at worst – not as deleterious male same sex attraction. According to the Add Health data (a nationally representative U.S. teen/young adult sample), the predominant (de facto) orientation of non-heterosexual women is some sort of bisexual, indeed “mostly heterosexual” (from Udry & Chantala, 2006):
(My own personal suspicion is that most of the men claiming to be “mostly heterosexual” are in fact gay.)
As a check, I looked at the General Social Survey (GSS) to see what the reported overall behavior of non-hetero woman was. I looked at women (all races) who reported 1 or more female sex partners. This is the number of male sex partners these women claim to have had:
As we can see, non-hetero women are apparently quite promiscuous; such women with no or only a few male sex partners are very much the exception. Indeed, a third or more have had more than eight male partners; ~15% or more claim to have had more than 20 male partners!
The second chart is the number of female sex partners women who report one or more female sex partners claim to have had (all races). As we see, the most common value is just the one. All these indicate that such women are indeed primarily attracted to men.
If this is representative of past potential inclination (not necessarily realized behavior]), then the fitness impact of female SSA couldn’t have been too negative, at worst. An interest in other women likely did not preclude marrying and having children for women historically, especially if they were primarily attracted to men.
Also, for the record, I checked the GSS to see if the apparently highish frequency of women reporting SSA was driven by racial differences in SSA. As we see, even when we look at Whites only, we see a noticeable generational rise in the fraction of women who report sexual experiences with other women. I also looked at racial differences, and the values are similar for other races, except for Hispanics, who have consistently reported a 10-13% female-female sex rate for all of these cohorts. Whites and Blacks have merely converged with the Hispanic rate as of late.
Could the fitness impact of female SSA have been positive? That is, was it specifically selected for? I suspect not. While it is common, its nonetheless minority status would entail some sort of balancing selection to remain at its low level. The most plausible type, frequency-dependent selection, implies that female SSA is beneficial when it is rare. I can’t see how this would be the case (especially since it would be tough for such a girl who can’t find other women who are interested in her).
No, I don’t think female SSA is an adaptation at all. Rather, if it is actually genetic in nature, then the most likely explanation appears to be that it is some sort of side effect of something else. I suspect that it may be due to sexual antagonistic selection. That is, its existence may be driven by selection on alleles that have positive effects in men.
Key to this idea is the apparently near neutral past fitness impact of female SSA (its present impact is decidedly deleterious, as per the GSS). It was not rapidly selected out, unlike any alleles which would cause male homosexuality.
A clue here is the characteristics of non-hetero women. They are often masculinized relative to other women, with higher sex drives and, as we see, greater promiscuity.
Here again, twin studies are informative. One twin study (Burri, Spector, and Rahman, 2015) found that in female twins, masculinity (measured by childhood “gender non-conformity”) was genetically correlated both with female non-heterosexuality and number of sex partners, through a latent genetic factor. EDIT: added the genetic pathway image:
One idea that we can lay to rest here is the notion that female masculinization and SSA stem from prenatal exposure to male hormones. The way to test this idea is to look at females with a male fraternal twin (Fm) compared to women with female fraternal twins (Ff). If the Fm women were more masculine that Ff women, then it would imply prenatal hormones were at work. A massive review looking at such twin studies (Tapp, Maybery, and Whitehouse, 2011) found little support for this notion, particularly from the larger studies examined. Another recent twin study out of Denmark (Ahrenfeldt et al, 2015) found no such effect on women’s academic performance (Fm twins didn’t exhibit a more male-typical cognitive profile).
It also has been said that non-heterosexual women look different from straight women, the former appearing more masculine. Unfortunately, I haven’t been able to find much by way of good studies examining female appearance and sexual orientation. There are a few small and questionable ones, but nothing I’d take too seriously. That said, there’s another way to look indirectly at the matter.
Two twin studies by the same team (Mitchem et al, 2014 and Lee et al, 2014) looked at the heritability of facial attractiveness and facial masculinity-femininity in two sets of large and well-measured samples. They found that both are highly heritable (primarily driven by additive genetic factors), but what’s more, high facial masculinity in men led to high facial masculinity in their sisters, decreasing these women’s attractiveness.
This spillover of male traits on their female relatives can also be seen in “sociosexuality” (promiscuity). A largish twin study out of Australia (Baily et al, 2000) found sociosexuality in men predicted the same in their female co-twins. As well, there is the Zietsch et al (2008) study that found that masculinized women were more likely to be non-heterosexual, and that straight women with a non-heterosexual female twin reported somewhat more sexual partners.
Unfortunately, all these fall short of a more ideal of study, one that examines the morphological and psychological characteristics of women and their male relatives to pin down good familial predictors of female SSA.
Nevertheless, taken together, these point in the direction of masculinity being a distinct suite of traits and that appears related to female SSA. In terms of facial features, that masculinity is distinct from attractiveness in men is interesting. It speaks to perhaps a set of “masculinity promoting” genes that act somewhat orthogonal to those that lead to good looks. Research is mixed on the extent that women find masculine facial features attractive, but I’d say it’s safe to say that these alleles underwent positive selection in men. However, unfortunately, manly men beget manly daughters. Some of these alleles may serve to increase “gynephilia” (attraction to women), and they may have this effect in both sexes. This may be where SSA comes from in women. Unlike male SSA, female SSA appears to be continuously distributed – consistent with what we’d expect if it arose from the general load of various gynephilic alleles (resulting in pure lesbianism in the most extreme cases). The female SSA itself, being near selectively neutral, could reach high frequencies in women, just as masculinity in general has. However, the general suite of masculinized traits (e.g., sociosexuality, facial masculinity) was likely maladaptive in women, and was selected against, counteracting the positive selection in men. In other words, sexual antagonistic selection. A GWAS (Drabant et al, 2012) found no genetic hits to sexual orientation, indicating that female SSA – if primarily genetically driven – is caused by many genes of small effect, as we might expect.
Of course, much of this info comes from WEIRD countries (i.e., NW European and offshoots). As with much of social science in general, these investigations should be repeated with large samples from non-Western societies.
As for the male interest in girl-girl sex (*guilty*), I still suspect it’s a simple matter being able to have multiple women. Even men from highly conservative cultures may not express interest, but often such men harbor rather “colorful” sexual proclivities. Further research needed.
Now, is all of this compatible with a pathogenic source for female SSA? Absolutely, especially if the true heritability turns out to be truly low. See Peter Frost (Yes, Demons Do Exist). Perhaps the recent trend towards more women displaying SSA is due to the spread of a new pathogen. Time will tell. However, unlike male homosexuality, I don’t think we can retire the pure genetic explanation, yet.
The obvious theme song for this post:
One of the greatest pieces of evidence demonstrating that the family/rearing environment has no effect on eventual outcomes is the absence of birth order effects. Birth order is an excellent test for these effects: it is something that systematically differs between siblings and is bona fide non-genetic (mostly). Hence, it’s a great way to see if childhood environment leaves any sort of mark on people.
And it turns out that it does not. The study of birth order has been marred with poor research – faulty because it relies on the Standard Social Science Method:
This has prevented us from separating any putative causal effects of birth order from genetic confounds – most notably, the tendency of less intelligent/educated parents to have larger families. However, some decent research has been conducted demonstrating the absence of these birth order effects. One is an adoption study (Beer & Horn, 2000), which goes into good detail on the problems with birth order research and ways around these problems. They looked at adoptees from the Texas Adoption Project and the Colorado Adoption Project and found only tiny and statistically insignificant effects of birth order on personality traits. Another (tiny, N = 69 pairs) study looked within sibships for birth order effects on personality and found none (Blesk-Rechek & Kelly, 2015). A big review of the claims of Frank Sulloway (a major proponent of birth order effects) by Frederic Townsend (2000) also found no birth order effects on personality or on “rebellious” actions (as claimed by Sulloway).
But, perhaps better than these is a whole-population study out of Norway (Black, Devereux, & Salvanes, 2005). Unfortunately, this is a SSSM study, but its enormous size makes it invaluable for evaluating potential birth order effects. They performed an analysis of birth order controlling for family size as well as a within-family analysis of the effects of birth order on educational attainment. They did find modest but significant effects on educational attainment, with later-borns achieving less than earlier-borns – but I will return to this point. However, this study is useful because in addition to education, they looked at various real world outcomes, like income and likelihood of teenage pregnancy. Here, they found statistically significant but extremely small effects of birth order, with the birth order correlations of -0.04 or even closer to 0. This means birth order would explain less than 2 X 10^-5 worth of the variance – and this is without controlling for family size.
So we don’t see birth order effects on personality or important life outcomes. But some recent studies claimed to find a birth order effect on IQ of all things.
One large study of Norweigan conscripts (Bjerkedal et al, 2007) claimed to find a birth order effect on IQ within families between brothers. Younger brothers scored lower than their older brothers. The effect was small (less than 4 IQ points), but owing to the very large sample, significant.
It gets better. Another very recent study (Barclay, 2015) claimed to find a birth order effect on education with a large sample (N > 6000) of adoptees in Sweden. Again, the effects were small, and even with this large sample, only just barely statistically significant.
So there you have it. Have we found real birth order effects after all? An environmental one at that, as some have suggested? Well, if you’ve been following this blog, you’ll know I’m going to say not so fast.
First of all, these putative effects – where they’re found at all – are all tiny. That itself is a red flag – one that demands we subject it to closer scrutiny. Now, there’s nothing saying that extremely tiny effects can’t exist, but it is suspicious. But these findings come from very large samples, so we can’t dismiss them off-hand.
So what else could be going on here? It has been said that these birth order effects could be the result of the Flynn effect. This would mean that there’s no real change in intelligence by birth order, merely systematic variation in test scores, along what whatever it is that drives the Flynn effect. Indeed, one study seem to show exactly that.
Sudet et al 2010 looked at those Norwegian conscripts and studied the trends in the Flynn effect in Norway at the time. The Flynn effect wasn’t undergoing a monotonic increase but rather stalled at times and as of late has been reversing.
Notice the pattern? Birth order effects track the direction of the Flynn effect in Norway during this time. When the Flynn effect tracked upward, the difference between brothers decreased with increasing years between their births. When the Flynn effect reversed, we see the opposite pattern. And we see no change with years separation during neutral Flynn effect times. What does this mean? Well, this, coupled with research showing whatever the Flynn effect is, it is “hollow” with respect to g, show that a big part of this observed pattern is just testing variability from cohort to cohort.
But is that everything? I don’t think so. There exists another factor that could be behind this result. One birth order study (Barclay and Myrskylä, 2010) out of Norway describes this:
A substantial proportion of children in Sweden experience family complexity in one form or another as they growup. Amongst those borns in the 1960s, 23% of individuals have at least one half-sibling, and for those born in the 1970s the corresponding figure is 25%
Many of these brother pairs do not share a father (since they are matched by mothers in most of these studies). If we assume that people with children tend to “marry down” so-to-speak – that is, pair off with a mate less intelligent than their previous one, then that could easily explain the small apparent birth order effects. Re-analysis of these data excluding “blended families” could serve to address this issue.
(Indeed, the Barclay and Myrskylä study itself found small birth order effects in physical fitness – however, upon analysis with “non-blended” families these effects were greatly attenuated.)
Confounding stemming from half-siblings demonstrates a key weakness with paying too much attention to small effects. That, and (especially) the apparent role of the Flynn effect in these birth order findings show the importance of cohort effects (i.e., secular changes) which can confound even within-family designs. These two factors likely explain another study out of Norway that claimed to find a birth order effect on IQ (Kristensen & Bjerkedal, 2007). Their analysis didn’t even look within sibships. EDIT: [
Their effect went away when they controlled for family size, as usual. In their sample, those families where one sibling died seem to oddly score higher than the those that did not. (See the table here.) I don’t trust that result for a second. I’d like to see an ethnic breakdown of this sample as well as control for “blended families.”]
But is that all? What about the effect on education? Surely that’s not a Flynn effect? (Or is it?) Well, for one the Barcley 2015 study did look at adoptees, but those adoptees weren’t ethnic Swedes; they were in fact almost entirely foreign-born. What’s more, they were largely non-European. They found, as Emil Kirkegaard had, EDIT: [See also Heiner Rindermann and James Thompson] they these foreign adoptees performance varied according to their region of origin. Who’s to say that these adoptive families got both of their adoptees from the same country? I wouldn’t be surprised if they had to “go cheap” for their second adoption.
And, even going beyond that, showing an “environmental” effect on educational attainment wouldn’t be too meaningful, because, as described in my post The Son Becomes The Father, there is a shared environment on education, but one that doesn’t translate to later outcomes. “Family/rearing environment” does impact educational attainment. Hence, finding an effect of family dynamic on educational attainment isn’t unexpected. (For the record, the shared environment captures all the effects of rearing environment – a nonzero shared environment – beyond what we can ascribe to assortative mating – indicates the presence of such an effect, and likewise, for reasons described previously, its absence indicates no such effect.)
None the less, this whole enterprise on these latest supposed birth order effects has been the baby of a certain subset of researchers who are ardent “half-slatists.” This is the “nature AND nurture” crew. That is, these individuals acknowledge the role of heredity in human traits and outcomes, but seem to find ways to slip “nurture” in with reliance on questionable research and unduly unskeptical attitudes. Well, I’ve been around here long enough to learn a good rule of thumb:
If your research shows some “environmental” effect (one we can’t pin down to pathogens or developmental noise, isn’t incredibly superficial, or isn’t a secular change), it’s probably wrong.
This topic will lead into my next post, where I intend to finally lay it down on the “environment.”
This will likely be my final post of 2014. As such, Merry Christmas and Happy New Year to you all! To those of you who have donated, thank you. However, I am sad to report that my wife’s grandfather has passed away. As such, I dedicate this post to him, my wife, and her family.
I’ve added a new page, which covers many of the key facts about obesity – facts which are conveniently ignored or misunderstood in the many emotionally charged discussion of the matter. See:
I’ve made this a page rather than a post because I anticipate updating it fairly frequently, as more information becomes available. I link to all the relevant papers on the matter there. From the heritability of obesity, to the ineffectiveness of all obesity treatments, to the overblown case for its inherent dangers, I cover it all.
Posting will be light around here. As I am nearing my 200th post, I intend to make infrequent but comprehensive posts in the coming weeks and months. If there’s something you think I need to address, now is the time to speak up…
Please direct all relevant comments on the topic of the page on the page, not here. Thanks.
There are many comments I get that, while not necessarily being disrespectful or mean-spirited, nonetheless add little value, are egregiously wrong and ignorant, and would waste a lot of my time and energy to address. Fortunately, many of them are by first-time commenters and get caught by the moderation filter. I have deliberately left many of those comments there. While I’m not certain whether or not that’s fair or wise, it has been expedient. For now, I will continue to do so, and institute a de facto policy of denying hopelessly stupid comments from getting through. If you have a comment that’s been sitting in moderation for a long time, that’s why.
I would like input on this. What do you think? Is this a fair practice? Suggestions?
With that, I announce that I have returned! Comment moderation has been lifted, and things are back to the previous policy of requiring approval only for brand new commenters.