Post updated, 9/13/14. See below!
I haven’t always made it explicit, but some of you might gather that I am rather hard on most “environmental” explanations. You have inferred correctly. The reason? Several, which I’ll review here. The biggest of these? There is no good evidence for the vast majority of them.
That’s right, there is little evidence linking most “measurable” aspects of the environment to human physical or behavioral traits. And on this point, it’s important to note that poorly controlled correlational studies (which make up the bulk of the commonly touted evidence for most environmental explanations) are not, by in large, evidence for environmental impact. Most of the solid evidence we do have for environmental impacts come in the forms of things that do physical damage (e.g., maiming limbs or traumatic brain injury) – a category which includes poisons; or are developmental deficits, such as malnutrition. Much of the rest of it (take your pick) is lacking.
Let me be clear: “strict” hereditarianism – that claims human traits are “all in the genes” is wrong.
Oddly, the impact of pathogens – particularly behavioral impacts such as the previously discussed gay germ hypothesis of Greg Cochran – is amongst the most solid known examples of true “environmental effects” – in this case, on a behavioral trait. The paper referenced in that post explained that pathogens may be a significant force behind variation in health and behavioral outcomes.
This paper, by Cochran & Ewald, noted that even many “physiological” outcomes, such as health, can’t reliably be pinned to environmental sources. So much for power of lifestyle!
A good bit of this was discussed by James Thompson in his post Diet is an IQ test. Contra what we’re told, we simply don’t have reliable evidence for environmental impacts on health outcomes or behavioral traits.
You may now be wondering what’s this about not thinking heredity is “all there is” after what I’ve just said. Allow me to clarify my position, and in so doing consolidate some of my recent comments on the matter.
See this comment of mine at HBD Chick’s (emphasis not in the original):
Behavior, and more broadly behavioral traits are environmentally context-dependent. This is a fine point that many, conceptually, fail to fully grasp. The reason why this is so is mainly because the socio/cultural/technological landscape of the day sets the playing field. People with different genetic predispositions have to adopt different tactics depending on what works; they receive a different set of incentives and feedback to their behavior [depending on the socio-technological landscape of the day]. Obviously, some people play the game of the day better than others. This is what sets up selective forces every society exerts. Of course, when the landscape changes, behavior can change over all, and who has the advantage changes.
The effective landscape explains how you can get rapid changes in behavioral traits all without comparable genetic change. As you say, the rise in irreligiosity, increasing acceptance of same-sex marriage, etc, are examples. This confuses many people, because they somehow assume that if you can have rapid environmental change on behavioral traits, that they can’t be so “heritable” after all (despite the fact that they all are). This stems from the misconception that heritability = degree of mutability, which is wrong. Average height for example has increased considerably in America over the past century (after decreasing for some time), and virtual no one then claims that height is “less heritable” than we thought because of this. The rise in obesity is another example. Some take the increase to signal that environment is much more important that it is let on.
Of course, these people mean “environment” in the sense of the environment that differs between people living today, where is the change over time was brought on by an environmental change that (in a fashion) affects everybody. The playing field is different. But that knowledge doesn’t necessarily guide you in how to change it, or if an effective change is even possible.
I’m not sure if that helps to clear up the issue for those confused about it, because it is admittedly a difficult concept to grasp.
This is a key fact that underlies my thinking, but doesn’t seem appreciated in the minds of many. The strongest evidence for some sort of environmental impact is broad secular changes in behavioral or physical traits that occur too fast to be the result of genetic change, i.e., evolution. This occurs because one’s genome unfolds in the environment it finds itself in. A change in the environment might alter the outcome of the genetic programming. Of course, this doesn’t mean that anything goes. We don’t open the door to any old environmental theory because of homeostasis. The genes are designed to produce a working copy of the organism despite a temperamental environment. The genetic code is built in with buffers that keep development on track. This is not exactly a perfect process (and some individuals’ buffering seems to work better than others), but it is a key phenomenon to keep in mind.
This also doesn’t mean that because this process occurs, we can necessarily isolate the aspects of the environment that brings about these secular changes. Often, we can’t. Two poignant examples (and two big ones in the “Dark Enlightenment” sphere) are marriage/mating behavior (i.e., the decline in marriage rates and rise of unwed motherhood) and the rise in obesity rates. In both cases, we don’t know for sure what the causes are, even if we think we have ideas about them. This is especially so in the case of obesity. Determining the causes with any certainty is difficult.
Going beyond the difficulty of isolating a cause of secular changes, assuming one even knew what theses causes were, knowing that changing an environment could affect people’s outcomes in principle doesn’t mean that it’s always possible to make the necessary changes in practice. This may ultimately prove to be a mistake, but I’ll leave it to readers for now to figure out why this is so.
OK, but that’s the grand-scale environment, the world of difference, so to speak. What about individual differences? What about that “nature and nurture” mantra we’re often fed by behavioral geneticists and others on the matter? Well, turns out that’s a bunch of bullshit too. See the post on the matter over at HBD Chick’s, it’s not nature and nurture…, where she quotes Steven Pinker (HBD Chick’s emphasis):
“Even the technical sense of ‘environment’ used in quantitative behavioral genetics is perversely confusing. Now, there is nothing wrong with partitioning phenotypic variance into components that correlate with genetic variation (heritability) and with variation among families (‘shared environment’). The problem comes from the so-called ‘nonshared’ or ‘unique environmental influences.’ This consists of all the variance that is attributable neither to genetic nor familiar variation. In most studies, it’s calculated as 1 – (heritability + shared environment). Practically, you can think of it as the differences between identical twins who grow up in the same home. They share their genes, parents, older and younger siblings, home, school, peers, and neighborhood. So what could make them different? Under the assumption that behavior is a product of genes plus environment, it must be something in the environment of one that is not in the environment of the other.
“But this category really should be called ‘miscellaneous/unknown,’ because it has nothing necessarily to do with any measurable aspect of the environment, such as one sibling getting the top bunk bed and the other the bottom, or a parent unpredictably favoring one child, or one sibling getting chased by a dog, coming down with a virus, or being favored by a teacher. These influences are purely conjectural, and studies looking for them have failed to find them. The alternative is that this component actually consists of the effects of chance – new mutations, quirky prenatal effects, noise in brain development, and events in life with unpredictable effects.”
Here she continues, quoting me on the matter (HBD Chick’s emphasis):
“The heritability of behavioral traits is typically on order of 50%. However, what’s left (after you subtract the ‘shared environment’, which is generally 0, but more on that soon) is just the ‘unexplained variance.’ We don’t know what that is. Much of it, perhaps a good deal, is measurement error. Evidence suggest that that is actually missed heritable influence.
“However, what’s left over, after you’ve accounted for ‘attenuated heredity’ may be what’s known developmental noise. This is ‘environmental’ in the sense that it’s not inherited, but is essentially random and not subject to controlled manipulation.
“Or we think it’s random. See Kevin Mitchell on it:”
“Even developmental noise appears to heritable, to a degree. Whether or not this is ‘on purpose’ or an evolutionary accident is unclear.
[Edit, 9/13/14: And now we have additional evidence that this is the case. Experiments on multiple strains of genetically identical fruit flies have found that some strains are more prone to having variable trait expression despite an identical genotype than are others. The range of variation is itself influenced by the presence of certain genes. Additionally, these genes don't seem to allow for greater variation across the board, but rather, greater phenotypic variation in specific traits. In short, the degree of variation, in the case of humans, between identical twins, may indeed be a function of the genotypes of those twins. See Ayroles, et al, 2014]
“And finally, and this is an ‘advanced’ topic, impact of the ‘unique environment’ – what makes identical twins raised together different from one another – could itself significantly genetic in nature, because identical twins aren’t actually genetically identical, but have different de novo mutations.
“You see why I’m a little hard on the ‘nurturists’ out there. Broadly, the evidence has not been kind to ‘environmental’ influences. Note that this is not to say that they don’t exist.”
About that 50-50 split, I noted that much of the 50% not ascribed to genes is in fact measurement error. Staffan had a post on that matter (emphasis added):
So, what does the “new” research from the 1980s, that is now finally beginning to reach public awareness, tell us about human nature? The most obvious part is that nature is a major factor. This is typically summed up in textbooks in the 50/50 rule, claiming that genes and environment can explain about half of the variance each of things like intelligence, personality, psychopathology etc. Which is easy to remember – but also incorrect. This is due to the fact that there is something called measurement error. Most studies are done in a way that doesn’t distinguish this error from the environmental factor. So it’s 50 percent nature and 50 percent environment plus measurement error. Studies that have managed to minimize measurement error typically yield heritabilities for personality traits and similar characteristics around 70 percent. You also have the fact that some of the traits linked to the most important life outcomes, like intelligence and impulsiveness, have even higher heritabilities, around 0.75-0.80.
Here’s a quote from the abstract of one of these studies Staffan mentioned (emphasis mine):
Our analysis of self-report data replicates earlier findings of a substantial genetic influence on the Big Five (h2= .42 to .56). We also found this influence for peer reports. Our results validate findings based solely on self-reports. However, estimates of genetic contributions to phenotypic variance were substantially higher when based on peer reports (h2= .51 to .81) or self- and peer reports (h2= .66 to .79) because these data allowed us to separate error variance from variance due to nonshared environmental influences. Correlations between self- and peer reports reflected the same genetic influences to a much higher extent than identical environmental effects.
And of course, there is one additional factor, something that’s greatly under-appreciated (because it’s inconvenient for researchers) but is likely very powerful. Quoting myself from over at HBD Chick’s (emphasis in original):
And finally, perhaps most poignant of all, but greatly underrated, is the fact that that identical twins are not actually genetically identical, but possess subtle differences due to de novo mutations. While behavioral geneticists and others like to ignore these, identical twins are our metric of the effects of heredity. We think we can precisely measure the genetic effect vs “environmental” one by looking at identical twins raised together – anything different between them must be due to environment, so the story goes. But the differences between them could be due to genes, so in reality, we have no idea how big the effect of the “environment” truly is.These differences are starting to recognized as being potentially powerful, as seen from the differences of supposedly (but not truly) genetically identical mice:
Genetic tests that can distinguish between identical twins are becoming availible. This is an underappreciate goldmine in future research into genes and environment.
There’s a dude over at Steve Sailer’s that was trying to argue with me about this key point. He’s trying to claim that since most mutations are of neutral effect, we can ignore these subtle genetic differences between identical twins. Well, the mouse studies indicates that we can’t. Tiny genetic differences can lead to large differences in expressed traits. This has practical significance up and down the board. For one, it does cast into question the wisdom of assuming twins are perfect genetic control in observational studies (as I said to Staffan, the genetic confound never goes away).
This post is a teaser because I plan a longer, much more thorough post on the topic soon. However, I wanted to summarize what I have said on the topic so far. The key problem with recognizing the true pervasiveness of heredity and the relative insignificance and capriciousness of the environment is that it makes it all the more difficult to craft a better a world. This isn’t a problem for only the blank-slatist types. The HBD-aware often share these hopes. Many in this space leave the door open for the environment in the hopes that we can engineer better outcomes if we try (not just harder, as utopian liberals believe, but, perhaps smarter as well). From, parenting, to lifestyle, to social engineering, unfortunately, it turns out, the reality is not so simple. There isn’t always something you can do. The truth calls for a type of serenity – accepting what you cannot change. Perhaps this makes heredity an even harder sell than it is, but in all our marketing, we (or at least, some of us) have to be sure we aren’t sacrificing the truth in the process.