Friday, October 26, 2012

The true meaning of "candidate" genes revealed

The biology of behavior
I take a deep breath.  If you were here with me you'd have noticed that it was breath signifying annoyance, annoyance over something I've just read.  The annoyance triggered my brain to trigger my diaphragm to contract and elevate my lower ribs and expand my thoracic cavity vertically, while at the same time my external intercostal muscles and interchondral muscles have elevated my upper rib cage to expand the width of my thoracic cavity to allow the intake of air.  The process is reversed as I breathe out. It's a biological thing.  My annoyance also surely triggered hormonal releases of some sort as well, and other downstream reactions that may or may not catch up with me someday in the form of "stress-related illness."

But ok, that deep breath out of the way now, I start to type.  My brain has begun to formulate sentences in response to what I've just read, and now transferring those sentences to the screen requires a complex interplay between the parts of my brain that think (clearly or not) and the muscles that govern my fingers on the keyboard.

More biology.  Genes are firing all over the place, creating and controlling the complex interactions that make all this, and more, happen simultaneously without me making it happen or even being aware of what's going on.  That's because in many senses I'm nothing but an automaton controlled by my genetic makeup to respond to my environment with biological impulses. 

But I'm also eating a pear as I type.  My hunger is a biological drive -- a genetic predisposition, even -- to which I'm responding.  I have to eat or I can't fulfill my darwinian destiny to survive and reproduce.

But why am I eating a pear and not a durian fruit?  Or a betel nut?  Or a peanut butter and jelly sandwich on Wonder Bread?  Because durians and betel nuts aren't sold at my local grocery stores, or even my local farmers' markets, and I don't like Wonder Bread.  (Have you tried peanut butter and pickle sandwiches though?  My mother's favorite lunch, a taste passed down to me.)  So my clearly biological drive has to be satisfied in culturally specific ways, and based on my own personal taste.  In part taught to me by my mother. 

Let's go back to the source of my annoyance.  It's a commentary in this week's Nature: "Biology and ideology: the anatomy of politics," about how biology shapes our politics.
An increasing number of studies suggest that biology can exert a significant influence on political beliefs and behaviours. Biological factors including genes, hormone levels and neurotransmitter systems may partly shape people's attitudes on political issues such as welfare, immigration, same-sex marriage and war. And shrewd politicians might be able to take advantage of those biological levers through clever advertisements aimed at voters' primal emotions.
Many of the studies linking biology to politics remain controversial and unreplicated. But the overall body of evidence is growing and might alter how people think about their own and others' political attitudes.
Of course biology affects our beliefs and behaviors, in much the same ways that it affects what we choose to eat or our responses to things that annoy us, which in turn have been affected by our culture and upbringing.  The work described in this commentary annoys me but it might strike you as perfectly fine.  We are biological beings, and everything we do and are is affected by genes and hormones and neurotransmitters.  But that is not the same as saying that everything we do is determined by our biology.  I eat a pear but not a durian fruit, if I'm a southerner I voted Democratic in my youth and Republican now.

Genes 'for' 
Genetics is now becoming deeply entrenched in the social sciences; economists, psychologists, sociologists, political scientists are being seduced by the appeal of genetics and Darwin as they try to explain why humans do what they do.  Hell, evolutionary theory is even used to explain why characters in classic novels behave the way they do.

But this shows how little social scientists understand what genetics can actually tell us about complex traits like, well, like all the traits of interest to these disciplines.  We can't even find genes 'for' truly biological traits like type 1 diabetes or clinical depression, even if the commentary assumes we have:
The past few decades have seen a wave of research connecting genes to disorders such as schizophrenia, depression and alcoholism, and to complex outcomes such as sexual orientation and how far people progress in education.
Well, but we have made very little progress in geneticizing such things, and where we've found genetic variants that affect such traits, they usually have very little, and inconsistent, effect.  Indeed, when we throw in the effects of culture and learning, not to mention neuroplasticity of the brain, almost all bets are off in terms of identifying biological forces that shape what we believe or how we behave.

And then there's the question of just what phenotype is being measured anyway.  This is hard enough for biological traits -- what constitutes 'high' blood pressure, obesity, or autism?  Very large studies to find genes for obesity find essentially entirely different candidates depending on the measure being used (e.g., body mass index, waist-hip ratio), or the obesity-related traits like diabetes, hypertension, or Alzheimer's disease.  So how on Earth do you measure political belief in such a way that it is a proxy for some protein coded for by some gene?  

What about this sentence, that you might have just glided over above:
...shrewd politicians might be able to take advantage of those biological levers through clever advertisements aimed at voters' primal emotions.
We've been down this road before.

Once Darwin gave people, especially the noble science class, the idea that Nature not God made people what they were, and that through their insight they the scientists rather than clergy, could divine what was good and bad, they (like clergy) are the ones who should evaluate who was naughty and who was nice, and indeed could help Nature out by doing something about the offenders.  Of course it was all for the good.  Just like clergy helping to save souls, scientists would help save society.  And since Darwin showed that our essence was not our soul, but our biology, which within decades became  genes, their term for their wise engineering was not absolution, but eugenics.

The temptation was of course to believe that they, through their science, could find out people's true essence, and recommend what to do about it.  All for the protection of society.  Does it sound a lot like the inquisition, where clergy decided how to test, and judge, and engineer (get rid of) those who polluted the true and faithful?

Eugenics in its early form, which crept in on little cat's feet, led by the biomedical research establishment, was all for human good, of course.  But of course power corrupts and demagogues are always ready to use it, and scientists as we know very well from the past -- and today -- are easily co-opted by the hands that feed them.  And of course that kind of thinking, in its various guises, led to the Nazi exterminations (and, here and elsewhere, incarcerations, involuntary sterilizations, and the like).  It also led to the abuses of the Stalinist era called Lysenkoism, which was the inverse of Darwinism out of control.

Well, you might say, that was then and this is now.  Yes, the early eugenicists were the well-respected scientists and physicians, but they were misguided.  Now, we know better, and our scientists have only everybody (else's) good at heart, don't they?  Intrusive abuses couldn't happen any more, could they?


Holly Dunsworth said...

This is great Anne.
Also, wouldn't it be fun if more people were talking about how political preference or religion shapes biology? That your biology is the way it is because of how you've trained it to be and, more importantly, how others and your circumstances have trained it to be as you lived your life? Your memories (which include memories of thought processes and preferences), after all, are just that: biology determined by behavior/experience. Etc etc etc...

Holly Dunsworth said...

To continue... what I'm saying is... learning to love peanut butter and pickle sandwiches (which could hardly happen anywhere but in your family ;)) is molding your biology. But hardly anybody talks about this. It's considered "culture" but a preference for PB&P is ultimately biology/chemistry/physics or else it's magic.

Anne Buchanan said...

Absolutely agreed, Holly. It's a rich interplay, a feedback loop without end. But clearly people looking for genes for how we vote don't see it the same way. Well, for that matter, nor do people looking for genes for heart disease.

Anne Buchanan said...

Is your mouth watering for a PB&P sandwich yet? ;-)

Ken Weiss said...

The commitment of our era in science to the idea that genes are individually of high predictive value for any sort of trait, is an understandable fact of our culture and technology history, and of the failure of other means of prediction.

That we know better, doesn't stop this. That's why from 23andLess to genome mapping, to neo-eugenics, even to popular metaphor, genes are 'it' for the moment.

It's little different in many ways from the role religion played until not too long ago (and, for many, still does).

Holly Dunsworth said...

Yes. It truly does sound good. I'm going to try it the next time I have pickles in the house.

Anne Buchanan said...

Magic. :)

Holly Dunsworth said...

This has GOT to be because ATCG is easier to compute/study than ...

Anne Buchanan said...

Of course, as we and others have said many times, part of the reason for the seduction of Mendelian genetics is that for many traits it has worked. Single genes do explain a lot of (mostly rare, mostly pediatric) diseases and disorders, even if the story has gotten more complex as more is known about each of them.

So, it's no surprise that this is the route that everyone from political scientists to geneticists, who should know better given how much we've learned about complexity, want to go down this route. But that doesn't make it correct.

But I have no illusions that today's post will convince anyone who believes that how you vote is genetic that it's not. Won't even challenge their belief. Just as the Nature commentary didn't challenge my belief that the science behind this kind of work is pretty thin. We've blogged about this a lot recently. But this subject has to be talked about because the potential consequences of not talking about it range from a whole lot of money spent on poor science to a new eugenics age.

Anne Buchanan said...

Exactly. Just what I tried to say below with way too many words!

Ken Weiss said...

You can buy machines to do it. You can get big grants and prestige because it seems very precise and technically esoteric. You don't have to think about the real problem, because you can excuse what you do as early-stage reduction to identify causes. Plenty of rationales for this.

If we had the genes 'for' PBP, then why don't they eat 'em in, say, Amazonia? No peanuts? No pickles? That makes it cultural, even if taste buds in normal people like them (we don't know about you, Holly!). The genes even if the geneticists dreams were true, pick out PBP only when it's an available choice. That may change tomorrow, and it hasn't been true since the invention of peanuts or pickles, either.

By far the better way to understand the strange loving of PBP is cultural.

Holly Dunsworth said...

And my point Ken is that culture is biology too. And calling it "cultural" for many out there conjures souls and magic or at least super-biological or super-scientific concepts in folks when it is just biology/chemistry/physics like everything else.

Ken Weiss said...

Right, Holly, but then we get into semantic issues. The general idea that had been accepted in ethnology and social sciences is that humans were, for all practical purposes, identical relative to cultural traits. For example, there was no biological explanation for why Chinese is spoken in China and German in Europe, nor for the nature of those languages (tone, guttural, etc.).

Of course there is biological variation and it plays into cultural traits on individual and even in some cases population basis. But is biological _variation_ the major determinant of cultural variation? How specifically predictive is genotype of cultural traits?

In a trivial sense, if you're tall that has a genetic component of course and affects your likelihood of being a good basketball player. For exceptions like Einstein or Bach or Magic Johnson, most of us would guess that there may be some genetic contributor in those individuals specifically.

Every trait has some nontrivial heritability, but that doesn't mean that a specific gene or genotype is very usefully predictive.

The problem to me is that the failure of social sciences (say, economics, sociology, or psychology) to solve the major issues in society that they're paid to solve, should not be used to justify turning them into genetic lab sciences.

Holly Dunsworth said...

Not all our behavior is due to genes or to the mere presence of some alleles in our genomes.

Further, my claim that everything that our bodies do is natural is not an ipso facto claim that everything our bodies do is predictable!

Holly Dunsworth said...

How about we start a bibliography of published genes for flexible traits, plastic traits, mechanisms that are involved in learning, building, etc... to show that genes aren't so myopic. And I'm not talking about pleiotropy, I mean larger more flexible processes involved in body maintenance, etc etc... that will show that genes really are required for our behavior but that they're not coded for many particulars about our behaviors.

Holly Dunsworth said...

Apparently I'm not done talking...

I just assume that most bio-types understand this but then again, so many published articles get out there, past 2 or three or more others who have to approve... so I think I'm finally seeing the scary light: Scientists either really believe it OR they don't and they publish because it's the game and they don't care (or know) of the negative cultural and societal repurcussions. ... Both? But either way, it's way too common than it should be. If only long term, nuanced science was prized over any other kind.

Anne Buchanan said...

Yes. We're beyond the old nature/nurture dichotomy here, into a gene/experience/biology/culture/gene/experience/biology/culture sort of endless loop.

Anne Buchanan said...

Yep. I think it's both; some scientists really believe it, and some do it because it's the game. And labs are set up to address questions in one way. And it's a lumbering system that's very slow to change and adapt, unless it's to new technology for answering the same questions, but faster.

JQ said...

Ann, the endless loop you mention could be encompassed by the mechanism known as Autopoiesis. Living organism will use whatever is at their disposal to maintain Autopoiesis as they make their way in an often hostile world.