pz

These are observations used to bolster claims of genetic determinism, and the authors typically do use these studies with the rationalization that they are trying to isolate genetic contributions from environmental ones. While you may be perceptive enough to see that the question is much murkier than purported, the message from the literature is very different.

I would also disagree that they have extracted SES from the equation. How many wealthy people give up children for adoption? How many of these adopted children received the same prenatal and infant care that the adoptive parents would have given to their own children?

For some perspective on how these studies are seen by the public and also, how they are presented by the authors, take a look at <a href="http://www.washingtonpost.com/wp-srv/national/longterm/twins/twins1.htm" target="_blank">this article in the Washington Post</a>, which claims on its first page that "Nurture is out, nature is back. And science is largely the reason why.":
This is the kind of crap that gives this whole field a bad name, and those are anecdotes peddled by Bouchard. I wonder which chromosome the toilet-flushing gene is on, and where the bias to prefer Mary to Linda is encoded?

ps418

Pz,

Before we get to your latest batch of questions, I have to request (for the 3rd time) that you provide support for the claim, which you invoked in your reductio, that twin studies have shown a heritability of specific religious beliefs, such as Wicca or Catholicism? Do you still stand by this claim, or do you admit that you invented this claim out of thin air?

Also, do you agree or disagree with me that there is a firm concensus amongst behavior geneticists that IQ and some personality traits are moderately heritable? You are of course entitled to your own skepticism, but it does not seem to be shared by the vast majority of researchers in the field. This is not my field of expertise, but I have looked at reviews on the genetics of human personality in journals such as Science, Nature, Behavior Genetics, American Journal of Human Genetics, Human Biology, Personality and Individual Differences, Intelligence, Pychological reports, Psychological Bulletin, Current Directions in Psychological Science and the concensus seems overwhelmingly to support my contention that there is substantial genetic influence on some personality traits (not my specific claim that measures of religiosity show low to moderate heritability). I could post a bibliography of review articles, if you like.

As an example, I cite from the American Journal of Human Genetics 1997 statement on <a href="http://www.faseb.org/genetics/ashg/policy/pol-28.htm" target="_blank">Recent Developments in Human Behavioral Genetics: Past Accomplishments and Future Directions,</a> which states:


You're beating the stuffing out of the strawman. Where did that article say that those behaviors were heritable? It didn't, and neither does Bouchard et al., or any other twin researcher. This is your (mistaken) assumption. You seem to be blaming twin researchers for the naivete of the Washington Post article itself, or other popular accounts of twin research, which hardly seems reasonable. In fact, I bet that if you looked at all of Bouchard et al's twin data, you'd find a big, fat zero heritability for wife-name preference, and a zero heritability for the "flush-before-you go" behavior. The very article you cited has a twin researcher stating that "Science . . . generally does a good job of dealing with the statistical properties of aggregates. It does a lousy job of dealing with the behavior of individual particles."

And you phrased the question wrongly to begin with. Even if flushing-before-you-go showed some degree of heritability (though no such claim was ever made and would seem a priori unlikely), it would not entail that there is "a gene for toilet flushing," any more than the well-demonstated moderate heritability of obsessive-compulsive disorder in humans, or maze-brightness in mice, implies that there are "genes for" these behaviors. I'm sure you agree that there need be no single gene for these traits, even when they clearly show some heritability. They are almost certainly mediated by the effects of many genes, modulated in a more or less complex way both by each other and by the environment.

We should also distinguish between direct and indirect genetic effects. For instance, there may be no gene for "excessive handwashing," but there may be genes or combinations of genes that increase the probability of "obsessive compulsive behavior," such as variant alleles for neurotransmitter receptors or whatnot that play a role in phobias or mood regulation. Thus, genes could play some role in obsessive compulsive behaviors (or whatever), without there being a "gene for" handwashing (or whatever).

That's just silly. Not only is behavioral genetic determism not supported by observations of twins reared apart, it is conclusively falsified by them! Twin and adoption studies show overwhelmingly that environmental influences are important, and account for half or more of the variation in most human behavioral traits! What this research shows is that both environmental determinism and genetic determinism are false. For most traits, the truth is in between these extremes.

Patrick

[ December 08, 2002: Message edited by: ps418 ]</p>

RufusAtticus

Err no. "Heritability" and "heritable" are not the same thing. Fitness traits are highly heritable but show zero heritability. "Why?" you ask? That is because "heritability" requires phenotypic variation, and variation is one thing that fitness traits lack.

We also need to make sure we distinguish "broad sense" and "narrow sense" heritability.

Narrow Sense (True) Heritability: additive genetic variance over phenotypic variance

Broad Sense Heritability: genetic variance over phenotypic variance

Heritabilty was designed for animal breeders to use in connection with selection and is perhaps unfit for species with low fecundities and which have traits that are not going to be selected for.

Maybe when Galn'axot returns and wants to continue his husbandry experiments, he might be interested with what the heritability of religiosity is but until then I don't think it solves many genetic questions.

Quetzal

Vork: I agree with you that the neuroarchitecture of the brain and the perceptual system provide an adequate explanation for the capacity to believe. Also, that Wilson's group selectionism is one of my principal arguments with his sociobiology (I guess it's called evo psych now) theories. I can only see group selection occurring when we start talking about cultural/memetic evolution, rather than genetic. "Religion" (as in a codified set of beliefs with a particular hierarchy and set of rituals) appears to have a societal rather than behavioral basis. I like to think of organized religions as early experiments in organized group behavior - the basis of the first "civilizations" - rather than something intrinsic or innate. "Religion" doesn't appear to have a genetic basis. "Faith" or the "capacity to believe" does appear to have a genetic basis.

My 12 kopeks (*current exchange rate*)

Vorkosigan

Vork: I agree with you that the neuroarchitecture of the brain and the perceptual system provide an adequate explanation for the capacity to believe. Also, that Wilson's group selectionism is one of my principal arguments with his sociobiology (I guess it's called evo psych now) theories.

No, don't get confused. The ev psych crowd hates sociobiology. I think <a href="http://www.amazon.com/exec/obidos/ASIN/0195101073/internetinfidelsA/" target="_blank">The Adapted Mind : Evolutionary Psychology and the Generation of Culture</a> contains an explanation of this. The Ev Pysch people love to rip on sociobiology. Have you seen this <a href="http://www.psych.ucsb.edu/research/cep/primer.html" target="_blank">Website with Primer on Evolutionary Psychology</a>?

"Religion" doesn't appear to have a genetic basis. "Faith" or the "capacity to believe" does appear to have a genetic basis.


I am not sure how to think about religion at the social level. I completely agree that the capacity to have faith is genetic, and probably related to the ways humans are socialized to have in-group identities.

Vorkosigan

KC

I agree. I think the capacity for such things as faith and religion do have genetic components, but probably not specifically tied to 'faith' or 'religion'. For example, could it be that belief in the supernatural was just a way to explain dreams about people who had died? In that case, just our innate capacity for curiosity could be responsible for religion, not some specific 'god gene'.

As for identical twins, when we talk about environment, we have to not only think about how they we were raised, but to what differences ocurred in the specific physiological environment during development as well, among a myriad of other factors. These can contribute to differences in thinking and personality that may far outweigh the genetic similarities.

Cheers,

KC

abe smith

Response to OP &gt;&gt;&gt; "Is religion in our genes?"

If "religion" is a matter of IDEAS, &gt;&gt;&gt;&gt; it is VERBAL. And, words are manmade/ human artifacts; hence not genetically-determined. I'd answer simply then that religion is NOT in our genes.
Altho the Gasp&Freeze response may indeed be genetic &gt; selected = like the (apparently) built-in avoidance response to snakes = probably a pre-human selected response.

Quetzal

I knew the evo psych folks hated sociobiology. Sociobiology isn't "socially acceptable" anymore since they pretty much shot themselves in the foot with some of their "out there" ideas and and a sort of reductio insistence on genetic basis for everything. However, aren't some of the early genetics types now focusing on memetic evolution (Dennett for one, and Dawkins's extended phenotype for another)? Maybe it only appears to me that there's some overlap...

I'd say the capacity to believe is more related to our rotten ability to correctly differentiate between correlation and causation, coupled with a well-developed ability to associate two or more events or phenomena and infer pattern (even when there isn't any). It could have had an adaptive (survival-oriented) origin. Now why we inflicted religion upon ourselves is probably as you said - a measure related to socialization.

Stephen T-B

Not a gene; a variable.
There is a wide range of variable behaviours in any human community and in any human family - it’s why people who are closely related to one another can fall out so badly.
Isn’t it the case that the same bit of the brain which is implicated in addictive behaviour is also stimulated by religious fervour?
Needing to believe and experiencing the rewards which Belief can bring are things which happen in the brain, like needing to gamble or needing to climb dangerous mountains or break into people’s houses, or lie, or be kind and help old ladies cross the road.
Are any of these traits inherited? I don’t think so. Some are passed on by example, some are developed because of peer pressures and some, I think, arise innately.
Variable behaviours may, I think, have a survival benefit in a generalised, highly adaptive species such as Homo Sapiens for the reason that particular situations will favour the survival of one mode of behaviour but not another.
You wouldn’t expect to see it among ant eaters because an ant eater showing an individual preference for eating bees won’t breed because it’ll die of starvation.
The human being which breaks loose and tries something completely different may also die, but it might, in particular circumstances, survive while the rest of the clan perishes.
Thus we do inherit a tendency, or an ability, to behave differently from our fellows, and this comes as part of a bigger package which includes the variable ways in which we respond to certain stimuli. Religion is a stimulus - we can all speculate as to why, and how it evolved - and it is one which just happens not to do anything for me. So I’m an atheist.

ps418

Thanks for this clarification. I should have written "substantial heritability" rather than "substantially heritable."

Actually the need to differentiate between the two senses has not yet arisen, because no one has cited any heritability coefficients. I purposely restricted myself to arguing for "substantial" genetic influence.

I'm not sure I understand. I doubt you mean to say that artificial breeding experiments are necessary to demonstrate a role for genes in human behavioral variation. If so, then would you require the same artificial breeding experiments to demonstrate heritability of obesity, alzheimers, extraversion, ADHD, hypertension, major affective disorder, schizophrenia, rheumatoid arthritis, and so on? There is no need to do husbandry experiments to determine heritability of traits in humans, since twin and adoption studies provide 'natural experiments.'

Patrick