Wednesday, May 03, 2006

Brothers under the skull

As I mentioned in the last post, I recently got into an argument with someone who justified his claim that "women are prey" by pointing to the one-chromosome difference between ladies and fellas. (We'll call him Jack, short for... well, it's obvious what it's short for.) "There are demonstrated physical differences, therefore there are cognitive differences" seemed to be the basic gist. Being apparently devoid of a sense of irony, Jack also invoked "marketing" as proof that women have different thoughts and desires.

Then my mom sent me a link to a Richard Cohen column in which he starts off talking about the very interesting case of Donor 401, but then waxes rhapsodic about Nicholas Wade's book Before the Dawn, presumably to show that he reads. (I fondly remember a long-ago article, maybe by Gene Weingarten, calculating the density of the words "I" and "me" in Cohen's column.) Cohen is very pleased with his newfound determinism (look, ma, I'm a scientist!), but his description of the book shows that in his enthusiasm he's plunged in o'ershoes. Wade, according to Cohen, apparently "chides PC-addled scientists who insist there is no such thing as race when, just for starters, certain medicines work differently on whites than blacks. As with the noble savage, the raceless world is a myth." I'll get to Donor 401 later, Mom, but let's deal first with why this statement worries me.

I would have to be blind, deaf, and in all other ways insensate to claim that there were no physical differences between men and women, or between different races. Secondary sex characteristics, bone structure, muscle mass, and vocal cord size are all genetically influenced; so are skin melanin, facial structure, hair texture, lactose tolerance, alcohol-digesting enzyme production, ear wax composition, and so forth. So yes, what Wade is saying is right, and what Jack is saying has truth to it, too. These statements aren't false. But without some qualification, they can be dangerous.

See, from the neck up and the scalp inward, the rules change. The brain is surprisingly plastic and adaptable, and while there are certain glass ceilings installed by genetics, it's amazing how wide a berth we really have for learning, training, and new connections. For instance, take a look at this article on photographic memory, in which Josh Foer quite rightly points out that it doesn't actually exist. There has never been replicable evidence of a truly photographic, i.e. accurate in every detail, visual memory. Furthermore, such a phenomenon wouldn't fit with what we know about change blindness; if, in the course of normal cognitive processing, we ever really took in every single detail of a scene, such phenomena wouldn't occur. And yet we have people like Stephen Wiltshire, the "Human Camera." Stephen doesn't have some kind of spooky, ill-explained magic talent like "photographic memory" is supposed to be. What he has is a really, really, really good visual memory, combined with great skill at reproduction. And plenty of people, not just savants, have really really really good visual memory. (Foer mentions the Shass Pollaks, who demonstrably memorized over 5000 pages of the Talmud.) It's not an innate superpower; it's a matter of training and attention.

Then there are people who lose a whole brain hemisphere but compensate with the other, or have no arms but develop extreme motor control in their feet. The brain is an amazingly adaptable tool, and those adaptations don't only occur on an evolutionary time scale. Influences like poverty, cash- and teacher-starved public education, and peer pressure to look cool by not looking studious can lead to blacks getting lower average IQ scores, just as social pressure to both flaunt and hate one's body can lead to women who act like those "Sex and the City" chicks. At the same time, there are demonstrable, undeniable physical differences among races and between sexes. But this doesn't mean that the gene for book-smarts is on the same chromosome as the one governing skin pigmentation, or that having a uterus means you've got a natural disadvantage in thinking logically. Neural architecture is just too mutable for these ideas to hold water. A basic understanding of the brain debunks the idea that someone of normal development can be naturally unable to (say) think logically -- such things are too easy to train -- while an even more basic understanding of sociology makes it clear that any disparity in mental abilities has more than enough explanation available. So accept the idea of genetic difference, because you can't deny it. But accept it with a grain of salt, because it stops at the mind.

9 Comments:

Lynne said...

Incidentally, completely separate from the brain discussion, I have heard things about the results of the human genome project that support what you're saying about racial differences (i.e. that they are small). The statistical similarity between different racial populations is something like 95%, though I can't cite that. I assume they're talking about the overlap of the variances, but I'm not sure how exactly they did these statistics. Still, interesting, and could contribute to your argument.

5/04/2006 12:29 AM  
jess said...

I mean, granted, we also share 90-something percent of our DNA with chimps, per conventional wisdom.

My mother actually wrote a pretty great article about this in the Times magazine a while back... too much of a while back to still be publicly available and shut my mouth, no it's not, it's right here. Francis Collins would apparently put the numbers at 99.9. Anyway, the article's definitely worth reading, and it acknowledges the social aspects of interracial health differences as well as the genetic ones.

5/04/2006 1:27 AM  
jess said...

I forgot to finish that joke because I was looking up the article, and now I forget what I was going to say about us sharing DNA with chimps. It was supposed to make clear that I didn't think that such a fact conflicted in any way with the assertion that the genomic differences between populations are statistically insignificant.

5/04/2006 1:29 AM  
JP said...

The statistical similarity between different racial populations is something like 95%, though I can't cite that.

you're probably thinking of this one

"Within-population differences among individuals account for 93 to 95% of genetic variation; differences among major groups constitute only 3 to 5%"

is that a lot or a little? it all depends on what you want to argue.

Secondary sex characteristics, bone structure, muscle mass, and vocal cord size are all genetically influenced; so are skin melanin, facial structure, hair texture, lactose tolerance, alcohol-digesting enzyme production, ear wax composition, and so forth...from the neck up and the scalp inward, the rules change

the clear line you want to draw isn't so clear. Do you think alcohol-digesting enzyme production has no role in alcoholism, for example?

you're right that genes affecting intelligence or other hard-to-measure mental traits have limited evidence. but then again, the genetic influence on some of those physical traits you mentioned is still far from understood.

The brain is plastic, yes, but it's still "just" an organ.

5/04/2006 4:54 PM  
jess said...

I probably didn't make it clear in this particular post, but I'm the last person who's going to go anything-determinist. I don't think that the things I described as genetically influenced are controlled only by genes (that's why I said genetically influenced) and I don't think that the brain is totally unaffected by genetics (which is what I meant by talking about glass ceilings). But I don't think it's justified to claim an across-the-board cognitive or intellectual difference based on genetics alone. In other words, it's not valid to say "women differ from men by one chromosome, and this supports my idea that they are mentally inferior." There's just too much wiggle room there.

Which is not to say that non-cognitive traits are completely unchangeable -- far from it. Even leaving aside environmental influences on gene expression, there's the fact that you can train some physical features in the way I was talking about -- say, you might have a glass ceiling on your muscle mass, but you can bulk up pretty damn far, with enough work, before you hit it. The point I intended to make was that this kind of change is daily and inevitable with the brain, which makes it hard (and, I think, unjustified) to pin it with a broad statement, genetically justified.

I'm not sure what the alcoholism was getting at... I don't think alcoholism is a purely cognitive phenomenon. Intelligence, logical thinking, math skills, etc. aren't purely cognitive, but there's not a lot more brain-bound than that.

5/05/2006 11:07 PM  
Anna said...

I think I can help you all out with some citations.

Though the bit about sharing genetic material with Chimps has been estimated for years, it was actually demonstrated last year when a draft sequence of the Chimpanzee genome was published. It looks to be about 96% shared. I haven't read this article but it's the best I can do at the moment, sorry! Also, blogger is not accepting my code, so must paste URL, second apology.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16339373&query_hl=7&itool=pubmed_DocSum

Here's an
article
I have read, by Tang et al. They mapped the genomes of populations of Caucasians, African-Americans, Han Chinese and Japanese. There is also one very small population of Texas Latinos but I encourage you to ignore that because Latinos were barely represented in this study, as the authors acknowledge. To cut to the chase, genetic variation in these populations did cluster by ethnicity and race. However, that difference is still incredibly small compared to the similarities.

In either case, it's the wrong question. I mean, it's interesting, but quantifying the variation in the code doesn't get us very far. It's only useful to answer the question "Is there any point to studying genetic difference?" Everyone's terrified to examine these questions for social reasons, to which I'm sympathetic. This line of questioning can't really get rid of that whiff of eugenics. And of course, there's the near certainty of morons like Jack arguint that difference equals inferiority. No wonder people are skeptical. But to avoid studying race punishes minority populations. In cases where there truly are differences, then not studying them is to take a one-size-fits-all approach, and that size is White Male.

What we really want to know, for good or ill, is how much of the difference leads to difference in function. And on that question everyone's clueless. We can't even explain what separates us from the other Chimps. In the absence of anything approaching evidence, your opponent in this debate is invited to blow his half-baked ideas out his ass.

5/06/2006 2:27 AM  
jess said...

See, this is why I have smart friends. Thanks, Anna.

In cases where there truly are differences, then not studying them is to take a one-size-fits-all approach, and that size is White Male.

I'm with you on that, and so, for the record, is Francis Collins. Racial differences are not without a biological component, and it looks like this might contribute to disparities in disease susceptibility, medication effectiveness, etc. (as opposed to those disparities being entirely environmental). It's not something we can ignore for the sake of being PC, because that shuts down some important avenues of research. But that's exactly when we have to be really clear about what these differences can be taken to mean, and when people like Cohen are running around saying "race is biological! The raceless world is a myth!" without any qualifications, that opens some pretty nasty doors. Even when there's a grain of truth to it.

5/06/2006 2:48 AM  
Frank said...

"So accept the idea of genetic difference, because you can't deny it. But accept it with a grain of salt, because it stops at the mind."

Doesn't this kind of strict human exceptionalism about genetic differences strike you as somewhat dogmatic? Genetic differences don't stop at the brain between individuals, and there is no logical reason to suggest that some form of genetic differences between groups doesn't exist, especially in terms of differences between the sexes in social behaviors.

5/10/2006 8:42 PM  
jess said...

Short answer: Yes, it would be, but see this clarifying post (and my comment on your blog). It's not that I want to completely ban any consideration of the brain as genetically influenced, because that would be nonsense. But I don't think genetic distinctions between groups are sufficient to assume cognitive differences.

5/11/2006 12:40 PM  

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