Exorcising flawed concepts of Hox function

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beetle hox

One of those difficult misconceptions that is hard to root out of people's heads is the idea that individual genes 'make' something. We all have this bias, this tendency to reify the gene into something concrete—scientists do it all the time, too. You can see it in the list of gene names at OMIM, for instance; many are named after diseases or their consequences in adults. The message of which I try to always remind myself (not always successfully) is that genes don't make things, interactions between collections of genes and the environment make things. Biology arises out of the processes, not the structures; it's the reactions, not the end-product.

A paper in the latest BioEssays reminds me of this. It's a short review of Hox genes and insect wing formation that carries the same message, that morphology is a consequence of patterns of gene interactions.

Continue reading "Exorcising flawed concepts of Hox function" (on Pharyngula)

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Go. Read. from Pacific Views on June 22, 2005 7:32 PM

World O'Crap: The Sunday Cinema edition brings us the house odds on the Cruise/Holmes hookup, and a delightful review of the life lessons to be gained from Eyes Wide Shut. Also, we get a carnival of the wingnuts and the... Read More

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Extremely interesting. Some relatively rare human cancers have characteristic translocations within their karyotypes, and sometimes, the homologues of these insect genes are involved. The obvious common theme is differentiation.

But on to something a little off-topic. I’ve been trying to point out how un-Christian ID and the tactics of it “advocates” are from time to time. I’d also like to point out a motivation for ostensibly pro-ID posters, other than the crisis of religious faith that we often assume, which may be overlooked.

At this point in time, there exists a political movement in the US known as the “conservative movement”. It isn’t actually conservative, and it does not by any means include everyone who is. Its goals are diverse and well-known, and I won’t waste space by describing them all here. Members of this movement often make reference to “Christianity”, but almost exclusively with regard to sexuality (eg homosexuality, abortion, birth control, and so on). It’s worth noting that such “movements” arise and fall over time across societies. Please note that I am not, in this post, either condemning or endorsing this movement in general.

One of the characteristics of the “conservative movement” is its emphasis on unity. Unlike certain left wing movements, which have shown a consistent tendency to splinter into rival factions, those who self-identify as “movement conservatives” are kept in line. It’s also a strongly victory-oriented movement, to the extent that ruthless tactics are encouraged. The left wing satisfaction with being “ahead of the times” or “pure” does not seem to characterize it.

A fair number of people base their self-image on identification with the “conservative movement”, and these people will always claim to agree with whatever is perceived as the “conservative” party line. I am not suggesting that such people don’t exist with regard to other political movements, including some on the left, but that’s not germane at the moment.

The point is that “ID” has been adopted very much as “politically correct” by the “conservative movement”. In fact, to make this particularly obvious, the DI web site used to have lots of articles on “conservative” topics utterly unrelated to ID. Furthermore, and not necessarily unrelatedly, conflict has arisen between “movement conservatives” and science on other issues, such as human-induced climate change.

What makes this relevant is that people who hold strong “conservative” views on issues such as taxes or gays may feel absolutely compelled to argue in favor of ID, out of loyalty. It’s just another possible motivation to consider.

In reality, of course, neither science in general not the theory of evolution in particular has any relevance whatsoever to the question of what political system human societies should adopt, and I’m not suggest that it does. Nor am I suggesting that being a scientist or interested in science in any way predicts someone’s political views, as that, also, would be false. But I am saying that someone who self-identifies as a “movement conservative” may feel compelled to defend ID, even if doing so produces very severe cognitive dissonance.

HideeHo,

I am reading “Endless Forms Most Beautiful” just out by Sean B. Carroll, and I found your post quite helpful at understanding some of the details of Hox genes that I had not understood earlier.

Thanks.

I have a general question first and then a comment for Harold.

Where can a sophisticated layperson such as myself (or at least that’s how I like to think of myself wrt evolutionary biology) go to get a basic overview of the evo-devo controversy?

My comment for Harold is that I agree with you on several points and found most of what you have to say to be quite insightful. Of course the left can be equally vicious in its own way of enforcing “loyalty” on any number of issues and yet the left still fractures. Conservatives have been ingenious at putting together and maintaining “the big tent”. I agree that ID has become part of that big tent-though I think there are some emotional and cognitive reasons why.

I disagree that evolution has **no** political implications or metaphysical implications. The correspondence is never one to one. But accepting the premise, for example, that the human mind has evolved and that it has specifically limited information processing abilities for example, does have **implications**. I don’t think Darwinism is metaphysically neutral, nor should it try to be.

As a cell biologist, I must point out that genes DO make something (or rather they each encode for a particular substance) - proteins. This is the main confusion out there. Much of the public (and higher order biologists) were surprised by the low number of genes in the human genome - not cell biologists … the bulk of genes encode proteins that are needed for cellular functions. If you look at worms, flys, mice and humans - we all have (more or less) the same cell types (gut cells, muscle cells, neurons …), which perform the same cellular functions. These functions are mediated by proteins.

So to abstract the “function” of a particular gene to higher level phenotypes is tricky and not straightforward (as you point out) … so to study these genetic “functions” you must study the proteins and their most direct effects - how each protein affects cellular function. You may call this reductionalism - how ever I see this as examining the “proximal effects”.

Chip Poirot -

I didn’t actually realize there was an evo-devo “controversy”, per se. I thought the term referred to the fascinating issue of how the process of development evolved, and impacts on future evolution. Modern biology in general is hard - although by no means impossible - to get an “overview” of. At the professional level, it assumes a solid background, including knowledge of general and organic chemistry, general physics, statistics, math through “freshman” calculus, as well as strong familiarity with the principles of biochemistry, molecular biology, genetics, and probably some organism-level course. You can get some pretty good idea of it without all that, of course, but your understanding will improve as you build the foundation.

“I disagree that evolution has **no** political implications or metaphysical implications. The correspondence is never one to one. But accepting the premise, for example, that the human mind has evolved and that it has specifically limited information processing abilities for example, does have **implications**. I don’t think Darwinism is metaphysically neutral, nor should it try to be.” What are the implications? Can you be a bit more specific? I’m honestly not sure if I agree with this statement or not in its current form :).

Almost any philosophical stance accepts that the human mind has limited information processing abilities, I would hope.

Bill,

Of course you are correct-one needs a foundation to understand these issues and as I have found, one can build the foundation up as one goes along.

Is there not an evo-devo “controversy”? Perhaps not. But then again, perhaps. At least I keep picking up hints occasionally on PT and other sources that there is interesting work being done on developmental processes that challenges more “conventional” assumptions of the synthesis. For the record, its my understanding that this “controversy” is being misused by the ID movement.

So, all that said, I would be grateful for any reasonably accessible source that might clear up some of my confusion. A suggested journal article, book, website-anything that breaks some of these issues down would be most welcome.

As to the other issue: I don’t think that Darwinism maps one to one onto specific political ideologies. But I suspect it does rule some things and rule other things out.

Darwinism (I think) presents a problem for utopian ideologies or grand scheme to “remake” humanity. Thats not to say that Darwinism necessarily creates problems for a generally egalitarian political philosophy.

Darwinism does not confuse “is” and “ought” (though I sometimes think some individuals do), but it does suggest that systems of morality and social mores in general evolved rather than having been laid down by supernatural beings or all wise ancestors.

It seems to me that an evolutionary-cognitive view of the mind also makes a number of theorems of free market economics inoperable.

That’s what I was referring to. Anyway, probably best not to get too far off topic.

Chip, there is no longer any controversy worth your time. There were always ideas of a deep connection between evolution and embryological development, but until fairly recently we lacked technical means to clarify this connection. The best introduction is Sean Carroll’s Endless Forms Most Beautiful .

very modern Harold Wrote:

Modern biology in general is hard - although by no means impossible - to get an “overview” of. At the professional level, it assumes a solid background, including knowledge of general and organic chemistry, general physics, statistics, math through “freshman” calculus, as well as strong familiarity with the principles of biochemistry, molecular biology, genetics, and probably some organism-level course.

Maybe a bit about organisms, and never mind ecosystems? Harold, are biologists only supposed to see Nature on TV? Believe it or not, there are still biologists who know a a lizard from a lilly and even get their boots muddy. You’ll never find out what’s going on out there if you don’t go out there.

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