Generating right-left asymmetries


We’re only sorta bilaterally symmetric: superficially, our left and right halves are very similar, but dig down a little deeper, and all kinds of interesting differences appear. Our hearts are larger on the left than the right, our appendix is on the right side, even our brains have significant differences, with the speech centers typically on the left side. That there is asymmetry isn’t entirely surprising—if you’ve got this long coil of guts with a little appendix near one end, it’s got to flop to one side or the other—but what has puzzled scientists for a long time is how things so consistently flop over in the same direction in individual after individual. There has to be some deep-seated mechanism that biases developmental events to favor one direction over the other. We know many of the genes involved in asymmetry, but what is the first step that skews development to make consistent asymmetrical choices?

In mammals, we’re getting close to the answer. And it looks to be beautifully elegant—it’s a simple trick to convert an anterior-posterior difference into a left-right one.

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Maybe they could switch to depleted uranium

Hunters should be allies of conservationists—in the best situations, hunting and wildlife groups have been great advocates of preserving habitat, which is the core issue, I think, in protecting biodiversity. If they’re doing it so they can go in and blow away a few big meaty game animals, well, OK…setting aside that acreage also means a richer array of songbirds and arthropods and plants and fish and lizards and amphibians, which normally aren’t shot up, have a better chance of survival.

Sometimes, though, short-sightedness and denial and a refusal to deal with a minor inconvenience undercut that whole plan. An article on the California condors is a perfect example: the use of lead ammunition is killing the birds indirectly. Wild condors have a ten times greater concentration of lead in their blood compared to captive birds, and the source is the flurry of lead hunters are flinging into the environment.

“The condor food supply is almost completely contaminated,” says Noel Snyder, a retired biologist with the U.S. Fish & Wildlife Service. He adds that Hunt’s research [5.1MB PDF] shows that deer flesh is tainted after the animals are shot; this raises questions about human health as well. “When you look at these X-rays, you have to ask yourself, ‘Why would I eat deer meat?’”

In recent years, California has attempted to limit the use of lead ammunition in the condor range, but introduced legislation continues to get defeated. Kelly Sorenson of the Ventana Wildlife Society says that hunting groups and the National Rifle Association are resisting change but that lawsuits filed in July by environmental groups may force state legislators to act. Although it is costly, ammunition made from other metals is available.

Every fall, I know that lots of my students take off for opening weekend of deer season—I even consult the DNR schedule when putting together my exam calendar—and it’s nice to know now that they’re putting their brains at risk. Chronic Wasting Disease is scary enough, now it’s also a question of lead poisoning. I think I’ll avoid the venison.

The PIG-fest continues

The ongoing dissection of Wells’ The Politically Incorrect Guide to Darwinism and Intelligent Design continues, with two new disembowelments on display.

Andrea Bottaro rips up Chapter 9, “The Secret of Life”. In this one, Wells makes the tired old argument that only intelligent agents can create information, therefore informational macromolecules must have been created by intelligent agent(s). It’s also got a sharp, succinct critique of the Sternberg affair, in which Stephen Meyer smuggled an ID paper into Proceedings of the Biological Society of Washington. (Don’t ask what those two subjects were doing together in this chapter. Wells is not big on logical organization.)

Mark Perakh takes on Chapter 16, “American Lysenkoism”. You can guess the subject from the title: the Darwinists are persecuting the proponents of heterodoxy, confining them to the gulags of right-wing think tanks, like the Discovery Institute, and not allowing them to be represented in the universities. Yeah, right. We also don’t let flat-earthers get professorships in geology.

Expect more in the near future. We divvied up the chapters a few weeks ago, and everyone is working through them at their own pace (for the record, mine was ready to go a week and a half ago, and I held off to give a few people a chance to catch up—doesn’t everyone whip out a few thousand words in a few hours?), and they’re getting released as they’re done. When they’re all organized, it’s going to represent a very substantial rebuttal of some extraordinarily shoddy scholarship.

One of the things all of us are noting that may not get communicated well in the rebuttals is how much is wrong in each of Wells’ chapters. We’d have to write a whole book for each chapter just to explain all of his foolish errors and dishonest cheats, and what we’ve all been electing to do (by necessity!) is to focus on just a few examples and shred those. This is a book that would be slashed to bits by competent reviewers—I have a growing sense of amazement that it got published at all. But then, all I need to do is note that it was put out by Regnery, where incompetence and lies are a prerequisite for publication.

Symmetry breaking and genetic assimilation


How do evolutionary novelties arise? The conventional explanation is that the first step is the chance formation of a genetic mutation, which results in a new phenotype, which, if it is favored by selection, may be fixed in a population. No one sensible can seriously argue with this idea—it happens. I’m not going to argue with it at all.

However, there are also additional mechanisms for generating novelties, mechanisms that extend the power of evolutionary biology without contradicting our conventional understanding of it. A paper by A. Richard Palmer in Science describes the evidence for an alternative mode of evolution, genetic assimilation, that can be easily read as a radical, non-Darwinian, and even Lamarckian pattern of evolution (Sennoma at Malice Aforethought has expressed concern about this), but it is nothing of the kind; there is no hocus-pocus, no violation of the Weissmann barrier, no sudden, unexplained leaps of cause-and-effect. Comprehending it only requires a proper appreciation of the importance of environmental influences on development and an understanding that the genome does not constitute a descriptive program of the organism.

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The apostate kidney

What a strange story: a woman donates one of her kidneys to another woman in need. Later, the recipient leaves the Christian faith. Now the donor wants her organ back.

Smith was aghast when she heard of the conversion, and she quickly wrote a letter asking Felks to re-convert to Christianity or return the organ, saying it was donated under false pretenses.

“I feel helpless,” she says. “Part of my body, my DNA, is stuck inside a person who’s going to hell.”

There’s some freaking weird theology going on here. Does she think her DNA is going to be assumed into the afterlife? Do spirits have DNA? Do you need a kidney as an angel?

She also has some strange anxieties, since the recipient is a pagan.

Smith suffers nightmares of her former organ filtering “strange Asian teas, pig blood and witch doctor brews in Africa,” she says. She wonders if the Lord really wanted her to donate the kidney, or if she acted on a “triple-espresso high” she had that morning. She is also concerned that when her body is resurrected, it might be incomplete.

That’s tragic. The kidney is also missing the opportunity to filter the body and blood of Christ, transforming Jesus’ protein into urine. Oh, to never again deaminate the amino acids of the God of Abraham, to never again extract Jesus’ sodium ions, and to have to settle for filtering the ichor of little animist gods…what a sad fate.

I don’t know about this bodily resurrection thing. I would think that running a little lapsang souchong through the ol’ nephric ducts is small potatoes compared to being perfused with embalming fluid and later rotting into a putrid film of bacterial goo. Apparently, the Holy Ghost can reanimate that, but foreign tea is going to have It scratching It’s immaterial and invisible Head.

The theological absurdity goes on.

“I’m all for spiritual curiosity,” she says, “but you’ve got to settle these things beforehand. My kidney belongs to Christ. It will never be Pagan.

Hmm. Yes. Various organs in your body all make intellectual and emotional decisions about what religion they should follow. Personally, I’ve had my organs all committed to different and appropriate philosophies: my colon is a good disciplined Calvinist, my lungs are Breatharians, my right forefinger is an acolyte of the cult of Macintosh (*click*, praise Jobs!), and my penis is observant of some hysterically hedonistic faith which doesn’t require much in the way of intellectual expression. My brain, however, is godless.

Smith’s brain is definitely fundamentalist Christian: inert, uninformed, and irrational.

(via God is for Suckers)

P.S. Some people aren’t getting it. The article is satire, although if you do think about it, there is some weird stuff going on with this whole idea of an afterlife.

Michael Gerson and the new Republican alibi for crippling stem cell research

This Newsweek article on the latest innovation in stem cell research is infuriating. The author, Michael Gerson, is a Republican hack with no competence in biology, which seems to qualify him to be a serious judge of science to this administration.

The issue of stem cells was the first test of the infant Bush administration, pitting the promise of medical discovery against the protection of developing life and prompting the president’s first speech to the nation. His solution–funding research on existing stem-cell lines, but not the destruction of embryos to create new ones–was seen as a smart political compromise. In fact, the president was drawing a bright ethical line. He argued that no human life should be risked or destroyed for the medical benefit of another. This was an intentional rejection of the chilly creed of utilitarianism–the greatest good for the greatest number–because the greatest number would gain the unrestricted right to extend their lives by ending or exploiting the lives of the weak.

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