Saturday, January 31, 2009

Newsweek drops the ball

What the hell, Newsweek. You act like you want to be taken as a serious journalistic source for, you know, news. And yet you go publishing this utter nonsense about a supposed re-emergence of Lamarckist theory?

The short version of Lamarckist theory is that it is "evolution via acquired traits." The article gives a good example of the theory, which is that giraffe's necks got longer because short-necked giraffes stretched their necks to reach the trees, and their offspring were born with the longer necks. This is tantamount to claiming that if a very light-skinned person spends a lot of time in the sun and gets tan, he or she will have tan-skinned offspring. The theory is obviously absurd to us today, but before Darwin hit on natural selection, the jury was still out on how exactly evolution took place (although the fact that it did take place was not generally under dispute).

The explanation of Lamarckism is about the only thing this article gets right.

First of all, what the hell is this Sharon Begley character doing writing Newsweek's science articles? A glance at other articles to her credit include "Can God Love Darwin, Too?" and "Science Finds God." I'm sure that's just a coincidence.

She starts this article with the following:

Alas, poor Darwin. By all rights, 2009 should be his year, as books, museums and scholarly conclaves celebrate his 200th birthday (Feb. 12) and the 150th anniversary of "On the Origin of Species" (Nov. 24), the book that changed forever how man views himself and the creation.

That's right. Not the universe. The "creation."

Oh, but it gets better. From Begley's biography:

Sharon Begley, widely known for her ability to break down complex scientific theories and write about them in simple prose, returned to Newsweek in March 2007 from the Wall Street Journal, where she wrote the "Science Journal" column for five years.

This woman is supposed to be an actual science writer. It would seem that by "breaking down complex scientific theories," the writer of this biography (no doubt Begley herself) means "completely misunderstanding and misrepresenting complex scientific theories, so that they can be explained simply and reach the conclusion she desires."

Though granted, I'm only going off one abysmal article. Maybe her others do better, but I haven't read them so I can't address them. Let's talk about the current article.

Some water fleas sport a spiny helmet that deters predators; others, with identical DNA sequences, have bare heads. What differs between the two is not their genes but their mothers' experiences. If mom had a run-in with predators, her offspring have helmets, an effect one wag called "bite the mother, fight the daughter." If mom lived her life unthreatened, her offspring have no helmets. Same DNA, different traits. Somehow, the experience of the mother, not only her DNA sequences, has been transmitted to her offspring.

Second paragraph in, and already she's got so much wrong. Only the mother's DNA sequences are transmitted to her offspring. Her experiences affect the expression of those DNA sequences. Ms. Begley, science writer extraordinaire, seems not to grasp the fundamental difference between a phenotype, and a genotype.

I'm not a programmer, so I can't put this into an actual programming language like a clever blogger, but the developmental process we're talking about basically works like this:

For TRAIT A:
-if CIRCUMSTANCE B is present, express TRAIT A
-if CIRCUMSTANCE B is not present, do not express TRAIT A

That's the very very very simplified version of what we're dealing with here. Begley's article makes it sound like if a water flea's mother is in threatening circumstances, the offspring is spontaneously born with a spiny helmet, apropo of nothing as far as the DNA is concerned.

But the truth of the matter is quite different: the gene for the spiny helmet (TRAIT A) exists in every water flea. It is part of the genotype of that organism. The ones whose mothers were not put in a threatening situation (CIRCUMSTANCE B) simply did not express the trait, meaning that the organisms of the same genotype are of a different phenotype.

It is a well-known principle of gestational development that chemical triggers cause genetic traits to be expressed, or not. For one example, a chemical trigger applied to a human fetus at the right time will cause the fetus to express male traits, i.e. it makes a boy; if that chemical trigger is not applied, the fetus will develop to be a baby girl.1

It is also well-known that environmental factors can affect both the gametes of an organism, and the development of offspring even after the egg has been fertilized. That's why you shouldn't smoke or drink during pregnancy: it screws up the chemical processes of the body, and as the fetus develops, some important functions may never be triggered on; or some traits that ought to stay off get turned on.

I really shouldn't keep using code analogies since I'm not a programmer, but here goes: Since evolution has been a blind process, extraneous information has not necessarily been culled from the genome to keep things tidy. Each version of the software has added or altered code as needed, but not necessarily subtracted if not needed, only made it inactive. There's a lot of legacy code in our genes, some of which can be very harmful if it is re-activated.

All that to say that the existence of a life-threatening situation simply results in a particular chemical trigger that kicks in during some water fleas' gestational development, causing them to express different traits than water fleas without that chemical trigger.

It is not a level of science that is outside the understanding of a layperson, and certainly not an observation that gives those who accept Darwinian evolution "heart palpitations" as she claims. If a human woman experiences a great deal of stress during pregnancy it can affect the child's development, too. This is no different in principle, the only difference is that the water flea genome has a contingency trait should that situation arise (TRAIT A for CIRCUMSTANCE B).

Begley makes another example about the diets of pregnant mice affecting traits in their offspring, by altering the DNA of their eggs (gametes). Begley "emphasizes" that "this is not a mutation," and Begley is frankly stupid to do so. Of course this is a mutation. The alteration of DNA is the definition of genetic mutation.

Let me emphasize something in my own turn: what she is talking about are not acquired traits. The mother flea does not get a spiny helmet from somewhere else and pass that onto her kids. The mother rat does not turn brown and pass that onto her kids. They undergo experiences which alter the development of their offspring, either at the DNA level or during key stages in development, to express dormant or recessive traits. That is just standard genetics. Nothing new or revolutionary here at all.

So let's skip right to the end here:

The existence of this parallel means of inheritance, in which something a parent experiences alters the DNA he or she passes on to children, suggests that evolution might happen much faster than the Darwinian model implies. "Darwinian evolution is quite slow," says Whitelaw. But if children can inherit DNA that bears the physical marks of their parents' experiences, they are likely to be much better adapted to the world they're born into, all in a single generation. Water fleas pop out helmets immediately if mom lived in a world of predators; by Darwin's lights, a population of helmeted fleas would take many generations to emerge through random variation and natural selection.

It's true that natural selection usually moves fairly slowly. The point, which anyone with even a passing understanding of evolution would manage to grasp, is that those many generations to create the genetic code for helmeted fleas have already occurred, leaving us with the water fleas as we observe them today. The helmets are not a new trait, they are an existing trait that is either expressed or not.

It is certainly interesting that they developed in such a way that allows environmental factors to inform the expression of the trait, rather than just automatically having all water fleas be helmeted. But this is in no way an affront to the theory of evolution via natural selection, and is in fact easily accounted for as a positive survival adaptation. The fact that this article attempts to make it sound like it could invalidate or undermine the theory is not only sensationalism, it's just plain bad science, and Newsweek should be ashamed.


  1. The human Y chromosome is a modified X chromosome. This throws something of a wrench into the arguments of those creationists who would claim that scientific discoveries are only proving information that has always been in the Bible. Gestational development indicates that Adam, in fact, comes from Eve.

2 comments:

google said...

She may have read a recent article about the epigenome and gotton confused. Twins have identical DNA and can have different traits expressed by envirormental factors.

TheGamut said...

I've said for many years that guys are missing 1/4 of a chromosome. :) I have no genetic background, but it seemed pretty obvious when most genderless creatures have only X-shaped chroms. That makes the Y the oddball. The whole male-pattern-baldness thing nailed it home for me that there was a "leg" missing.

There was (or is, I dunno if it has changed) a situation in Brownsville, TX, where children were developing anacephalic in numbers many times greater than anywhere else. (Of course, the condition is SO rare that it's still rather rare, but the statistics showed a definite localized situation that did not exist elsewhere.)

What genetic code suddenly popped up to determine that the spinal column shouldn't close?

There wasn't one.

They've traced it to dumping of toxins right across the border there (by both American and Mexican companies) that would have been illegal in the USA (among other countries). If true (as I have not seen the research on it), this is the case in point that environmental conditions have a lot to do with development.