At tributes to Darwin, Lamarckism—inheritance of acquired traits—will be the skunk at the party.

[BridgeTheGap]

The Sins of the Fathers, Take 2

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. Teamed with genetics, Darwin's explanation of how species change through time has become the rock on which biology stands. Which makes the water flea quite the skunk at this party.

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.

That gives strict Darwinians heart palpitations, for it reeks of the discredited theory of Jean-Baptiste Lamarck (1744–1829). The French naturalist argued that the reason giraffes have long necks, for instance, is that their parents stretched their (shorter) necks to reach the treetops. Offspring, Lamarck said, inherit traits their parents acquired. With the success of Darwin's theory of random variation and natural selection, Lamarck was left on the ash heap of history. But new discoveries of what looks like the inheritance of traits acquired by parents—lab animals as well as people—are forcing biologists to reconsider Lamarckism.

The lab mice, of course, came first. Since 1999 scientists in several labs have shown that an experience a mouse mother has while she is pregnant can leave a physical mark on the DNA in her eggs. Just to emphasize, this is not a mutation, the only way new traits are supposedly transmitted to children. Instead, if mother mouse eats a diet rich in vitamin B12, folic acid or genistein (found in soy), her offspring are slim, healthy and brown—even though they carry a gene that makes them fat, at risk of diabetes and cancer, and yellow. It turns out that the vitamins slap a molecular "off" switch on the obesity/diabetes/yellow-fur gene. (Don't try this at home: no one knows which human genes soy, B12 and folic acid might silence.) This was the first evidence, now confirmed multiple times, that an experience of the mother (what she eats) can reach into the DNA in her eggs and alter the genes her pups inherit. "There can be a molecular memory of the parent's experience, in this case diet," says Emma Whitelaw of Queensland Institute of Medical Research, who did the first of these mouse studies. "It fits with Lamarck because it's the inheritance of a trait the parent acquired. There is even some evidence that the diet of a pregnant mouse can affect not only her offspring's coat color, but that of later generations."

http://www.newsweek.com/id/180103?gt1=43002

[Buzz Clik]

1. Sweet jeebus. It's called gene expression.

[TZ]

2. exactly.

genes can switch on and off depending on whats going on in the environment.
This is NOT Lamarckian at all.

[salvorhardin]

3. Right

It's epigenetics not Larmarcism.

[Buzz Clik]

4. This biblical quote (out of context) fits nicely:

"In those days they shall say no more, 'The fathers have eaten a sour grape, and the children's teeth are set on edge.'"

[laconicsax]

5. Shh! Reality doesn't go well with sensationalism.

[semillama]

6. Begley gets it all wrong

Pharyngula explains it all at his blog.

http://scienceblogs.com/pharyngula/2009/01/sharon_begley_how_could_you.php

"She's describing real and interesting phenomena, but it isn't new and it isn't revolutionary. These are results of plasticity and epigenetics, and we aren't having heart palpitations over them (you're also going to have a difficult time finding any "strict Darwinians" in the science community who are even surprised by this stuff). We load up pregnant women with folate and maternal vitamins and recommendations to eat well, and we tell them not to get drunk or smoke crack for a few months, because it is common sense and common knowledge that extra-genetic factors influence the health and development of the next generation. Genes don't execute rigid, predetermined programs of development — they are responsive to the environment and can express radically different patterns in different contexts. The same genes build a caterpillar and a butterfly, the difference is in the hormonal environment that selects which genes will be active.

It's the same story with the water fleas. Stressed and unstressed mothers switch on different genes in their offspring epigenetically, which lead to the expression of different morphology. It's very cool stuff, but evolutionary biologists are about as shocked by this as they are by the idea that malnourished mothers have underweight babies. That environmental influences can have multi-generational effects, and that developmental programs can cue off of the history of the germ line, is not a new idea, especially among developmental biologists.

This is just wrong on evolution:

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 misses the whole point. The population of water fleas have a genetic attribute that allows the formation of spines under one set of conditions, and suppresses them under others. This gene regulatory network did not pop into existence in a single generation! If it did, then Begley would have a big story, evolution would have experienced a serious blow, and we'd all be looking a little more carefully into this 'intelligent design' stuff. The pattern of gene regulation was the product of many generations of variation and selection; only the way it was expressed in a phenotype experienced a shift within a single generation."

[GreenPartyVoter]

7. Actually, Folic acid was considered an important thing to take when I was preggers. Has

that changed?

[On the Road]

8. 1) Lamarck Was a Pseudoscientist

2) This is NOT Lamarckianism:

"...if mother mouse eats a diet rich in vitamin B12...her offspring are slim, healthy and brown—even though they carry a gene that makes them fat..."

It is simply the effect of the intrauterine chemical environment.

3) Having said that, I have long felt that there have to be ways environmental factors are carried into future generations. Genetic mutation is a blunt and erratic instrument.

[SemiCharmedQuark]

9. LOL...Oh Newsweek...why?

x(