Monday, October 22, 2007
Jean-Baptiste Lamarck Vindicated
The image, stolen from Wikipedia is of one Jean-Baptiste Lamarck. He was a naturalist in the 19th century and was one of the earliest proponents of evolution. The difference between his theory and Darwin's was the idea of when changes or adaptations occurred. Lamarck believed that changes occurring during the life time of a given animal would be passed on to it's young. So basically, if you're a giraffe, and you're constantly stretching your neck to get at higher leaves, then your children will have longer necks because your neck got infinitesimally longer throughout your life.
It turns out that Lamarck wasn't totally wrong. He was just not right in the way he thought.
Nova is the single best science show in the history of mankind. I got into an argument with a friend the other day about the idea of epigenetics. He had never heard of it, though I had just watched Nova's new documentary, Ghost in Your Genes.
Here's the deal. DNA is the blueprint for an organism. That much is certain. But there has to be a mechanism built into our cells that interprets that DNA and decides which bits of it to use. This mechanism is what's responsible for things like cell differentiation. It's why eye cells are different from heart cells are different from liver cells. Different bits of the DNA are turned on in each different type of tissue in your body. Basically, if the DNA--the genome--is the blueprint, then methylation and chromatin remodelling--the epigenome (literally "above the genome")--is the architect that interprets it.
Okay, but the crazy thing is that, as it turns out, some of these epigenetic features--sometimes those acquired during your lifetime--appear to be transgenerational. That is: they are passed down from one generation to the next. Your bad eating habits, in other words, could affect whether your grandchild gets diabetes.
Yeah. Fucked up.
DNA is largely static. It doesn't change much. It is very, very good at duplicating itself with near impossible accuracy. But it appears that natural selection has a place for nurture. It's like a quicker version of evolution. It's evolution on the fly that happens in the short term (short meaning hundreds of years rather than thousands or millions). It won't make new species, but it will change the way species are affected by their environment.
There's a lot of really interesting research into this stuff, and you'd be hard pressed to find a more frantically researched aspect of genetics in this day and age. I mean, a few years ago, when they were scrambling to finish up the Human Genome Project, they thought that they were inches from the key to understanding everything. They were wrong, of course.
It seems like the deeper you burrow down the rabbit hole, the deeper it appears to be.