Drawing the Wrong Conclusion from Giant Bacteria
DaveScot has an article over at Casa Dembski about Epulopiscium fishelsoni. Judging by the article that he links to (from the Journal of Bacteriology, 1998), this bacterium looks like a pretty interesting beastie: it changes size by up to 20 times. That’s individual cells, not variation in a population: a single E. fishelsoni can grow to become 10-20 times larger than it was some hours ago. Not only that, but at its largest, it’s over half a millimeter long, making it visible to the naked eye.
But what interests DaveScot is the size of its genome: about 1 trillion base pairs, more than 300 times as much as in humans, which he evidently takes to be evidence for intelligent design. Unfortunately, to do so he must ignore the conclusions of the very paper he cites.
As mentioned above, E. fishelsoni is a) large, and b) has a huge amount of DNA. One might wonder whether the two are related somehow. And in fact, the first paper he links to says as much:
DNA quantity is proportional to cell volume over cell lengths of ~30 µm to >500 µm.
In this paper, we initially demonstrate that DNA quantity is directly proportional to cell volume rather than to length or surface area, and that large quantities of DNA are almost equally divided and distributed to developing daughter cells.
As the Bresler et al. paper explains, E. fishelsoni makes copies of its DNA prior to forming daughter cells. In other words, not only does the size of its genome vary, but when it has the most DNA is when it’s “pregnant” (although there seem to be other mechanisms at work as well). This does not mean that this bacterium carries more information — however you want to interpret that — than humans.
Yes, DNA contains information. But it’s also a molecule, which means it has all of the properties that molecules have, like size and mass. When a bacterium copies its DNA, the copy has to go somewhere. It’s going to take up space. And this can require the cell to grow.
Organisms can take advantage of this as well: let’s say you have a computer, and for one reason or another you want to make it heavier (e.g., to make it more stable, so that it doesn’t tip over when there’s an earthquake). One easy way to do this would be to pack it full of hard drives. Yes, disks contain information. But they also have weight, so they can serve as ballast, if you have more disks than sand bags.
So if, in some environment, larger cells are better than smaller ones, one easy way for cells to adapt is to duplicate a chromosome or two: the extra size of the DNA means that the nucleus has to be larger, which also forces the cell to be larger. Yes, it’s weird, but nature is often counterintuitive.
In short, if DaveScot wants to prove ID and front-loading through large genomes, he’s still got an awful lot of work ahead of him.