I haven't commented on the controversy about including "Intelligent Design" in school curricula, but I don't want that to be interpreted as any kind of approval. On the contrary - until it offers some testable predictions, which would seem an unlikely thing to hope for, I don't see how ID even rises to the level of a preliminary theory, much less one that can compete with the level of evidence backing up evolution. Many of ID's advocates, to a greater or lesser degree, strike me as intellectually dishonest.
Intelligent Design proponents are fond of arguing about "irreducible complexity", the idea that some structures are too complicated to have been generated through stepwise evolution. They argue this on the anatomical level, which I don't buy, but I'm not going to debate that one in this forum. (Allow me to refer the curious to my fellow Corantean Carl Zimmer, who's had plenty of run-ins with these folks, and his fine introduction to evolution. Those interested in the latest news on the ID/evolution battles should check out The Panda's Thumb. For sheer mockery, often irresistible in these cases, try this.)
But when they start making arguments at the chemical level, the what-are-the-odds stuff about proteins and DNA, well, that's when I come out of my lair. A paper in the latest issue of the journal ChemBioChem got me thinking about this today. (If you have access to Wiley journals, it's here as a PDF.) It's an update of the analytical work still being done on the Murchison meteorite (a href="http://www.publish.csiro.au/?act=view_file&file_id=AS03060.pdf">PDF), which fell in Australia in 1969. The more than 100 kg of recovered Murchison material have been attacked over the years with just about every instrument of the constantly shifting state of the art in analytical chemistry.
Why all the interest? Well, a short answer is that the pieces of this meteorite reek. Even now, they smell like low-grade gasoline, and they had a powerful odor indeed when they were freshly collected. The Murchison fall is a wonderful example of a rare class of meteorites called carbonaceous chondrites. Many people don't realize how much organic gunk is floating around out in space, but there are surely millions of tons of this stuff wandering around our solar system alone.
What's in the Murchison pieces? The list continues to lengthen. We're up to at least 500 different soluble compounds, but much more of the material is dark polymeric asphalty stuff that's hard to analyze. Most famously, the meteorite contains many amino acids. Save glycine, those come in left- and right-handed isomers, and a major find is that the Murchison material is slightly biased toward the left-handed ones, which happen to be the ones that life on Earth is built around. This is an important point: the chemicals that life as we know it is composed of are not at all odd or unlikely. They're all over our solar system, they're in interstellar clouds, and there's every reason to think that they're smeared and splatted all over the universe.
And more of the stuff is being made all the time. In 2002, several research groups took icy mixtures of water, methanol, ammonia, HCN, carbon dioxide and carbon monoxide (just the sort of mixtures that you see in cometary ices and the above-mentioned interstellar clouds.) They irradiated them with ultraviolet light - as would come from the Sun or untold billions of other stars - at cold outer-space temperatures, and obtained over a dozen of the most common amino acids - here are some more details.
So, here's another key point: the really big step is between making random chemical combinations and having carbohydrates and amino acids as inevitable products. Believe me, the molecules of life are an infinitesmal sliver of all the possible backbones of up to ten or twelve carbon, nitrogen, and oxygen atoms. But organic chemistry, with no active hand on the controls, turns out uncountable heaps of them. Compared to that, the gaps that need to be filled in on the way to living systems don't seem so large.
This, to me, is one of the major stories of the last few decades. Starting hundreds of years ago, astronomy gradually moved the Earth out of its supposed spot in the center of the universe and placed it in the huge (and hugely strange) context of the universe that we now know. Now chemistry is moving us away from the view of life as a strange and precious anomaly - granted, perhaps, by a divine being? - to something that could be everywhere and may well start of its own accord. The building blocks are ubiquitous, and if you give them half a chance they start to stack themselves up.
For better or worse, the presence of an active Designer does not suggest itself. That may not seem right to some people, for many different reasons. But if there's one thing that science has been showing us, it's the the universe doesn't much care what we think about it.