"What a piece of work is man! How noble in reason! How infinite in faculty! In form and moving how express and admirable! In action how like an angel! In apprehension how like a god! The beauty of the world, the paragon of animals!" Hamlet, (Act II, Sc. II).
Throughout my time as a scientist, I’ve always been curious about genetics and evolution, and our recent capacity to accurately and rapidly sequence whole genomes is shedding all sorts of new light on life and how different organisms go about it.
Certainly, it stands to reason that our big brains (Beverly Hills Chuhuahua being #1 at the box-office and the current financial climate notwithstanding) reflect on a macro-level our excellence at the genomic level. If “survival of the fittest” rules, then our genome should rock, right?
Wrong. It turns out that only about 5% of our genome is what’s required to make us, well, us. The rest? More or less crap. As a species, we’ve incorporated lots of genetic flotsam into our 3.4 billion base-pair genome – the majority of it consists of repetitive stretches of DNA called LINEs and SINEs (Long – and Short – INterspersed Elements) – which are the debris of DNA copying machinery mistakes. It is the equivalent of storing all your junkmail into a giant spare room.
Well, maybe all species are like that? Nope. Some species do better – much better. Microorganisms have incredibly lean genomes. Among vertebrates, the winner for efficiency (dare I say the most Intelligent Design?) is the puffer fish. The puffer fish has just as many functional genes as you or me (~30,000), but its total genome is about 1/8th the size of ours. The reason for this efficiency: the puffer fish has developed a way to keep the spare room of his genome clean. Go fugu!
Does that help the puffer fish in any meaningful way? (And conversely, does our accumulated crap hurt us?) Not that we can tell, and it seems like the nucleus can carry a bunch of extra baggage and not really care. But to me, it’s sort of a humbling lesson – that at a very fundamental level, we’re not remarkably special. Many genomes are much larger (wheat’s genome is five times the size of ours) and many are better organized.
More than 500 years ago, Copernicus taught us that we weren’t the center of the astrophysical universe. Turns out, we’re not center of the biological one, either.