Paying Down Darwinism's Explanatory Debt
Confronted with problems in life, it's useful to think in terms of trends. Whether I am a consumer strapped with paying off credit card debit or a Darwinian biologist strapped with trying to explain the origin and development of life, is a given problem's power to bedevil me getting, on the whole, bigger or smaller? If smaller, then that's a cause for relief. Evolutionists talk grandly, seeking to give the impression that their problem is increasingly in hand, or in the bag, or under control, whichever metaphor you prefer. But this is mostly bluff, as a report in Nature Structural and Molecular Biology reminds us.
If the evolutionary origin of DNA coding remains an enigma, try adding to that the origin of histone coding that's associated with it. A group of researchers from Emory University School of Medicine have revealed ways that histones receive modifications in such a way as to convey information that in turn allows the information in DNA to be properly read.
When things like cells and the proteins that make them go were understood to be simple blob- or crystal-like entities, then explaining how their structure could be accounted for in terms of natural selection seemed a task that was not far out of reach. On the contrary, it appeared to be intuitively easy to imagine how a full and satisfying account could be detailed.
Histones are proteins that form the nucleosome spools on which DNA is coiled tightly to fit the stuff into the minute confines of the cell. Steve Meyer observes in Signature in the Cell, "[I]t is the specific shape of the histone proteins that enables them to do their job....Thanks in part to nucleosome spooling, the information storage density of DNA is many times that of our most advanced silicon chips."
The Emory scientists used X-rays to explore how two enzymes, PHF8 and KIAA18718, modify histones by removing methyl groups from their tails. Lead researcher Xiaodong Cheng explained to ScienceDaily that it's like finding a book in a vast library: "[Y]ou need some signs telling you how the stacks are organized. Similarly, the machinery that reads DNA needs some guidance to get to the right place."
The enzymes that are the heroes of this story ensure that the signage that lights the way to just the right book out of thousands doesn't itself mislead or confuse the reader. In Signature, Meyer characterizes as "uncanny" the matching of positively charged to negatively charged regions on the histone proteins and the coiled DNA. The way histone modification works increases the mystification. It's all the problem of explaining specified complexity -- expressed in the shapes proteins take and the arrangement of their amino-acid building-blocks -- but magnified yet again.
Ah, poor old Darwinists. It's quite a bit like having a credit card debt towering over your head and then getting a letter from your bank saying they've decided to up your interest rate. How will evolutionary theory ever pay down its obligation to explain all this?