Following up on yesterday’s post, the July 21 issue of Science also contained this review article, entitled “Evolution of the Molecular Machines for Protein Import into Mitochondria.” The authors write:
Here we look at how protein import pathways were established to create mitochondria. The protein import pathway is driven by a set of molecular machines, and these machines are of modular design. Each machine has a core module that seems to be common to all eukaryotes. Additional modules have been added to each machine over time, with these add-ons being common only to particular eukaryotic lineages. The evolution and comparative aspects of the function of these mitochondrial machines provides a blueprint for understanding the evolution of cellular machinery in general and a rich means of determining the precise function of these sophisticated machines. That most of the machinery was created de novo and established in the mitochondrial membranes of the first eukaryote supports the idea that all eukaryotes are descendants of a single ancestor species.
So here we have a complex set of machines importing protein into mitochondria. Indeed, as the remainder of the article makes clear, these machines satisfy the ID definition of irreducible complexity. Yet, while the precise nature of these machines varies from eukaryote to eukaryote, all are merely variations on the same basic theme. I find that rather suggestive.
From here the article goes on to provide a detailed discussion of the likely evolutionary history of the various proteins involved in these systems. Alas, this part is rather dense and short on quotable nuggets, but it does become clear that cooptation of preexisting parts for new functions played an important role. For example:
In the course of transforming from endosymbiont to mitochondria, most of the genes encoding bacterial proteins were transferred into the host nucleus. To ensure the delivery and the assembly of these proteins in the newly established organelle, protein import machinery was needed. Some of the preexisting protein translocation apparatus of the endosymbiont appears to have been commandeered, with molecular chaperones such as mHsp70 and Oxa1 derived from the bacterial chaperones DnaK and YidC, respectively.
The authors close the article with a nice summary and a description of possible directions for future research:
Through looking further afield into the genomes of more and more classes of eukaryotes, it now appears that the molecular machines that drive protein import into mitochondria are of modular design. Core modules representing the translocation channels for each machine are common to all eukaryotes. Additional modules have been added over time, being common only to particular eukaryotic lineages. This provides additional means to analyze the vexing questions in the evolution of eukaryotes. Evolutionary details of the machines also provide a means from which to decipher aspects of machine function, complementing details gained from biochemical studies on the machines of one or more model species. Some exciting questions are being raised from considerations of evolution:
They then list several questions that are more technical than what I wish to include here.
This, you see, is how real scientists respond to the fact of biological complexity. By rolling up their sleeves and getting their hands dirty. This was a short review article, yet it had fifty-seven references. The authors ferreted out the patterns that were emerging from the hard work done by numerous previous scientists and demonstrated that they point to a clear evolutionary scenario for the formation of these complex machines. They then showed how evolutionary reasoning points towards possible furture research.
Compare that to the way ID folks treat complex molecular machines. They just sit there, slack-jawed, never getting beyond childish bleats about how they’re just too darn complex to have evolved. If they respond to this article at all it will only be to dismiss it, unread, as insufficiently detailed for their tastes.
A common refrain from ID folks is that they are not treated respectfully by scientists. One reason for that lack of respect is the fact that there is no respect coming the other way. Countless scientists toil in obscurity to unravel the evoution of one particular set of complex molecular machines. The sheer hard work and brain power leading up to this article is remarkable.
The ID folks don’t care. Instead, Ann Coulter publishes a hundred pages or so of wall-to-wall lies about evolution, and William Dembski brags about being her science consultant. Jonathan Wells writes a book called The Politically Incorrect Guide to Darwinism and Intelligent Design for the right-wing press Regnery. You can be sure it will contain nothing that is both true and important. Michael Behe can only fold his arms and shake his head when confronted with the enormous amount of empirical evidence against his argument (meanwhile making no contributions of his own beyond some breathtakingly unrealistic mathematical models). And the whole lot of them screech, banshee-like, about how ID is going to carry the day, and how Darwinism is just an empty ideology.
Shame on anyone who deals with respectfully with such people.