We have seen that some critics have acknowledged that evidence of bolts in biology would amount to evidence of design. So are there any bolts in life?
If we hypothesize that life is indeed carbon-based nanotechnology, we ought not expect that the bolts used by life would have the same form and composition as those used in your car or lawnmower. Instead, we need to think of the design objective that the bolt carries out – it is a device used to connect things. By bolting parts together, we are holding the independent parts of a machine together such that the various parts can function as a whole. This generic function explains why we find bolts in all sorts of unrelated machines.
So does the cell contain such bolts?
It would seem so.
I pulled this one off the top of my head – the TPR domain:
Almost all proteins contain multiple, discrete domains, where the domain is a localized region that carries out a function. For example, a transcription factor might have one domain that allows the protein to gain entry into the nucleus, another that allows it to bind to a specific region of the DNA, and yet another domain that attracts other factors after binding such than the process of transcription occurs. That proteins are built around the design theme of modularity is itself a topic worth discussing. But for now, let’s remain focused on the TPR domain.
What is the function of the TPR domain?
TPR repeats mediate protein–protein interactions and the assembly of multiprotein complexes. The smallest functional unit that is widely used appears to be three tandem-TPR motifs.
By mediating protein–protein interactions and the assembly of multiprotein complexes, it functions as a bolt. The TPR domain is used to connect different proteins together so the other domains in both (or more) proteins can function as a whole.
If the TPR domain is indeed one of the bolts used in carbon-based nanotechnology, we might expect to find it distributed throughout the living world. And this is exactly what we see. The TPR domain “is present in over 800 different proteins.” It is widely distributed among archaebacteria, eubacteria, and eukaryotes.
Also, just as bolts are used in all sorts of different machines designed by humans, the TPR domain is used to bolt together protein complexes involved in all sorts of functions, including cell-cycle control, transcription repression, stress response, protein kinase inhibition, mitochondrial and peroxisomal protein transport and neurogenesis.
While the TPR domain is just one of the bolts used by life, it would clearly seem to functionally qualify as a bolt – a devise that is widely used to connect parts together so the parts can function as a whole.
Yet I need to remember that those who are insistent that there is “no evidence for design” also advocate the God-of-the-gaps approach. So perhaps we should ask where the TPR domain came from. I don’t know, for as I said, I picked this example off the top of my head. But we can consider some facts.
That the TPR domain is so widely distributed among all domains of life means one of two things. Either it was present in the last common universal ancestor of all cellular life or it arose later and was spread about by lateral transfer. My guess is that both explanations apply, as both explanations fit seamlessly into a teleological perspective.
So how did this bolt come into existence? If it was not the product of design, it had to come into existence from a pre-TPR precursor or arise by spontaneous assembly. If it is the latter, then this would suggest the bolt was front-loaded to exist by the laws of Nature (echoes of teleology). If it is the former, someone needs to identify the precursor or acknowledge of the existence of a gap. What’s more, what was the original protein that contained the first TPR domain? If there is no answer, the gap deepens.
In the end, while a couple of critics have acknowledged that evidence of bolts in biology would amount to evidence of design, now that a candidate has been identified, rest assured that it will not be acknowledged as evidence of design.