How DNA Encodes a Program: Causal Selection, Control Flow, and the Secrecy of Pyramids
|Date||Thursday 17 May 2018|
|Time||3pm - 4:30pm|
|Presenter||Brett Calcott (University of Auckland)|
"A commonly expressed idea in biology is the DNA contains "information", or a "blueprint" or a "program" for building a complex multicellular organism, despite the fact that a multitude of other factors are necessary for development. Why pick out DNA as special, then? The issue is more puzzling when, on closer examination, these terms appear to be little more than hand-waving: DNA does not resemble a blueprint or a program, and if it can be said to contain information, then so can everything else.
Here begins a longstanding debate, with two main schools of thought. Either we reject these ideas as misleading and demote genes to just another factor in development, or we provide some principled way of recognising the distinctive role of genes. In this paper I take the second option, and focus on recent work that recasts the problem as one of *causal selection*. That is, we allow that there are many causes in development, but show that genes play a special role because they are more *causally specific*, or have more fine-grained control, than other factors. I argue that despite the appeal of these arguments, they don't get us far.
Current discussion assumes that this specificity extends to protein coding, which falls short of the kind of control over development expressed by biologists when they use terms like "information" or "program". I propose that we extend the idea to show that DNA has fine-grained control over the organisation of developmental processes, and I draw on the architecture of modern software programs to supply us with a set of concepts to give substance to this idea. I say "modern" software programs, for though I concede that the notion of a "genetic program" has been misleading, it is misleading because a narrow and over-simplistic conception of a program permeates the literature. I outline the concept of *control flow* in a program, and show that the way it is implemented in modern programs resembles the processes controlling the expression of DNA during development. On this picture, DNA is special because it provides fine-grained control over the re-organising the order, timing, and coordination of a multitude of crucial events in development. This grounds a principled way to state that DNA encodes a cellular program"
(Text supplied by presenter)