As an evolutionary biologist, I am shocked at the poor grasp of evolutionary concepts among many (non-creationist) biochemists and molecular biologists, and I am not alone in this view [5]. Students in these fields are taught how cells work using diagrams and 3D animations where each molecule somehow knows what it is supposed to do, and efficiently does only that. The colossal mess, waste, redundancy, and confusion of real molecular processes, although increasingly apparent in today’s era of systems biology, are generally ignored in biochemistry and molecular biology classrooms. Students are presented with images of clean molecular machines [6], backed up by canonical and unrepresentative examples, e.g. from viruses. No wonder some of them then find intelligent design intuitive! If students knew just what an inefficient mess real biological systems fundamentally are, they might be more open to the frequently unintelligent nature of “design” via natural selection. My colleagues and I just published a paper identifying circumstances in which the crossing of wide adaptive valleys, i.e. irreducible complexity, is not just possible, but common [11]. And we made the decision to put “irreducible complexity,” a term coined by a creationist, in the title of our paper. Why? Because it’s a good term. It’s a much better term than using a continuous metaphor of a “landscape” to describe a discrete space, among other known flaws of the term [12, 13]. And the definition in Behe’s book is a good definition. I am happy to give credit where credit is due, including to a creationist. The topic of irreducible complexity / valley-crossing was understudied in evolution until recently, and deserved more attention than it was getting. Where Behe sees the concept of irreducible complexity as an illustration of the failure of the theory of natural selection, I see it as pointing to a set of exciting and understudied evolutionary biology problems... Behe believes that irreducible complexity occurs, that this would be impossible via evolution by natural selection, and hence that evolution by natural selection must be wrong. In contrast, I am intrigued by the fact that irreducible complexity might occur, believe that if it does occur then of course it occurs via evolution by natural selection, and conclude that my job as an evolutionary biologist is to work out how. The answer in our paper, in part, was that evolutionary biologists had been asking the question wrongly. They were defining both a starting point and an end point for evolution across a valley in genotype-fitness space. But evolution does not move towards one particular end. The possibilities are, if not limitless, then combinatorially large. Say you have 100 mutations to choose between in the search for a fitter genotype. That means you have up to 100-choose-2 = 4,950 2-way combinations available to you. And you have 161,700 3-way combinations and nearly 4 million 4-way combinations. Even if finding any particular irreducibly complex adaptation is extraordinarily unlikely to evolve, this must be balanced against the extraordinarily huge number of potential complex adaptations. And for this reason, we were able to find circumstances under which irreducible complexity was not only possible, but actually common [11]. In other words, space is big. Not just the big physical space that we are familiar with from astronomy, but also the more abstract genotype space of all the things that are possible. We humans have limited intuitions about spaces that big, but we can overcome our cognitive limitations through the use of formal mathematical models. And in some of those models, irreducible complexity is a common phenomenon. Continuing with this third lesson, my future plans for the study of evolution include Behe’s observation of the predominance of loss of function mutations in observable evolution [14] and a question that sometimes goes by the name of “Haldane’s dilemma” [15]. I think some really exciting evolutionary biology lies ahead... _____ Joanna Masel is an evolutionary biologist at the University of Arizona. Her research investigates the robustness and evolvability of biological systems and the nature of different types of competition in both biology and economics. scientiasalon.wordpress/2014/09/16/what-can-evolutionary-biology-learn-from-creationists/
Posted on: Sat, 20 Sep 2014 22:30:08 +0000
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