Evolvability is Inevitable

I’m excited that a fun paper I’ve co-written with Ken Stanley, entitled “Evolvability is Inevitable: Increasing Evolvability without the Pressure to Adapt,” has just been published in PLoS ONE.

What’s really interesting about our study is that it shows that the drive towards more complex organisms in nature may not need special explanation, in contrary to what many have previously thought. In fact, an increasing ability to evolve (called evolvability) may be a fundamental feature of evolutionary processes in general. That is, once evolution begins, it might naturally accelerate, like a rock rolling down a mountain.

Interestingly, there’s a press release out from the University of Central Florida, so perhaps the paper will get a little traction in the blogosphere/press.

How do organisms become more evolvable?

The underlying idea is simple but counter-intuitive: If you assume that an organism’s ability to further evolve (its evolvability) is hereditary, then over time, even allowing organisms to reproduce randomly can actually separate more evolvable organisms from those that are less evolvable. While this might first seem surprising, the reason is that over many generations, the more evolvable organisms will change more in form than the less evolvable ones.

After many rounds of randomly letting organisms reproduce in a simple model, the most evolvable ones tend to travel furthest from the original niche in the center. (Lighter colors mean more evolvable organisms)

That is, if you started with a large population of organisms all with the same DNA, and allowed them to reproduce randomly, at the end, you could look at the organisms, and the most evolvable ones would be the ones that were most different. So the space of possible phenotypic forms acts like a filter that separates more evolvable organisms from less evolable ones. If you couple this idea with the fact that diverging forms might lead a species to spread through more biological niches (lead to new ways of life), you have a simple mechanism for evolvability to continually increase, like we seem to observe in nature.


Of course, this new hypothesis takes its place among many competing theories for how evolvability increases in nature — and indeed many factors may each contribute to increasing evolvability. This theory is different though because it does not depend upon there consistently being particular kinds of competition between organisms. For example, another leading theory is that evolvability increases because organisms have to survive across changing environments, which requires constant adaptation. So what’s really interesting here is that the results hint that increasing evolvability may not require such special explanations, and may be more fundamental than previously thought.

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