One of the more intriguing topics when it comes to evolution is the concept of “evolvability.” A concept now fairly well-accepted in the literature the earliest mention occurred only in the late 1980s. Tracing the contemporary evolution of the term suggests some evolvability of the concept itself, with a mere 86 articles appearing in a search limited to the year 2000, followed by rapid growth as evidence by some 960 articles by 2010. An article by geneticist, evolutionary biologist and philosopher Massimo Pigliucci provides some interesting insights into the question Is evolvability evolvable?
He begins by tackling the meaning of the term itself, writing “…a remarkable number of people have attempted formal definitions of it, generating some conceptual confusion….I will consciously refrain from providing my own definition because I am convinced that we are actually dealing with a family of related concepts that are well characterized by available definitions.” Those definitions, writes Pigliucci, range from placing evolvability within the concept of heritability (along the lines of standing genetic variation, thought to be responsible for many instances of contemporary evolution) to variability or “the propensity of characters to vary (whether or not they actually do)”, to the far more dramatic phenotypic change including the evolution of phenotypic novelties – or major “transitions in evolution.”
Pigliucci suggests that rather than any one concept defining evolvability they each instead fall “under a general umbrella of evolvability.”
Here are some interesting quotes from the article:
The major point that authors do agree on is that there is some connection between the modularity of the genetic architecture and evolvability. [p77]
It seems clear to me that evolvability – no matter how it is defined – does evolve. The evidence for this is beyond reasonable doubt. However, whether the evolution of evolvability is the result of natural selection or the by-product of other evolutionary mechanisms is very much up for discussion and has profound implications for our understanding of evolution in general. [p78]
Although evolvability represents one of the major conceptual novelties since the Modern Synthesis, there are two imminent problems facing the field, one theoretical the other empirical. The theoretical problem is to agree on definition….The empirical problem is to determine how evolvability itself can evolve, and whether natural selection is responsible.” [p80]
I’ve been trying to understand the ongoing controversy and current ideas about evolvability, and came across two interesting books. One, on the genetics of evolution and changing ideas about the pace and mechanisms is Evolution a view from the 21st century by Stephen Shapiro, a tough read for the non-evolutionary geneticist – but informative none-the-less. The book Darwin in the Genome, by Lynn Helena Caporale explores in her words, the notion that natural selection doesn’t just work on individual mutations but on “the very mechanisms that generate genetic variation …” It’s an easier read, with some interesting ideas as well. At some point I will post reviews and commentary about these books and the authors.