To anyone searching for a cool theoretical biology/evolutionary mechanisms book, Biology’s First Law by Daniel W. McShea and Robert N. Brandon is a pretty radical read! While its arguments are too complex to summarize in one blog post, its overarching argument proposes genetic drift as the first Zero-Force Evolutionary Law (ZEFL) of biology:
“ZFEL (general formulation): In any evolutionary system in which there is variation and heredity, there is a tendency for diversity and complexity** to increase, one that is always present but may be opposed or augmented by natural selection, other forces, or constraints acting on diversity or complexity” (3).
“ZFEL (special formulation): In any evolutionary system in which there is variation and heredity, in the absence of natural selection, other forces, and constraints acting on diversity or complexity, diversity and complexity will increase on average” (4).
There are some problematic aspects to this argument, however. It’s unclear how much value it holds as a null hypothesis, and it conflicts with the traditional view of drift as a constraint on variation. In addition, a 2012 review, “Puzzles for ZFEL: McShea and Brandon’s zero force evolutionary law,” by Barret et. al, rebutes McShea and Brandon, deeming the special formulation of ZFEL impossible as if it holds true that mutations indicate the presence of a force, and the absence of mutations indicate a constraint of the force, then a force or a constraint must always be present (2012). ZFEL also butts heads with Hardy Weinberg equilibrium, which McShea and Brandon regard as “problematic as a zero-force law because it mixes genuine evolutionary forces … with a non-force, namely drift” (McShea, Brandon 100). But despite the dissent over ZEFL as a viable biological law, I still considered Biology’s First Law a valuable read. ZEFL is elegant, intuitive, and holds a potentially formative perspective on what we consider the “norm” in evolutionary history. I also found its contrast with inertia (the zero-force law of physics) intriguing.
Browsing the literature available about this hypothesis gave me an interesting glimpse into the philosophy of science and how theoretical disputes play out in the academic world. If any of you guys have also happened to have read this book, or have put it on your reading list, let me know what you think!
**defined as the number of part types” or “degree of differentiation among parts” to avoid the anthropocentric connotations of colloquial complexity.
