Uma lei em biologia de qualquer outro nome seria doce demais

terça-feira, novembro 23, 2010

Science 19 November 2010: 
Vol. 330 no. 6007 pp. 1048-1049 
DOI: 10.1126/science.1197366

A Law by Any Other Name Would Smell as Sweet

Biology's First Law The Tendency for Diversity and Complexity to Increase in Evolutionary Systems by Daniel W. McShea and Robert N. Brandon University of Chicago Press, Chicago, 2010. 184 pp. $55, £35.50. ISBN 9780226562254. Paper, $20, £13. ISBN 9780226562261.

Roberta L. Millstein

The reviewer is at the Department of Philosophy, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.

McShea and Brandon argue that biological complexity is the expected outcome of being alive—in the absence of any other forces, both diversity and complexity will increase as the inevitable consequence of cumulative changes.


A Law by Any Other Name Would Smell as Sweet

Roberta L. Millstein

The laws of physics are sufficiently well known that they have permeated popular culture. This is especially true of Newton’s laws of motion: Everyone has heard that “an object in motion will stay in motion unless an external force acts on it” (Newton’s fi rst law) and “for every action, there is an equal and opposite reaction” (Newton’s third law). Even F = ma (Newton’s second law) is fairly well known. But what of the laws of biology? Does biology even have any laws?

Biologists and philosophers of biology have been debating this question for decades. Some take the position that biology lacks laws—that the contingency of evolutionary processes means that biological entities and processes are not lawlike. Others argue that it does have laws, e.g., the principle of natural selection itself.

Biologist Daniel McShea and philosopher of biology Robert Brandon dive into this debate with their provocative Biology’s First Law: The Tendency for Diversity and Complexity to Increase in Evolutionary Systems. McShea and Brandon (both at Duke University) boldly contend that they have uncovered a “zero-force law” for biology that is analogous to Newton’s fi rst law (also called “the law of inertia”). The basic idea behind their proposed “Zero-Force Evolutionary Law” (ZFEL) can be understood through one of the thought experiments they describe in the book. Imagine a yard containing a number of trees, and imagine that the wind blows from each point of the compass with equal probability. Come autumn, the result will be an increase in the dispersal of the leaves over time. This, they suggest, is a zero-force state because there are no directional forces acting on the leaves.