Natural Selection

By Richard C. Lewontin
The New York Review of Books, May 27, 2010
 

Edited by Andy Ross
 

   What Darwin Got Wrong
   By Jerry Fodor and Massimo Piattelli-Palmarini
   Farrar, Straus and Giroux, 264 pages

A modern formulation of evolution by natural selection consists of three principles:

1. The principle of variation: among individuals in a population there is variation in form, physiology, and behavior.

2. The principle of heredity: offspring resemble their parents more than they resemble unrelated individuals.

3. The principle of differential reproduction: in a given environment, some forms are more likely to survive and produce more offspring than other forms.

To explain continued evolution of new forms we must also add a fourth principle:

4. The principle of mutation: new heritable variation is constantly occurring.

This outline does not explain the actual forms of life that have evolved. An immense amount of biology is missing.

Fodor and Piattelli-Palmarini say that Darwin's theory of selection is empty. They discuss a number of complexities at the molecular, cellular, developmental, and physiological level that need to be taken into account as well.

First, the proteins that result from the processing of genetic information may enter into multiple metabolic and developmental pathways. The interaction is not universal, or the organism would be so inflexible as to make life impossible. The intensity of interaction between parts is also strongly dependent on the circumstances of life.

Second, there are molecular interdependencies that arise from the fact that genes are organized onto chromosomes. The translation of a gene in the process of producing a protein is sensitive to changes in DNA that is nearby on the chromosome strand. So several genes of quite different specificity can be affected by the same change in the chromosome.

Third, the organization of genes onto the chromosomes in the cell means that when an offspring has inherited a particular form of one gene from a parent, it will probably also inherit the forms of a number of other genes that lie nearby on the same chromosome strand. Selection on one function may result in inherited changes in other functions.

In natural selection it is not traits that are selected but organisms. The traits they possess will determine their contribution to the next generation. Organisms are selected as a consequence of their total biology.

Every living creature must be in some sort of adaptive correspondence to its conditions of life or else it would be dead. But the "adaptation of organisms to their environment" is a characterization that misses half the story. It is based on the metaphor of the "ecological niche," a preexistent way of making a living into which organisms must fit or die. But there is an infinity of ways that organisms might make a living.

Every kind of organism reforms the world around itself and creates its own ecological niche that is in constant flux as the organism behaves and metabolizes. Organisms do not fit into niches, they construct them.

Evolutionary theory is under attack by religious fundamentalists using the ambiguity of the word "theory" to suggest that evolution as a natural process is "only a theory." When two accomplished intellectuals make the statement "Darwin's theory of selection is empty," they generate an anger that makes it almost impossible for biologists to give serious consideration to their argument.
 

AR  Fodor's decision to put his name to a book with that title is a scandalous lapse for a serious philosopher. Darwin didn't get it wrong, he just didn't have the whole story.