New Breakthrough in Evolution Theory

 
Imagine a culture of yeast cells growing in a medium where sucrose is the only carbon source. Sucrose isn't the preferred carbon source for yeast but yeast can handle it if need be. Cells secrete an enzyme called invertase that breaks down sucrose to glucose and fructose


The products of the reaction, glucose and fructose, can be taken up by the cell or they may diffuse away before being taken up. Molecules produced by the invertase from one cell can be absorbed by a neighboring cell.

As the concentration of free glucose and fructose rises in the medium, cells that lack the ability to synthesize and secrete invertase may survive. Thus invertase negative mutants may accumulate because they don't need to make their own invertase in order to have a source of carbon. In game theory, such mutants are called "cheaters."

Hands up, all you people who think that the existence of a stable equilibrium of cheaters and cooperators is a new discovery in evolutionary theory.

Right, it's not.

The editors of Nature think it is, so they published the paper from the Dept. of Physics at MIT (Gore et al., 2009).

The MIT PR department thought it was revolutionary enough to warrant a press release that was picked up by ScienceDaily [Cooperative Behavior Meshes With Evolutionary Theory].

One of the perplexing questions raised by evolutionary theory is how cooperative behavior, which benefits other members of a species at a cost to the individual, came to exist.

Cooperative behavior has puzzled biologists because if only the fittest survive, genes for a behavior that benefits everybody in a population should not last and cooperative behavior should die out, says Jeff Gore, a Pappalardo postdoctoral fellow in MIT's Department of Physics.

Gore is part of a team of MIT researchers that has used game theory to understand one solution yeast use to get around this problem. The team's findings, published in the April 6 online edition of Nature, indicate that if an individual can benefit even slightly by cooperating, it can survive even when surrounded by individuals that don't cooperate.

In short, the study offers a concrete example of how cooperative behaviors can be compatible with evolutionary theory.

I agree that this is an interesting example but I don't think the public is well served by presenting it as a new contribution to evolutionary theory. The public is entitled to think that evolutionary biologists must be really stupid if they've never thought of this before.

They (the public) would be really confused if they happened to read the Wikipedia entry on John Maynard Smith (1920 - 2004).

There are no references to Maynard Smith's work in the citations at the end of the Nature paper, although there is a reference to "Smith, J.M." who wrote the book Evolution and the Theory of Games.

---

Gore, J., Youk, H., and van Oudenaarden A. (2009) Snowdrift game dynamics and facultative cheating in yeast. Nature advance online publication 6 April 2009. [DOI: doi:10.1038/nature07921]