This may be another example of kaleidoscope twirling.

Yeast may seem unlikely subjects for a study of cooperative behavior, but in fact they are perfectly suited to such studies. . . Unlike humans, yeast have no emotions or thoughts that interfere with rational decision-making; their actions are solely driven by their genetic response to the environment. . .

Sucrose is not yeast's preferred food source, but they will metabolize it if no glucose is available. To do so, they must secrete an enzyme called invertase, which breaks sucrose into smaller sugars that the yeast can absorb.

Much of that sugar diffuses away and is freely available to other yeast cells in the environment. In this scenario, yeast that secrete invertase are known as cooperators, while those that don't secrete invertase and instead consume the simple sugars produced by others are called cheaters.

If all of these simple sugars diffused away, with no preferential access to the yeast that produced it, then it would always be better to cheat, and the cooperators would die out.

The researchers observed that cooperating yeast have preferential access to approximately 1 percent of the sucrose they produce. That benefit outweighs the cost of helping others, allowing them to successfully compete against cheaters.

In addition, no matter the initial starting numbers of yeast in a given population, the microbes always come into an equilibrium state, with both cooperators and cheaters present. . .

I don't buy it. This has nothing to do with either cooperation or cheating, it's just differential abilities. The yeast that secrete invertase are fitter since they have more food options than those who do not, but the advantage disappears if all yeast have the ability.

Yeast, unlike humans, have no emotions or thoughts that interfere with rational decision-making, or interpretation of data.