IDolatrous bloggers ask Is altruism all about cost-to-benefit ratios?, and conclude after reviewing a paper in Science that lays out the current thinking on the evolution of altruism:
Of course, there is another avenue for thinking about altruism: but this means going beyond neodarwinism and entertaining the thought that human beings need to be explained not only in terms of law and chance, but also in terms of design.
Let’s set aside that they never bother to explain how “design” would actually resolve this. That would require some sort of “theory of design,” and we all know no such thing exists. Absent the explanatory power that a theory provides, “design” cannot offer explanations, just ill-informed critiques.
What I want to focus on here is that David Tyler clearly does not understand why evolution matters.
Modern thinking on altruism goes back to an observation that W. D. Hamilton made in the 1960s. Before then, you heard a lot of talk that was, in retrospect, fairly silly. Individuals were spoken of as doing things “for the good of the species.”
Hamilton saw that this was impossible as phrased. An organism that sacrifices itself for the good of other would die out, and any genetic component to its altruistic behavior would die with it.
Hamilton’s solution was “kin selection,” the idea that an individual who sacrifices somewhat for the benefit of related individuals will wind up with more surviving copies of it genes, including any “altruism genes” than individuals that don’t sacrifice like that.
This makes testable predictions about behavior, such as that altruistic behavior should be less common between less related individuals, a prediction confirmed in many species. Ground squirrels, for instance, are more likely to make warning calls about a predator when related individuals are nearby. When surrounded by unrelated individuals, they tend to just quietly head for cover.
When individuals don’t spread out too much, you can have something called “deme selection,” in which individuals sacrifice for the good of a population because that population is, on average, very closely related.
For these and other theories about altruism, the question that scientists ask is not about “law and chance,” nor about “design.” They ask: under what conditions could another population or individual successfully invade a group that behaves in the way predicted by my model? If the behavior would allow other behaviors to successfully invade, then the first behavior could not persist in nature, and something else must be at work.
So, if the IDol crafted Adam and Eve with some heritable propensity for altruism, that propensity would only persist if it were impossible to change the heritable material responsible, or if it encoded some sort of uninvadable evolutionarily stable strategy. And since selfish behavior is quite common, we have falsified the first possibility, leaving only the hypothesis that the IDol’s behavior is indistinguishable from what evolutionary biology predicts, and we can leave out the IDol’s interference as superfluous to the hypothesis.