Obsessing about different accounting methods runs the risk of turning evolutionary theory into a kind of postmodernism in which there are no facts, only different ways of viewing. In his book Fear of Knowledge: Against Relativism and Constructivism, philosopher Paul Boghossian shows, for anyone who needs reminding, that nothing has happened in philosophy to prevent us from making factual statements such as “mountains existed before people”. So it is with the factual claims associated with inclusive fitness theory.
How can we distinguish fact from perspective? It’s easy when you get the hang of it. Merely state your factual claim in a way that can be evaluated by any perspective. Here’s an example involving the first and (at the time) the most important claim associated with inclusive fitness theory–that it explains altruism without invoking group selection.
The phrase “without invoking group selection” isn’t used much any more, but it was once mandatory for authors who wanted their ideas about social evolution to be taken seriously. Their scrupulous avoidance of group selection was not a statement of preference for a particular accounting method but a factual claim–that their theory invoked a certain process, different than the process invoked by group selection, such that one could be just plain right and the other just plain wrong. That’s how science is supposed to work. Different hypotheses invoke different processes that make different predictions about the real world. Some predictions conform to reality better than others, qualifying them as provisional facts. Perspective has nothing to do with it.
Here’s how to state the factual claim in a way that can be evaluated by any perspective: “According to group selection theory, altruism is selectively disadvantageous within groups of individuals who are socially interacting with each other and can evolve only on the basis of a selective advantage at a larger scale (between groups). My theory of social evolution explains altruism in a way that does not invoke group selection in this sense.”
This way of stating the factual claim forces us to make certain comparisons. In particular, it forces us to compare selection differentials within single groups to selection differentials in the total population. All theories of social evolution include the information for making this comparison, but some retrieve the information more easily than others. In my previous post, I compared two banks that both record the same information, but one reports it according to date and the other according to tax-exempt status. Let’s say that you want to know the tax-exempt status of a certain check. If you belong to one bank, this information is immediately available to you. If you belong to the other bank, you have to work harder to retrieve the information because of the way it is categorized, even though it is available.
So it is with multilevel selection theory and inclusive fitness theory. The former is designed to compare selection differentials within and between groups, but the latter accounts for the costs and benefits of altruism in a different way. In its original formulation, it counts the effect of an altruistic gene on itself in the actor (a negative effect) and on copies that are identical by descent in the recipients (a positive effect). When the net effect is positive, altruism is assumed to evolve in the total population.
All well and good, but what is the fitness of an altruist compared to a non-altruist within the same group? Unless we can answer this question, we can’t say whether inclusive fitness theory counts as an alternative to group selection. If you find it hard to answer this question based on my description of inclusive fitness theory, don’t feel bad. Neither could Hamilton or anyone else at the time. The Price equation was required to show Hamilton that altruism is selectively disadvantageous within groups, even when the groups are composed of kin, and evolves only by virtue of groups with more altruists contributing more to the gene pool than groups with fewer altruists. The significance of relatedness is that when groups are composed of kin, altruists and non-altruists are segregated into different groups more than when the groups are composed of non-relatives.
In short, Hamilton had discovered a nifty way of calculating when altruism evolves in the total population, but he had not discovered an alternative to group selection as the process whereby altruism evolves. It is remarkable how easily Hamilton accepted this conclusion once he “saw the light” through the lens of the Price equation. In his own words:
I was on the phone telling him enthusiastically that through a “group-level” extension of his formula I now had a far better understanding of group selection acting at one level or at many than I had ever had before (see my previous post on Hamilton for more).
In other words, Hamilton now regarded his earlier belief that inclusive fitness theory explains the evolution of altruism without invoking group selection as just plain wrong. Perspective didn’t have anything to do with it, any more than when he regarded the claim as factually correct. Just because the role of group selection wasn’t obvious on the basis of his earlier formulation did not prevent it from being a fact. His earlier belief was like saying “my check is not tax deductable because it was cashed on July 18″.
All of this took place in the 1970′s. Historians of science are needed to explain why Hamilton’s new interpretation didn’t quickly become the consensus view of all evolutionary biologists. Instead, the majority continued to treat his original formulation as an alternative to group selection just because the role of group selection is opaque.
The same story can be told for every other theory of social evolution that claimed not to invoke group selection. All of them assume that social interactions take place among sets of individuals that are small compared to the total population. They must, because it is a biological fact of life. All of them assume that most traits labeled cooperative or altruistic are selectively disadvantageous within groups and evolve only by virtue of the differential contribution of groups to the total population. The only reason that they were ever regarded as alternatives to group selection is because their way of accounting for evolutionary change in the total population makes the local disadvantage of altruism opaque.
Against this background, we can return to the current controversy over the rightness and wrongness of inclusive fitness theory. Is it a nifty way of accounting for what evolves in the total population? Perhaps. Does it explain altruism in a way that does not invoke group selection? The answer to that question is just plain no. Mountains existed before people and altruism evolves by group selection. Perspective has nothing to do with it.