We are often told that the science on Darwinism is settled. Advocates of academic freedom urge that teachers be allowed to challenge students and encourage critical thinking skills by sharing scientific strengths and weaknesses of evolutionary theory — “teach the controvery,” in other words. Darwin defenders respond with expressions of disbelief. The theory has no weaknesses, they say, and no controversy exists.
There might be minor disputes at the fringes, but no scientist doubts the certainty of Darwinian evolution. We can see them now, nodding in agreement: “Evolution itself has long since passed out of the field of scientific controversy,” as William Patten of Dartmouth opined in 1930. “There is no other subject on which scientific opinion is so completely unanimous. It is the one great truth we most surely know.”
How about the controversy over the central tenet of Darwinian evolution?
Nothing could be more central to Darwinian evolution than natural selection. It was in the title of Darwin’s Origin. It is the major “mechanism” along with random mutation that comprises neo-Darwinian theory. Natural selection and Darwinian evolution are inseparable. But what does natural selection mean? What entity does natural selection act on? It’s a controversy that has raged since 1859.
One current battle, showing no sign of abating, is between the kin selectionists and the group selectionists (see Casey Luskin’s play-by-play call in 2011 here and Denyse O’Leary’s post-skirmish analysis in 2015 here). Kin selectionists think that natural selection favors genes of related individuals. The idea, also called inclusive fitness, purports to explain self-sacrifice in animals and humans — why worker ants serve the queen without reproducing themselves, and why humans put themselves in danger for their families. Some of their genes, presumably, will be passed on through their kin. Kin selection theory was given a mathematical formulation by W. H. Hamilton in 1964, to the relief of many Darwinians eager to find an explanation for altruism. It was promoted by E.O. Wilson, father of sociobiology (which led to evolutionary psychology), Richard Dawkins, father of Selfish Gene theory, Jerry Coyne, and many other Darwinians.
But when E.O. Wilson jumped ship in 2004, expressing doubts about the empirical evidence for kin selection, his former friends turned on him. Wilson had joined forces with mathematicians who cast doubt on “Hamilton’s Rule” undergirding the theory. When Wilson, with Martin Nowak and Corina Tarnita criticized kin selection as empirically lacking in 2011 in Nature, 150 other evolutionists banded together to defend it, attacking Wilson’s motivations and arguments. There’s been a standoff ever since.
Now, in the Proceedings of the National Academy of Sciences, Wilson, Nowak and two others have launched another attack, with a vengeance: kin selection is not just wrong, it’s not even scientific! Here’s the fightin’-words title of the new paper: “The general form of Hamilton’s rule makes no predictions and cannot be tested empirically.”
Hamilton’s rule is a well-known concept in evolutionary biology. It is usually perceived as a statement that makes predictions about natural selection in situations where interactions occur between genetic relatives. Here, we examine what has been called the “exact and general” formulation of Hamilton’s rule. We show that in this formulation, which is widely endorsed by proponents of inclusive fitness theory, Hamilton’s rule does not make any prediction and cannot be tested empirically. This formulation of Hamilton’s rule is not a consequence of natural selection and not even a statement specifically about biology. We give simple and transparent expressions for the quantities of benefit, cost, and relatedness that appear in Hamilton’s rule, which reveal that these quantities depend on the data that are to be predicted. [Emphasis added.]
Not even a statement about biology? Ouch! We can expect some fireworks over this paper. It gets worse:
Hamilton’s rule asserts that a trait is favored by natural selection if the benefit to others, B, multiplied by relatedness, R, exceeds the cost to self, C. Specifically, Hamilton’s rule states that the change in average trait value in a population is proportional to BR−C. This rule is commonly believed to be a natural law making important predictions in biology, and its influence has spread from evolutionary biology to other fields including the social sciences. Whereas many feel that Hamilton’s rule provides valuable intuition, there is disagreement even among experts as to how the quantities B, R, and C should be defined for a given system. Here, we investigate a widely endorsed formulation of Hamilton’s rule, which is said to be as general as natural selection itself. We show that, in this formulation, Hamilton’s rule does not make predictions and cannot be tested empirically. It turns out that the parameters B and C depend on the change in average trait value and therefore cannot predict that change. In this formulation, which has been called “exact and general” by its proponents, Hamilton’s rule can “predict” only the data that have already been given.
In short, Nowak, McAvoy, Allen, and Wilson are saying that proponents of kin selection are deluded. They think they have a natural law, when all they have is a tautology. It’s not just that evidence is lacking for their “intuition” about kin selection; the mathematical formulation it rests on is vacuous.
Is this just a minor dispute about particulars of Darwinism? Notice that the authors claim it is “commonly believed to be a natural law” about evolution, and “its influence has spread from evolutionary biology to other fields including the social sciences.” The whole apple barrel is rotten! Wilson’s friends have launched this salvo in an open-access paper, viewable by the public. Are school boards and teachers going to be allowed to quote this paper, seeing that it is by mainstream scientists for mainstream scientists? Can they teach this controversy that gets to the core of Darwinism?
Wilson’s colleagues note three “astonishing facts” about Hamilton’s Rule:
- “First, HRG is logically incapable of making any prediction about any situation because the benefit, B, and the cost, C, cannot be known in advance. They depend on the data that are to be predicted.”
- “The second astonishing fact of HRG [Hamilton’s Rule – general] is that the prediction, which exists only in retrospect, is not based on relatedness or any other aspect of population structure.”
- “The third fact of HRG is that no conceivable experiment exists that could test (or invalidate) this rule.” I.e., it violates the falsifiability criterion.
From there, the mathematicians get to work, proving these assertions. In the ending discussion, they illustrate the problems with a joke:
The predictive power of HRG is equivalent to the following example: If you give me the shoe sizes and heights of a group of people, then I can predict the heights. My algorithm also works if you gave me the wrong shoe sizes.
They also say, “In short, there is a startling discrepancy between the common intuitive understanding of Hamilton’s rule and the derivation of this rule that has been described as exact and general.” Kin selection’s proponents have basically been trusting in fake science for over 50 years!
We can safely predict a powerful comeback by the proponents of inclusive fitness. Look for it in the pages of PNAS or elsewhere in the coming days and weeks. But it doesn’t matter, because they’re all wrong. Tom Bethell wrote in Darwin’s House of Cards that natural selection is unscientific no matter how it is formulated. After looking at the logic of it in Chapter 5, and the presumed evidence for it in Chapter 6, he concluded, “Natural selection functions in the realm of philosophy, not science.” For support, he quotes none other than staunch Darwinian Richard Lewontin of Harvard, who at least had the intellectual rigor to critically examine the meaning of natural selection:
For what good is a theory that is guaranteed by its internal logical structure to agree with all conceivable observations, irrespective of the real structure of the world? If scientists are going to use logically unbeatable theories about the world, they might as well give up natural science and take up religion. Yet is that not exactly the situation with Darwinism? (Lewontin, “Testing the Theory of Natural Selection,” Nature 236, no. 543 (1972): 181-182, cited by Bethell, p. 65).
We expect E.O. Wilson would be quick to defend natural selection. The dispute between the kin selectionists and group selectionists, he would probably respond, is about the target of selection, not the fact of selection. That would reduce the controversy to the deluded majority that believes kin selection is a law of nature or a valid target of natural selection. The problem runs deeper than that. How can any target of selection — from the gene to the group — be empirically or mathematically validated? Interestingly, Wilson does not attempt to offer a mathematical rule for his favorite alternative, group selection. We think that’s because his opponents could shoot his arrows back at him.
For an independent check, look at what Charles Lineweaver said about evolution in an interview in New Scientist back in November 2012. Asked about one proposed definition of life as “anything that undergoes Darwinian evolution,” he responded,
We pretend that makes sense, but if you look at it, it makes no sense at all. What is the unit of Darwinian evolution? Is it the gene? Is it the cell? Is it a multicellular organism? Is a city evolving? How about Gaia? Is that a life form?
To make matters worse (for the Darwinians), natural selection theory would still have deep problems even if all biologists could agree on the unit of selection. Bethell began his journey as a Darwin skeptic by pondering the circular reasoning inherent in selection theory. “Is there any way of deciding what is ‘fit’ other than seeing what survives?” he asks in the Introduction (p. 11). “If not, maybe Darwin was arguing in a self-confirming circle: the survival of the survivors.” Throughout his journey, as he documents in the book, he found leading Darwinists admitting to this core flaw in the logic of natural selection. In the end, he confirmed his hunch that “natural selection is not remotely law-like. All attempts to state it as a law collapse into the truism that I reviewed in earlier chapters” (p. 244).
Perhaps you’ve watched a magician tie a complex knot, rub it in his hands, and make the knot disappear before your eyes. The trick works because the ends never pass through any of the loops. Natural selection is like that; it can be complexified through jargon, mathematical tricks, and consensus. But when you tug on it, it unravels.
As the battle rages on between the kin selectionists and the group selectionists, or between the gene selectionists and the planet selectionists, keep in mind that the very idea of natural selection — the core principle of Darwinian evolution if there is one — is logically flawed. E.O. Wilson claims that kin selection is unscientific. His opponents will counter that group selection is unscientific. Perhaps it’s all unscientific. Its definitions are fuzzy, its units are unspecified, and it predicts opposite outcomes with equal ease. It cannot be falsified. Students, and thoughtful adults, deserve to know such things.
Photo: Weaver ant prepares for attack, via Wikicommons.