In an interview with Richard Dawkins, Jim Holt writes:

"Why did humans lose their body hair? Why did they start walking on their hind legs? Why did they develop big brains? I think that the answer to all three questions is sexual selection," Dawkins said. Hairlessness advertises your health to potential mates, he explained. The less hair you have on your body, the less real estate you make available to lice and other ectoparasites. Of course, it was worth keeping the hair on our heads to protect against sunstroke, which can be very dangerous in Africa, where we evolved. As for the hair in our armpits and pubic regions, that was probably retained because it helps disseminate "pheromones," airborne scent signals that still play a bigger role in our sex lives than most of us realize. (It occurred to me that becoming hairless also meant we didn't have to spend all our leisure grooming one another to remove lice, like other primates, thereby freeing up time to create capitalism. But I kept this thought to myself.)

Let me offer some thoughts that I won’t keep to myself. While there are many lessons to be derived from this hypothesis, for today, I will hit on one. I would agree with Dawkins that humans evolved. After all, I have not heard a good creationist explanation for armpit and pubic hair. I would also agree that sexual selection occurs (although one evolutionary biologist declared that Darwin’s theory of sexual selection is dead ). However, does the acknowledgement of human evolution and sexual selection mandate that we all must embrace Dawkins’ hypothesis?

Of course not. What Dawkins offers is a hypothesis, otherwise known as an educated guess. And there are problems with the hypothesis. For example, how does such a generalized explanation work to explain such an unusual event – mammals losing their hair? Surely there are many other primates and mammals where hairlessness would also advertise their health to potential mates. Dawkins would need to explain why his hypothesis applies to the lineage that led to humans, but not chimps (etc.). Furthermore, less real estate available to lice and other ectoparasites means less need to groom, which means less opportunity to evolve social bonding, which is a problem for explaining such a thoroughly social being as a human.

Yet even if there were no problems with Dawkins’ hypothesis, would we still be expected to embrace it as history? No. By its very nature, it remains a hypothesis and thus it is Dawkins’ job to turn his hypothesis into history. As a skeptic, one acknowledges the hypothesis as a reasonable, even testable, speculation. But the proponent of the hypothesis has no epistemic justification for demanding others embrace it and insulting them if they don’t. That would be an attempt to turn a hypothesis into history with the use of rhetoric and public intimidation.

At what point does any hypothesis become history? There is no objective standard or checklist. There is no AI program. Instead, what happens is the hypothesis is used to make predictions. Successful predictions become a track record of success. Humans are drawn to success and thus a consensus develops within a community. In other words, the transformation of a hypothesis is a squishy endeavor, depending on judgments of success, the accumulation of data that can be viewed as circumstantial evidence, and the extent to with which an idea becomes popular among a community of inquirers.

With judgments of success, we should be concerned about human psychology and our tendency to cherry pick and engage in revisionism. A proponent of a hypothesis is more likely to focus on the successes and remember only the successes. With circumstantial evidence, there is always of the Lesson of Microsporidia, where a hypothesis that was so strongly supported turned out to be fundamentally wrong. There is also the fact that data only become evidence as a function of mind. With consensus, we should be concerned about sociological factors and cultural reasons that may influence such mass agreement. Like I said, it’s squishy. In the end, the decision to turn a hypothesis into history is a function of our free will. There is no neuro-algorithm that will automatically transform the input of data into the output of belief. And there is no guarantee that belief must necessarily reflect actual history. With respect to any hypothesis about history, there will always be at least three options: 1) reject the hypothesis as wrong; 2) remain agnostic about the hypothesis; 3) embrace the hypothesis as history. Those who choose one of the options will plead their case and the circle continues.

So there is no objective criterion that is used to convert a hypothesis into history. On the contrary, the transformation is ultimately a decision. We can try to make the decision as objective as possible by appealing to evidence and the consensus of a community, but it nevertheless remains less than objective. Unfortunately, it can be worse than this.

Above, I cited two reasons to be skeptical of Dawkins’ hypothesis about the evolution of hairlessness. However, I also noted that we did not need these reasons in order to excuse ourselves from accepting the hypothesis. Because the hypothesis is only a hypothesis, the burden is on its proponents to come up with powerful reasons to coax the skeptic into reaching the decision to turn the hypothesis into history.

Yet imagine that a follower of Dawkins was a True Believer in this hypothesis. He then confronts the skeptic as follows: “Look, we know that humans evolved. We know that during this evolution, they lost most of their hair/fur. We also know that sexual selection is common place in evolution. Thus, your skepticism is misguided.”

Of course, the conclusion does not follow. Skepticism is not misguided; it is required. Without it, there is no reason to do any further science, as we need only deduce this particular piece of history from the general principles of evolution. The True Believer is thus converting his hypothesis into history by converting science into philosophy.

But it can get much worse if the skeptic is an ID evolutionist. At this point, the True Believer dips deeply from the well of rhetoric. His argument continues: “What do you want? A video tape of the actual evolution in progress? Of course we don’t have every little detail figured out, but at least we have a scientific, testable hypothesis. After all, what does ID have to say about this? Nothing? I thought so. Face it, you reject this scientific hypothesis simply because it causes discomfort to your religious views. Don’t worry, I don’t expect you to admit this as we all know ID has nothing to do with religion [wink, wink].”

Since the scientific hypothesis about history is testable, the skeptic can wait to see the test results. And even if the test results support the hypothesis, we are still faced with the decision between a supported hypothesis and a belief about history. Y’see, despite the appeal to general principles and the added avalanche of rhetoric, the point remains that the original hypothesis remains only a hypothesis and does not mandate that all reasonable people embrace it.

If these points ring true for you, simply change the topic slightly. Instead of arguing about the evolution of hairlessness in humans, imagine the argument is about the evolution of a molecular machine. And instead of appealing to the commonality of sexual selection, substitute the commonality of things like natural selection and cooption. Does the demand that we all convert hypothesis into history suddenly become reasonable? Or does the same basic problem remain?