The weather up here has finally started warming up, and we’ve taken every opportunity to open up the windows and air out the house. A couple nights ago, we left the kitchen window open overnight. When we woke up the next morning, it was pretty chilly, which prompted my daughter to ask me:

“Daddy, why do we get goosebumps?”

Ermagerd, erverlurtion!

I considered telling the truth: “I have no idea.” Then I remembered that we live in an era where we have Internet-ready computers masquerading as telephones, and therefore you’re never justified in saying you don’t know something. To Wikipedia!

We quickly learned that goose bumps are caused by the same subcutaneous “arrector pili” muscles that give hairier mammals the ability to make their fur “stand on end”. On the one hand, this trait can make an animal look bigger and more intimidating, and might serve to ward off predators. On the other, it creates a thermos-like layer of air insulation between the fur’s horizon and the skin that helps keep the animal warm.

Of course, humans no longer have much in the way of fur, so these primary functions probably don’t work any more — they have become “vestigial”. I took this as a “teachable moment” to talk about evolution with my little girl. We talked about how organisms aren’t put together in clean modules like human-built machines. Because evolutionary change is driven by random mutations, it’s unlikely that all components of a biological system will change at the same time.

Humans lost their fur for reasons that almost certainly don’t have anything to do with the goose-bump function. Maybe losing fur gave our ancestors an advantage of some kind — like making them look sexier than their hairier relatives — and furlessness spread by natural selection. Or maybe once we figured out how to cut other animal’s skins off and wear them ourselves, the fur didn’t matter one way or the other and it just sort of “drifted away” by random chance. Regardless, once humans had lost their fur, the arrector pili muscles became pretty much useless. Nevertheless, they’re small and don’t take up a lot of resources, so there’s no real pressure for them to be lost by evolution, and therefore it might take a very long time for them to finally go away. Basically, the way I explained it to my daughter, goose bumps are an evolutionary anachronism, kind of like your appendix.

Or, if you’re one of these guys, your brain.

Great, science lesson for the day. But, as happens all too often when I talk to my kids about science, I started second-guessing myself later in the day. Was this scenario true? Do goose bumps serve any useful purpose in modern humans? I started thinking about all the scenarios where we get goose bumps. Certainly, we get them when we’re cold or scared, just like our hairier relatives. But we also get them in moments of intense emotion — but not just any emotion. At least in my own experience, I don’t get goose bumps when I’m angry, or when I’m doting on my kids. Frustration doesn’t do it, or stress, or intense happiness or satisfaction.

No, I get goose bumps when I experience a suite of emotions I usually classify as “religious-like”. Specifically, these are things related to the aesthetic sense: awe, the perception of beauty, the sublime sense of smallness before nature, the eureka moment of discovery or creation. In fact, I would go so far as to say that the visceral experience of these emotions is what lends them their weight, and perhaps assists in the “suspension of disbelief” necessary for the proper experience of religion and its close relative, art. And I’m pretty sure I’m not the only person who feels this way.

A long time ago, when I first started getting interested in evolution, I spent a lot of time thinking about the evolution of religion. There are many voices amongst scientists that scoff at the whole notion of belief in gods. Otherwise serious people contend that religion is just a silly fantasy, and that it demonstrably harms those unfortunate half-wits who don’t have the mental muscle to give it up.

Built by mentally challenged, delusional pseudo-chimps in the 13th century.

I never found these voices compelling. It just doesn’t add up: if religion was pathological, and was the root cause of war and suicide and self-destruction, why did it arise independently in every human population on Earth? And why does it persist, aeon after aeon, even though every population of humans — since FOREVER — has surely sampled atheism many thousands of times in every generation? If you saw these characteristics — parallel development and stability in the face of alternate character states — in any other phenotypic trait, you would assume they were supported by strong natural selection.

So I concluded, and still believe, that religion evolved by natural selection. I also believe (with very little evidence) that religion and religion-like behaviors remain the lynchpin of the numinous collective trait called “culture” that stabilizes large-scale human groups (or “races”, sensu lato). I’ve often wondered if there are “God genes” in humans that make it easier to believe in these kinds of ephemera. And while thinking about goose bumps, I started to wonder if they might shed some light on where one might look for those God genes.

Ever heard the term “God-fearing?” I always thought it was a goofy, hellfire-and-brimstone revivalist preacher trope. But what if the aesthetic/religious sense of modern humans evolved from a re-purposing of the limbic system (the part of the brain that controls goose bumps, sexual desire, terror, etc.) from simple fight/flight decisions to the “loftier” goals of god-making? One can imagine that the first counterfactual thoughts originated in fear: what if there’s a wolf behind that tree? And from the imaginary (but not really imaginary) wolf, it’s a short jump to imaginary (but not really imaginary) people, or grand immortal generation-spanning abstractions like deities. The signals originating in the limbic system feel external to our consciousness: for instance, when you fight down your fear of something, or learn to control some impulse or reflex, it feels distinctly like your “software” is dominating something external to it. Thus, fantasies arising in the limbic system would feel more “real” than the products of cerebral imagination. Mix all that limbic soup together — terror and sex and subconscious hallucination — and bam, god and art and human culture pop out the other side.

Or maybe not. Like the title says, wild speculation based on a 5-minute conversation with an 8-year old. Something fun to think about over the Easter/Passover weekend.