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Did Humans Evolve Susceptibility to Placebo Effects?

Suspending disbelief may have significant survival advantages.

Key points

  • Evidence shows that humans lie and BS a lot, and yet are surprisingly gullible too.
  • Placebo effects are not limited to medicine; they are also operative in any religious, spiritual, or political ideology.
  • Our susceptibility to placebo effects may have evolved because it affords big biological, reproductive success advantages.
  • We can't expect to overcome our gullibility, so it's best to learn how to gain its benefits without letting it get out of hand.

Hope isn't everything but it's something, and placebos have been providing it for millennia. People who believed the shaman's, priest’s, and fortune teller’s hopeful pep talks had a survival advantage—calmer confidence and a can-do attitude in sickness and in war that may have resulted in greater biological reproductive success.

Humans are an uncommonly anxious species. Having language floods us with anticipation of threats and missed opportunities. Compare the variety of worries you and any other creature could have, and it’s no contest. Humans are trudging through a sandstorm of motivation-eroding possibilities.

Studies show that we're a credulous species. Though we lie lots, we're also very gullible—too gullible for how readily we lie. Some researchers attribute this to the pressures of human sociality. People have go along to get along. That’s one source of our gullibility, but there are others. Another is the cost of verification. It’s much easier to take someone’s word for things than it is researching whether what they’re saying is true.

In their book, Denial: Self-deception, False Beliefs, and the Origins of the Human Mind, Varki and Brower posit that with human language, we gained “death wisdom,” an ability to foresee our own deaths (the ultimate FOMO). They argue that we would not have survived the terror of such foresight had we not also gained what they call a “capacity for denial”.

It’s common for researchers to posit all manner of modules to handle particular survival challenges. I do not see these as distinct modules. Rather, foresight and denial come as a package deal with language. Language floods us with worries but also affords us easy ways to rationalize ignoring them.

Indeed, to assume some added capacity for denial may reverse the challenge. It suggests that we are born with a coherent interpretation of truth and reality, an inability to believe inconsistent things. There’s little evidence supporting that assumption. To suggest that we had to acquire incoherence is a fall-from-grace myth.

Coherence is an ideal we can imagine through math and logic. In practice, humans can believe whatever they want in order to get by and will naturally believe inconsistent things. We take our word for things as readily as we take other people’s words. We don’t have to even consider or believe what we claim to believe. More than we care to admit, a lot of our communication is judged simply on “If it feels good, say it.”

Language is first and foremost functional. People often just repeat word-sounds that help them get by. We have word habits that are often more like animal noises than rigorously coherent concepts.

Still, we would have a capacity for motivated denial, as the authors suggest. We all have our “noping strategies,” our ways of saying “nope, don’t go there,” when exposed to worries. And we might have evolved ever-greater capacity for contented or proud blind faith in placebo effects since motivated optimism is often a way to protect our wishful thinking, trudging as we are through the sandstorm of demotivating possibilities.

I think of confirmation bias—the tendency to favor encouraging over discouraging evidence—as a natural extension of the selective interaction common to all creatures. All organisms interact selectively with their environments, for example, eating food not poison.

The universe is inherently degenerative. Energy generally scrambles things up. A windstorm doesn’t sort things, it shuffles them. Organisms have to protect against natural degeneration and regenerate what degenerates them. This is the paradox of life. To survive we need energy we can use to regenerate ourselves and protect against the energy that will degenerate us.

Apply that to human language and you get confirmation bias, the "noping" strategies by which we protect against motivation degeneration. Confirmation bias manifests collectively through cultish tribalism and is often a huge collective advantage. Religions, which I regard as a collective confirmation bias placebo effect, afford their adherents profound benefits, many of which play out in greater well-being.

We've barely begun to research all of the range and benefits of placebo effects. Religions are placebo effects, and that's not knocking them. Whatever gets us through hard times, though of course, they’re dangerous too. They could be the death of us if we don’t learn to manage them better.

Much of my research focuses on how to enjoy placebo effects safely. I call it optimal illusion, strategic gullibility, or safe escapism—kidding ourselves in ways that help, not harm. I think it’s unrealistic to assume that people could be completely realistic. Escapism is inescapable for us anxious humans. It’s not how far out you go into escapism but whether you remember to come back. We need to get better at taking our flights of placebo-influenced fantasies but always with a return ticket to reality secure in our heart pockets. For that I distinguish between belief and relief. I seek ways to embrace a careful double standard: “I believe in scientific research methods; I relieve in placebos.”


Varki, A., & Brower, D. (2013). Denial: Self-deception, false beliefs, and the origins of the human mind. Hachette UK.

Gregg, Justin (2022) If Nietzsche were a Narwhal: What animal intelligence reveals about human stupidity.

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