Humans evolved the ability to use symbols, arbitrary signs held in common by social convention – letters and words,  numbers and operators strung together to represent anything real or imaginary.

Symbols aren’t just how we communicate. They’re also how we think. They’re the reason you can, and a dog can’t imagine a pink rhino balancing the universe on its nose. Or peace and justice for all.

Symbols have us humans living in two worlds, the here and now where all organisms live, and what’s conceptually imaginable. Symbols are what make us so different from all other organisms here on earth. “Intelligent” life forms elsewhere in the universe would also be symbol-, or language-users too. Any signals they sent us would be symbols.

 All organisms interact selectively with their environments, trying to take in what they can use to regenerate themselves and keep out what would degenerate them, for example eating food, not poison.

With language, we humans tend to interact selectively with concepts, taking in the ideas that bolster our confidence and keeping out the ideas that shake our confidence. That’s confirmation bias, escaping into our imaginations when reality gets too rough.

With language, you have vastly more potential worries than a dog has. Humans trudge through a sandstorm of confidence-eroding possibilities – all the real and imaginary threats and missed opportunities that can fill us with doubts and self-doubt. 

You also have way more ways to deflect and deny your worries than does a dog. Symbol-use both fills us with doubt and affords us easy ways to escape them. Such easy denialism is a major threat to human survival.

That would be so for any symbolic species like us anywhere in the universe. Indeed, it’s quite likely that climate change and climate change denial have led to the extinction of other extraterrestrial symbolic species. Symbol use would be late to evolve. The remains of earlier organisms would be fossil fuels that, upon discovery, symbol users would exploit like there’s no tomorrow, denying the peril just as we have.

How language use evolved is a hot research topic in academics. Yet researchers are strangely silent about the adaptive consequences for us symbol users. That’s what my research here is about.