Dr. Eliza Middleton

The conceptual leap between nociception and experiencing pain, I think, really started to gain momentum in 2019 with Greg Neely's work at UCEDD with his team.

And that was where they showed that the fruit flies can develop chronic pain.

So that's not a reflex.

Reflexes don't generalise across the body.

Reflexes don't persist over weeks.

That requires some central nervous system involvement.

Bumblebees can make motivational trade-offs around pain.

So they're willing to endure a noxious heat for a sufficiently valuable food reward.

And that willingness scales with the reward's value.

So reflexes also don't make trade-offs.

Trade-offs require the brain to evaluate those competing priorities.

And that's a signature of experience, not of a mechanism.

But we used to make the same kind of argument about fish, that they couldn't feel because they lacked a neocortex.

But fish don't need a neocortex.

They have their own neural architecture that does the same job.

And I think it's really about what is the question that we're asking?

It isn't, do they feel pain the same as us?

Because they definitely don't.

They don't have the same architecture as we do.

But that doesn't mean that that experience is absent.