The behavioural cue of ‘flexible self-protection’ is a way to establish whether an animal feels pain, scientists say
Crickets that received the hot probe “overwhelmingly” directed their attention to the affected antenna – they groomed it more frequently, and tended to it over a longer period of time, he says. “They weren’t just agitated and flustered. They were directing their attention to the actual antennae that was hit with this hot probe.”


But, feeling is such an efficient and proven manner of influencing behavior of complex systems. Make it feel hungry, then it looks for food. It’s phenomenal. Why would we assume simpler beings rely on anything different?
I’m not going to say they make sense, I’m just listing the beliefs I’ve come across.
To be fair to you (and the beliefs you’ve come across), I just like pointing out common sense like it’s the exact opposite of that. I’d argue both that what you said is common sense, and that common sense is wrong about this. I’m not really sitting here confused, or shocked, or anything of that sort.
Some people don’t even believe in evolution, do there it is.
And besides that, some people want to believe their food don’t have feelings.
It makes sense all organisms feel some sort of pain because it’s related to self preservation, but not all of them have an ability to communicate about the pain. And even less number of them communicate pain in a way we could understand, and even less that we actually care to listen.