Notes

The following text explores, in a speculative manner, the evolutionary question: Did high-intensity affective states, specifically Pain, emerge early in evolutionary history, or did they develop gradually over time?

Note: We are not neuroscientists; our work draws on our evolutionary biology background and our efforts to develop welfare metrics that accurately reflect reality and effectively reduce suffering. We hope these ideas may interest researchers in neuroscience, comparative cognition, and animal welfare science.

This discussion is part of a broader manuscript in progress, focusing on interspecific comparisons of affective capacities—a critical question for advancing animal welfare science and estimating the Welfare Footprint of animal-sourced products.

Key points

Ultimate question: Do primitive sentient organisms experience extreme pain intensities, or fine-grained pain intensity discrimination, or both?

Scientific framing: Pain functions as a biological signalling system that guides behavior by encoding motivational importance. The evolution of Pain signalling —its [...]

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Outline:

(00:15) Notes

(00:21) Key points

(01:41) Introduction

(04:17) The Function and Evolution of Affective Scales

(09:02) Which is evolutionary cheaper for a Pain scale: high resolution or wide range?

(09:22) Costs of Increasing Range

(10:12) Costs of Increasing Resolution

(11:35) Trajectories for the Evolution of Range and Resolution

(13:48) Low Resolution, Low Intensity (LrLi): Basic Survival Signals

(14:53) High Resolution, Low Intensity Range (LiHr): Subtle but Mild Signals

(15:35) Low Resolution, High Intensity (HiLr): Strong but Undifferentiated Signals

(17:15) High Resolution, High Intensity (HiHr): Rich and Extreme Signals

(18:16) Tentative Conclusion

(23:19) Acknowledgements

(23:28) References

The original text contained 3 footnotes which were omitted from this narration.

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First published:
May 17th, 2025

Source:
https://forum.effectivealtruism.org/posts/novnNcFiWaaAvTKEi/do-primitive-sentient-organisms-feel-extreme-pain

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Narrated by TYPE III AUDIO.

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Images from the article:

Color spectrum diagrams showing high and low intensity and resolution variations.

Graph showing hedonic resolution versus hedonic range with intensity levels and examples.

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