Metazoa
"Dip below the ocean's surface and you are soon confronted by forms of life that could not seem more foreign to our own: sea sponges, soft corals, and serpulid worms, whose rooted bodies, intricate geometry, and flower-like appendages are more reminiscent of plant life or even architecture than anything recognizably animal. Yet these creatures are our cousins. As fellow members of the animal kingdom--the Metazoa--they can teach us much about the evolutionary origins of not only our bodies, but also our minds. In his acclaimed 2016 book, Other Minds, the philosopher and scuba diver Peter Godfrey-Smith explored the mind of the octopus--the closest thing to an intelligent alien on Earth. In Metazoa, Godfrey-Smith expands his inquiry to animals at large, investigating the evolution of subjective experience with the assistance of far-flung species. As he delves into what it feels like to perceive and interact with the world as other life-forms do, Godfrey-Smith shows that the appearance of the animal body well over half a billion years ago was a profound innovation that set life upon a new path. In accessible, riveting prose, he charts the ways that subsequent evolutionary developments--eyes that track, for example, and bodies that move through and manipulate the environment--shaped the subjective lives of animals.
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- Peter Godfrey-Smith discusses this topic at length in his recent-ish book Metazoa and uses observations of insects and other invertebrates to argue, compellingly in my opinion, that sentience and cognitive abilities are not intrinsically linked, but rather depend on the specific organism's evolutionary/reproductive strategies.
Most insects do not exhibit the classic signs of pain responses (the new findings discussed in this New Yorker article, notwithstanding). For example insects generally don't groom or guard an amputated limb. This puzzling (lack of) response can be explained as being aligned with their reproductive strategy: they reach breeding age quickly and die soon after. Thus, it's better not to waste energy avoiding limb loss for a future that won't happen.
Despite this lack of sentience, insects can be quite intelligent and learn complex cues and behaviors. Other invertebrates that look superficially like insects, prawns for example, have quite different life cycles and lifespans and often do exhibit signs of pain / sentience.
Basically pain/sentience emerge when there is a reason for the organism to protect the body from damage, and does not evolve (or is subsequently lost!) when there are more important short term goals. One wonders, for example, whether salmon experience pain when they fling their bodies up rivers, over and onto rocks, damaging them horribly in the process: all for purposes of spawning.
- In his book Metazoa, Peter Godfrey-Smith mentions that life in the ocean was more diverse than life on land, until a 130 million years ago, when diversity on land became exceptional, mostly driven by a feedback loop between insects and plants, as plant diversity allowed insect specialization and insect diversity allowed plant specialization. (Until finally we arrived at a situation where every species of fig tree had a specialized species of wasp responsible for pollinating that species of fig tree.)
https://www.amazon.com/Metazoa-Animal-Life-Birth-Mind-ebook/...
- An interesting fact that I learned from the book Metazoa is that biological diversity was greater in the seas than on land, until about 130 million years ago, and then the explosion of diversity on land, at that time and still now, was because of a feedback loop that developed between plants and insects, with the insects allowing greater specialization among the plants, and the greater diversity among plants allowing greater diversity among insects. This was a true feedback loop, in that it would be impossible to say what the starting point was, the insects or the plants.
https://www.amazon.com/Metazoa-Animal-Minds-Birth-Consciousn...
- Peter Godfrey Smith covers some of this in his book Metazoa but he rejects pan-psychicism and tries to make us believe that pure materialism can explain consciousness, as it emerged in animals over the last 750 million years, going back to an unknown ur-brain that might have existed in the first bilaterian:
https://www.amazon.com/Metazoa-Animal-Minds-Birth-Consciousn...
However, I was not convinced by the material argument, which seems just as magical as any other explanation, as there comes a moment when we have to believe “then something magic happens and the creatures suddenly have real awareness of their surroundings.” Having read the book, which denounced pan-psychism, I actually found myself more favorably inclined to pan-psychism , since it clearly is no more magical then any other explanation.
