Convergent evolution of sentience?

Abstract

Mikhalevich & Powell make a compelling case that some invertebrates may be sentient and that our moral obligations in the context of welfare should hence extend to them. Although the case is similar to that made for fishes, there is one obvious difference in that examples of invertebrate sentience probably arose independently from vertebrate sentience. We have unequivocal proof that complex cognition arose multiple times over evolutionary history. Given that cognition is our best tool for indirectly quantifying sentience, it seems highly likely that this multiple polygenesis may also have occurred for sentience. In acknowledging this, we must accept that the anthropocentric structure-function arguments that have surfaced in the context of pain are almost certainly too simplistic and cannot account for cases of convergent evolution.