Whether invertebrates have a capacity for valenced experience is still uncertain. Rethink Priorities has been systematically exploring this issue during the past months. Here, in the fourteenth post of this series, I explore our attitudes towards invertebrates, draw attention to different possibilities of ‘indirect advocacy’ and suggest some questions that deserve further research. As remarked in our previous post, even if we concluded that invertebrates are conscious and even if we had the means to help them, we would still need to determine how likely it is that specific interventions on their behalf will be supported and adopted. Future research on this matter will allow us to better determine the tractability of improving invertebrate welfare.

Whether invertebrates possess the capacity to have valenced experiences is still uncertain. On the assumption that invertebrate welfare is a relevant cause area, we explore here different possibilities of assisting invertebrates, both those living in the wild and those under human control. When possible, specific interventions to reduce invertebrate suffering are presented. In other cases, I suggest which questions should be further investigated in order to better understand the problem and to study feasible intervention strategies.

Whether invertebrates have a capacity for valenced experience is still uncertain. Given that uncertainty, we argue that supporting the cause of invertebrate welfare means, at present, promoting additional research. To that end, we explore and outline key research questions in two areas: (i) invertebrate sentience and (ii) philosophical research into consciousness. Regarding the first, we propose further research on those features which, according to expert agreement, seem to be necessary for consciousness (e.g., nociceptors and centralized information-processing structures). We also suggest looking into the quality of invertebrates’ lives. Finally, concerning philosophical research into consciousness, we suggest that the inherent difficulties in the detection of morally significant pain and pleasure in nonhumans should be further investigated. We also highlight other more specific problems about phenomenal consciousness and its moral implications.

In this post, four members of Rethink Priorities’ invertebrates team—Daniela R. Waldhorn, Marcus A. Davis, Peter Hurford, and Jason Schukraft—outline their views on the value, feasibility, and danger of quantitative estimates of invertebrate sentience. Marcus and Peter provide numerical estimates of sentience for each of the taxa we investigated for our invertebrate sentience project, Daniela offers a qualitative ranking of the same taxa, and Jason argues that we are not yet in a position to deliver estimates that are actionable and robust enough to outweigh the (slight but non-negligible) harm that publishing such estimates prematurely might engender.

More than 99.9% of animals are invertebrates. There is modest evidence that some large groups of invertebrates, especially cephalopods and arthropods, are sentient. The effective animal activism community currently allocates less than 1% of total spending to invertebrate welfare. That share should rise so that we can better understand invertebrate sentience and investigate the tractability of improving invertebrate welfare.

Rethink Priorities has been compiling and analyzing relevant scientific evidence regarding invertebrate consciousness. As explained in a previous post, we selected 53 features potentially indicative of the capacity for valenced experience as criteria for discerning whether invertebrates of 12 biological taxa are conscious or not (see database). However, if a specific feature can effectively operate non-consciously in humans, that function –by itself– may provide no evidence that an individual is conscious. Hence, we investigated which of those 53 features can occur unconsciously in humans. We observe that different noxious stimuli reactions and some simple forms of learning are the most likely to occur unconsciously in humans. These and other findings are presented and discussed in this report.

Invertebrate welfare has been gaining recent traction in the scientific literature and among the effective altruism community. However, whether invertebrates have the capacity to experience pain and pleasure in a morally significant way is still very uncertain. Given this current epistemic state, Rethink Priorities has been compiling and analyzing relevant scientific evidence regarding invertebrate consciousness and exploring criteria that evaluate whether individuals of a given invertebrate species or taxon have valenced experience. These data have been gathered and displayed in this database. In a prior post, we summarized our main findings by feature. Here, we present our results by taxa.

Invertebrate welfare has been gaining recent traction in the scientific literature and among the effective altruism community. However, whether invertebrates have the capacity to experience pain and pleasure in a morally significant way is still very uncertain. Given this current epistemic state, Rethink Priorities has been compiling and analyzing relevant scientific evidence regarding invertebrate consciousness and exploring criteria that evaluate whether individuals of a given invertebrate species or taxon have valenced experience. These data have been gathered and displayed in this database. In this post, the first one of two pieces on our main findings, we present our results by feature.

The database is an interactive table, where we summarize scientific data about 53 features potentially indicative of the capacity for valenced experience and examine the degree to which these features are found throughout 18 representative biological taxa. 12 invertebrate taxa are included: honey bees (genus Apis), cockroaches (genus Periplaneta), fruit flies (Drosophila melanogaster), ants (family Formicidae), spiders (order Araneae), the nematode Caenorhabditis elegans, sea hares (genus Aplysia), moon jellyfish (genus Aurelia), crabs (infraorder Brachyura), crayfish (family Cambaridae), and octopuses (family Octopodidae). For comparative purposes, we included three kinds of non-animal organisms – prokaryotes, protists and plants (kingdom Plantae) – and three vertebrate species – chickens (Gallus gallus domesticus), cows (Bos taurus), and humans (Homo Sapiens).

In this, the final of three posts on features potentially relevant to invertebrate sentience, we assess 9 learning indicators, 4 navigational skills, and 7 mood state behaviors.

In this, the second of three posts on features potentially relevant to invertebrate sentience, we assess 5 drug responses, 5 motivational tradeoffs, and 5 feats of cognitive sophistication.

In this, the first of three posts on features potentially relevant to invertebrate sentience, we assess 10 anatomical and evolutionary features and 5 types of noxious stimuli reactions.

Rethink Priorities reviewed the scientific literature relevant to invertebrate sentience. We selected 53 features potentially indicative of the capacity for valenced experience and examined the degree to which these features are found throughout 18 representative biological taxa. These data have been compiled into an easily sortable database that will enable animal welfare organizations to better gauge the probability that (various species of) invertebrates have the capacity for valenced experience. This essay details what we’ve done, why, and the strengths and weaknesses of our approach.

Other humans merit moral concern. We think many nonhumans merit moral concern too. But how do we know? And which nonhumans? Chimpanzees? Chickens? Bumblebees? Protozoa? Roombas? Rocks? Where and how do we draw a line?