The Daily Ant hosts a weekly series, Philosophy Phridays, in which real philosophers share their thoughts at the intersection of ants and philosophy. This is the fourth contribution in the series, submitted by Cheryl Abbate.

Consider the Ant

Many people object to raising and killing animals like cows, chickens, and pigs for food because they are conscious (i.e., sentient). Farmed animals clearly have interests, such as the interests in not suffering and continued existence, and there is “something it is like” to be a cow, pig, or chicken. But what about insects, like ants? Are they conscious? Is there “something it is like” to be an ant? If not, perhaps we ought to consume insects, like ants, in lieu of factory farmed animals.

A common belief is that insects lack the neuro-physiological capacity to be consciously aware of pain. Even though insects have a centralized nervous system and a brain, and withdraw from noxious stimuli, some argue that consciousness requires a certain degree of nervous-system complexity that insects lack. For one, insects do not have a neocortex, leading some to conclude that they lack the capacity for subjective experiences. On this view, only a mammalian neocortex can generate consciousness (Key 2016; Rose 2010). After all, there is evidence that the neocortex is where the perception of pain in humans is generated (see footnote [1]).

This view is challenged by studies concerning convergent evolution, which inform us that different species can use different brain structures and systems to handle the same function, such as the function of pain-processing. For instance, while fish lack a neocortex, they possess a pallium, which is said to be equivalent to the neocortex, argues fish scientist Braithwaite (2010). Likewise, a homolog of the mammalian neocortex, the dorsal ventricular ridge, is found in the brain of birds (Dugas-Ford et al. 2012). Thus we should consider the possibility that insects are capable of sensing pain through a neural mechanism that is analogous, but not identical, to the structure that supports the capacity for subjective experience in humans.

Moreover, there is considerable disagreement about what supports the capacity for subjective experience in humans. While a popular view is that the cortex gives rise to subjective experiences in humans, others argue that the integrated structures of the vertebrate midbrain supports the capacity for subjective experience (Merker 2007). If the midbrain is what supports the capacity for subjective experience in humans, then the case for insect consciousness is a compelling one. After all, a recent study concludes that the central ganglion of insects is equivalent to the mammalian midbrain, as it is involved in processing sensory information, selecting targets, and directing action (Barron and Klein 2016). The central ganglion, then, may support a capacity for the most basic aspect of consciousness: subjective experience (Barron and Klein 2016).

The case for insect consciousness is all the stronger when it comes to ants, as these insects demonstrate some degree of cognitive complexity. To begin with, ants, which are paradigm eusocial insects, are known for their remarkable degree of sociality. Jeffrey Lockwood suggests that highly social animals must have awareness of how other minds operate. As he argues:

A critical step in the evolution of animal societies is the establishment of efficient interactions, and these interactions depend on group members’ abilities to understand each others’ thoughts, intentions, and feelings. Therefore, social insects must correctly judge the frame of mind, as it were, of one another. To carry out the processes of climatic regulation, feeding, brood care, foraging, etc., individuals must be aware of the needs of their nestmates (1987, 80).

Moreover, there is evidence of communication, teaching, and memory in ant communities, which suggests that there is some level of ant mental activity. Here is just a sampling of studies that indicate this:

Ant communication: A 2016 study finds that ants communicate with each other and collectively influence their communities during the fluid exchanged by trophallaxis, which is described as the process of shifting proteins, hormones, and other small molecules from mouth to mouth (LeBoeuf et al. 2016). The researchers conclude that trophallaxis “underlies a private communication channel that ants use to direct the development of their young” (LeBoeuf et al. 2016).

Ant teaching and bidirectional feedback: A study conducted by Franks and Richardson (2006, 153) concludes that the ant technique known as “tandem running,” which involves one ant leading another from the nest to food, “is an example of teaching, to our knowledge the first in a non-human animal that involves bidirectional feedback between teacher and pupil.” According to the researchers, when tandem running occurs, the ants involved (both the “tandem leader” and “tandem follower”) send signals to one another that control both the speed and course of the run.

Ant memory: One study demonstrates that there is cognitive complexity in ant navigation, as ants “backtrack” when they find themselves in unfamiliar places, which indicates the “presence of a type of ‘memory of the current trip’ allowing lost ants to take into account the familiar view recently experienced” (Wystrach et al. 2013).

Even though some animals have different behaviors and different neurological structures from that of humans, we, more likely than not, are the same in a way that matters. The evidence of ant sociality, communication, teaching, and memory, taken together with Barron’s and Klein’s (2016) finding that the insect brain supports a capacity for subjective experience, provides us with compelling reasons to believe that even “mere” ants are conscious and thus deserving of our moral consideration. The behavior of ants is highly complex and arguably intelligent, and it indicates that there is something that happens in ant life other than mechanical stimulus-responses similar to reflexes.

Given that scientists cannot even agree on what supports the capacity for subjective experience in humans, it is indeed arrogant to dogmatically insist that ants lack the neural mechanisms that support a capacity for subjective experience, especially when there is compelling evidence that indicates otherwise. Consequently, in our future encounters with ants, we might heed the recommendation of Lockwood (1987, 70): “we ought to refrain from actions which may be reasonably expected to kill or cause nontrivial pain in insects when avoiding these actions has no, or only trivial, costs to our own welfare.” This implies that since we can subsist on a plant-based diet, we should cease all proposals to introduce ants, or any insect, into our diet.

[1] In the case of humans, the process of sensation looks something like this: an injury stimulates nociceptors (sensory neurons), which send electrical signals through nerve lines and the spinal cord to the neocortex, where injuries are processed into a sensation of pain. For humans (and other mammals), it is in the neocortex where the perception of pain is generated. In the case of mammals, pain is a product of higher brain center processing.

References

Barron, Andrew B., and Colin Klein. 2016. “What Insects Can Tell Us about the Origins of Consciousness.” Proceedings of the National Academy of Sciences 113 (18): 4900–4908. doi:10.1073/pnas.1520084113.

Brian Key. 2016. “Why Fish Do Not Feel Pain.” Animal Sentience 3.

Dugas-Ford, J., J. J. Rowell, and C. W. Ragsdale. 2012. “Cell-Type Homologies and the Origins of the Neocortex.” Proceedings of the National Academy of Sciences 109 (42): 16974–79. doi:10.1073/pnas.1204773109.

Franks, Nigel R., and Tom Richardson. 2006. “Teaching in Tandem-Running Ants.” Nature 439 (7073): 153–153. doi:10.1038/439153a.

LeBoeuf, Adria C, Patrice Waridel, Colin S Brent, Andre N Gonçalves, Laure Menin, Daniel Ortiz, Oksana Riba-Grognuz, et al. 2016. “Oral Transfer of Chemical Cues, Growth Proteins and Hormones in Social Insects.” eLife 5 (November). doi:10.7554/eLife.20375.

Lockwood, Jeffrey A. 1987. “The Moral Standing of Insects and the Ethics of Extinction.” The Florida Entomologist 70 (1): 70. doi:10.2307/3495093.

Merker, Bjorn. 2007. “Consciousness without a Cerebral Cortex: A Challenge for Neuroscience and Medicine.” Behavioral and Brain Sciences 30 (1). doi:10.1017/S0140525X07000891.

Rose, James D. 2002. “The Neurobehavioral Nature of Fishes and the Question of Awareness and Pain.” Reviews in Fisheries Science 10 (1): 1–38. doi:10.1080/20026491051668.

Victoria Braithwaite. 2010. Do Fish Feel Pain? New York, NY: Oxford University Press.

Wystrach, A., S. Schwarz, A. Baniel, and K. Cheng. 2013. “Backtracking Behaviour in Lost Ants: An Additional Strategy in Their Navigational Toolkit.” Proceedings of the Royal Society B: Biological Sciences 280 (1769): 20131677–20131677. doi:10.1098/rspb.2013.1677.

Cheryl Abbate is a philosophy doctoral candidate at the University of Colorado, Boulder. Her primary research interest is in applied ethics, especially military ethics, environmental ethics, and nonhuman animal ethics. Journal articles include: “Adventures in Moral Consistency: How to Develop an Abortion Ethic from an Animal Rights Framework” (Ethical Theory and Moral Practice), “How to Help when it Hurts: The Problem of Assisting Victims of Injustice” (Journal of Social Philosophy), and “The Search for Liability in the Defensive Killing of Nonhuman Animals” (Social Theory and Practice).