\n<\/p>\n
One of the stranger effects of Brexit was that, after the United Kingdom left the European Union, in 2020, it no longer recognized animals as \u201csentient beings.\u201d When the U.K. was an E.U. member state, it was bound by European laws, including the Lisbon Treaty, which invoked sentience in order to shield animals from sensations such as pain, hunger, and fear. But, after Brexit, the U.K. was no longer subject to the treaty. Numerous advocacy groups demanded a replacement animal-sentience law. Twenty-nine leading veterinarians, who treated cattle, birds, fish, dogs, and other animals, sent a letter<\/a> to the Daily Telegraph<\/em>. \u201cScientific evidence demonstrates the ability of animals across a range of species to have feelings,\u201d they wrote. \u201cWe have fought for legislation that places a duty on the state to recognise this.\u201d<\/p>\n In 2021, the U.K. government introduced a bill that covered only vertebrates\u2014animals with backbones. More protests followed. Ninety-seven per cent of animals\u2014think clams, crabs, cicadas\u2014are invertebrates. An octopus does not have a backbone, but in the Netflix documentary \u201cMy Octopus Teacher,\u201d from 2020, we see one that appears curious, uses shells as body armor, and seems to bond and play with a person. In the naturalist Sy Montgomery\u2019s nonfiction book \u201cThe Soul of an Octopus<\/a>,\u201d she visits an octopus and observes that the animal \u201chad not only remembered us and recognized us; she had wanted to touch us again.\u201d And whatever happened to considering the lobster<\/a>?<\/p>\n The government asked Jonathan Birch, a philosopher at the London School of Economics, to lead an investigation into which animals should be considered sentient. Because scientists cannot ask an animal about its feelings, they tend to study whether it has a complex nervous system, and if its behaviors suggest that it experiences pain and other sensations. Birch\u2019s team developed eight criteria for sentience and collected research into whether various species met them. (Crabs, for example, will groom injured parts of their bodies and endure a stronger electric shock in order to acquire better shells to live in.) The team ultimately helped persuade the government to recognize sentience in cephalopod mollusks, such as octopuses and squid, and decapod crustaceans, which include crabs and lobsters. Even after the government passed the Animal Welfare (Sentience) Act of 2022, however, Birch felt unsettled. The new law made no mention of the most widespread animals on earth: insects. \u201cOnce you\u2019ve got to that stage with octopuses, you very quickly start to wonder about other invertebrates as well,\u201d he told me.<\/p>\n Insects make up about forty per cent of all living species. An estimated trillion insects are farmed per year; quadrillions are killed by pesticides, and many species have gone extinct as humans have cleared habitats for farms, factories, and cities. Most of us do not think much about their inner lives, and our laws do not usually consider their welfare. Insects are small, they don\u2019t scream or bleed red, and many are considered pests; we tend to kill or mutilate them without pause. \u201cThe default view of the vast majority of the general public, as well as many of my colleagues, is that insects are largely reflex machines,\u201d Lars Chittka, a behavioral biologist who researches bees at Queen Mary University of London, told me. If humans seriously considered the possibility that insects are sentient, he said, we would need a \u201ccompletely different connection with the natural world.\u201d<\/p>\n Several years ago, Tilda Gibbons, an early-career scientist with shaggy blond hair, came across an opening for a Ph.D. student in Chittka\u2019s lab. As an undergraduate, she had studied chronic-pain pathways, using mice as a model for humans, but she had never worked with insects. When she typed four words into Google\u2014\u201cDo insects feel pain?\u201d\u2014the search engine suggested that the answer was no. Still, Gibbons was intrigued by the question, and she joined Chittka\u2019s team in the fall of 2019. A few months later, the U.K. went into a pandemic lockdown.<\/p>\n When Queen Mary University closed its laboratories, Gibbons visited campus and picked up a cardboard box with about a hundred bees. She carried it onto the London Underground and back to her apartment in East London, where she planned to study how machinelike bees really were. The box droned noisily next to her bed; her cat examined it cautiously. \u201cIt kept me awake for the first few nights,\u201d Gibbons told me. \u201cThen I just got used to it.\u201d<\/p>\n Gibbons set up a plastic arena that contained two color-coded bee feeders. One feeder was room temperature; the other was heated to a hundred and thirty degrees Fahrenheit, roughly the temperature of hot coffee. When she filled them both with the same sugar water\u2014four parts sugar, six parts water\u2014the bees reliably chose the cool one. When Gibbons reduced the sugar content in the cool feeder, however, the bees sought out the hot one.<\/p>\n At first, the bees found ways to drink the sugar water without coming into direct contact with the hot feeder. \u201cThey were really cheeky,\u201d Gibbons said. But, when she redesigned the feeders, forcing the bees to make contact with the heated surface if they wanted the liquid, they continued to choose the sweeter liquid in the heated feeders.<\/p>\n The bees in Gibbons\u2019s experiment had satisfied at least one of the criteria developed for the Sentience Act: an animal may be sentient if it responds to \u201cmotivational trade-offs.\u201d The bees reacted to heat in a way that was more than automatic. They put up with the heat to get a better reward. Gibbons was impressed.<\/p>\n The other seven criteria consider neurobiology and behavior. If an animal seeks out painkillers, or can learn based on associations with painful stimuli, that can suggest sentience. So can nociceptors, nerve cells that sense harmful stimuli\u2014especially if the nociceptors are integrated with other sensory systems in the brain. In 2022, Gibbons worked with Birch, Chittka, and other colleagues to review research into six orders of insects, including juvenile and adult cockroaches, termites, bees, ants, butterflies, and crickets.<\/p>\n The literature showed insects to be far more sophisticated than one might expect of an automaton. Many have nociceptors that send signals to other parts of the insect brain, such as the central complex (associated with spatial navigation and locomotion) and the mushroom bodies (linked to learning, memory, and sensory integration). Cockroaches have a nervous-system pathway that leads up from the body to the brain and back again. In a 2019 study, researchers exposed cockroaches to a hot stimulus and a neutral stimulus; the neutral stimulus prompted a weaker signal from the body to the brain, and the hot stimulus led the roaches to try and escape. (Unsettlingly, cockroaches without heads responded to the heat but did not try to escape.) A recent genomic study of mantises, which are notorious for eating their mates during and after sex, found genes that code for nociceptive ion channels\u2014proteins that respond to pain.<\/p>\n Gibbons and her colleagues ultimately found \u201cstrong evidence for pain\u201d in adult flies, mosquitoes, cockroaches, and termites. Such insects did not appear to be at the bottom of a hierarchy of animals; they met six out of eight criteria developed for the Sentience Act, which was more than crustaceans. Other insects, like bees and butterflies, met three to four of the criteria, showing \u201csubstantial evidence\u201d for pain. \u201cWe found no good evidence that any insects failed a criterion,\u201d the researchers wrote.<\/p>\n Pain is difficult to capture. Virginia Woolf observed that a person who falls in love can draw on the words of Shakespeare or Keats. \u201cBut let a sufferer try to describe a pain,\u201d she wrote, \u201cand language at once runs dry.\u201d A physician might ask a patient to rate pain on a scale from one to ten, or to pick between illustrations of faces in progressively greater distress, or to select from the McGill Pain Questionnaire, a list of seventy-eight words such as \u201ctugging,\u201d \u201csharp,\u201d and \u201cwretched.\u201d The pain of nonhuman animals is even further out of reach. Ren\u00e9 Descartes believed that it was \u201cnot necessary to conceive of any vegetative or sensitive soul\u201d to explain the actions of nonhuman animals; in his view, they were stimulus-response robots.<\/p>\n In a Scientific American<\/em> article<\/a> from 1927, Harold Bastin, a respected entomologist and photographer, reported that insects have sensory experiences that people cannot imagine: ants, for example, can see ultraviolet light. Still, he wrote, \u201cwe are faced by the extraordinary fact\u2014attested by many students of insect psychology\u2014that insects do not feel pain.\u201d He described gruesome experiments that appeared to prove the point. One cut away the front part of bumblebees\u2019 heads; the insects would still fly to flowers and try to feed. In another, a dragonfly that had had its abdomen amputated ate parts of its own body, and the \u201cfood\u201d fell out of its gaping thorax.<\/p>\n In 1964, Ruth Harrison challenged the idea that animals were machinelike in her book \u201cAnimal Machines<\/a>,\u201d which uncovered the horrors of factory farming. A decade later, Peter Singer<\/a> provoked mainstream interest in the experience and subjectivity of nonhuman lives. Insects, however, are generally still seen as automatons. Singer wrote<\/a>, in 2017, that it was too soon to campaign for insect rights, and that we should first give \u201cserious consideration to the interests of vertebrate animals, about whose capacity for suffering there is much less doubt.\u201d (He has since signed in support of insect-welfare declarations.)<\/p>\n One of the most influential papers on the subject, \u201cDo Insects Feel Pain?,\u201d was published, in 1984, by C. H. Eisemann, an Australian entomologist at the University of Queensland, and several co-authors. After surveying research into the neuroscience and behavior of insects, the authors wrote that insects were unlikely to feel pain, noting that their nervous systems are different from those of vertebrates. In some experiments, insects did not seem to respond to high temperatures, electrical shocks, or bodily harm. The paper\u2014which has hundreds of citations in entomology, comparative cognition, and animal welfare and ethics\u2014concluded that insects follow \u201clargely pre-programmed behavior patterns.\u201d<\/p>\n It\u2019s only very recently that other scientific perspectives on insect pain have been considered. This year, Gibbons, Chittka, and their colleagues evaluated whether bees meet a sentience criterion called \u201cflexible self-protective behavior.\u201d When a person bumps her elbow, she might rub it (and not her knee) to try to ease the pain. Gibbons pressed hot and unheated probes to the antennas of various bees; a control group wasn\u2019t touched at all. She found that bees were more likely to groom antennas that had been touched by the hot probe. Gradually, her perspective on insects changed. Before she began studying them, she told me, she avoided killing bugs when she could, but she didn\u2019t give them much more thought than that. Lately, her research has prompted her to imagine what insects are experiencing. \u201cMaybe they were<\/em> feeling something,\u201d Gibbons said.<\/p>\n On a warm day last May, I met Sarah Skeels, a postdoc in Chittka\u2019s lab, in the lobby of the biology building at Queen Mary University. Her brown hair was pulled back into a ponytail, revealing a necklace shaped like a ginkgo leaf. (She also had a bee necklace.) Skeels was studying one of the most commonly farmed insects, crickets, and her colleagues had been studying black soldier flies and their larvae. We walked upstairs and into a small room with a red overhead light. Crickets are mostly nocturnal, and red lights, which they can\u2019t detect, minimize disruptions to their sleep cycle.<\/p>\n Another student leaned over the crickets, which had small numbers glued to their backs. The student had touched one cricket with an unheated probe and would now watch its grooming behavior for fifteen minutes. We watched the crickets silently for a minute or two but did not see any grooming.<\/p>\n In a different room, Skeels showed me a wooden box inside of which a homemade, clear-plastic tunnel forked in two directions: on one side, toward a yellow circle on the floor of the enclosure, and on the other, toward a purple one. The soft sound of chirping echoed around us. The yellow circle contained a well of sugar water and a piece of carrot, while the purple one did not; Skeels was trying to train the crickets to associate color with a reward. After that, Skeels planned to test whether they, too, engage in motivational trade-offs by exposing themselves to heat for a better reward.<\/p>\n<\/div>\n\n","protected":false},"excerpt":{"rendered":" One of the stranger effects of Brexit was that, after the United Kingdom left the European Union, in 2020, it no longer recognized animals as \u201csentient beings.\u201d When the U.K. was an E.U. member state, it was bound by European laws, including the Lisbon Treaty, which invoked sentience in order to shield animals from sensations […]<\/p>\n","protected":false},"author":1,"featured_media":36006,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12022],"tags":[23602,23603,4293,23601,8980,10113,3229,23604],"dealstore":[],"offerexpiration":[],"class_list":["post-36005","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-activist","tag-animal-rights","tag-entomologists","tag-feel","tag-insects","tag-pain","tag-research","tag-science","tag-yorker"],"yoast_head":"\n