Who says that animals don't experience pleasure?

They feel remarkably similar emotions to humans - including euphoria, love and mischievousness, argues Jonathan Balcombe in an extract from his new book
Published: 31 May 2006
Science has neglected animal pleasure. Research tends to focus on evolutionary explanations for natural phenomena. By considering only natural selection and reproductive success, it overlooks the experiences of animals - their feelings, emotions and pleasures.
To appreciate the importance of pleasure to animal survival, consider the interplay of evolution and experience. Evolution concerns the adaptiveness of what an animal does or doesn't do. It is the stuff of genes and survival. Experience, on the other hand, relates to an animal's conscious, sensory encounters with the world.
Evolution and experience are complementary, not exclusive. Just as an animal is the product of genetics and environment, so too do both evolution and experience guide decisions and behaviours. When an animal - let's say a raccoon - eats, she is satisfying a basic need of survival: to sustain herself. But in choosing, seeing, smelling and tasting food, she also experiences it.
The physical pleasures of life - like the pains - are current, even though they have evolutionary significance too. It is these experiences, not the deeper evolutionary forces underlying them, that put wind in the sails of a racoon's existence. And a mouse's. And a pigeon's.
Pleasure helps animals to maintain a stable state. When we are cold, we seek warmth and it feels good. When we are hot, that same warmth no longer feels pleasant and we seek a cooler spot. The same phenomenon applies to tastes (pleasant when hungry, unpleasant when full), though not to sounds and lights. Michel Cabanac, a professor at Laval University, Quebec, calls this phenomenon "alliesthesia", from the Greek, meaning "other-perception". Alliesthesia applies to other animals as well as humans.
Nature rewards a cold animal who finds warmth, and vice versa. All an animal needs for alliesthesia to work is the capacity to experience surroundings as pleasant or unpleasant, and to move to a preferred environment. Sensory pleasure induces behaviours that improve homeostasis, or the regulating of the body's condition.
Here's another illustration of the dichotomy between evolution and experience. Many birds bathe - dipping their bodies, flapping their wings and shaking their feathers while standing in shallow water. The American biologist Bernd Heinrich, working in the Maine woods, has compiled many observations of ravens bathing, and he acknowledges several possible adaptive bases for this behaviour. These include hygiene, combating skin parasites and thermoregulation (maintaining a stable body temperature). But when a raven bathes, she is surely not aware of any evolutionary benefits. She is probably responding to a desire to get wet and cool, just as we enjoy the feeling of cool water or air on our skin when we are sweltering.
So, while Darwinian evolution and survival undoubtedly influence animals' actions, animals aren't responding consciously to these influences. On the other hand, it does seem as though they are behaving according to their moods, their desires and perhaps even a pre-planned daily schedule. Heinrich concludes that they do it simply because it feels good.
A recent theory of feline purring is another variation on the theme of pleasure having direct survival benefits. The theory, proposed by Elizabeth von Muggenthaler of the Fauna Communications Research Institute in North Carolina, maintains that a cat's purr has mechanical healing properties that speed up the repair of broken bones and other damaged tissues. Several cat species purr, including pumas, ocelots, servals, cheetahs and caracals, as well as the domestic cat. Purring may be cats' answer to ultrasound therapy, which appears to improve bone growth and density. That purring in cats is believed to display contentment raises the question of whether purring evolved first as a healing benefit, then later as a communication signal, or vice versa.
For pleasure to aid animals, they need the physical equipment to with which to experience it. That we experience bliss, joy, comfort and satisfaction suggests that some other animals do too, because they are built like us in all the relevant ways. All vertebrates - mammals, birds, reptiles, amphibians and fishes - share the same fundamental body plan: a bony skeleton that supports a muscular system that enables the animal to move about, a nervous system that shuttles signals to different parts of the body and whose centre of operations is the brain, a circulatory system that transports oxygen and other nutrients to body tissues, digestive and excretory systems that process food and eliminate wastes, a hormone system that helps to regulate body processes, and a reproductive system evolved to ensure propagation.
To this shared foundation we can add a sensory system. All vertebrates, with rare exceptions, have the same five basic senses as us: sight, smell, hearing, touch and taste. With all this equipment in common, it is no surprise that humans and animals share much of the same physiological and biochemical responses to sensory events.
The senses are the interface between an animal's nervous system and its surroundings. When we experience something painful or pleasurable, our brains signal to our glands to secrete chemicals to help us deal with the situation. Human emotions are linked to two brain structures, the amygdala and the hypothalamus, and mediated by biochemicals including dopamine, serotonin and oxytocin. Many animals, especially mammals, possess the same neurological structures and brain chemicals as we do. That needn't necessarily mean that they share our feelings, but careful observation suggests that they do. There are, for example, remarkable similarities in brain regions in guinea pigs experiencing parent-offspring separation distress and in human brains during feelings of sadness.
It is known that a variety of discrete emotional-behavioural control systems inhabit the same regions of the brains of all mammals. According to the American neuroscientist Jaak Panksepp, the core emotions - fear, rage, panic, play, seeking and lust - arise from the deep recesses of our primitive brains, and are believed to have evolved long before consciousness.
The brain releases dopamine in response to rewards like sex, food and water. The ability to produce dopamine has probably existed in animals for hundreds of millions of years. Even the humble sea pansy, a jellyfish relative, produces it, though probably not in relation to pleasure and pain. Goldfish prefer to swim in places where they have received amphetamine, which stimulates the release of dopamine from their brains.
Opiate receptors in human brains allow us to perceive pleasurable stimuli such as sweet tastes. Panksepp has shown that, when rats play, their brains release large amounts of dopamine and opiates. When both humans and rats are given drugs that block these receptors, they rate the sweetness of normally "liked" foods as less pleasant than normal.
Kent Berridge at the University of Michigan has devoted much of his career to the study of pleasure in the animal brain. Working mainly with taste in rats, Berridge's work suggests that brain networks cause "liking" reactions to certain things in the animal's environment. These reactions suggest the conscious experience of pleasure. The crucial feature of positive states, he argues, is that potentially pleasurable events (eg the taste of sugar) be accompanied by positive patterns of behaviour (eg, licking of the lips).
Animals' brains appear to respond to many types of sensory pleasure, including food, drugs and sex. More abstract forms of pleasure - including social joy, love, intellectual pleasure, aesthetic appreciation and even morality - are still largely unexplored, but interest in these is stirring.
Dr Jonathan Balcombe is an ethologist and research scientist with the Physicians Committee for Responsible Medicine, in Washington DC. He will be speaking at the Dana Centre, Science Museum, London SW7, on Thursday 1 June. Tickets are free but must be pre-booked (020-7942 4040; http://www.danacentre.org.uk/). His book Pleasurable Kingdom: Animals and the Nature of Feeling Good (Macmillan) is out now
The pleasure principle
* Sheep prefer a photo of the face of a just-fed sheep to that of a hungry one, and a smiling human face to an angry-looking one.
* In African springs, hippos spread their legs and toes to allow fish to nibble between them, much like pampered clients going for a massage or manicure at a spa.
* Reef fish line up to receive the attentions of cleaner fish, who advertise their services.
* When researchers experimentally brushed horses' necks, the animals' heart rates dropped, particularly in preferred spots for being groomed by other horses.
* Birds, as you might expect, have musical minds: trained finches can assign newly heard pieces to familiar composers, and pigeons can differentiate Baroque from modern genres.
* Bathing birds are known to lift a wing at the spray of garden sprinklers on hot days.
* Calvin Klein's fragrance Obsession for Men is strongly seductive to female cheetahs.
* Lemurs and capuchins pass around large millipedes like a marijuana joint, rubbing and mouthing them. Powerful defensive chemicals send them into a blissful stupor.
* Dolphins mischievously sneak up on gulls resting on the water. They dunk the bird before letting go.
Science has neglected animal pleasure. Research tends to focus on evolutionary explanations for natural phenomena. By considering only natural selection and reproductive success, it overlooks the experiences of animals - their feelings, emotions and pleasures.
To appreciate the importance of pleasure to animal survival, consider the interplay of evolution and experience. Evolution concerns the adaptiveness of what an animal does or doesn't do. It is the stuff of genes and survival. Experience, on the other hand, relates to an animal's conscious, sensory encounters with the world.
Evolution and experience are complementary, not exclusive. Just as an animal is the product of genetics and environment, so too do both evolution and experience guide decisions and behaviours. When an animal - let's say a raccoon - eats, she is satisfying a basic need of survival: to sustain herself. But in choosing, seeing, smelling and tasting food, she also experiences it.
The physical pleasures of life - like the pains - are current, even though they have evolutionary significance too. It is these experiences, not the deeper evolutionary forces underlying them, that put wind in the sails of a racoon's existence. And a mouse's. And a pigeon's.
Pleasure helps animals to maintain a stable state. When we are cold, we seek warmth and it feels good. When we are hot, that same warmth no longer feels pleasant and we seek a cooler spot. The same phenomenon applies to tastes (pleasant when hungry, unpleasant when full), though not to sounds and lights. Michel Cabanac, a professor at Laval University, Quebec, calls this phenomenon "alliesthesia", from the Greek, meaning "other-perception". Alliesthesia applies to other animals as well as humans.
Nature rewards a cold animal who finds warmth, and vice versa. All an animal needs for alliesthesia to work is the capacity to experience surroundings as pleasant or unpleasant, and to move to a preferred environment. Sensory pleasure induces behaviours that improve homeostasis, or the regulating of the body's condition.
Here's another illustration of the dichotomy between evolution and experience. Many birds bathe - dipping their bodies, flapping their wings and shaking their feathers while standing in shallow water. The American biologist Bernd Heinrich, working in the Maine woods, has compiled many observations of ravens bathing, and he acknowledges several possible adaptive bases for this behaviour. These include hygiene, combating skin parasites and thermoregulation (maintaining a stable body temperature). But when a raven bathes, she is surely not aware of any evolutionary benefits. She is probably responding to a desire to get wet and cool, just as we enjoy the feeling of cool water or air on our skin when we are sweltering.
So, while Darwinian evolution and survival undoubtedly influence animals' actions, animals aren't responding consciously to these influences. On the other hand, it does seem as though they are behaving according to their moods, their desires and perhaps even a pre-planned daily schedule. Heinrich concludes that they do it simply because it feels good.
A recent theory of feline purring is another variation on the theme of pleasure having direct survival benefits. The theory, proposed by Elizabeth von Muggenthaler of the Fauna Communications Research Institute in North Carolina, maintains that a cat's purr has mechanical healing properties that speed up the repair of broken bones and other damaged tissues. Several cat species purr, including pumas, ocelots, servals, cheetahs and caracals, as well as the domestic cat. Purring may be cats' answer to ultrasound therapy, which appears to improve bone growth and density. That purring in cats is believed to display contentment raises the question of whether purring evolved first as a healing benefit, then later as a communication signal, or vice versa.
For pleasure to aid animals, they need the physical equipment to with which to experience it. That we experience bliss, joy, comfort and satisfaction suggests that some other animals do too, because they are built like us in all the relevant ways. All vertebrates - mammals, birds, reptiles, amphibians and fishes - share the same fundamental body plan: a bony skeleton that supports a muscular system that enables the animal to move about, a nervous system that shuttles signals to different parts of the body and whose centre of operations is the brain, a circulatory system that transports oxygen and other nutrients to body tissues, digestive and excretory systems that process food and eliminate wastes, a hormone system that helps to regulate body processes, and a reproductive system evolved to ensure propagation.
To this shared foundation we can add a sensory system. All vertebrates, with rare exceptions, have the same five basic senses as us: sight, smell, hearing, touch and taste. With all this equipment in common, it is no surprise that humans and animals share much of the same physiological and biochemical responses to sensory events.
The senses are the interface between an animal's nervous system and its surroundings. When we experience something painful or pleasurable, our brains signal to our glands to secrete chemicals to help us deal with the situation. Human emotions are linked to two brain structures, the amygdala and the hypothalamus, and mediated by biochemicals including dopamine, serotonin and oxytocin. Many animals, especially mammals, possess the same neurological structures and brain chemicals as we do. That needn't necessarily mean that they share our feelings, but careful observation suggests that they do. There are, for example, remarkable similarities in brain regions in guinea pigs experiencing parent-offspring separation distress and in human brains during feelings of sadness.
It is known that a variety of discrete emotional-behavioural control systems inhabit the same regions of the brains of all mammals. According to the American neuroscientist Jaak Panksepp, the core emotions - fear, rage, panic, play, seeking and lust - arise from the deep recesses of our primitive brains, and are believed to have evolved long before consciousness.
The brain releases dopamine in response to rewards like sex, food and water. The ability to produce dopamine has probably existed in animals for hundreds of millions of years. Even the humble sea pansy, a jellyfish relative, produces it, though probably not in relation to pleasure and pain. Goldfish prefer to swim in places where they have received amphetamine, which stimulates the release of dopamine from their brains.
Opiate receptors in human brains allow us to perceive pleasurable stimuli such as sweet tastes. Panksepp has shown that, when rats play, their brains release large amounts of dopamine and opiates. When both humans and rats are given drugs that block these receptors, they rate the sweetness of normally "liked" foods as less pleasant than normal.
Kent Berridge at the University of Michigan has devoted much of his career to the study of pleasure in the animal brain. Working mainly with taste in rats, Berridge's work suggests that brain networks cause "liking" reactions to certain things in the animal's environment. These reactions suggest the conscious experience of pleasure. The crucial feature of positive states, he argues, is that potentially pleasurable events (eg the taste of sugar) be accompanied by positive patterns of behaviour (eg, licking of the lips).
Animals' brains appear to respond to many types of sensory pleasure, including food, drugs and sex. More abstract forms of pleasure - including social joy, love, intellectual pleasure, aesthetic appreciation and even morality - are still largely unexplored, but interest in these is stirring.
Dr Jonathan Balcombe is an ethologist and research scientist with the Physicians Committee for Responsible Medicine, in Washington DC. He will be speaking at the Dana Centre, Science Museum, London SW7, on Thursday 1 June. Tickets are free but must be pre-booked (020-7942 4040; http://www.danacentre.org.uk/). His book Pleasurable Kingdom: Animals and the Nature of Feeling Good (Macmillan) is out now
The pleasure principle
* Sheep prefer a photo of the face of a just-fed sheep to that of a hungry one, and a smiling human face to an angry-looking one.
* In African springs, hippos spread their legs and toes to allow fish to nibble between them, much like pampered clients going for a massage or manicure at a spa.
* Reef fish line up to receive the attentions of cleaner fish, who advertise their services.
* When researchers experimentally brushed horses' necks, the animals' heart rates dropped, particularly in preferred spots for being groomed by other horses.
* Birds, as you might expect, have musical minds: trained finches can assign newly heard pieces to familiar composers, and pigeons can differentiate Baroque from modern genres.
* Bathing birds are known to lift a wing at the spray of garden sprinklers on hot days.
* Calvin Klein's fragrance Obsession for Men is strongly seductive to female cheetahs.
* Lemurs and capuchins pass around large millipedes like a marijuana joint, rubbing and mouthing them. Powerful defensive chemicals send them into a blissful stupor.
* Dolphins mischievously sneak up on gulls resting on the water. They dunk the bird before letting go.