A rare and reclusive leopard that hunts among the dense island forests of Borneo and Sumatra in south-east Asia has been identified as an entirely new species of great cat.

Genetic tests and pelt examinations have revealed that the animal, now called the Bornean clouded leopard (Neofelis diardi), is as distinct from other clouded leopards that roam mainland Asia as lions are from panthers.

On the islands the clouded leopard is the top predator, preying on monkeys, deer, wild pigs and lizards, and has a crucial influence on the regional ecosystems. At their largest they reach just over 1m long, and for their size sport the largest canine teeth of the cat family. Their name comes from the mottled white patches that cover their skin.

Clouded leopards were first described in 1821 by the British naturalist Edward Griffith, but few of the animals have ever been sighted and from the sparse information available scientists suspected they were either all one species, or possibly divided into four sub-species.
By testing DNA from clouded leopard populations across Asia and the islands, scientists at the US National Cancer Institute in Maryland identified 40 genetic differences between the island cats and those found elsewhere, confirming them as two distinct species whose evolutionary paths divided 1.4m years ago.

"Almost 200 years on we are just beginning to learn about these creatures," said Mark Wright, chief science adviser with the conservation group WWF-UK, which is working to protect the leopard's Borneo habitat from deforestation.

There are estimated to be only 5,000 to 11,000 of the leopards on Borneo and 3,000 to 7,000 on Sumatra. The island species has small cloud markings, a double stripe down its back, and its grey fur is darker than the mainland species. The leopards are extremely agile and can hunt by staging ambushes from the trees. Little else is known about their behaviour.

"These are big animals, but we know next to nothing about them and that's very telling. We meddle in the tropics at our peril, because we really don't know enough about what's going on there," said Dr Wright. "We know now these are two distinct species, so we have to direct conservation efforts at both the island and mainland populations."

http://environment.guardian.co.uk/conservation/story/0,,2034219,00.html

Dolphin 'dying of broken heart' after keeper is stabbed to death


By Peter Popham in Rome
Published: 20 February 2007

A rare grampus dolphin, rescued 18 months ago after it swam into an Italian port, seems to be dying of a broken heart after the woman who reared it like her own child was murdered.

Tamara Monti, 37, the creature's keeper, was stabbed to death two weeks ago by the man who lived in the flat above her. Police found an unemployed man, Alessandro Doto, 35, standing in the street outside the block where they lived, frozen like a dummy with a blood-spattered knife in his hand. He told them Ms Monti's two dogs barked all day and it drove him mad.

The issue had been simmering between them for months. Ms Monti and her partner had found a new place to live with their cat and dogs and were due to move the next day.

Ms Monti was from the Lake Como region, hundreds of miles north-west of Riccione, a resort on the Adriatic coast just south of Rimini, but Riccione had taken her to its heart. The town was in mourning on hearing of her death. But no one missed her like Mary G.

The grampus dolphin was a calf in June 2005 when she and her mother blundered into the port of Ancona, south of Riccione, and ran aground. They were rescued and brought to hospital, but Mary G's mother died three days later. After two months the dolphin had recovered sufficiently to be brought to Oltremare Park in Riccione, a seaside theme park, where she was given a pool of sea water and the constant attendance of experts. They bottle-fed her a mixture of herring, vitamins and mineral salts, rocked her like a baby and gave her swimming lessons. But only one of the keepers talked to her as if she were her own child, and that was Ms Monti.

As Mary G grew, she became the park's big attraction. Her fame spread through Italy, via websites, television programmes and blogs. Visitors flocked to Riccione to see her.

"We wanted to return her to the open sea," said Sauro Pari, head of the organisation that runs the park, "but international experts advised against it. They told us she would not survive."

Instead the grampus dolphin with the comical rounded forehead and cartoon-like grin, and her surrogate mother, remained together - for life, or so it appeared.

But now Mary G is dying. The word began to spread within days of Ms Monti's murder, through the blogs and websites devoted to her. One message read: "Since Tamara's death, Mary is unwell. Let's help her." She would either refuse her diet of milk and squid, or eat it then spew it out.

Mary G's weight plummeted from 210kg to 160kg in a couple of weeks. As happened 18 months ago, she is being attended by specialist vets, but has so far failed to respond to treatment.

At the theme park, dolphin experts are going out of their way to deny any firm connection between the keeper's murder and the dolphin's sickness. They say there is a simple explanation for her rejection of food: an intestinal parasite which she could have acquired at any time.

"From a strictly scientific point of view we absolutely cannot assert that the two facts are connected," Mr Pari said. "But there is no doubt that her grief for the death of Tamara is great. We are very worried about what will become of her."

Andes field trip reveals new species of climbing rodent

By Steve Connor, Science Editor
Published: 25 January 2007

Zoologists have discovered a new species of squirrel-like mammal, which they have described as a strikingly unusual creature, in the high mountains of Peru.

The nocturnal animal looks similar to a squirrel, and is about the same size, but DNA tests have shown that it is more closely related to a family of South American spiny rats, whose fur bristles with spines.

The new species is a climbing rodent with strange-looking, long, dense fur, a broad head and thickly furred tail tipped with white. It also has a distinctive blackish crest of fur on its crown, nape and shoulders.

Scientists discovered the rodent during a field survey in 1999 of Peru's Manu National Park and Biosphere Reserve Mountains on the lush eastern slopes of the Andes in southern Peru, which is one of the richest regions in the world for wildlife.

Its formal scientific description and official naming has only now been made public with the publication today of a description of the Manu reserve findings in the journal Mastozoologia Neotropical. The same field trip, which extended from 1999 to 2001, uncovered 11 additional species new to science, namely one opossum, seven bats and three other rodents.

"Like other tropical mountain ranges, such as the Himalayas, the Andes support a fantastic variety of habitats. These in turn support some of the richest faunas on the planet," said Bruce Patterson, the curator of mammals at the Field Museum in Chicago, who led the research team.

"The new species is not only a handsome novelty. Preliminary DNA analyses suggest that its nearest relatives, all restricted to the lowlands, may have arisen from Andean ancestors," Dr Patterson said.

"The newly discovered species casts a striking new light on the evolution of an entire group of arboreal rodents," he added.

Little is known about the species - which has been named Isothrix barbarabrownae after a Field Museum scientist called Barbara Brown - except that it lives in the cloud forests at an altitude of 6,200 feet and probably feeds on seeds, nuts, berries and small insects.

Subsequent attempts to find further specimens of the rodent have failed. The species is known to have five other close relatives belonging to the same genus living in South America.

The Manu reserve extends from the lowland forests of the Amazon basin to open grasslands above the Andean tree line.

It is home to more species of mammals and birds than any other area of the world of comparable size. In total, the team recorded 222 species of mammals, 94 of which were bats, and 1,003 species of birds, twice the number of breeding bird species in North America, during the three-year field trip.

Sam Turvey, a research fellow at the Zoological Society of London, said that this region of South America is renown for being one of the richest regions in the world for biodiversity.

"It covers an area from low to very high altitude, which supports many different kinds of ecosystems. It's very much a centre for biodiversity," Dr Turvey said. "People think it's very unusual to describe a new species of mammal such as this one but in fact several new mammals and birds are routinely reported each year. There's still a lot of new species of relatively large animals in the world left to be described, certainly more than we think."

Protect Goa’s pangolins

by Nandkumar Kamat


WHEN the ‘Goa News’ cable TV channel on Monday beamed the image of a Pangolin (manis crassicaudata) rescued at Colva by an animal activist Julio Quadros, I was instantly alerted. The forest department should reward him suitably for rescuing the animal which otherwise could have been chased, hunted, killed or sold as a pet by the trappers. These animals cannot be paraded as circus animals or be kept in captivity because they are included in IUCN red list of threatened species.

The IUCN Red List is set upon precise criteria to evaluate the extinction risk of thousands of species and subspecies. These criteria are relevant to all species and all regions of the world. The aim of the Red List is to convey the urgency of conservation issues to the public and policy makers, as well as help the international community to try to reduce species extinction.

India is a member of IUCN and it is the duty of every member country to protect all the threatened species in the red list. Violations are viewed very seriously by experts, non-governmental organisations and countries failing to protect and conserve their threatened species can get blacklisted and may invite international sanctions. Immediately, I contacted the state chief wildlife warden Achalendra Reddy. He informed me that the pangolin has been taken into custody and would be then released in the wild where it can feed on its normal diet of ants and termites. I urged him to create awareness among the people and the media about this important and rare mammalian species of Goa.

Pangolins are cute toothless mammals. Taxonomically they belong to phylum chordata, class mammalia, order pholidata, family manidae, genus manis which comprises eight species (Indian, Chinese, Malayan, Pangwan, Giant, Cape, Tree and long tailed) found in South east Asia and Africa. The physical appearance of pangolins is marked by large, hardened, plate-like scales, which are actually mats of hair. The hair is clumped together in such a way that makes them look like scales. The animal walks with difficulty due to its long front claws. Its large tail is advantageous in balancing. Although terrestrial the pangolins can climb the trees in search of ant nests. The pangolins have huge salivary glands which lubricate their large tongues. After breaking the ant nests or the termite hills with its powerful front claws the pangolin removes the ants or termites with its very large, sticky tongue. Ants and termites are totally defenseless before such a predator.

Locally pangolins are known as “tiryo’’ or “khavlae majar”. The origin of the word pangolin is traced from the Malayan ‘pengguling’ which means ‘curling”. Pangolins curl themselves like the “armadillos’ into tight balls and look funny when they do so. This may entertain people but it is stressful for this animal if it is forced to perform the feat repeatedly for purely human entertainment. Pangolins have powerful legs which they use for digging. Pangolins or scaly anteaters were once found in coastal areas of Goa. But people began to kill them for no reason. I am not sure whether pangolin meat was used in Goa but the Chinese slaughter pangolins for medicinal purpose. The Chinese believe scales of pangolin purportedly reduce swelling, promote blood circulation and help breast-feeding women produce milk. These beliefs have no basis in modern medicine.

I had received a report a few years ago that a private party had kept a pangolin in captivity at Calangute and then it died. There are many reports of pangolin sightings from coastal belt of Goa. This points to a certain habitat preference. Perhaps the pangolins prefer the coastal sand dune habitat. They are burrowing mammals. The pangolin found at Colva indicates that there may be a small breeding population in that place. In that case the forest department needs to explore the location in detail with the help of the local village panchayat and verify this fact.

Pangolin females are smaller than the males. They produce at least one but maximum three offsprings. It is difficult to predict the number of surviving pangolins in Goa. But the Colva specimen shows that this species is not yet extinct. Rampant violations of coastal regulation zone, illegal sand mining, destruction of the sand dunes and fragmentation of fragile coastal habitats has already made survival difficult for wild plants and animals.

Pangolins are important members of the ecosystem. They keep the population of ants and termites in check. Certain species of nest building arboreal ants are dangerous for the trees and the humans. The pangolins spot the nests, climb the trees and destroy these nests. Termites are known as ferocious and persistent pests which attack the timber and damage the houses. Pangolins keep a check on their population by reducing their numbers. Nature has provided a system of checks and balances. Very little is known about the specific diet preference or feeding behaviour of local pangolins.

Perhaps the Colva pangolin may not survive in Bondla wilderness unless it can use the termites found in abundance in the mounds. Pangolins are shy and harmless animals. They have a right to exist and survive.

The future of wildlife in Goa outside the forests and the wildlife sanctuaries appears bleak. The capture of a panther which strayed at Miramar has already shown the pressure which the wildlife is facing. There are also shocking reports that another protected species of mammals, the marine dolphins are caught, cut and sold in the Vasco fish market. The forest department needs to warn owners of mechanised fishing vessels about the implications of capturing dolphins. People should also refuse to buy the meat of dolphins. The forest department has to issue a set of guidelines or ethics for all those animal lovers or activists who capture/rescue wild animals. There are stringent and elaborate rules in the western countries on such aspects. Wild animals do not exist for human entertainment. It was ethically wrong to parade the hungry, stressed and scared pangolin in front of crowds. Better sense is likely to prevail as Goans get more educated and enlightened and aim to build a truly compassionate society.

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.