A Day in the Life of a Neanderthal

May 21, 2009

Please be sure to check out this week's Discovery News story concerning evidence that a modern human may have eaten a Neanderthal child.

Credit: Knut Finstermeier

I recently spoke with Gerrit Dusseldorp, an expert on Neanderthals and early humans who is at the University of the Witwatersrand's Institute for Human Evolution. Here's what he had to say about these puzzling hominids who may have been our relatives, our dinner or both.

<<JV: Your research suggests that Neanderthals and hyenas occupied the same top carnivore place on the early European food chain. But didn't Neanderthals edge them out by being superior hunters?

GD: First, hyenas, like Neanderthals were capturing very dangerous animals. However, it appears (from the few sites that I have looked at) that, if circumstances allow, hyenas prefer to focus on smaller game. In this case: At a French hyena den (called Lunel Viel) located in a forested environment, deer were the most common prey, followed at some distance by horse and aurochs. In a den (Camiac also in France) located in a Mammoth Steppe environment, bovids and horse are common, followed by woolly rhinoceros while cervids are rare. From extant spotted hyenas (of which we know that they are genetically indistinguishable from European cave hyenas) we know that they prefer to forage alone. When foraging in groups they are able to take much larger prey. However, since there is a strong dominance hierarchy, especially low-ranking animals may take part in hunting a large animal and not profit from the kill at all. It appears that in forested environments, where prey is dispersed, foraging alone is successful. On the mammoth steppe, prey is concentrated in large herds. Therefore foraging in groups becomes necessary and this leads to larger prey being represented at sites.

JV: So what then was the hunting strategy of Neanderthals?

GD: Neanderthals on the other hand appear to have focused in warm environments, even if many other alternatives were available. I looked at a site in forested environment in Germany (called Taubach) where rhinoceros and brown bear were the most common prey, followed by bison. Several species of deer were also available, as well as horses, donkeys and wild boar, but they were not exploited. (We know this because butchery marks were present on hundreds of bear and rhino bones and absent on bones of cervids, boars, horses, donkeys and so on).

 

At the colder French site of Biache-Saint-Vaast, rhinoceros and brown bears were also hunted, but here the smaller aurochs were the most common prey. As the environment becomes colder, herd animals become more common prey, while bears are not hunted anymore. (Again butchery marks indicate which species were exploited. Although here too, boar and different species of deer were present they do not seem to have been selected by Neanderthals. Horses do seem to have been selected in the latest coldest phase of occupation).

 

Even more striking is the fact that all of the bison at Taubach of which the sex could be ascertained, were bulls. At Biache-Saint-Vaast, about 60 percent were male and 40 percent were female.

JV: What's the significance of that finding?

 

GD: I interpreted this as signaling that Neanderthals prefer large prey. However, in warm, forested environments, available biomass was scarce, since most of it was locked up in trees as wood and leaves, which hominins cannot digest. Therefore, they were present in lower population densities. In contrast to hyenas, Neanderthals as primates are not carnivores equipped with natural weapons such as powerful jaws and claws. Their most important weapon likely was their big brain. Locations of sites suggest that they usually hunted using ambush strategies. When living in smaller groups in forests, they probably could not easily ambush herds of large animals like female bison, or horses. They therefore concentrated on solitary animals: rhinoceros, brown bear and bulls of bison, since they live solitary most of the year.

 

As the environment becomes more open, biomass is available in larger quantities. Neanderthals could live in larger groups. This led to increased exploitation of herd-living animals such as female bison. The very dangerous brown bear was dropped from the diet, because killing this solitary animal may have been easier for small groups it was probably more dangerous than ambushing a herd of bison or horses.

JV: Do you then think that Neanderthals fared better when they were in more open and less forested areas? That seems hard to fathom.

 

GD: The conclusion that forested environments may have been less suited to Neanderthals may seem counterintuitive, but is supported by data on animal species in modern European forests. At Bialowice National Park in Poland for example, there is about 2 tonnes of herbivore biomass per square kilometer. For the mammoth steppes, divergent estimates have been proposed, but 14 tonnes per square kilometer appears reasonable.

JV: Is it possible that competing Neanderthals and hyenas ate each other?

 

GD: Neanderthals may have consumed hyenas, but there is little evidence for this (there are no sites with large quantities of hyena bones with butchering marks). Some Neanderthal bones have been found in hyena dens and some of these bones show clear traces of gnawing by hyenas. (A nice illustration is found in the paper I attached). Therefore they may have been eaten at least occasionally by hyenas. Their remains in these contexts are always few in number though.

JV: I've also read that Neanderthals and hyenas shared cave dwellings. Do you think that happened?

GD: Some caves provide clear evidence that they were used by both species. However, often they were used in different points in time. This is signaled by the use of caves by hyenas to raise their young. Young spotted hyenas are fully dependent on their parents for the first 15 months of their lives and are hidden at secure places. We know from studies on extant hyenas that once a site is disturbed, the cubs will be moved and the site will be avoided for some time. Battles for caves seem therefore unlikely. Especially since hyenas often use burrows that they dug themselves. They are therefore not dependent on caves as living spaces.

JV: Why do you think Neanderthals went extinct?

GD: On the question of Neanderthal extinction, it is still uncertain what caused it. However, the focus of Neanderthals on the very largest animals, though brave may have brought some problems with it as well. Large animals are present in low population densities and have low rates of reproduction. In an unstable environment these species may not respond well to crises. Anatomically modern humans appear to have sometimes also exploited small animals like rabbits, hares, birds and fish. These species may be difficult to exploit efficiently, unless one invests in traps, nets or snares. However they are present in larger numbers and they reproduce rapidly. They may therefore bounce back from crises more quickly than larger species. Therefore anatomically modern humans may have had a more reliable palet exploited foods. After environmental crises modern humans may then have recovered more quickly than Neanderthals, and may have started usurping territories that before the environmental crisis were occupied by Neanderthals.

JV: What research are you conducting at present?

GD: I am now investigating how and when anatomically modern humans started exploiting this kind of resources in South Africa. Here a few sites have been found with very early indications for “modern behaviour” such as symbolism. I want to track the concomitant changes in foraging strategies and see how this affected indications for population density. I hope to be able to document if and when modern human foraging strategies enabled a growth in their populations.>>

Marine Mammal Brains Are Full of Contaminants

From the Woods Hole Oceanographic Institution:

<<The most extensive study of pollutants in marine mammals’ brains reveals that these animals are exposed to a hazardous cocktail of pesticides such as DDTs and PCBs, as well as emerging contaminants such as brominated flame retardants.

Fur Seal
(Credit: Lieutenant Philip Hall, NOAA Corps)

Eric Montie, the lead author on the study currently in press and published online April 17 in Environmental Pollution, performed the research as a student in the Woods Hole Oceanographic Institution-MIT Joint Graduate Program in Oceanography and Ocean Engineering and as a postdoctoral fellow at the Woods Hole Oceanographic Institution (WHOI). The final data analysis and writing were conducted at College of Marine Science, University of South Florida, where Montie now works in David Mann’s marine sensory biology lab.

Co-author Chris Reddy, a senior scientist in the WHOI Marine Chemistry and Geochemistry Department, describes the work as “groundbreaking because Eric measures a variety of different chemicals in animal tissues that had not been previously explored. It gives us greater insight into how these chemicals may behave in marine mammals.”

Humpback Whale

(Credit: Stan Butler)

The work represents a major collaborative effort between the laboratories of Reddy and Mark Hahn in the WHOI Biology Department, where Montie was a graduate student and post doc, as well as Robert Letcher at Environment Canada. Montie traveled to Environment Canada in Ottawa to learn the painstaking techniques required to extract and to quantify more than 170 different pollutants and their metabolites. He then brought the methods back to WHOI and performed the analyses in Reddy’s laboratory. Reddy describes the methods as extremely unforgiving and explains, “This is not making Toll House cookies. The fact that Eric pulled it off so seamlessly is amazing considering that he did this by himself far away from Ottawa.”

Montie analyzed both the cerebrospinal fluid and the gray matter of the cerebellum in eleven cetaceans and one gray seal stranded near Cape Cod, Mass. His analyses include many of the chemicals that environmental watchdog groups call the dirty dozen, a collection of particularly ubiquitous pesticides that were banned in the 1970s because of their hazards to human health. But the Montie study goes much further in the scope of contaminants analyzed. And many of the contaminants are anything but benign.

The chemicals studied include pesticides like DDT, which has been shown to cause cancer and reproductive toxicity, and PCBs, which are neurotoxicants known to disrupt the thyroid hormone system. The study also quantifies concentrations of polybrominated diphenyl ethers or PBDEs (a particular class of flame retardants), which are neurotoxicants that impair the development of motor activity and cognition. This work is the first to quantify concentrations of PBDEs in the brains of marine mammals.

The results revealed that concentration of one contaminant was surprisingly high. According to Montie, “The biggest wakeup was that we found parts per million concentrations of hydroxylated PCBs in the cerebrospinal fluid of a gray seal. That is so worrisome for me. You rarely find parts per million levels of anything in the brain.”

Spotted Dolphin

(Credit: NOAA)

The particular hydroxylated PCB found at these soaring concentrations, called 4-OH-CB107, has some serious side effects. In rats, it selectively binds to a carrier protein called transthyretin, which has been found to be abundant in cerebrospinal fluid in mammals. This protein plays a role in thyroid hormone transport throughout the brain, though its exact role is not known. Thyroid hormone plays a key role in the development of the brain, as well as sensory functions, in particular hearing in mammals. Compromised hearing would have significant impact for dolphins, because as Montie points out, “these animals rely on hearing as their primary sensory modality to communicate and to find and catch food.”

Just how these chemicals might impact marine mammal health is something Montie plans to pursue. This summer, Montie, Mann, and Dr. Mandy Cook (from Portland University) will partner with scientists from NOAA to test the hearing in dolphins living near a Superfund site in Georgia and compare it to dolphins from locations where ambient concentrations of pollutants are significantly lower. Montie is also working with Frances Gulland, director of the Marine Mammal Center in Sausalito, CA, to examine how California sea lions’s exposure to PCBs may increase their sensitivity to domoic acid, a naturally produced marine neurotoxin associated with “red tides.”

The work of Montie and his colleagues lays the groundwork for understanding how environmental contaminants influence the central nervous system of marine mammals. Montie sees this work as the forefront of a new field of research, something that might be called neuro-ecotoxicology. For years, most of the work in this area focused on how concentrations of marine pollutants affected the animal’s immune system or its hormone systems. The research by Montie, Reddy, Hahn, and their coauthors provides tools to ask deeper questions about how the ever-growing list of contaminants in the ocean affect the neurological development of marine mammals.

And what sort of results does Montie expect this new field of neuro-ecotoxicology to produce? “I think we don’t really know the brunt of what we are going to see in wildlife.”

This study was performed with funding form the WHOI Ocean Life Institute, WHOI Marine Policy Center, Walter A. and Hope Noyes Smith, and an EPA STAR fellowship. Supplemental funding was provided from the Natural Science and Engineering Research Council (NSERC) of Canada (to Robert Letcher), David Mann at the College of Marine Science, University of South Florida, and a NOAA Oceans and Human Health postdoctoral traineeship provided by Jonna Mazet (UC Davis Wildlife Health Center), Kathi Lefebvre (Northwest Fisheries Science Center), and Frances Gulland (The Marine Mammal Center).>>

Dinosaur Footprint Tour of Spain and Portugal

May 20, 2009

Dinosaur track sites exist in many places throughout the world, but one of the richest sources is at the Iberian Peninsula. Scientists from the Catalan Institute of Palaeontology (ICP) and the University of Manchester are now trekking through this sunny, rugged region in search of dinosaur footprints. They've already found 10 such dino-rich sites in Portugal and Spain.

Although not yet official, it sounds like the area will soon be declared a UNESCO World Heritage Site.

Here's a look at the trek currently taking place. Credit for all images goes to ICP and the Autonomous University of Barcelona.

Paleontologists are using high tech equipment normally reserved for oil prospecting to find places where dinosaurs once trod.

 

Sauropod tracks

If you were a dinosaur, wouldn't you want to savor this view?

 

Tracks galore

 

A pterosaurus left its footprint here

 

This structure shields some of the tracks.

 

You can see why the researchers would want to protect them. Dinosaur tracks don't get much better than this.

 

Getting an up-close look

 

And another

 

Gazing at a sea of dinosaur tracks

 

Video: Remarkably Well-Preserved, 47-Million-Year-Old Fossil Sheds Light on Primate Evolution

May 19, 2009

Komodo Dragon Bite Deadlier Than Thought

Here's a face you wouldn't want to stare into outside of this safe, virtual realm.

(Credit for all pics: Chris Kegelman)

The Komodo dragon lizard, seen above, causes its victims to die in a rather morbid way. After being pierced by the carnivorous reptile's sharp fangs, the hapless creatures go into shock before keeling over. Scientists at first thought poisonous bacteria in the Komodo's mouth did in prey, but now new research in the latest Proceedings of the National Academy of Sciences shows that a combination of the reptile's teeth and venom packs a deadly one-two punch.

"The view that the Komodo routinely kills using dirty oral bacteria is wrong," says research co-author, Dr Stephen Wroe from the University of New South Wales, Australia. "The dragon is truly poisonous. It has modified salivary glands that deliver both hypertensive and anti-blood-clotting agents, which, in combination with lightweight but sophisticated cranial and dental adaptations, allows it to kill large animals through rapid blood loss."

Wroe and his colleagues used computer modeling to analyze the Komodo dragon bite and found that dragons have much weaker bites than crocodiles of a similar size. However, magnetic resonance imaging revealed the dragons have complex venom glands as well.

After surgically excising the glands from a terminally ill dragon in a zoo, the researchers used mass spectrometry to obtain a profile of the venom, finding that the toxin was similar to that of the Gila monster and many snakes. The venom causes a severe loss in blood pressure by preventing blood clotting and widening blood vessels, thus inducing shock in a victim.

The researchers also examined fossils of the giant extinct dragon relative Varanus megalania and determined that this nearly 23-foot-long lizard was one of the largest venomous animals to have ever lived.

A member of the goanna family with ancestors dating back more than 100 million years, the Komodo dragon is the world's largest living lizard and inhabits the central Indonesian islands of Komodo, Rinca, Flores, Gili Motang and Gili Dasami. It grows to an average length of nearly 10 feet and weighs over 154 pounds. The reptile's unusual size is attributed to a phenomenon known as island gigantism, since there are no other carnivorous mammals to fill the niche on the islands where they live.

The lizards are apex predators and dominate the ecosystems in which they live. Although Komodo dragons eat carrion, they also hunt and ambush prey including invertebrates, birds, and mammals.

The dragon's large size and fearsome reputation has made it a popular zoo exhibit since Western scientists first brought it to world attention in 1910. In the wild its total population is estimated at 4,000 to 5,000. Its range has contracted due to human activities and it is listed as vulnerable by the International Union for Conservation of Nature.

Due to these new findings about Komodo dragon venom, this Animal Planet video could use revising, but there's some eye-catching footage in it nonetheless. 

Giant Shrew Had Red Teeth, Toxic Saliva

May 18, 2009

Researchers from the University of Zaragoza have just discovered the remains of a giant shrew that had red teeth, toxic saliva and lived nearly one million years ago in northern Spain. 

Part of the shrew's lower jaw, showing redness on the fang tip

(Credit: J. Trueba)

"To date, all the medium to large-sized Soricidae (shrew family) fossils discovered in the deposits of the Sierra de Atapuerca belonged to Beremendia fissidens, a species of plio-pleistocene shrew that was distributed throughout Europe," said Juan Rofes, lead author of the study that has been published recently in the Zoological Journal of the Linnean Society and a researcher in the Paleontology Department at the UNIZAR.

Rofes and his team think the shrew, Dolinasorex glyphodon, first emerged in eastern Asia before heading over to Spain. Once in Spain, the animal likely lived in a warm, wet and comfy environment, which could explain why some species made the trek to Espana.

The researchers say the shrew had "the looks of the devil," given its unusual red teeth, big size (for a mouse-like shrew) and toxic saliva.

Part of the shrew's jawbone
(Credit: Juan Rofes y Gloria Cuenca-Bescós)

It injected venom similar to how snakes administer their poison, via a "narrow and conspicuous channel" located on the inside surface of its lower incisors. "This was a mechanism very similar to that of the modern solenodons and almiquis, which are close relatives of the shrews and live on the islands of Cuba and Haiti," explained Rofes.

I can only guess that the red color of its teeth had to do with some chemical component of the shrew's poisonous saliva, but am not sure.

This particular shrew met a rather grisly end itself. The scientists think it was eaten by a bird of prey and then its bones were regurgitated. Essentially, the researchers discovered a new mammal then out of bird barf.

The below video shows footage of some of the existing relatives of the now-extinct red-toothed Spanish shrew. This rare zoo birth occurred just a few months ago.

World's Largest Population of Leatherback Sea Turtles Found

From the University of Exeter:

<<An international team of scientists has identified a nesting population of leatherback sea turtles in Gabon, West Africa as the world's largest. The research, published in the May issue of Biological Conservation, involved country-wide land and aerial surveys that estimated a population of between 15,730 and 41,373 female turtles using the nesting beaches. The study highlights the importance of conservation work to manage key sites and protected areas in Gabon.

Leatherbacks are of profound conservation concern around the world after populations in the Indo-Pacific crashed by more than 90 percent in the 1980s and 1990s. The International Union for Conservation of Nature (IUCN) lists leatherback turtles as critically endangered globally, but detailed population assessments in much of the Atlantic, especially Africa, are lacking.

The research was led by the University of Exeter working in collaboration with the Wildlife Conservation Society (WCS) which spearheads the Gabon Sea Turtle Partnership, a network of organisations concerned with the protection of marine turtles in Gabon.

(Credit: NPS - Canaveral National Seashore)

During three nesting seasons between 2002 and 2007, the team's members carried out the most comprehensive survey of marine turtles ever conducted in Gabon. This involved aerial surveys along Gabon's 600 km (372 mile) coast, using video to capture footage for evaluation, and detailed ground-based monitoring. By covering the entire coastline, they were not only able to estimate the number of nests and nesting females, but also to identify the key sites for leatherback nesting, data which are crucial to developing conservation management plans for the species. Leatherbacks were first described nesting in Gabon in 1984.

Lead author on the paper, Dr Matthew Witt of the University of Exeter, said: "We knew that Gabon was an important nesting site for leatherback turtles but until now had little idea of the size of the population or its global ranking. We are now focusing our efforts on working with local agencies to coordinate conservation efforts to ensure this population is protected against the threats from illegal fisheries, nest poaching, pollution and habitat disturbance, and climate change."

The study also revealed that around 79 percent of the nesting occurs within National Parks and other protected areas. This gives added hope that Gabon can continue to be one of the world's most important countries for these magnificent creatures.

Dr Angela Formia of the Wildlife Conservation Society, a co-author of the paper, said: "These findings show the critical importance of protected areas to maintain populations of sea turtles. Gabon should be commended for creating a network of National Parks in 2002 that have provided a sanctuary for this endangered species as well as other rare wildlife."

###

This study was carried out by the University of Exeter, Wildlife Conservation Society, University of Florence, IUCN-France, PROTOMAC (Gabon), CNDIO-Gabon, IBONGA-ACPE (Gabon), Agence Nationale des Parcs Nationaux (Gabon), Gabon Environnment, Aventures Sans Frontières (Gabon) and WWF-Gabon.

The study was made possible through funding by the Natural Environment Research Council (UK), the United States Fish and Wildlife Serve (USFWS) Marine Turtle Conservation Fund (U.S Department of the Interior), and the United States Agency for International Development (USAID) – Central African Regional Program for the Environment (CARPE). The team has now also received £300,000 (approx. $450,000 USD) Darwin funding for a three-year project, working with local agencies to improve marine biodiversity management in Gabon.

About leatherback turtles

• The leatherback is the largest sea turtle, reaching up to nearly two metres (6.5 feet) in length and 540kg (1190 pounds) in weight.
• Unlike other sea turtles, the leatherback does not have a hard shell. Its shell is made-up of a mosaic of small bones covered by firm, rubbery skin with seven longitudinal ridges.
• Leatherbacks are the most widely spread marine turtles, and are found in the Pacific, Indian and Atlantic oceans, particularly in tropical regions.
• Leatherbacks are the deepest diving of all sea turtles. The deepest recorded dive is 1.2 kilometres (3/4 mile), which is slightly more than the deepest known dive of a sperm whale.
• As with other reptiles, the sex of leatherbacks is determined by the temperature of eggs during incubation. With leatherbacks, temperatures above 29 degrees centigrade (84 degrees Fahrenheit) will result in female hatchlings.
• Leatherbacks are strong swimmers and tagged individuals have been known to cross ocean basins and are known to travel many thousands of kilometres in search of their jellyfish prey.>>

Extreme Mammals Preview

May 14, 2009

The American Museum of Natural History in New York opens its long-awaited exhibit Extreme Mammals this weekend. I shared some images earlier, but here's more of what's in store:

Batodonoides
An insectivore said to have been the smallest mammal that ever lived

Indricotherium
A prehistoric animal that looked like it was part rhino, part giraffe

Uintatherium
A browsing rhino-sized beast, now extinct, that had a unique head

Macrauchenia
A three-toed, humpless camel-resembling creature that died off 10,000 years ago; here it goes "nose" to nose with an elephant

Glyptodont
These were huge ancient relatives of modern armadillos. Note the recreation in the back. Some were the size of a VW bug automobile.

Megatherium
Its name means "great beast." This giant ground sloth was one of the world's largest mammals, pounding around the planet pavement from two million to 8,000 years ago.

Ambulocetus
"Walking whale" could both walk and swim. It lived 50 to 49 million years ago.

Puijila darwini
This most primitive known seal lived 21-24 million years ago.

This diorama shows Ellesmere Island in what is now part of the Canadian Arctic.

As the below video suggests, take advantage of the City Pass for an unforgettable day in the Big Apple.

World's Oldest Depiction of a Human Found

May 13, 2009

Archaeologists have just found what is arguably the world's oldest known depiction of a human. The Venus from Hohle Fels, named after the cave in Germany where the object was excavated, has been dated to being at least 35,000 to 40,000 years old. Over 30 radiocarbon measurements were taken at the site. Without question, it's the world's earliest known representation of a woman.

(Credit: H. Jensen; photomicrographs by B. Ligouis; copyright University of Tubingen)

In the story, I wasn't able to delve into what the possible use and meaning of the object might have been. This subject has been hotly debated for other so-called Venus figurines dated to later periods. A few possibilities include:

• The object could have held shamanic, spiritual significance, perhaps meant to convey certain attributes or powers to the wearer or holder of the artifact.
• It might have been used in fertility rituals.
• The figurine could have been associated with a possible sacred goddess, worshiped by Europe's first modern humans.
• Art for art's sake might have existed way back when. Our ability to symbolically represent ourselves, other creatures and inanimate things through art appears to have really exploded just 5,000 to 10,000 years later, right when anthropologists suspect we were evolving complex language and representational skills.
• One word: sex. According to Paul Mellars of the University of Cambridge, other early European sites have yielded explicitly sexual objects, such as bone, ivory and horn phallic carvings. Both men and women were depicted in all of their anatomical glory during the Gravettian and later periods.

My own view is that all of the above could be true. Today we tend to think very categorically, often separating sex from spirituality, art from ritual. Perhaps our prehistoric ancestors weren't quite as rigid in this regard. Hollywood had its pre-code movies. Here we have prehistoric pre-code: a no holds barred look at the human body from the mindset of Neanderthal-era modern humans.

I invite you to watch the below video, which describes a somewhat similar, yet later, Venus figurine.

Animal Joy: Q&A with Dr. Jonathan Balcombe

May 12, 2009

Please check out this week's Discovery News story about pleasure-seeking animals, along with its accompanying slideshow.

Today I'd like to share with you a transcript of one of my interviews with Dr. Jonathan Balcombe, a senior research scientist for the Physicians Committee for Responsible Medicine. He is also the author of the absolutely wonderful, must-have book Pleasurable Kingdom: Animals and the Nature of Feeling Good (Macmillan, 2007) and the forthcoming book Exultant Ark: A Pictorial Tour of Animal Pleasure (University of California Press, 2010).

JV: Based on the many examples provided in your book and new paper, it appears that both humans and non-human animals do some things "just for fun," as the saying goes. Do you think pleasure itself can be the end-all reward, meaning that not all behaviors need to be tied to some specific survival/evolutionary benefit?

JB: I think so, but it is hard to demonstrate in animals, who don’t tell us why they do what they do. Do lemurs fumigate themselves with millipede toxins just for the drug high, or is it primarily done to repel parasites? What we can be more confident in saying is that regardless of the evolutionary benefits of a behavior, animals often do things because they are rewarding. I doubt that a monkey thinks “If I eat this fig it will sustain me,” but rather, “Ooh, yummy, a delicious fig!”

<<Here, a wild green vervet monkey enjoys a fruit snack at Abuko Nature Park, Gambia

And hippos luxuriate in "spas" where fish clean them of dead skin and parasites>>

JV: You probably read the recent papers about dancing birds. It appears that dancing may be a byproduct of vocal mimicry skills, explaining why birds, elephants, humans and possibly dolphins can boogie down. I'm wondering if some instances of pleasure might also be a byproduct of other attributes and behaviors. Could that help to explain the possible existence of happiness just for pleasure's sake?

JB: Animals lead complex lives and while most biologists who are thinking about it believe pleasure evolved to encourage adapteive (“good”) behaviors that promote survival, some pleasures may be emergent properties of the behaviors themselves. I certainly think animals can feel happy, that is, they can be feeling generally good about things. Studies of captive starlings at the University of Newcastle, England, show that they can develop optimistic or pessimistic outlooks according to their quality of life. It’s the same for rats.

JV: You piqued my curiosity with your mention that some animals may experience "realms of pleasure unfamiliar to humans." Could you take the examples you mention a step further, by hypothesizing how these attributes (echolocation, for example) might allow animals to experience other forms of pleasure?

JB: Yes, it seems to me that because some animals can perceive things that we cannot, they may experience pleasures alien to us. Some dolphins perform “genital buzzing,” directing a rapid stream of low-pitched buzzing clicks toward the genital area of another. It appears to be a way of giving pleasure to another. A dolphin vibrator. Maybe there’s a certain pleasure felt by migrating birds which we know can detect and orient by the Earth’s magnetic field. I would think it at least feels good to realize they are nearing their destination. I have no idea if an electric fish can get a “charge” out of another electric fish, but I think we should be open to the possibility.

JV: Just to clarify re. a famous herring gull study- the birds appeared to swoop and catch clams for no obvious purpose other than enjoyment, like humans playing catch?

JB: That’s right. Many birds play drop-catch, including crows, ravens, swallows, and birds of prey.

JV: What non-human animals engage in oral sex?! And here I'm curious about oral sex that doesn't lead to procreation, such as what happens in certain fishes that store eggs and/or sperm in their mouths.

JB: As far as I know, mouth brooding in fish is not a form of oral sex in the pleasurable sense. However, oral-genital contact is widespread in mammals, though we need to be cautious about interpreting it as a pleasure-based behavior. Male ungulates, such as cattle and deer, as well as cats and some other mammals, will often lick and sniff the genital area of a female, then perform “flehmen,” a grimacing facial expression that engages the sense of smell and facilitates gauging the timing of her reproductive cycle and thus her readiness to be fertilized. But it might also help get her in the mood. Oral sex that appears purely for pleasure has been documented in goats, hyenas, various primates, manatees, bats, and sheep. It is probably more common than we think.

JV: Do you think some animals do not experience pleasure? If so, which ones? Is it possible, for example, that even very simple creatures, like sponges and jellyfish, can experience pleasure? If so, what's the evidence for that?

JB: The experience of pleasure requires some level of conscious awareness, so we may fairly safely exclude sponges and jellyfish from the list. I believe all vertebrate animals (mammals, birds, reptiles, amphibians and fishes) can feel pleasure and there is good evidence to support this. Goldfish, for example, prefer to swim in an area of a fish-tank where there are pleasure-stimulating drugs. There is also emerging scientific evidence that some invertebrates experience pain, and thus, which suggests they are also capable of feeling pleasure. Robert Elwood at Queens University in Ireland has done some experiments that show quite convincingly that crabs and prawns don’t like painful experiences.

JV: It seems that pleasure-seeking in both humans and non-humans isn't always for the good of the individual's survival. Food comes to mind, and I was reminded of your lettuce-eating iguanas mention. We might crave a chocolate bar, for example, more than a nutritious bowl of granola, just as iguanas appear to crave lettuce more than nutritious reptile chow. Why do you think that's so often the case? How can it be that pleasure sometimes outweighs other more pressing survival needs?

JB: Actually, there are good reasons why we may shun a salad for potato chips. There was a time in our distant evolutionary past when we may not have known when we would get our next meal, so eating something high in fat was a good choice. In the case of the lettuce-craving iguanas, I believe they were tired of the chow and naturally favored a fresh food they would normally get in the wild.

JV: You make a compelling argument that science underrates pleasure in the animal kingdom, focusing more on pain and other negative feelings in non-human species. Do you think scientists, conservationists and other animal rights activists should include human denial of animal pleasure in their campaigns? Or how might your view best be applied to specific efforts?

JB: Yes, we should view the denial of opportunities to experience pleasures as a serious animal wellbeing issue. I regard pain and pleasure as being on a continuum of sensory experience, with agony at one extreme and ecstasy at the other. So, campaigns that seek to reduce animal pain and suffering may also be granting animals more opportunities for pleasure. However, that’s not to say that we should think larger battery cages for hens is a victory, even if it’s less bad than smaller cages. Hens can only really enjoy their lives if they have access to open space outdoors. The same goes for all the animals we cage in factory farms, laboratories, circuses and zoos.  

The capacity for pleasure means that an animal’s life has intrinsic value, that is, value to the individual independent of his/her value to anyone else (e.g., humans). So, for example, every time we kill a chicken—and we kill about 300 of them every second in the United States—we take away that chicken’s opportunity to enjoy life. For me, this is the great significance of animal pleasure to questions of morality.