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21 – dolphins, bonobos, sex and pleasure

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bonobos at Jacksonville zoo

I enjoyed a little boat trip off the north-east coast of Kangaroo Island recently. The owner, our guide, bounced us up and down the shoreline east of Christmas Cove to view caves in the limestone cliffs, seabirds such as wedge-tailed eagles on the cliff-tops, and above all to search for a pod of dolphins known to be using the area as a daytime resting-place.

After a few bouts of bouncing eastward and westward we were becoming skeptical, though by no means annoyed. A year before, the island, Australia’s third largest after Tasmania and Melville Island, had been ravaged by bushfires, devastating vegetation and wildlife, and seriously damaging the island’s fragile economy, not to say ecology, and we were happy to make our tiny contribution without great expectations of sighting fabulous beasties. 

So we were delighted, on heading eastward again, to spot a few fins bobbing and dipping in the water ahead. Slowing toward them, we were told there were about 25 dolphins in this pod (the term was first used by whalers in the early nineteenth century, for reasons unknown). I soon gave up trying to count them as identical-looking fins appeared and disappeared and vaguely discerned bodies twisted and turned just below the surface. They seemed to form pairs now and then, breaking the surface sleekly and synchronously in elegant arcs. Dolphins, I learned, spend their days lolling about near the shore in these pods after a night of hunting out at sea. They seemed aware but unconcerned about our presence, and at one time the whole group disappeared then reappeared on the other side of our boat, bobbing and slow-twirling as before. 

I was struck by a remark by our guide that dolphins are one of the few mammals that mate for fun or pleasure. Of course I made an immediate connection with bonobos, but then I wondered, what does the verb, to mate, exactly mean? We humans never describe ourselves as mating, that’s for the birds, etc. We fuck, screw, bonk, shag, hump and bone, we more coyly sleep together, and more romantically make love (not allowed for other species), but we’re way above mating.

‘Mating’ brings up two internet definitions, the action of animals coming together to breed, and copulation. So dolphins, and bonobos and humans, often come together to breed – but actually not to breed. As for copulation, that’s rarely used for humans, just as fornication is rarely used for non-humans. The latter is, of course, a term of mostly religious disapproval, and non-humans are too lowly to be worthy of moral judgment. 

Of course we do apply mating to humans with a pinch of irony, as in the mating game, and this blurs the line between humans and others, but not enough for me. The point is that dolphins and bonobos use sex, which may not be the full rumpy-pumpy (dolphins don’t even have rumps to speak of), to bond with each other, to ease tension, to have fun, as our guide said. But then, don’t all species have sex purely for pleasure, or at least because driven to do so, by sensation? Do cats, dogs, birds and flies have sex with the intention of reproducing? I don’t think so. 

Human sex is pleasurable, so I’ve heard, and I expect bonobo sex is too. Fly sex probably not, or so I thought, but I’m probably wrong. Researchers have found that male fruit flies enjoy ejaculating, and tend to consume alcohol when denied sex. I know exactly how they feel. Anyway, fruit flies have long been favourites for biological research, and more recently they’ve found that ‘a protein present in the ejaculate of male fruit flies activates long-term memory formation in the brains of their female partners’. It rather makes me wonder what effect this kind of research has on the researchers themselves, but I’m sure it’s all for the best. 

One thing is certain, cats and dogs, and I’ve had a few, feel pleasure. Cats are appallingly sensual, and I’ve probably had more sexual advances from dogs than from humans, though whether they involved pleasure I can’t be sure. Generally our understanding of non-human sex has expanded in recent decades, as our sense of our specialness in everything has receded. It’s also true that we’ve tended to look at other species with a scientific instrumentalism, that’s to say from the viewpoint of evolution, breeding, genetics and other forms of categorisation, rather from an emotional or sensory viewpoint.

When I was very young I read a book by Ernest Thompson Seton called The biography of a grizzly. This story of Wahb, a male grizzly whose family was wiped out by hunters, and who survived to become the most powerful bear in the region, before inevitable decline and death, had an unforgettable emotional impact. I’m glad I read it though, as, sentimentalised though it might’ve been, it inoculated me against the scientific tendency, now changing, to see any animal as an it, rather than he or she or dad or mum or brother or sister. So this idea of putting oneself in the paws of a grizzly or the feet of a bonobo has long been perfectly legitimate to me. 

In 2014 Jason Goldman wrote an article entitled Do animals have sex for pleasure?, in which he cited many instances of other species – bonobos of course heading the list – engaging in oral and penetrative sex ‘out of season’, when pregnancy is precluded. They include capuchin monkeys, macaques, spotted hyenas, bears, lions and fruit bats. It stands to reason that the physiological, whole-of body pleasure we derive from sex is shared by other species, and is indulged by them, and this includes what we call homosex, and masturbation. Australia’s premier science magazine, Cosmos, claimed a few years ago that some 6000 species (or was it 600?) have been observed engaging in homosexual activity, which does sound funny when talking about what we would habitually call lower life forms. 

All of these findings have had the effect, and perhaps the intention, of loosening our uptight attitudes toward sex, as well as upending our notions of human specialness. But the behaviour of bonobos, who at times look strikingly like us, is more immediately impactful than anything fruit flies or fruit bats might do. Just the other day I watched a video of bonobos in Jacksonville zoo, Florida. Two of them were lying on the ground close together, and kissing each other, on the lips, again and again. Were they male? female? one of each? Who knows, it was so beautiful to watch.  

References

Ernest Thompson Seton, The biography of a grizzly, 1900. 

https://www.the-scientist.com/news-opinion/male-fruit-flies-take-pleasure-in-having-sex-30867

https://www.the-scientist.com/news-opinion/sex-promotes-lasting-memories-in-female-flies-66763

Bonobos at Jacksonville Zoo (video)

 

Written by stewart henderson

January 10, 2021 at 1:31 pm

a bonobo world, and other impossibilities 14

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graph showing the rising number of PhDs in neuroscience compared to other sciences

is it all about sex? a few thoughts on sex and behaviour

When I was young there were always a lot of books around, fortunately. My mother was a psych nurse who went on to be a teacher of nursing, so psychology textbooks were plentiful, and I learned with some fascination early on about the id, the ego and the superego. But my greatest excitement was reserved for two other Freudian terms, sublimation and polymorphous perversity. They allowed me to think of sex in a kind of superior way. 

Sublimation refers to the process of transformation from a solid to a gas, without the intermediate step of melting into a liquid. You can observe it simply by opening your freezer door, especially if you have an old-style freezer caked with ice. But Freud’s use of the word was much hotter, to my teenage self. To Freud, there were two driving instincts, eros, the sex drive, and thanatos, the death drive. That’s enough about thanatos. Freud proposed these two opposing drives in Beyond the Pleasure Principle and other essays, but I probably got them from pamphlets floating around the house, summarising Freud’s ideas in a few paragraphs. As I understood it, eros was life-affirmative, but it needed to be harnessed, reigned in, sublimated to a more general, civilising and creative (rather than procreative) force. So it was all just sex diverted to science, technology, empire-building and the like. Sounded perfectly cromulent to me, even before that word was invented. So everything was polymorphously perverse; church spires, slippery-dips, kindergartens and business schools, they all manifested the perversity of our drive, in an infinitude of stop-thinking-about-sex-but-do-this-instead ways. Having discovered the secret of civilisation thanks to Meister Sigmund, I took great secret pleasure in upending said civilisation by masturbating like there was no tomorrow. 

I realise now of course that sublimation isn’t always about channelling out the sexual impulse, it’s about any equally unacceptable impulse, such as murderous rage. But being me I wanted to keep the sex, and stuff all the civilisation. Or couldn’t we somehow keep both sex and civilisation, and dispense with the murderous rage? 

Many anthropologists would agree that bonobos have a culture, but none would say they have a civilisation. So what exactly is the difference, and does civilisation require the degree of sexual repression that we generally suffer from? Though there are the odd erotomanic subcultures, in no established nation is it acceptable, or legal, to walk about naked, let alone have sex, in public. It’s generally called indecent exposure. A loincloth, and some extra bits of cloth for females, might protect you legally if not socially, but what precisely is so upsetting, currently, about those parts we’re obliged to hide, and will we ever socially evolve out of this condition?

Freud believed we were born polymorphously perverse, little libido capsules, and some of his observations – such that we’re all born bisexual, seemed obvious to me from the get-go. However, Freud knew nothing about bonobos, who were barely known to humanity at the time of his death. His theories of masculinity might have benefitted from such knowledge, and in fact the incredibly rapid pace of our neurological knowledge from the beginning of the 21st century – as the neurologist and primatologist Robert Sapolsky points out in his monumental book Behave – has wrought havoc with psychoanalytic and other theories that seek to understand human behaviour without attending to their detailed neurological underpinnings. The shaping of masculinity and femininity by culture has been a problem that psychologists, feminists and all other interested parties have long wrestled with. Which culture, after all? And are there differences beyond culture? Can culture be separated from biology?

I don’t think so. Our brains function the way they do because of the environment in which they were nurtured since conception – every environment different of course. And there’s also evolution – what might be called pre-conceptual, or historical, or prehistorical influences. Researchers have often tried to pinpoint essential differences between the male and female brain in humans. They’re far less concerned to pinpoint such differences between male and female cats, dogs or mice, presumably because their overall catty, doggy and mousey natures tend to overwhelm minor gender differences. Recent research has found statistical differences only, rather than categorical differences between male and female brains. In other words, female brains don’t have a vagina and male ones don’t have a penis. Even if you’ve devoted a lifetime to neurological research, studying the brain in all its white-and grey detail, you wouldn’t be able to state categorically that the warm, disembodied human brain placed in your hands to somehow keep alive and probe its electrochemical circuitry and its hormonal flow, belonged to a male or a female. Researchers who want to find key differences between Venus and Mars will find them, but the differences among female brains are greater than those that separate them from male brains. 

And yet, statistics are important. Statistically speaking, males are more violent than females, regardless of nation, culture or time period (going back to the first days of statistical data). It seems to have to do with hormones, and group behavior. Young males often join gangs – bikie gangs, street gangs, crime gangs, ethnic gangs, white supremacist gangs, nogoodnik gangs, whatever. Females, not so much. The largest cause of violent death and injury in long-peaceful countries such as Australia is a young male aged 15-24 or so behind the wheel of a motor vehicle. This is about risky and show-offy behaviour – they kill and injure themselves as much as others. Such behaviour is seen too in male chimps, in young bull elephants during musth, and in male dolphins – all very smart and social animals. Does all this relate to sex? Apparently, in more or less roundabout ways. For chimps it’s not so roundabout. It’s called the sexual coercion hypothesis, for which much evidence has been collected from various East African field sites:

Males who directed aggression at certain females mated more often with those females than did other males. Moreover, these aggressive males were actively solicited for mating by those females at the time of peak fertility. Critically, aggression over the long term had a greater effect than violence in the immediate context of mating. 

This aggressive disposition apparently leads directly to reproductive success. So male domestic violence isn’t all bad?

Elephants in musth – which literally means ‘drunk’ – have very highly elevated testosterone levels, but how this links to aggression is unclear. Sapolsky has much to say about cause-correlation between testosterone -and androgens generally – and aggression in humans, which is relevant here. Social learning appears to play an important role in male aggression, which raises testosterone levels, and so we have a chcken-and-egg issue. As to elephants, the aggression they display during musth makes close scientific analysis a bit problematic, but it’s known that the secretion of temporin from the temporal glands in this period, and the accompanying swelling of those glands, causes irritation, which can be acute in some cases. This extreme irritation may cause aggressive behaviour, as when Dad kicks the cat after Mum has berated him for the previous two hours. Interestingly, aggressiveness, sometimes murderous, in young bull elephants, most often happens in the absence of older males. Their presence has a tempering effect. In any case, the violence displayed during musth, which is the male reproductive period, seems more of a side-effect than a ‘turn-on’ for females. Older males learn to use this period effectively, becoming more energetic in moving around and increasing territory in search of females, and preserving their energy during the warmer, non-musth months. 

Dolphins are not generally the fun-loving joyful creatures of contemporary myth, and male dolphins often gang up on females and rape them, to use a term humans like to reserve for themselves. I could go on, but the general point is that we, as humans, might want to learn how not to behave as well as how to behave from other species, especially those most like us – not just in their closeness genetically, but in their smarts, and in their negative or positive treatment of others, of their own and other species. 

References

R Sapolsky, Behave: the biology of humans at our best and worst. Bodley Head 2017

https://asunow.asu.edu/content/aggression-male-chimpanzees-leads-mating-success

https://en.wikipedia.org/wiki/Musth

https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2656.13035

https://slate.com/human-interest/2009/05/the-dark-secrets-that-dolphins-don-t-want-you-to-know.html

http://www.bbc.com/earth/story/20160204-cute-and-cuddly-dolphins-are-secretly-murderers

Written by stewart henderson

November 27, 2020 at 12:44 pm

the latest on dolphin language

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dolphins

I wrote, or semi-podcasted, on the brain of the dolphin a while back, and much of my focus was on language, often described as the sine qua non of cerebral complexity and intelligence. In that piece, posted about eight months ago, I reported that there there was little clear evidence of any complex language in dolphins, but there had been some interesting research. Allow me to quote myself:

Dolphins do sometimes mimic the whistles of other dolphins too, particularly those of their closest relatives, but signature whistles as a form of recognition and differentiation, are a long way from anything like language. After all, many species can recognise their own mates or kin from the distinctive sounds they make, or from their specific odour, or from visual cues. However, a clever experiment carried out more recently, which synthesised these whistles through a computer, so that the whistle pattern was divorced from its distinctive sound, found that the dolphins responded to these patterns even when produced via a different sound. It seemed that they were recognising names. It’s undoubtedly intriguing, but clearly a lot more research is required.

So it was with some interest that I heard, on a recent SGU podcast, an account of what seemed an elaboration of the experiments conducted above, further confirming that dolphins recognised names. Or were they just reporting the same experiments? Having re-listened to the SGU segment, I find that they didn’t give any details of who did the study they were talking about, the only mention was to a news article. So I’ll just report on anything I can find, because it’s such a cool subject.

There’s a nice TED talk, from February 2013, on dolphin language and intelligence here, which is about researches over many years in the Bahamas with Atlantic spotted dolphins. As always, I suggest you listen to the talk and do the ‘research on the research’ yourself, as I’m not a scientist and I’m only doing this to educate myself, but hopefully I can also engage your interest.

Dolphins have a brain- to-body ratio (a rough but not entirely reliable guide to intelligence) second only to humans, they pass the mirror self-awareness test (another standard for intelligence that’s been questioned recently), they can be made to understand very basic artificial human language tests, and they’re at least rudimentary tool users. But the real interest lies in their own, obviously complex, vocal communication systems.

I probably misrepresented the information on signature whistles before: they’re only what we humans have been able to isolate from all the ‘noise’ dolphins make, because they’re recognisable and interpretable to us. Denise Herzing, in her TED talk, refers to ‘cracking the code’ of dolphins’ communication systems. She and her team have been working with the dolphins over the summer months for 28 years. They work with underwater cameras and hydrophones to correlate the sounds and behaviours of their subjects. This particular species is born without spots, but is fully black-and-white spotted by age 15. They go through distinct developmental phases making them easy to track over the years (dolphins live into their early 50s). The distinctive spotted patterns make them easy to track individually. Females are sexually mature by about age 9, males at around 15. Dolphins are very sexually active with multiple partners, so paternity is not always easy to determine, so this is worked out by collecting fecal matter and analysing its DNA. So, over 28 years, three generations have been tracked.

What really interests me about the dolphin communication question is their relation to sound and their use of sound compared to ours. Herzing describes them as ‘natural acousticians’ who make and hear sounds ten times as high as humans do. They also have highly developed vision, so they communicate via bodily signals, and they have taste and touch. Sound is of course a wave or vibration which can be felt in water, the acoustic impedance of tissue in water being much the same as on land. Tickling, of a kind, does occur.

Signature whistles are the most studied dolphin sounds, as the most easily measured. They’re used as names, in connecting mothers and calves for example.  But there are many other vocalisations, such as echo-location clicks (sonar), used in hunting and feeding, and also socially, in tightly-packed sound formations – buzzes, which can be felt in the water. They’re used regularly by males courting females. Burst-pulse sounds are used in times of conflict, and they are the least studied, most hard to measure of dolphin sounds.

Interestingly, Herzing notes that there’s a lot of interaction and co-operation in the Bahamas between spotted and bottle-nose dolphins, including baby-sitting each others’ calves, and combining to chase away sharks, but little mention is made, in this talk at least, of any vocal communication between the two species. When she goes on to talk about synchrony, I think she’s only talking about within-species rather than between species. Synchrony is a mechanism whereby the dolphins co-ordinate sounds and body postures to create a larger, stronger social unit.

As I’ve mentioned, dolphins make plenty of sounds beyond the range of human hearing. Underwater equipment is used to collect these ultrasonic sounds, but we’ve barely begun to analyse them. Whistle complexity has been analysed through information theory, and is highly rated even in relation to human languages, but virtually nothing is known about burst-pulse sounds, which, on a spectrogram, bear a remarkable similarity to human phonemes. Still, we have no Rosetta Stone for interpreting them, so researchers have developed a two-way interface, with underwater keyboards, with both visual and audible components. In developing communication, they’ve exploited the dolphins’ natural curiosity and playfulness. Dolphins, for example, are fond of mimicking the postures and vocalisations of humans, and invite the researchers into their play. Researchers have developed artificial whistles to refer to dolphins’ favourite toys, including sargassum, a kind of seaweed, and ropes and scarves, so that they can request them via the keyboard interface. These whistles were outside the dolphins’ normal repertoire, but easily mimicked by them. The experiment has been successful, but of course it isn’t known how much they understand, or what’s going through their minds with all this. What is clear, however, is that the dolphins are extremely interested in and focused on this type of activity, which sometimes goes on for hours.

This research group has lately been using an underwater wearable computer, known as CHAT (cetacean hearing and telemetry), which focuses on acoustic communication. Sounds are created via a forearm keyboard and an underwater speaker for real-time Q and A. This is still at the prototype stage, but it uses the same game-playing activity, seeking to empower dolphins to request toys, as well as human game-players, through signature whistles. It’s hoped that the technology will be utilisable for other species too in the future.

All of this is kind of by way of background to the research reported on recently. This was really about dolphin memory rather than language – or perhaps more accurately, memory triggered by language. Dolphins recognise the sounds of each others’ signature whistles, but would they recognise the whistle of a dolphin they’d not been in contact with for years. And for how many years? Researcher Jason Bruck tested this by collecting whistles of dolphins in captive facilities throughout the US. Dolphins are moved around a lot, and lose contact with friends and family. Sounds a bit like the foster-care system. Bruck found that when dolphins heard the signature whistles of old companions played to them through an underwater speaker, they responded with great attention and interest. One dolphin was able to recognise the whistle of a friend from whom he was separated at age two, after twenty years’ separation. As biologist Janet Mann put it, this is a big breakthrough but not so surprising, as dolphins are highly social animals whose lives, like ours, are criss-crossed by profound connections with others, with effects positive, negative and equivocal.  It’s important, too, for what it suggests – the capacity to remember so much more, in the  same coded way. in other words, a complex language, perhaps on a level with ours. Will we ever get to crack this code? Why not. Hopefully we won’t stop trying.

Written by stewart henderson

August 24, 2013 at 3:55 pm

fountains 2: dolphins and their brains

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comp_brain_size

dolphins and their brains

Here’s the transcript of my second ‘fountains of good stuff’ podcast, ‘dolphins and their brains’, (linked to above) minus some bits at the beginning and end.

Dolphins have long been considered our cute, smart underwater friends. In fact you might be surprised at how far back such observations go, and at how interested the ancients were in dolphinkind. Aristotle recognised that dolphins weren’t fish, that they couldn’t breathe underwater, that they had lungs and had to return to the surface to breathe just like us. The ancient poet Oppius of Corycus had this to say about them:

Diviner than the dolphin is nothing yet created; for indeed they were aforetime men and lived in cities along with mortals, but by the devising of Dionysus they exchanged the land for the sea and put on the form of fishes.

In these remarks we find the mixing of genuine observation and fascination with mythologising which still persists today. Some modern claims are that dolphins are idyllically happy and playful creatures, that they have a special bond with humans, that they’re at least equivalent in intelligence to us, bearing in mind the vastly different medium they inhabit, and that they have a highly developed language and a social and cultural complexity that we’ve barely begun to tap into.

So how much truth is there to these claims? Well I think we should first look at the grandest of the claims, about dolphin language and culture.

Many of the more hyperbolic claims for a rich dolphin language and culture, as yet beyond the ken of mere humans, were made by John Lilly, a pioneering researcher of the fifties and sixties. Lilly worked with bottle-nosed dolphins, and that is the species I’m referring to, though of course, all thirty or so species of dolphins and porpoises, as well as the forty or more species of whales, tend to be lumped in together as highly communicative and cultured.

Lilly’s attempts to back up his claims about dolphin language didn’t work out so well, however, and his writings on dolphins became increasingly drug-influenced and fantastical. Another researcher in the mid-sixties, Duane Batteau, tried to translate Hawaiian phonemes into the whistle-sounds frequently used by dolphins, using them to convey simple instructions. However, Batteau could only use the sounds as holophrases, that’s to say, instructions with complex elements, such as ‘jump through the hoop I’m holding’. The dolphins couldn’t be taught to recognise individual semantic elements within the complex instruction, such as ‘hoop’, ‘leap’ or ‘five feet high’, which are essential to building up a whole language, at least one that humans would recognise, and using it in a flexible and creative way. The dolphins took some years to learn about a dozen holophrastic sounds, which indicated none of the complexity or nuance of human language.

Since these early researches, little headway has been gained in trying to teach dolphins, or any other species, to understand human language, which is hardly surprising, as they’ve evolved to communicate very differently. Dolphins are very vocal animals, forever sounding off with whistles and clicks that are incomprehensible to most of us, and many of which we’re not even equipped to hear. But is this dolphin language?

Well, early research on dolphin whistles didn’t come up with anything too promising. Individual dolphins produce their own unique whistles, described as ‘signature whistles’, doubtless for the purpose of identifying themselves to others. Interestingly, female dolphins develop signature whistles that are quite different from their mothers’, while male dolphins don’t. This is explained by the fact that male dolphins, after weaning, hang around together in ‘adolescent gangs’ just as male humans do [and quite a few other species too, such as elephants]. Females tend to stick to their mothers, becoming young mothers themselves. They need to be able to differentiate between mothers and children, which is unnecessary for the males.

Dolphins do sometimes mimic the whistles of other dolphins too, particularly those of their closest relatives, but signature whistles as a form of recognition and differentiation, are a long way from anything like language. After all, many species can recognise their own mates or kin from the distinctive sounds they make, or from their specific odour, or from visual cues. However, a clever experiment carried out more recently, which synthesised these whistles through a computer, so that the whistle pattern was divorced from its distinctive sound, found that the dolphins responded to these patterns even when produced via a different sound. It seemed that they were recognising names. It’s undoubtedly intriguing, but clearly a lot more research is required.

Most attempts to elicit information about dolphin language, and dolphin intelligence generally, suffer from a difficulty in imagining a language system completely alien to our own, so that we always try to translate communication into something that might make sense to us. It’s a kind of anthropomorphism problem, which we can probably only overcome by a greater insight into the social life of these creatures and what they might use language for. It will no doubt be a long and painstaking process.

One of the reasons given for the supreme intelligence of the dolphin is its very large brain, and on first thought, it seems a very sound reason. The human brain is considerably larger, both in absolute terms and in terms of brain body ratio, than that of other primates.

In fact the human brain has become so large that we have trouble pushing our babies’ heads through the birth canal, and their skulls at birth are still soft and collapsible in places to facilitate the birth process. In the few months after birth, the baby’s head has to be supported until it becomes used to carrying that great bony weight on its shoulders all by itself. The average dolphin brain is slightly larger than ours, but so is its body, so its brain body ratio averages out at about the same, or a little less than ours.

The real key to human intelligence, however, is the growth of a specific part of the brain, the neocortex. In most mammals, the neocortex takes up between 10 and 30% of the total brain mass. In primates in general, it takes up 50%. For humans, though it has climbed to a very impressive 80%. So big is our neocortex that is has to be folded in on itself to fit inside our heads.

So what about the dolphin neocortex? Well, it was John Lilly, the sixties researcher, who first discovered that it was even bigger than our own, a fact that led him to to the quite understandable conviction that dolphins were, at the very least, our equals, intelligence-wise.

However, size isn’t everything, especially when we compare land mammals with their underwater cousins. Mammals on land all have about the same nerve cell density, that is, the same number of neurons per square centimetre. Aquatic mammals have far less densely packed neurons in their brains. In fact, their brains are only a quarter as densely packed with neurons as land mammals, and that’s a big difference. It seems that, because dolphins have evolved in water and don’t have to contend with gravity the way we do, their brains have been able to spread out over a larger area, without necessarily increasing complexity. Which isn’t to say that the dolphin brain isn’t extremely complex. We’re only at the beginning of understanding a small fraction of it.

Some of this research has highlighted that the neocortex in dolphins, which naturally reflects more recent evolutionary development, is used for very different purposes, such as breathing, which is regulated by more primitive brain processes in land mammals. Hearing in dolphins requires a far larger proportion of grey matter than in humans, and it’s likely that their complex sonar system is regulated by the neocortex.

In recent years it’s been discovered that spindle neurons, previously only found in higher primates, exist in large numbers in many whale and dolphin species. These neurons are associated with the processing of emotions and social interaction. They’re relatively large and allow for high-speed communication and response across the large brains of hominids, so the fact that many cetaceans [the order that whales, dolphins and porpoises belong to] have some three times the number that humans do, is certainly food for thought.

“The discovery of spindle neurons in cetaceans is a stunning example of neuro-anatomical convergence between cetaceans and primates,”

says Lori Marino of Emory University in Atlanta, Georgia.

“The common ancestor of cetaceans and primates lived over 95 million years ago, and such a highly specific morphological similarity as the finding of spindle cells is clearly due to evolutionary convergence, not shared ancestry,”

she says. The term ‘convergence’ refers to a similarity in adaptive structures and behaviours in unrelated or only distantly related species.

Exactly how these spindle cells function in cetaceans is still unclear, but it’s believed that they’ve been present in these mammals for some thirty million years, compared to 15 to 20 million years in our primate ancestors.

The term ‘intelligence’ is really quite fuzzy, even when we’re applying it only to humans, let alone comparing humans to such vastly different creatures as dolphins, but years of studying the social interactions of cetaceans in general are gradually revealing a world much worth exploring. However, it isn’t necessarily the playful world we associate with the bounding, squealing, apparently perpetually laughing and eagerly performing creatures formerly associated with marinelands the world over.

Some years ago, beginning in 1997, a growing mystery developed when dead porpoises and juvenile dolphins were found washed up on beaches in Scotland and on the other side of the world in Virginia. The animals had suffered massive internal damage, as it turned out, from dolphin attacks. They had literally been beaten to death. A well-known documentary, ‘the Dolphin Murders’, relates the story. Researchers are still unclear as to the motive for these murderous attacks, but they remind us that evolutionary pressures and brutality are just as much a part of life in the oceans as on land, and that even dolphins, who’ve often been reported as saving human lives at sea, can turn themselves into killers.

Dolphin-hugging, metaphorically speaking, has been all the rage in recent decades, but for all its positivity, it risks obscuring what dolphins really are. They’re not always playful and cute, but they’re certainly among the most fascinating creatures on our planet, and the best compliment we can pay them is to try to get to know them a whole lot better.

Written by stewart henderson

December 27, 2012 at 12:22 pm