Posts Tagged ‘intelligence’
Back to bonobos, and remembering Kanzi
Here’s looking at you, kid
So, back to bonobos, and the question, how/why did they become female dominant? My guess, which I think is a reasonable one, has always been that they managed, after their separation from chimps due to the formation of the Congo River a couple of million years ago, to find themselves in a region of abundance, in terms of fruit and nuts and small game, so that physical strength wasn’t such an advantage for basic survival (a situation that the WEIRD world finds itself in today, just saying). They seemed to huddle together more, which led to a discovery of erogenous zones, adding to a sense of fellow-feeling. Mmmm. A situation that the WEIRD world does not find itself in today, what with the boxes we live in and the clothes we wear. And our consequent sense of privacy. And all that religious indoctrination, re Sodom and Gomorrah, etc .
So, that fellow-feeling seems to have made bonobos less murderously violent – though they are violent, generally in a protective way, females ganging up against obstreperous males, since the males are still on average the weightiest gender, though that’s apparently reducing. And they’re pretty strong on rough-and-tumble play like chimps, and us, when we’re allowed to be.
A quick bit of research on the reasons for the differences chimes with what I’ve just written – abundance and closeness makes for less work and greater intimacy. And maybe there’s something about females being more of a sisterhood – and that may be because physical, genito-genital rubbing is more pleasurable between females than between males, or between males and females. I suspect that exploring this sexual side – this sexual explanation for the ultimate female supremacy of bonobos – has not been taken very far because of our own sexual coyness. We prefer to think of it as just a matter of hanging out, of females preferring each others’ company in a natural, non-sexual way, or because they share the joys and labours of motherhood….
But I’ve been neglecting my job, and ignoring research findings. From Medical News Today (strangely enough) way back in 2019:
Recently, researchers from various academic institutions — including the Leibniz Institute for Farm Animal Biology in Dummerstorf, Germany, Harvard University in Cambridge, MA, and the University of Zurich in Switzerland — have been looking into why female bonobos display same-sex sexual behaviors. The researchers’ interest in female bonobos in particular arose from the fact that in the wild, all adult females engage in genito-genital rubbing (rubbing the genitals together) on a frequent basis. Although males also engage in same-sex sexual behavior, they do so with less frequency, making the females’ behavior even more remarkable by contrast.
So, there you go, but I must say I don’t find the bonobos’ female-female stuff remarkable. Girl-girl frottage in humans is much more common than the male variety, surely? Or am I just fantasising?
But this above-quoted article has really got me hooked. A key to it all is oxytocin:
After sexual interactions with other females, female bonobos also displayed higher levels of oxytocin in the urine. The same, however, did not occur after they had mated with males. Female bonobos, it seems, derive more pleasure from sexual engagement with other females. This may also allow them to establish themselves as equal to the males in the community — by sticking together.
Not just equal, but superior through force of numbers. Sisterhood is powerful, and female humans take note – more of the genito-genital stuff! More sex and less offspring, surely not such a bad idea. But then, there’s so much non-sexual stuff to deal with – the precise rate of expansion of the universe, and is our universe the only one, and just why is there something rather than nothing, and are such questionings worthwhile, shouldn’t we just shut up and calculate?
All of which makes me wonder – does too much sex, re bonobos, make you stupid? Should we be proud of our ability to sublimate (in the Freudian sense)? Is knowledge more important than kindness? Hmmm. Here’s a quote from the abstract of a 2010 study entitled ‘Differences in the Cognitive Skills of Bonobos and Chimpanzees’:
We compared both species on a wide range of cognitive problems testing their understanding of the physical and social world. Bonobos were more skilled at solving tasks related to theory of mind or an understanding of social causality, while chimpanzees were more skilled at tasks requiring the use of tools and an understanding of physical causality. These species differences support the role of ecological and socio-ecological pressures in shaping cognitive skills over relatively short periods of evolutionary time.
Hardly a surprising finding, though I’m not quite sure what ‘social causality’ means. And quite apart from these social findings, there’s a famous individual example – Kanzi, dubbed, rather ridiculously in my view, ‘the smartest ape that ever lived’ in a video referenced below. Whoever wrote that title seemed not to realise that humans are 100% ape, and also that many of the skills Kanzi learned from his human masters had little to do with the kind of intelligence required to survive and thrive in the bonobo world, not the human one.
Nevertheless, the Kanzi story is fascinating, and it’s unlikely that he was particularly exceptional, though the few bonobos that were also taught similar skills didn’t perform as well. Not only did he come to understand quite a lot of human language, but displayed a ‘theory of mind’, a recognition of others’ mental states as different from one’s own (though this concept seems a bit dicey – even a dog recognises when her master is angry or upset). His ability to chip away at rocks to make effective stone tools was particularly noteworthy and thought-provoking, though it’s likely that the spark for this would’ve come from human minders, and there’s an obvious question about whether he found such tools useful for his own survival, as he spent his life in captivity, without ever having to fend for himself.
Overall, though, Kanzi, who died last year in his mid-forties, has been something of a bridge-builder between human apes and our closest ape relatives. His ability to communicate effectively with humans raises lots of fascinating questions and hopes, especially as he was only a male, too stupid to lord it over the females of his own species. And writing this reminds me of a young, intelligent woman who I befriended at university back in the 90s. She, too, fell for the view that men were more naturally intelligent than women, on average. Such is the legacy of patriarchy.
References
https://www.bonobos.org/blog/bonobos-and-chimps-the-story-of-the-great-divide/
octopuses r n t us
I watched a video yesterday on those amazing sea creatures and was reminded of a couple of books I read a few years ago by Peter Godfrey-Smith, Other minds: the octopus and the evolution of intelligent life, and Metazoa: animal minds and the birth of consciousness. Yes, again it’s about being engrossed and then more or less forgetting everything, so this time I won’t go on about myself and focus solely on octopuses. There are around 300 species of these shape-and-colour-shifting cephalopods, ranging in size from the Giant Pacific (the largest ever found weighing at about 270 kgs) to the Octopus wolfi (less than a gram). Which makes me wonder, how smart could such a mini-octopus be…?
Octopuses have been living in our oceans for some 300 million years, pre-dating the dinosaurs. They are invertebrates, i.e no backbone, but they do have hard beaky bits, the only part that can’t shape-shift. They’re famously solitary, living in home-made rock shelters, or shells or crevices – in fact in all sorts of innovative hideaways, and they’re not very long-lived at all, for all their smarts. The Giant Pacific lasts about five years at most, others not so much. Basically, they live to breed, then they die – males and females alike. Talk about a mind-blowing orgasm. This is called semelparity, which contrasts with iteroparous us. There are sex-based differences though, in this senescence. The females guard their eggs for a while, wasting away and generally dying just as the eggs hatch. This wasting process is similar in both sexes (though sometimes the male is killed by the female), and is brought about by secretions of the optic gland, ‘an endocrine gland located near the optic lobes, between the brain and eyes’, according to AI, which doesn’t lie. Anyway, this death-on-giving-birth system ensures, if that’s the word, that every new-born octopus is an orphan. Nothing is learned from their parents. They have to rely on their own smarts.
So what’s most interesting about them, surely, is the stuff that makes them think, from the get-go. It’s not a brain, in the mammalian or birdian sense, it’s a kind of decentralised nervous system. They do have a brain, of sorts, but they have eight other ‘arm-brains’. So each arm works separately but they must also be co-ordinated for the creature to get anywhere. Hard to work all that out, but then they’ve had 300 million years to do it. As to how many neurons they have, you can imagine, with the vast difference in species sizes, that it varies considerably. The common octopus, Octopus vulgaris, has about the same number as a dog, two-thirds of which are in the arms, the rest in the head. Nine brains, sort of. It has the largest brain-to-body mass of any invertebrate, unsurprisingly. They’re very visual, and can distinguish human faces, and even make friends with them, sort of. The award-winning documentary ‘My octopus teacher’ apparently demonstrates this (I haven’t seen it, but I will, and I’ve watched a documentary on the documentary, and even that was an emotional experience).
So octopuses can be added to the list of smart, even super-smart critters, but there’s something very very different about them, it seems to me. They’re solitary, and this doesn’t seem to be emphasised enough. They’re orphans, effectively. Of course they mate, because it takes two, but they don’t have mates in the Aussie sense.
Think of what this means. They don’t have parents, or siblings, or relatives – at least not that they know of, though the giant Pacific octopus lays tens of thousands of eggs before it drops dead. They don’t have playmates or teachers. Nothing is passed from generation to generation. Nothing is accumulated. They have no society. Remember the apocalyptically imbecilic remark of Margaret Thatcher, ‘there’s no such thing as society’? Maybe she’d mistaken herself for an octopus. For me, it’s due to the society that I live in that I can write on this laptop, or that I can read or write at all. Through my society I’ve learned something about the ancient Egyptians and Minoans, about Plato and Aristotle, about Voltaire and Diderot, Newton and Maxwell, Planck and Einstein. I’ve learned to play and appreciate the skills of soccer, pool and table tennis. I’ve learned of the joys and miseries associated with countless alcoholic beverages, and the odd not quite licit drug. I’ve driven cars, flown in planes, studied at a university, and sampled many other pleasures, as well as pitfalls, that my WEIRD world has provided. All, or most, of this stuff was around before I was born. They were the accumulations of our culture, part of what all we humans plug into. Octopuses, living and dying for hundreds of millions of years, have had none of that. To survive, they’re still doing what they were doing when our ancestors were synapsid tetrapods, likely sharing their oceans. And of course, they may well survive us. But have they had as much fun?
References
Peter Godfrey-Smith, Other minds: the octopus and the evolution of life, 2017
three things: IQ and longevity, the Taliban and Americans, the real World Cup
Nerissa: …. superfluity comes sooner by white hairs, but competency lives longer
The Merchant of Venice, Act 1 , scene 2
Thing one
I don’t know what my IQ is, having never knowingly sat a test, but I assume it’s a number just short of infinity. So it was interesting to read, in Carl Zimmer’s book on genetics, She has her mother’s laugh, that IQ is highly correlated to longevity. Not that there’s a genetic link, at least not directly, but it stands to reason. The higher your IQ, the quicker it takes for you to ‘get’ things. This was more or less confirmed by a simple, ingenious brain processing test. Subjects were shown simple shapes flashing very briefly on a computer screen – two vertical lines spaced apart with a horizontal line sitting on top. The participants had to guess which of the two vertical lines was the longest each time. Researchers had worked out that if the images were flashed too briefly, the participants just resorted to guesswork. It required approximately 0.1 seconds for people, on average, to perceive the shape correctly. The key, though, lay in the variation of that perception. It ranged from 0.02 seconds to 0.136 seconds, and researchers found a pretty reliable correlation between accurate perception time and intelligence (presumably measured by IQ – Zimmer doesn’t say). Unfortunately it’s not quite reliable enough, apparently, for us to do away with those pesky, long-winded IQ tests and replace them snappy shape tests, but as mentioned, it does seem to confirm the intuition that intelligence has to do with sharpness and quick-wittedness. Which brings me back to longevity. Some work done in Scotland, which has turned out to be accidentally longitudinal, provides interesting evidence. In 1932 the Scottish government conducted a massive testing program of nearly 90,000 eleven-year-old students – just about the whole of the country’s kids of that age. They were all given a 71-question exam involving decoding, analogising and arithmetic among other things. Over time this ‘experiment’, or what you will, was forgotten, but the records were unearthed in 1997, and then researchers tried to get in touch, some 65 years later, with the ‘kids’ who’d been tested. They managed to gather together 101 elderly citizens in an Aberdeen hall to resit the gruelling test. They found that the score on the original test was a pretty good indicator – 73% – of the score second time around. But there was another interesting finding – the percentage of the test-takers who had scored well and were still alive in 1997 was considerably higher than those who’d scored poorly. Some 70% of the women in the top quarter of scores were still alive, compared to 45% in the bottom quarter:
Children who scored higher, in other words, tended to live longer. Each extra 15 IQ points, researchers have since found, translates into a 24% drop in the risk of death.
Carl Zimmer, She has her mother’s laugh, p296
Why is this so? Smarter people generally know what to do, and are quicker to learn what to do, to live longer, to make more, financially and otherwise, of the circumstances they find themselves in, to be safer, healthier and the like. Stands to reason.
Thing two
A huge fuss is being made of allegations, probably true, of Putin offering and paying bounties to the Taliban to kill American soldiers in Afghanistan. My first reaction to this news was – surely the fervently anti-American and anti-western Taliban were already hell-bent on killing infidel foreigners, and many of the purest ideologues among them would be insulted by the offer of bribes to do so? Then again, many of them would’ve been laughing up their ample sleeves at the thought of being paid by the Russkies, whom they likely consider only slightly less odious and infidelious than the Yanks, to do what they were already heaven-bent on doing. For this reason, it would surely be impossible to prove that any deaths of Americans, or their coalition partners – including Australians – at the hands of the Taliban, could be sheeted home to Putin and his fellow thugs. Even if money traced to Russia appeared in Taliban bank accounts after some atrocity or other, this doesn’t exclude the possibility that the atrocity would’ve occurred in any case. Win-win for the Taliban.
Thing 3
The announcement that the real World Cup will take place in Australia and New Zealand in 2023 makes life a little more bearable, though it’s three years away and I’m not getting any younger. This competition combines two of the most life-affirming enities in life, for me at least – women and soccer. Hopefully we’ll have learned many lessons from Covid-19 by then haha, and at least some of today’s thuggish political leaders will have been placed where they can do no more harm, and we can get on with the more exciting stuff of life, like having fun.
bird smarts and theory of mind
I like birds a lot – how could you not? I particularly like their brains, which considering their ‘beautiful plumage’, their grace in flight, their songs, their treatment of mates and offspring and their dinosaur history, is quite a big call. Not that I’ve ever seen or examined a bird’s brain, but I’ve seen and heard of some gobsmacking behaviour from some species, so I thought I might check out what’s known about their grey-white matter.
As with so many research fields, there’s been a surge in research into bird brains, and I’ve not heard the term bird-brain used as an insult in recent times. Still, when we think of bird intelligence, we tend to anthropomorphise, to compare them with us – do they play, do they use language or tools, do they recognise us individually, can they solve the same sorts of problems we can? That’s understandable enough, but in studying bird brains we should be just as thoughtful about the differences as the similarities.
The birds that have stood out for us so far are corvids – ravens, crows, jays and magpies, though many parrots such as the sadly endangered kea of New Zealand have also caught researchers’ attention. So how do these small-brained creatures manage to do the things that so impress us? Well for a start it may be more a matter of numbers than actual size (and it should be noted that birds have the largest brain to body ratio of any creature). Some research published in July 2016, which received a lot of media attention, found that bird brains pack neurons more densely than other animals. It was previously thought that neuron density didn’t vary much between species, but it’s now becoming clear this isn’t so, and actual brain size isn’t such a reliable guide to intelligence. But bird brains are really small compared to those of primates, so there must surely be other differences besides density.
But the 2016 research, which featured a revolutionary method for sampling brain tissue and making neuron counts, found that, in fact, a parrot brain contained as many neurons as some mid-sized primates. However, it’s also true that a bird’s brain is structurally different. Unsurprisingly, in the past, bird brains were thought of as primitive, and were classified as such, probably because they’re far removed from us on the evolutionary bush. Anthropomorphism again – understandably we used to feel that the only really intelligent creatures apart from us were those most closely related to us, but in recent decades we’ve learned that cetaceans, octopuses, elephants and birds, none of which are close to us evolutionarily, are highly intelligent creatures. And they’re not all mammals, and in the case of the octopus, not even vertebrates. This is quite exciting for our understanding of intelligent life forms – they can have a multitude of ‘brain plans’.
The first important bird brain anatomist was the 19th century German naturalist Ludwig Edinger, whose work was so influential that it provided the orthodox view until a few decades ago. Noting the very different structure of the bird brain, Edinger understandably assumed they couldn’t be as smart as mammals, and being one of the first to name brain structures in birds, he assigned names such as paleostriatum, suggesting a very basic region involving instinctual and motor activity. Basically, he assumed birds lacked a neocortex altogether. However, we now know that the bird brain evolved from the pallium rather than the striatum, and in 2005 it was agreed that an overhaul of bird brain nomenclature was required. All part of our more informed and respectful approach to these wondrous creatures.
National Geographic, in combination with other interested organisations, has declared 2018 the Year of the Bird, and has some fascinating pieces on bird behaviour on its website. That’s where I learned that, according to one researcher, birds’ brains are more distributed ‘like a pizza’, whereas the mammalian brain is more layered. However, the wiring that underlies long-term memory in birds (and they clearly have impressive long-term memory) and decision-making is similar to that in mammals.
Here are just a few of the extraordinary behaviours discovered. Green-rumped parrotlets of South America use calls as names for their chicks. Male palm cockatoos of New Guinea court females not only with calls but by drumming on hollow trees with twigs and seedpods – arguably a form of music. Goffin’s cockatoos, from Indonesia, make and use tools in captivity even though they’ve never been seen to do so in the wild. They’re also expert at opening locks. The National Geographic video ‘Beak and Brain: genius birds down under’ compares the kea of New Zealand’s South Island to the New Caledonian crow as problems solvers tasked with overcoming a variety of obstacles to obtain their favourite treats. It makes for riveting viewing. Other videos online show crows creating hooks on sticks and using them to pull food out of holes.
Another video, involving experiments with jackdaws by Princess Auguste of Bavaria (really), a behavioural scientist, shows that these birds are much influenced by the gaze of humans, and can be directed to act simply by the gaze of a human they have bonded with. They also appear to know when they’re not being watched, and can act more boldly in such circumstances. All of this raises obvious questions, voiced by Auguste in the video. How do jackdaws think? How is it similar to the way we think? Do they recognise intentions? Do they have a theory of mind?
This theory of mind issue comes up with a lot of birds, and other animals. It refers to whether and to what extent a creature has the ability to attribute any or all of the variety of possible mental states to itself and/or others. The question of an avian theory of mind was explored in a study entitled ‘ravens attribute visual access to unseen competitors’. In describing their experiment, the authors highlight what they see – or what skeptics see – as a problem with much experimental work that tests for theory of mind in other species. This is the question – as I understand it – of whether the bird or animal actually ‘sees’ or reads what conspecifics are thinking, or is simply following particular observable cues. It was a complex experiment involving caching (hiding a store of food for later consumption, a common raven behaviour), peepholes that were either open or closed, and inference (by the researchers) from observed behaviour to either ‘minimal’ or ‘full-blown’ Theory of Mind. As a dilettante I found much of the discussion and analysis beyond me, but I found these remarks interesting:
In conclusion, the current experiment, together with the other recent studies on chimpanzees11,12, provides strong evidence against the skeptical hypothesis that the social cognition of nonhuman animals is limited to behaviour-reading. Peephole designs can allow researchers to overcome the confound of gaze cues, but further experimental work is needed to determine the specific limits of ravens and other animals—including humans—on such tasks.
In my general reading on these matters I’ve definitely found something like a rift between the skeptics on the behaviour of higher primates, dolphins and other ‘smart’ creatures, and those who have pushed, sometimes naively, other-life smarts with regard to ‘language’, memory and emotional intelligence. What I think needs to be kept clearly in mind is that in examining intelligence, or brain power or whatever, human intelligence may be only one of a possible infinity of gold standards. Is Theory of Mind itself an anthropomorphic concept, or one that lends itself too easily to anthropomorphic thinking?
Meanwhile, experimentation and investigation of the neurological underpinnings of bird behaviour will continue, and I’ll be watching for the results. Just about to embark on Jim Robbins’ book The wonder of birds, and I hope to learn more especially about bird neurology in the future, and how it relates to birdsong. That’s a whole other issue.
fountains 2: 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.