Dolphins dolphins dolphins

I'm a little late to this particular debate, but it's long been one of my favorite subjects, ever since I had a most intriguing encounter with a wild member of the species Tursiops truncatus, in Australia 16 years ago. More about that later. I, too, was taken aback by the recent media coverage of Manger's study of dolphin intelligence. What was even more surprising than his study, however, was his flipper flippant comment that dolphins trapped in tuna nets must be stupid because, "If they were really intelligent they would just jump over the net because it doesn't come out of the water."

There's a very good response to Manger's postulate that dolphin brain morphology is the result of adapting to a cold marine enviroment. In fact, there are plenty. We'll get the obvious one out of the way first: not all dolphins, even all T. truncatus, live in cold regions. T. trunacatus are found in a wide range of thermal conditions, yet their brains are all pretty much the same size and shape. Coturnix also does a great job summarizing the difficulties of applying anthropocentric definitions of intelligence to other species.

An even better response comes in a chapter of a new book on such things. The author of the chapter is none other than Louis Herman, who's been studying dolphin behavior for as long as I can remember. Though he wasn't writing directly in response to Manger, his basic approach to studying intelligence is sound, as he outlines near the outset of his chapter on "Behaviour and cognition symbolic environments" (In S. Hurley & M. Nudds (Eds.) Rational animals? Pp. 439-468. Oxford University Press):

...intelligence manifests itself in behavioural flexibility, the ability to modify or create behaviour adaptively in the face of new evidence or changes in world conditions (cf. Herman and Pack 1994). The intelligent animal, in principle, can go beyond the boundaries of its familiar world, and beyond its biologically programmed or learned repertoire of behaviours that enable successful responding in that familiar world, to function effectively in new worlds or in new world conditions.

Herman then goes on to list a long series of examples of dolphin behavior. We're all pretty used to seeing such things in aquariums, and there are even more interesting examples in the wild.

... the responses of the dolphins to the challenges posed appeared to require logical inferences and innovative responding, as well as adaptive responding to new or changed 'world' conditions. These capabilities seem reflective of the exceptional adaptability of the bottlenosed dolphin in its natural world. This species exhibits remarkable diversity in its natural habitats, including all of the oceans within the temperate and tropical zones, as well as inshore and offshore ranges within those habitats, and migration between the two ranges. The different habitats may each demand unique foraging, feeding, antipredator, and social strategies, suggestive of an ability of bottlenosed dolphins to adapt behaviourally to diverse worlds or to changes in world conditions, including movement from the natural world to the world of the laboratory or marine park.

Herman also wrote in a post to a marine mammal listserv recently that "A problem is that Manger's review of the cognitive literature is limited and includes little of the large body of contemporary laboratory and field data showing advanced cognitive skills in dolphins." In other words, dolphins are too smart. I side with Herman for two reasons. First, he's in a better position to pass judgment on one of the trickiest subjects in wildlife ethology. Second, his description seems to explain what happened back in 1990 in Shark Bay, Western Australia.

You may have heard of the dolphins of Shark Bay, where after years of following fishing boats around in hopes of scoring some scraps of catch, the local bottlenose dolphins got so used to humans that they (at least, the females) would swim up to the shallows of the beach and allow tourists to pet them -- and take the odd fish if it was offered them. One sunny morning, I was one of those tourists.

The park ranger warned us all not to let our hands get too close to the bowhole, which is a sensitive body part for a dolphin, but my hand accidentally ended up coming very close to one dolphin's bowhole as she rolled while swimming slowly past me. In response, she rapped me good and hard on the shin with her beak, making quite a commotion in the process, before swimming rapidly off to join her companions, who were keeping a safe distance about 100 metres offshore. And it smart!

The ranger said he saw what happened, recognized it wasn't my fault, explained that that sort of thing happens from time to time and advised me not to worry about it. I felt like an idiot, of course, and retreated to the beach for an hour to mope. My shin hurt for at least half an hour.

When I returned to the water to try again to make friends with the dolphins, the one who had hit me (name of Puck, as identified by the distinctive dorsal fin) was nowhere to be seen. But a few minutes later, one dolphin broke away from the distant group and headed straight for me. It was Puck, of course. She swam moderately fast in my direction, abruptly slowed as she came within reach, swam past my legs, rubbing her beak ever so gently on the shin she had struck an hour before, then calmly swam off.

Remember, this was not a domesticated animal, but a wild marine mammal that chose do the equivalent of "I'm sorry" with a member of another species. So the comeback that "my dog can do that" doesn't hold water.

There are explanations that do not require an extreme degree of intelligence or moral sensibilities. New Scientist last year ran a fascinating review of conflict resolution and reconciliation behavior among several species, including primates and dolphins (New Scientist 7 May 2006, Issue 2498.), the basic thesis of which was reconciliation is an evolved response that strengthens community bonds, reduces stress and minimize conflict.

Fair enough. But all the species that express such behavior are also generally considered relatively intelligent. Gorillia and chimpanzees, are among the best non-human examples. So it would seem fair to afford other species that also demonstrate some level of sophistication when it comes to reconciliation behavior some degree of respect. I'm not by any means arguing they're comparable to humans. But to dismiss their obvious intelligence as Manger appears to do is just plain silly.

There's another piece of evidence from Shark Bay that I thought offers some strong evidence of intelligence, or at least cleverness: Sometimes, the dolphins will accept fish offered them by tourists. Sometimes they decline, evidently not hungry. Other times, however, if they've obviously had their fill, some dolphins would accept the fish, but not swallow it. Instead they'd swim out a ways, then discard it. The best explanation I can think of for such behavior is the dolphins like the option of the human-supplied fish, and want to make sure the supply continues, so they sometimes chose to be polite rather than turn down the offer and run the risk of the supply evaporating.

Or does anyone have a better answer?

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One of Manger's arguments is that dolphin sound production doesn't go outside the usual for a non-human mammal, therefore we should not accord it high intelligence.

However, Manger's exclusion of dolphin sound production leaves me scratching my head. He talks about neural control of vocal cords, yet it has been clear for the past couple of decades that dolphins primarily produce sound in the nasal passages above the bony nares (we now know the specific site as the phonic lips), not via the larynx. Manger talks about a paucity of whistle types, yet fails to discuss production of click train-based sounds and their very much more extensive repertoire.

Even if one were inclined to ignore all the rest of the evidence that Manger is ignoring, it seems to me that the arguments he does make have some major problems.

A few summers ago, I was fortunate to be able to participate in a bottlenose dolphin live capture study (for health assessments) - so captures of animals in the wild for examination. I got to spend some time with a number of animals while they were being poked and proded. What fascinated me the most was how calm they were while they were being examined - they easily could have used their tails and harmed some of the scientists - but most of them just slowed their breathing. Perhaps it was a stress response (to shut down) - and one of the marine mammal veterinarians also suggested that they didn't fear us because we weren't a known predator to them. Regardless, they were calm, and oddly communicative. Intelligent - for sure, but then I'm one who questions the intelligence of humans all of the time, so I'm biased.

i like it but you could make it better make the dolphins do triks dolphins are my favorotte animals i hop you stop the people from killing them its like some one killing us and al they want is some space and freedom i think its crewl to keep the dolphing in a little pool like on tv but in big masive pools im not botherd i tink thats good and then they all wont die out so i love dolphins i hate the people who kill them i think there good and they help you when youre in the sea so why carnt you help them and stop them from diying out it would be my dream

we were NOT trying to "steal bandwidth" when we clicked on the Google image of a dolphin. our students just wanted to look at the photo.

By denise brown (not verified) on 15 Nov 2007 #permalink