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August 23, 2006

Dolphins dumb, news report claims

Alon Levy reports on a new study about dolphin neuroanatomy.

South African biologist Paul Manger recently published a paper arguing that dolphins' large brains and high brain-to-body-size ratio evolved to insulate the brain in cold water. [Sun Times]

Manger found that dolphin brains have a lot of fatty, insulating white matter (glial cells) and proportionately less information-signally grey matter (neurons).

Chicago Sun Times reporter Tenille Bonoguore infers that the whole dolphin/intelligence thing is a big urban myth:

"Dolphins and whales are dumber than goldfish and don't have the know-how to match a rat, new research from South Africa shows."
If dolphins were an alien species that we'd never observed, this study might give us a reason to downgrade our provisionally estimates of dolphin intelligence. In fact, we have ample evidence that dolphins are intelligent because, well, they behave intelligently.

For example, dolphins maintain complex and dynamic social relations in the wild. They can be taught to perform complex tasks (like mine sweeping, shown above). Dolphins may even display mirror self-recognition--a capacity that was previously documented only in humans and other higher primates.

At a meeting of the Society For Philosophy and Psychology in Edmonton, I went to a talk given by a dolphin researcher from York University who worked on mirror self-recognition. She described how some of her dolphins not only recognized themselves in mirrors in experimental settings, but were also videotaped using the mirrors in spontaneous play. One dolphin devised a game that involved propelling a ring backwards underwater while staring at the mirror and watching the reflection to see where to catch the ring again.


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Scientists in South Africa found to be dumber than previously believed.

I'm not sure if the scientist actually said that dolphins were really dumb. I'm going to assume that the scientist has enough sense to limit his analysis to the ratio of white to grey matter in dolphin brains.

Some non-scientists assume that dolphins must have a Cosmic level of consciousness because they have such big brains, but no serious scientist believes that.

It is interesting that dolphin brains are wired up so differently from those of large terrestrial mammals with complex cognitive capacities.

I blame this one primarily on the Sun Times reporter.

Manger found that dolphin brains have a lot of fatty, insulating white matter (glial cells) and proportionately less information-signally grey matter (neurons).

Maybe it is the fault of the reporter ... either that or Manger is out of the loop in the latest buzz on neuro-anatomy: it turns out that white matter actually plays a major role in making sure the neurons are connected correctly, etc. -- thus, while the neurons "do the work" so to speak, an abundance of white matter doesn't necessarily just mean a lot of insulation -- it can mean that there's a lot of complexity in the brain, in spite of having a relatively small number of neurons.

I don't think this is the reporter's fault. I did a Google news search for Manger and Dolphin, and the resulting reports from all over the place, including Australia and Outside Online, have Manger clearly saying that dolphin behavior is not as complex as people have said, that training them has been slow and via unsophisticated stimulus-and-response methods, and that their previously lauded communication skills come down to seven species-specific noises.

Different media outlets with different interests in different countries have the same take on what he said, with different supporting quotes from different people weighing in that he may be right. This guy is right or he's wrong, but I see nothing to indicate that his position has been misinterpreted.

I expect that if he's off his rocker, a ton of research showing what a loon he is will land on him like a pallette of bricks in a few months. Either that, or bunches of otherwise intelligent scientists have totally given in to their impulse to see intelligence in an animal everyone likes. Occam's Razor tells me which outcome to expect.

There's also evidence, recently in the news, that dolphins have a material culture. That is, mother dolphins teach their daughters to use sponges to protect their snouts as they forage for food. Tool use per se isn't a marker of intelligence, but the teaching and learning aspect of tool use in dolphins is suggestive, especially if, as Kruetzen et al. demonstrate, that "genetic and ecological explanations for this behavior [the use of the tools, not the teaching] are inadequate."

Jamie's Trip to Syracuse

Michael Berube does a little hopeful but slightly skeptical exploration of "Facilitated Communication" I keep an open mind about dolphin intelligence, but recognize the possibilities for bias.

My dogs can tell time and temperature, as evidenced by how intensely they demand their morning walks. I kid you not.

Now that was a major major oops.

Here's Berube

Don't even follow the link above.

White matter is indeed far more than insulation; a relative lack of white matter (or surfeit of gray) is typical of autism. Dolphins might be called anti-autistic; I don't know that it makes them any less or more intelligent, but it probably indicates something about their social order, communication, etc.

Didn't I read somewhere that some researchers believe that dolphins gossip? ...Yeah, here it is.

That's a sign of intelligence ...of a sort. They're at least as intelligent as bloggers, at any rate.

You mean those fat heads did not say thanks for all the fish in the Hitchhikers Guid to The Galaxy?

I want my money back!

I’m certainly willing to believe that dolphin intelligence has been exaggerated. On the other hand, how much is really known about it? There are 33 or so species of “ocean” dolphins, three or four species of river dolphin, some twenty odd species of beaked whale, the sperm whale along with it’s two strange little cousins, and the baleen whales. We know a little about the minds bottlenose dolphins and a handful of others. Most of the other species are behavioral/mental terra incognita, some absolutely so. Of some, such as a couple of the beaked whales, we know only that a few have washed up on beaches.

Observing cetaceans ranges from difficult to impossible. I worked as a government marine mammal observer aboard tuna and other fishing vessels for five years. In some places, like in yellowfin tuna fishing areas I’d see dozens or hundreds of porpoise every day, often at close range. Even when they’re calm and you’re looking right down on top of them, you still have a hard time even counting them, much less figuring out what they’re doing.

I saw any number of porpoise (spinner and spotted dolphins mostly) die in tuna purse seines for the simple reason that they apparently couldn’t figure out how to jump over the cork line even though they leap all the time. The fishermen took this as evidence that they were stupid. But, consider, that in the Eastern Tropical Pacific where porpoise are deliberately encircled with purse seines (Yellowfin tuna follow the porpoise, so you catch the porpoise, then separate fish and porpoise by dragging the net out from under the porpoise. Usually works, sometimes doesn’t.) there is nothing like a net in any direction for thousands of miles. No coast. no islands, no reefs, nothing but the occasional log. Something solid or semi-solid, like a mile-long net, is normally quite literally beyond conception for the animals living there. Like us trying to picture the extra dimensions physicists assure us exist. Would you think of hopping over a fifth dimensional barrier?

I saw plenty of evidence that porpoise learn. Schools of porpoise that have experience being set on (seine encirclement) by tuna seiners learn how to evade the set, and once trapped, learn to stay relatively calm and wait for the “backdown” procedure that releases them. Once, within sight of Acapulco, where porpoise are constantly harassed by seiners, I watched a school of porpoise toy with us. We chased them every which way from Sunday, and each time we were at the moment of releasing the seine, they’d turn and we’d lose them again. Eventually, they waited just long enough for us to release the net, at which point the boat is committed to turn one direction. They turned one last time, heading out past the chase boats and seal bombs and out of harms way. This might be anthropomorphizing, but I had seen hundreds of sets by then, including sets on naïve porpoise in the Central Pacific where catching them is just taking candy from a baby. These Acapulco guys knew exactly what they were doing. I wouldn't go so far as to say they were laughing, but they had every reason to.

I’m not sure I’m buying the cold-water brain insulation theory as: 1- We don’t know enough about cetacean evolution to know whether it occurred in warm or cold water. 2- Many species of dolphins and whales spend their entire lives on warm water and I’ve never heard of their brains being any different from their cold-water relatives. And, 3- A counter-current heat exchange circulation system (a rete mirabile – a common evolutionary physiological trick) would take care of brain cooling.

"Mine sweeping"? I always thought that picture showed a jihadist dolphin from an aquatic sleeper cell attacking an unsuspecting American sailor.

My bad, I guess.

You know, this is one of those questions that should not be political, but it. Really, it's a simple matter of fact. But because some people sentimentalize dolphins, and because those people, if political, tend to be liberal, at least on issues like environmentalism and animal rights, saying "Dolphins are dumber than goldfish!" can be a sneaky way of saying "You environmentalists are so stupid!" and "I bet you believe in global warming too". It reflects that fact that what we have are less coherent political ideologies than political cultures.

Does this mean we can go back to the golden era of eating Dolphins and Tuna on Rye?

Does this mean we can go back to the golden era of eating Dolphins and Tuna on Rye?

"Dumber than goldfish" is a a priori ludicrous claim. There's a huge range of intelligence between the most exaggerated claims for dolphins and, well, goldfish.

As for insulation: yes, white matter (some glial cells) insulate. They insulate the axons of some neurons, allowing for much faster signal conduction, i.e. they're an key part of fast information processing.

Some links. I'd post all three directly but I fear tripping filters.

Isn't the real indicator of mental activity the number of synapses?

Dolphins' fast information processing isn't necessarily evidence of high-level thoughts. It may be evidence of quick sound processing, since dolphins are primarily aural creatures, and the speed of sound in water is four times what it is in air.

My main point was a nagging feeling that someone, somewhere, had read "insulation" in the context of white matter and come to horribly wrong conclusions. One extra thing I've just thought of is that at least in human brains, the white matter wiring is on the inside of the brain. The gray matter, which does the actual computation, is on the surface, with the white matter connecting different areas of gray matter. As an insulation scheme that seems rather backwards, though humans rarely have to worry about their brains being too cold.

Synapses wouldn't be conclusive either. The main evidence for high level thought would be behavior best explained by inferring high level thought behind it. Being adaptively social and tool-using with some proto-language research results seems pretty indicative.

cfrost mentions our knowing the most about bottlenose dolphins. According to the Guardian article in my link, bottlenoses have the highest brain/body ratio (encephalization quotient) of the many dolphin species, or of any species besides humans. Good reason for giving them priority.

Re goldfish: apparently they have a brain/body ratio higher than wolves, though lower than rats.


I have tried to comment, but it got too long so it is on my blog. One correction: glia are not white matter. Axons are white matter while neuronal bodies are grey matter. Glia surround both. It is the color of Schwann cells (a type of glia) that makes axons look whitish.

Thus, more grey matter means more neurons. More white matters means more connections. What is more important? I'd say connections.

Bora, the Sun Times article says that dolphins in fact have an excessive amount of glia, not white matter.

Yup, I know - I was correcting Lindsay and the commenters who continued with her error.

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