Underestimating dolphin’s brains

I have been reading in the social media an essay by Captain Paul Watson, and as I know nothing about his scientific credentials, I have been fact checking. Watson was associated over the years with a number of conservation groups, especially Sea Shepherd Conservation Society.

From other sites I find that his description of the dolphin brain is a good one. The cetacean brain has been large for a long time compared to humans and it is indeed very large. It is unusual in having four rather than three cerebral lobes. Its cerebrum is differently organized with an unusually large association cortex and a very close ‘cortical adjacency’ of the senses and motor areas.

The human brain, like most mammals, has a cerebrum divided into a rhinic lobe, limbic lobe and supralimbic lobe (divided into sub-lobes occipital, parietal, temporal, frontal). In the dolphin there are four lobes. The rhinic is somewhat different. The limbic lobe is large but similar to ours. Between the limbic and the supralimbic another lobe is inserted, the paralimbic. The supralimbic is not divided into sub-lobes and appears to be totally associative, like our frontal lobe. The sensory and motor areas occur in the paralimbic lobe, but they are organized differently: much more integrated and in close contact. Some believe that this gives a more unified perception without separate senses but with a single sort of perception. The cetaceans use an acoustic (sonar) sense that seems to be at one with their vision. The contact between sensory and motor areas may give the animals great speed of perception and action.

Watson’s essay (here) points out: Interspecies (intelligence) comparisons focus on the extent of lamination, the total cortical area, and the number and depth of neocortex convolutions. In addition, primary sensory processing relative to problem solving is a significant indicator; this can be described as associative ability. The association or connecting of ideas is a measurable skill: a rat’s associative skill is measured at nine to one. This means that 90 percent of the brain is devoted to primary sensory projection, leaving only 10 percent for associative skills. A cat is one to one, meaning that half the brain is available for associative ability. A chimpanzee is one to three, and a human being is one to nine. We humans need only utilize 10 percent of our brains to operate our sensory organs. Thus the associative abilities of a cat are measurably greater than a rat but less than a chimp, and humans are the highest of all. Not exactly. The cetacean brain averages one to twenty-five and can range upward to one to forty. The reason for this is that the much larger supralimbic lobe is primarily association cortex. (and not basic sensory and motor cortex)

In humans, the projection areas for different senses are widely separated from one another, and the motor area is adjacent to the touch area. For us to make an integrated perception from sight, sound, and touch, impulses must travel by long fiber tracts with a great loss of time and information. The cetacean’s paralimbic system makes possible the very rapid formation of integrated perceptions with a richness of information unimaginable to us. He gives an example: A dolphin can see a tumor inside the body of another dolphin. If an animal is drowning, this becomes instantly recognizable from being able to “see” the water filling the lungs.

…Based upon comparisons of cortical structure alone, a sperm whale would score 2,000 (in IQ). The truth of the matter is that we know absolutely nothing about what goes on in the brain of a whale or a dolphin. In our ignorance, we resort to the arrogance of denial and dismissal. We deny the physiological evidence and in general we have denied that other animals can think or even feel.

Sight in humans is a space-oriented distance sense which gives us complex simultaneous information in the form of analog pictures with poor time discrimination. By contrast, our auditory sense has poor space perception but good time discrimination. This results in human languages being comprised of fairly simple sounds arranged in elaborate temporal sequences. The cetacean auditory system is primarily spatial, more like human eyesight, with great diversity of simultaneous information and poor time discrimination. For this reason, dolphin language consists of very complex sounds perceived as a unit. What humans may need hundreds of sounds strung together to communicate, the dolphin may do in one sound. To understand us, they would have to slow down their perception of sounds to an incredibly boring degree. It is for this reason that dolphins respond readily to music. Human music is more in tune with dolphin speech.

While I was looking at Watson and some authorities on cetacean anatomy, there was a blog on Babel’s Dawn about dolphin names. (here) The message was that using names does not in itself make a language; language talks about some topic. It seems to me that looking for something that we would call a language in whales and dolphins is probably not a reasonable search. What we really want to know is how cetaceans communicate. We know that they have sophisticated ways of communicating from their behavior. We have no idea whether their communication is analogous to our language, with matching points of reference or structural relationships or whether it has a completely different sort of structure. We have no idea whether their communication is in any way superior or inferior to ours. We also have little idea of their knowledge and culture; they could be all the way from impoverished to rich.

2 thoughts on “Underestimating dolphin’s brains

  1. Amy

    This was really helpful for my science project. thank you so much. This is exactly what I have been looking for for a very long time. I really appreciate it. Make sure you know that you made my day when I found this. Again thank you so much.


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