Matching Wits: Dolphin vs. Primate

Gauging the depth of our intelligence

Posted May 30, 2013

A while back, I was taught a thing or two about thinking by an Atlantic Bottlenose Dolphin named Bugs. Among them was the embarrassing truth that we humans sometimes come up with the short end of the stick when we match wits with other animals – especially when the other animal is a dolphin.

Human notions about dolphin cleverness are hardly new.

Stories about intelligent dolphins knowing just what to do to rescue drowning human swimmers go all the way back to the ancient Greeks, and have been handed down to us in some of our favorite myths.

Increasingly over recent decades, science has borne out the truth about the intelligence of dolphins.

For one thing, the dolphin brain weighs slightly more than the hardware we carry around in our heads – about three and a half pounds for the dolphin compared to three pounds for us. Not only that, but the degree of surface folding, another measure of brain potential, is greater in dolphins than in humans.

Unlike many other animals – but very much like humans – dolphins possess an unusually high degree of self-awareness and are capable of abstract thought.

In the wild, dolphins actually name themselves and frequently begin underwater communications with a stream of bubbles accompanied by what has become known as a signature whistle.

Together, the bubble stream and signature whistle provide both visual as well as audio cues to nearby dolphins about who is communicating. Interestingly, signature whistles of individual dolphins carry sound fragments closely related to those found in the signature whistles of the individual’s mother. Dolphins, it seems, not only name themselves; they choose names that honor their matrilineal heritage. Self-awareness, indeed.

In captivity, dolphins have demonstrated self-awareness through a modified form of the mirror test commonly used by scientists as a measure of intelligence.

Dolphins observing themselves on a TV screen via live-feed recordings in their tanks recognized their own “mirror image” and pulled faces while angling their faces up and down as well as side to side just as a human might. They also refrained from such responses when the live-feed was replaced with earlier recordings of themselves.

What do dolphins do with all their intellectual prowess?

Well, sometimes they play games. But just as often, and especially when interacting with humans, they tackle puzzles and solve problems – frequently with more intellectual dexterity than their human trainers.

In a 1957 Marineland experiment with famed dolphin expert John Lilly, a dolphin being rewarded for audible whistles apparently became curious about the hearing range of its human handler. So, the dolphin began an experiment of its own.

After each rewarded whistle, the dolphin raised its whistle pitch until the rewards ceased. Lilly, the experimenter, could tell by the slight twitch of skin around the dolphin’s blow hole that the animal was still whistling. Only now, because Lilly wasn’t hearing the sound, he stopped rewarding his test subject.

The dolphin, having exceeded the upper limit of frequencies within the human hearing range, emitted several additional “silent” whistles before hitting again upon a tone Lilly could hear and, therefore, reward. The dolphin had learned something new about the sensory limits of humans and remained within audible limits for the remainder of the experiment. Personally, I suspect the dolphin later published an important scientific paper on the subject.

Which brings me back to my former dolphin co-worker, Bugs, who taught me an important difference about dolphin versus human thinking.

In the early phases of an experiment in which Bugs would eventually help scientists further their knowledge of dolphin echolocation abilities, I was tasked with training Bugs to station himself at a given point and report on the absence or presence of nearby target objects.

To establish the stationing point – which would eventually need to be six feet or so below the surface – I first asked Bugs to place his head through a metal hoop at the waterline. Bugs caught on quickly and soon was tentatively identifying the target objects as either missing or present. When he got really good at the task, I gradually lowered the hoop until Bugs was a couple of feet deeper.

Then I made a classic training blunder. Two of them, actually.

First, I kept the stationing hoop at the new depth for far too long. In training session after training session, while Bugs worked out the kinks in his object recognition task, he built up a long behavioral history of reward at the new depth.

My second mistake came weeks later when I again lowered the depth of the hoop – by far to great a distance, as it turned out.

I expected Bugs, who by then was a master at the object recognition game, to make the depth adjustment easily. After all, any human who had learned to place his head through a hoop for weeks on end would follow the hoop to a new location, surely. The problem was, of course, that Bugs wasn’t human.

So when I asked Bugs to get ready for the object recognition game, he eagerly dropped down into the water – exactly two feet below the surface despite the fact that the hoop station was another four feet directly below him.

I was frustrated with Bugs at first. In fact, it took me longer than I’d like to admit to realize that Bugs was actually behaving in a much more logical fashion than I, with my landlocked, two-dimensional perspective. In a dolphin’s three-dimensional world, depth matters.

In fact, it matters a lot.

The physical form of dolphin bodies provides a fairly obvious clue as to just how much it matters. Dolphin skin is pigmented dark above and light below for a very good reason. Sixty-five million years of evolutionary experience has resulted in shading and counter-shading that make dolphins difficult for predators to see from above while peering into gloomy depths, and challenging to spot from below against the relative brightness of surface-lit waters in the shallows.

Bugs and I worked together to repair my two-fold training blunder, and all was fine in the end. Along the way, Bugs proved himself to be a patient teacher, taking a little time out of his training regimen to pass along a lesson about perspective and multi-dimensional thinking to a well-meaning primate who hadn’t quite made the connection.

Copyright © Seth Slater, 2013