MRI scans demonstrate that dolphin brains, like human ones, are four or five times larger than those of other, similarly-sized animals, explained Lori Marino, a leading dolphin expert and senior lecturer in neuroscience and behavioral biology at Emory University.
“If we use relative brain size as a metric of ‘intelligence’ then one would have to conclude that dolphins are second in intelligence to modern humans,” she said.
Marino addresses two additional points to prove her case: first, the dolphin neocortex, which managed high-order thinking and emotional processes, is highly developed in dolphins, and second, dolphins exhibit many human-like skills, such as cultural learning, self-recognition, communication through symbols, and the ability to grasp abstract concepts.
Another study strengthens Marino’s claim, but from a different perspective altogether; dolphins may use complex, non-linear mathematics throughout their hunts.
Tim Leighton, study author, was first inspired to research the idea after watching the Discovery Channel’s ‘Blue Planet.’
“I immediately got hooked, because I knew that no man-made sonar would be able to operate in such bubble water,” he said, referring to the hundreds of bubbles that form around the dolphins’ prey during a hunt.
“These dolphins were either ‘blinding’ their most spectacular sensory apparatus when hunting- though they still have sight to rely on- or they have sonar that can do what human sonar cannot… Perhaps they have something amazing,” he continued.
“Bubbles cause false alarms because they scatter strongly,” Leighton explained, “and a dolphin cannot afford to waste its energy chasing false alarms while the real fish escape.”
Leighton believes the marine mammals rely on a complex mathematical process that is based on the fact that the emitted pulses vary in amplitude; one may have a value of 1, while the next is a half of that amplitude. If his theory is correct, there are two stages to the hunt.
“So, provided the dolphin remembers what the ratios of the two pulses were, and can multiply the second echo by that and add the echoes together, it can make fish visible to its sonar. This is detection enhancement,” Leighton said.
The second stage works to differentiate between bubbles and actual prey by subtracting the echoes from one another. The math is complicated, but basically renders the fish visible to sonar through addition, and then invisible by subtraction- confirming the target.
Further research is required to validate Leighton’s theory, but several different angles have implied that dolphins may indeed be the second most intelligent animals on Earth today.