Dolphins are intelligent enough to warrant rights as "non-human persons," according to a team of marine biologists. This view is based on wide-ranging analysis of dolphin behavior, social interaction, and anatomy.
Recent dolphin studies reveal a huge amount of evidence for both the breadth and depth of dolphin intelligence. Dolphins have displayed self-awareness, unique personalities, the capability to think about the future, complex cooperation and group problem-solving, the ability to not only recognize themselves in mirrors but also use it to look at different parts of their bodies, and even the capacity to learn symbol-based language.
One anecdote in particular illustrates the potentially human-like intelligence of dolphins. It shows the creatures teaching each other skills that confer no survival advantage and appear to be purely for the sake of enjoyment:
In one case a rescued dolphin in South Australia, taught to tail-walk during recuperation, in turn taught the trick to other wild dolphins in the Port Adelaide river estuary when she was released. According to marine biologist Mike Bossley it was "like watching a dance craze take off", with the dolphins apparently learning the trick just for fun, since tail-walking has no natural function.
There is also anatomical evidence to support the case for high dolphin intelligence. The ratio of brain mass to the overall mass of the body in dolphins is second only to that of humans, exceeding even that of chimpanzees. Of particular interest were the sizes of the neocortex and cerebral cortex in bottlenose dolphins, which were surprisingly comparable to those of humans. The dolphin cerebral cortex has the same complex folds that its human counterpart does. These folds both increase the cortex's volume and allow the brain to make more sophisticated connections.
Diana Reiss and Lori Marino, biologists who were behind two of these studies, believe these findings, taken as a whole, indicate dolphins possess an intelligence level shockingly close to that of humans. Indeed, they may be too smart for humans to ethically eat them or keep them in captivity for entertainment purposes. As such, Reiss and Marino argue they deserve rights as "non-human persons", essentially granting dolphins rights as intelligent individuals. They will look to kick off this ethical debate at a conference in San Diego later in January, at which time they will present the complete findings of their work.