The Case against Marine Mammals in Captivity - The Humane ...

Cetacean IntelligenceOne of the primary foundations for the moral andethical arguments against keeping cetaceans incaptivity is that they are intelligent. Ironically itis their intelligence that has made these animals desirablefor public display—their ability to understand humancommands and learn complex behaviors or tricks has beenexploited to provide humans with entertainment. Likewisetheir intelligence increases people’s rapport with andinterest in these animals. But exactly how intelligentare cetaceans?A recent debate on this topic resulted when a researcher namedPaul Manger postulated that the dolphin’s large brain could haveevolved for physiological reasons having to do with body temperatureregulation. 258 In his paper, he offered what he considered substantialevidence that dolphins were no more intelligent than manyterrestrial ungulates (to which cetaceans are evolutionarily related).However, a rebuttal to this hypothesis from several prominentcetacean biologists summarized far more thoroughly the large andgrowing body of literature examining small cetacean intelligenceand social sophistication. 259 In addition, these researchers notedthe temperature regulation hypothesis required a series of geologicevents during the dolphin’s evolution that did not match the paleontologicalrecord. Essentially Manger’s hypothesis requires eithermisinterpreting or ignoring a considerable amount of the scienceaddressing cetacean intelligence, reducing its legitimacy.Most studies demonstrating cetacean intelligence have been conductedon captive animals, albeit primarily in dedicated researchfacilities or non-profit public display facilities. Yet as these captiveanimals increasingly provide information to their captors abouttheir sentience and intelligence, the ethical and moral argumentsopposing cetacean captivity become increasingly convincing.Several studies have tried to assess marine mammal intelligence bylooking at the ratio between the size of the brain and the mass ofthe animal. 260 Although dolphins have smaller brains relative totheir size than modern humans have, they would be at least asintelligent as prehistoric humans according to this measure.The alert expression on this dolphin’s face is almost certainlya true reflection of the active mind behind it.However, this measure does not take into account several issues,one being that the structure of the dolphin brain is very differentfrom that of humans. If anything, those parts that deal with sophisticatedthought and cognition are more complex and have a relativelygreater volume than similar tissues in humans. 261 Anotherissue is that these calculations do not take into account the highproportion of a cetacean’s mass that is blubber, a tissue that needsno brain mass dedicated to its maintenance. Upon considerationof these factors, the potential for intelligence in dolphins thenbecomes far more comparable to that of humans. 262