Cetaceanintelligence

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Cetacean intelligence

Cetacean intelligence Cetacean intelligence refers to the cognitive capabilities of the Cetacea order of mammals, which includes whales, porpoises, and dolphins.

Brain size Brain size was previously considered an indicator of the intelligence of an animal. However, many other factors also affect intelligence. Recent discoveries concerning bird intelligence have called into question the usefulness of brain size as an indicator. Since most of the brain is used for maintaining bodily functions,[citation needed] greater ratios of brain to body mass may increase the amount of brain mass available for more complex cognitive tasks.Wikipedia:Identifying reliable sources Allometric analysis indicates that mammalian brain size scales at approximately the ⅔ or ¾ exponent of the body mass. Comparison of a particular animal's brain size with the expected brain size based on such allometric analysis provides an encephalization quotient (EQ) that can be used as another indication of the animal's intelligence. (Tursiops truncatus) brain (middle), compared with brains of wild pig (Sus scrofa) (left), and human (Homo sapiens) (right). • Sperm whales (Physeter macrocephalus) have the largest brain mass of any extant animal, averaging 7.8 kg in mature males. • Bottlenose dolphins (Tursiops truncatus) have an absolute brain mass of 1500-1700 grams. This is slightly greater than that of humans (1300-1400 grams) and about four times that of chimpanzees (400 grams). • The brain to body mass ratio (as distinct from encephalization quotient) in some members of the odontocete superfamily Delphinoidea (dolphins, porpoises, belugas, and narwhals) is second only to modern humans, and greater than all other mammals (there is debate whether that of the treeshrew might be second).[1] In some dolphins, it is less than half that of humans: 0.9% versus 2.1%.[citation needed] This comparison seems more favorable if the large amount of blubber (15-20% of mass) that dolphins require for insulation is omitted. • The encephalization quotient varies widely between species. The La Plata dolphin has an EQ of approximately 1.67; the Ganges River dolphin of 1.55; the orca of 2.57; the bottlenose dolphin of 4.14; and the tucuxi dolphin of 4.56; In comparison to other animals, elephants have an EQ ranging from 1.13 to 2.36;:151 chimpanzees of approximately 2.49; dogs of 1.17; cats of 1.00; and mice of 0.50. • The majority of mammals are born with a brain close to 90% of the adult weight. Humans are born with 28% of the adult weight, chimpanzees with 54%, bottlenose dolphins with 42.5%, and elephants with 35%. The discovery of spindle cells (neurons without extensive branching, known also as "von Economo neurons", or VENs) in the brains of the humpback whale, fin whale, sperm whale, killer whale, bottlenose dolphins, Risso's dolphins, and beluga whales is another unique discovery. Humans, the great apes, and elephants, species all well known for their high intelligence, are the only others known to have spindle cells(p242). Spindle neurons appear to play a central role in the development of intelligent behavior. Such a discovery may suggest a convergent evolution of these species.

Brain structure Elephant brains also show a similar complexity to dolphin brains, and are also more convoluted than that of humans, and with a cortex "thicker than that of cetaceans". However, in dolphins, "no patterns of cellular distribution, nuclear subdivision, or cellular morphology indicate specialization of the LC (coeruleus complex)" despite the large absolute brain size and unihemispheric sleep phenomenology of cetaceans. Moreover, it is generally agreed that the growth of the neocortex, both absolutely and relative to the rest of the brain, during human evolution, has been responsible for the evolution of intelligence, however defined. While a complex neocortex usually indicates high intelligence, there

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