Editing Cetacean intelligence (section)

===Structure===
[[File:Comparaison cerveau.jpg|left|thumb|Brain of a [[human]] (left), compared to that of a [[black rhinoceros]] (center) and a [[common dolphin]] (right)]]
[[Elephant]] brains also show a complexity similar to dolphin brains, and are also more convoluted than that of humans,<ref name="Elephant behaviour" /> and with a cortex thicker than that of cetaceans.<ref name="Roth" /> 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 human intelligence, however defined. While a complex neocortex usually indicates high intelligence, there are exceptions. For example, the [[echidna]] has a highly developed brain, yet is not widely considered very intelligent,<ref name="Abbie" /> though preliminary investigations into their intelligence suggest that echidnas are capable of more advanced cognitive tasks than were previously assumed.<ref>{{Cite journal |last1=Russell |first1=Fiona |last2=Burke |first2=Darren |date=January 2016 |title=Conditional same/different discrimination learningin the short-beaked echidna (Tachyglossusaculeatus) |url=https://www.evolutionarycognition.org/Russell_et_al-2016-Journal_of_the_Experimental_Analysis_of_Behavior.pdf |journal=Journal of the Experimental Analysis of Behavior |volume=105 |issue=1 |pages=133–54 |doi=10.1002/jeab.185 |pmid=26781053 |access-date=19 March 2020}}</ref>

In 2014, it was shown for the first time that a species of dolphin, the [[long-finned pilot whale]], has more neocortical neurons than any mammal studied to date including humans.<ref>{{Cite journal |vauthors=Mortensen HS, et al. |year=2014 |title=Quantitative relationships in delphinid neocortex |journal=Front Neuroanat |volume=8 |page=132 |doi=10.3389/fnana.2014.00132 |pmc=4244864 |pmid=25505387 |doi-access=free}}</ref>
Unlike [[terrestrial animal|terrestrial]] mammals, dolphin brains contain a [[paralimbic lobe]], which may possibly be used for sensory processing. It has also been suggested that similar to humans, the paralimbic region of the brain is responsible for a dolphin's self-control, motivation, and emotions.<ref>{{Cite web |date=2019-07-02 |title=An Ocean of Intelligence |url=https://saveourseasmagazine.com/an-ocean-of-intelligence/ |access-date=2023-12-12 |website=Save Our Seas Magazine}}</ref> The dolphin is a [[Control of respiration|voluntary breather]], even during sleep, with the result that [[veterinary anaesthesia]] of dolphins would result in [[asphyxiation]].<ref name="Anesthesia" /> Ridgway reports that EEGs show alternating hemispheric asymmetry in slow waves during sleep, with occasional sleep-like waves from both hemispheres.<ref>{{Cite journal |last=Ridgway |first=S. H |year=2002 |title=Asymmetry and symmetry in brain waves from dolphin left and right hemispheres: some observations after anesthesia, during quiescent hanging behavior, and during visual obstruction |journal=Brain Behav. Evol. |volume=60 |issue=5 |pages=265–74 |doi=10.1159/000067192 |pmid=12476053 |s2cid=41989236}}</ref> This result has been interpreted to mean that dolphins sleep only one hemisphere of their brain at a time, possibly to control their voluntary respiration system or to be vigilant for predators.

The dolphin's greater dependence on sound processing is evident in the structure of its brain: its neural area devoted to visual imaging is only about one-tenth that of the human brain, while the area devoted to acoustical imaging is about 10 times as large.<ref>{{Cite book |title=Our animal connection : what sapiens can learn from other species |others=Hehenberger, Michael,, Zhi, Xia |isbn=978-0-429-05332-0 |location=Singapore |oclc=1125007476}}</ref> Sensory experiments suggest a great degree of cross-modal integration in the processing of shapes between echolocative and visual areas of the brain.