Editing Encephalization quotient (section)

== Comparisons with non-mammalian animals ==
Birds generally have lower EQ than mammals, but [[parrots]] and particularly the [[corvid]]s show remarkable complex behaviour and high learning ability. Their brains are at the high end of the bird spectrum, but low compared to mammals. Bird cell size is on the other hand generally smaller than that of mammals, which may mean more brain cells and hence [[synapse]]s per volume, allowing for more complex behaviour from a smaller brain.<ref name="Roth2005"/> Both [[bird intelligence]] and brain anatomy are however very different from those of mammals, making direct comparison difficult.<ref name=pmid16553307/>

[[Manta ray]]s have the highest EQ among [[fish]],<ref>{{cite book |last=Striedter |first=Georg F.|title=Principles of brain evolution |year=2005 |publisher=Sinauer |location=Sunderland, Mass. |isbn=978-0-87893-820-9}}{{page needed|date=April 2019}}</ref> and either [[octopus]]es<ref name="Gould 1977 Ever since Darwin, c7s1">Gould (1977) Ever since Darwin, c7s1</ref> or [[jumping spider]]s<ref>{{cite web |url=http://tolweb.org/accessory/Jumping_Spider_Vision?acc_id=1946 |title=Jumping Spider Vision |access-date=28 October 2009}}</ref> have the highest among [[invertebrate]]s. Despite the jumping spider having a huge brain for its size, it is minuscule in absolute terms, and humans have a much higher EQ despite having a lower raw brain-to-body weight ratio.<ref>{{cite journal |last1=Meyer |first1=Wilfried |last2=Schlesinger |first2=Christa |last3=Poehling |first3=Hans Michael |last4=Ruge |first4=Wolfgang |title=Comparative quantitative aspects of putative neurotransmitters in the central nervous system of spiders (Arachnida: Araneida) |journal=Comparative Biochemistry and Physiology Part C: Comparative Pharmacology |date=January 1984 |volume=78 |issue=2 |pages=357–362 |doi=10.1016/0742-8413(84)90098-7 |pmid=6149080 }}</ref><ref>{{cite journal |last1=Rilling |first1=James K. |last2=Insel |first2=Thomas R. |title=The primate neocortex in comparative perspective using magnetic resonance imaging |journal=Journal of Human Evolution |date=August 1999 |volume=37 |issue=2 |pages=191–223 |doi=10.1006/jhev.1999.0313 |pmid=10444351 |bibcode=1999JHumE..37..191R }}</ref><ref name=houzel2009 /> Mean EQs for [[reptiles]] are about one tenth of those of mammals. EQ in birds (and estimated EQ in [[non-avian dinosaur|other]] dinosaurs) generally also falls below that of mammals, possibly due to lower thermoregulation and/or motor control demands.<ref>Paul, Gregory S. (1988) Predatory dinosaurs of the world. Simon and Schuster. {{ISBN|0-671-61946-2}}{{page needed|date=April 2019}}</ref> Estimation of brain size in ''[[Archaeopteryx]]'' (one of the oldest known ancestors of birds), shows it had an EQ well above the reptilian range, and just below that of living birds.<ref>{{cite journal |last1=Hopson |first1=J A |title=Relative Brain Size and Behavior in Archosaurian Reptiles |journal=Annual Review of Ecology and Systematics |date=November 1977 |volume=8 |issue=1 |pages=429–448 |doi=10.1146/annurev.es.08.110177.002241 |bibcode=1977AnRES...8..429H }}</ref>

Biologist [[Stephen Jay Gould]] has noted that if one looks at vertebrates with very low encephalization quotients, their brains are slightly less massive than their spinal cords. Theoretically, intelligence might correlate with the absolute amount of brain an animal has after subtracting the weight of the spinal cord from the brain.<ref>{{cite web |url=http://yoyo.cc.monash.edu.au/~tzvi/GOULD.html |title=Bligh's Bounty |access-date=12 May 2011 |url-status=dead |archive-url=https://web.archive.org/web/20010709234346/http://yoyo.cc.monash.edu.au/~tzvi/GOULD.html |archive-date=9 July 2001 }}</ref> This formula is useless for invertebrates because they do not have spinal cords or, in some cases, central nervous systems.