Data on braininess in mammals, part 5

STEINHAUSEN ET AL. (2016, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5043137/)

I have rearranged the species in Fig. 1 of this reference, in order of decreasing encephalisation quotient, within each order, as follows.

Asterisks* indicate domesticated spp./subspp.

(Please bear in mind that, by definition, an encephalisation quotient of 1.0 is average for mammals. Values >1 indicate brainy (encephalised) spp., whereas values <1 indicate non-brainy/decephalised spp.)

The greater the value for encephalisation quotient, the brainier the species.

PRIMATES

Homo sapiens 6.68 (https://www.inaturalist.org/posts/96127-data-on-braininess-in-mammals-part-5#activity_comment_6dc1762a-9bf4-422c-9361-ea7b2904354e)
Hylobates lar 2.86 https://www.inaturalist.org/taxa/43593-Hylobates-lar
Cebus capucinus 2.69 https://www.inaturalist.org/taxa/43432-Cebus-capucinus
Pongo pygmaeus 2.60 https://www.inaturalist.org/taxa/43582-Pongo-pygmaeus
Ateles geoffroyi 2.44 https://www.inaturalist.org/taxa/43411-Ateles-geoffroyi
Pan troglodytes 2.38 https://www.inaturalist.org/taxa/43577-Pan-troglodytes
Ateles fusciceps 2.26 https://www.inaturalist.org/taxa/43409-Ateles-fusciceps
Macaca mulatta 2.24 https://www.inaturalist.org/taxa/43460-Macaca-mulatta
Chlorocebus pygerythrus 2.13 https://www.inaturalist.org/taxa/68137-Chlorocebus-pygerythrus
Papio hamadryas 2.06 https://www.inaturalist.org/taxa/43535-Papio-hamadryas
Callithrix geoffroyi 2.01 https://www.inaturalist.org/taxa/43372-Callithrix-geoffroyi
Trachypithecus obscurus 1.77 https://www.inaturalist.org/taxa/43494-Trachypithecus-obscurus
Gorilla gorilla 1.23 https://www.inaturalist.org/taxa/43580-Gorilla-gorilla
Alouatta palliata 1.21 https://www.inaturalist.org/taxa/43436-Alouatta-palliata
Lemur catta 1.20 https://www.inaturalist.org/taxa/43617-Lemur-catta
Otolemur crassicaudatus 1.15 https://www.inaturalist.org/taxa/43567-Otolemur-crassicaudatus
Nycticebus coucang 1.01 https://www.inaturalist.org/taxa/43627-Nycticebus-coucang

My commentary:

• All primates sampled here are brainy (encephalisation quotients>1) for mammals.
• At least two genera in South America contain spp. brainier than the chimpanzee (also see https://www.inaturalist.org/posts/96127-data-on-braininess-in-mammals-part-5#activity_comment_3e491409-d023-406e-82bc-8b0826af73b5).
• The difference between gorilla (1.2) and human (6.7) is extraordinary, considering that these genera belong to the same family (Hominidae).
• The gorilla is hardly brainier than the most familiar sp. of lemur, and is far less brainy than the cercopithecid monkeys sampled.
• Also see https://www.inaturalist.org/posts/67337-the-most-human-like-primates-in-terms-of-intelligence-are-monkeys-not-apes# and https://www.inaturalist.org/posts/67893-introducing-three-of-the-brainiest-genera-of-south-american-monkeys#.

SCANDENTIA

Tupaia glis 1.05 https://www.inaturalist.org/taxa/46283-Tupaia-glis
Tupaia everetti 1.02 https://www.inaturalist.org/taxa/565410-Tupaia-everetti
Tupaia minor 1.01 https://www.inaturalist.org/taxa/46286-Tupaia-minor

My commentary:

• Treeshrews are hardly brainier than the average mammal.

ARTIODACTYLA

Muntiacus muntjak 1.67 https://www.inaturalist.org/taxa/42186-Muntiacus-muntjak
Antilope cervicapra 1.47 https://www.inaturalist.org/taxa/42416-Antilope-cervicapra
Rusa unicolor 1.32 https://www.inaturalist.org/taxa/75053-Rusa-unicolor
Vicugna vicugna 1.31 https://www.inaturalist.org/taxa/42236-Vicugna-vicugna
Cephalophus dorsalis 1.45 https://www.inaturalist.org/taxa/42302-Cephalophus-dorsalis
Cervus elaphus 1.25 https://www.inaturalist.org/taxa/204113-Cervus-elaphus
Ammotragus lervia 1.07 https://www.inaturalist.org/taxa/42422-Ammotragus-lervia
Rangifer tarandus 1.06 https://www.inaturalist.org/taxa/42199-Rangifer-tarandus
Cervus canadensis 1.03 https://www.inaturalist.org/taxa/204114-Cervus-canadensis
Dama dama 0.99 https://www.inaturalist.org/taxa/42161-Dama-dama
*Capra hircus 0.93 https://www.inaturalist.org/taxa/123070-Capra-hircus
Axis axis 0.91 https://www.inaturalist.org/taxa/42166-Axis-axis
*Lama glama 0.90 https://www.inaturalist.org/taxa/121026-Lama-glama
*Ovis aries 0.78 https://www.inaturalist.org/taxa/121578-Ovis-aries
Choeropsis liberiensis 0.75 https://www.inaturalist.org/taxa/74192-Choeropsis-liberiensis
*Bos grunniens 0.68 https://www.inaturalist.org/taxa/889089-Bos-grunniens
*Bos taurus 0.56 https://www.inaturalist.org/taxa/74113-Bos-taurus
Taurotragus oryx 0.56 https://www.inaturalist.org/taxa/75192-Tragelaphus-oryx
Sus scrofa 0.54 https://www.inaturalist.org/taxa/42134-Sus-scrofa
*Sus scrofa domestica 0.44 https://www.inaturalist.org/observations?taxon_id=324492
Hippopotamus amphibius 0.37 https://www.inaturalist.org/taxa/42149-Hippopotamus-amphibius

My commentary:

• All domesticated spp. are less brainy than the average mammal.
• The evolutionary convergence between duikers (bovids in Africa, also see https://www.inaturalist.org/posts/53981-how-the-intelligence-of-the-smallest-duikers-helps-to-explain-their-behaviour#) and muntjacs (cervids in Asia) seems to extend to braininess.
• Suiforms (pigs and hippos) are less brainy than ruminants including camelids.

PERISSODACTYLA

Equus quagga 'granti' 1.08 https://www.inaturalist.org/observations?taxon_id=447363
Diceros bicornis 1.08 (caveats: these authors give the genus as Rhinoceros', which casts doubt on the identification; and the body mass is misleadingly given as 655 kg, instead of about 1000 kg, which means that EQ has been exaggerated)
Equus caballus 0.92 https://www.inaturalist.org/taxa/209233-Equus-caballus
*Equus asinus 0.88 https://www.inaturalist.org/taxa/148030-Equus-asinus
Tapirus indicus 0.55 https://www.inaturalist.org/taxa/43356-Tapirus-indicus

My commentary:

• Also see https://www.inaturalist.org/posts/67396-decephalisation-in-domestication-part-4-more-on-equus-caballus#.

PROBOSCIDEA

Elephas maximus 2.22 https://www.inaturalist.org/taxa/43697-Elephas-maximus
Loxodonta africana 1.75 https://www.inaturalist.org/taxa/43694-Loxodonta-africana

HYRACOIDEA

Dendrohyrax arboreus 1.08 https://www.inaturalist.org/taxa/43092-Dendrohyrax-arboreus
Procavia capensis 0.74 https://www.inaturalist.org/taxa/43086-Procavia-capensis

CARNIVORA

Potos flavus 1.78 https://www.inaturalist.org/taxa/41678-Potos-flavus
Pagophilus groenlandicus 1.61 https://www.inaturalist.org/taxa/41702-Pagophilus-groenlandicus
Canis latrans 1.59 https://www.inaturalist.org/taxa/42051-Canis-latrans
Ailurus fulgens 1.50 https://www.inaturalist.org/taxa/41653-Ailurus-fulgens
*Canis familiaris 1.46 https://www.inaturalist.org/taxa/47144-Canis-familiaris
Taxidea taxus 1.40 https://www.inaturalist.org/taxa/41789-Taxidea-taxus
Zalophus californianus 1.39 https://www.inaturalist.org/taxa/41740-Zalophus-californianus
Urocyon littoralis 1.36 https://www.inaturalist.org/taxa/42077-Urocyon-littoralis
Vulpes vulpes 1.27 https://www.inaturalist.org/taxa/42069-Vulpes-vulpes
Lynx canadensis 1.23 https://www.inaturalist.org/taxa/41974-Lynx-canadensis
Procyon lotor 1.20 https://www.inaturalist.org/taxa/41663-Procyon-lotor
Suricata suricatta 1.16 https://www.inaturalist.org/taxa/41943-Suricata-suricatta
Otocyon megalotis 1.16 https://www.inaturalist.org/taxa/42095-Otocyon-megalotis
Canis lupus 1.08 https://www.inaturalist.org/taxa/42048-Canis-lupus
Ursus maritimus 1.02 https://www.inaturalist.org/taxa/41644-Ursus-maritimus
Panthera pardus 1.02 https://www.inaturalist.org/taxa/41963-Panthera-pardus
Hyaena hyaena 0.92 https://www.inaturalist.org/taxa/41888-Hyaena-hyaena
Ursus arctos 0.82 https://www.inaturalist.org/taxa/41641-Ursus-arctos
Leptonychotes weddellii 0.81 https://www.inaturalist.org/taxa/41731-Leptonychotes-weddellii
Mungos mungo 0.81 https://www.inaturalist.org/taxa/41921-Mungos-mungo
Ailuropoda melanoleuca 0.80 https://www.inaturalist.org/taxa/41659-Ailuropoda-melanoleuca
Callorhinus ursinus 0.77 https://www.inaturalist.org/taxa/41757-Callorhinus-ursinus
Panthera tigris 0.69 https://www.inaturalist.org/taxa/41967-Panthera-tigris
Panthera leo 0.68 https://www.inaturalist.org/taxa/41964-Panthera-leo

My commentary:

• The coyote is much brainier than its congener the wolf.
• It is noteworthy that the lion is the least brainy of the 24 spp. represented here.

RODENTIA

Glaucomys volans 1.31 https://www.inaturalist.org/taxa/46272-Glaucomys-volans
Sciurus vulgaris 1.22 https://www.inaturalist.org/taxa/46001-Sciurus-vulgaris
Dasyprocta 'agouti' 0.91 https://www.inaturalist.org/observations?place_id=any&subview=map&taxon_id=43711&view=species
Chinchilla lanigera 0.85 https://www.inaturalist.org/taxa/43818-Chinchilla-lanigera
Peromyscus maniculatus 0.81 https://www.inaturalist.org/taxa/44396-Peromyscus-maniculatus
Peromyscus gossypinus 0.74 https://www.inaturalist.org/taxa/44416-Peromyscus-gossypinus
Peromyscus leucopus 0.71 https://www.inaturalist.org/taxa/44395-Peromyscus-leucopus
Myocastor coypus 0.69 https://www.inaturalist.org/taxa/43997-Myocastor-coypus
Hydrochoerus hydrochaeris 0.67 https://www.inaturalist.org/taxa/74442-Hydrochoerus-hydrochaeris
Hystrix cristata 0.63 https://www.inaturalist.org/taxa/44171-Hystrix-cristata
Gerbillurus pyramidum 0.62 https://www.inaturalist.org/taxa/44215-Gerbillus-pyramidum
Cricetulus barabensis 0.60 https://www.inaturalist.org/taxa/44215-Gerbillus-pyramidum
Mus musculus 0.53 https://www.inaturalist.org/taxa/44705-Mus-musculus
Mastomys natalensis 0.51 https://www.inaturalist.org/taxa/45326-Mastomys-natalensis
Castor canadensis 0.46 https://www.inaturalist.org/taxa/43794-Castor-canadensis
Castor fiber 0.45 https://www.inaturalist.org/taxa/43793-Castor-fiber
*Rattus norvegicus 0.45 https://www.inaturalist.org/taxa/44576-Rattus-norvegicus
Mesocricetus auratus 0.43 https://www.inaturalist.org/taxa/44919-Mesocricetus-auratus
*Cavia porcellus 0.40 https://www.inaturalist.org/taxa/119405-Cavia-porcellus

My commentary:

• In general, rodents are less brainy than the average mammal.
• The only rodents that are brainier than the average mammal are squirrels.

LAGOMORPHA

Lepus europaeus 0.59 https://www.inaturalist.org/taxa/43128-Lepus-europaeus
Oryctolagus cuniculus 0.51 https://www.inaturalist.org/taxa/43151-Oryctolagus-cuniculus

My commentary:

• Hares and rabbits are far less brainy than the average mammal.

CHIROPTERA

Desmodus rotundus 0.87 https://www.inaturalist.org/taxa/41168-Desmodus-rotundus
Artibeus jamaicensis 0.84 https://www.inaturalist.org/taxa/41005-Artibeus-jamaicensis
Plecotus auritus 0.58 https://www.inaturalist.org/taxa/40416-Plecotus-auritus
Nyctalus noctula 0.41 https://www.inaturalist.org/taxa/40572-Nyctalus-noctula

'EDENTATA'

Choloepus hoffmanni 0.71 https://www.inaturalist.org/taxa/47101-Choloepus-hoffmanni
Bradypus griseus 0.63 https://www.inaturalist.org/observations?place_id=any&subview=map&taxon_id=47065&view=species
Tamandua tetradactyla 0.52 https://www.inaturalist.org/taxa/47104-Tamandua-tetradactyla
Dasypus novemcinctus 0.44 https://www.inaturalist.org/taxa/47075-Dasypus-novemcinctus

EULIPOTYPHLA

Erinaceus europaeus 0.36 https://www.inaturalist.org/taxa/43042-Erinaceus-europaeus

My commentary:

• Decephalisation in hedgehogs - as in the case of armadillos - is consistent with a reliance on armour.

MACROSCELIDEA

Elephantulus myurus 0.82 https://www.inaturalist.org/taxa/43213-Elephantulus-myurus
Elephantulus intufi 0.82 https://www.inaturalist.org/taxa/43212-Elephantulus-intufi

My commentary:

• Elephant shrews are less brainy than the average mammal.

CETACEA

Tursiops truncatus 4.52 https://www.inaturalist.org/taxa/41482-Tursiops-truncatus
Stenella attenuata 3.56 https://www.inaturalist.org/taxa/41500-Stenella-attenuata
Phocoena phocoena 3.07 https://www.inaturalist.org/taxa/41440-Phocoena-phocoena
Pseudorca crassidens 2.85 https://www.inaturalist.org/taxa/41539-Pseudorca-crassidens
Orcinus orca 2.69 https://www.inaturalist.org/taxa/41521-Orcinus-orca
Physeter macrocephalus 0.54 https://www.inaturalist.org/taxa/74890-Physeter-macrocephalus
Megaptera novaeangliae 0.40 https://www.inaturalist.org/taxa/41566-Megaptera-novaeangliae
Eschrichtius robustus 0.33 https://www.inaturalist.org/taxa/41478-Eschrichtius-robustus
Balaenoptera musculus 0.19 https://www.inaturalist.org/taxa/41553-Balaenoptera-musculus

My overall commentary:

Species with encephalisation quotients <0.5, with the adaptive correlates, are (in no particular order):

• armadillo (armoured),
• hedgehog (armoured),
• cavy (rodent and domesticated),
• beaver (rodent),
• hippo (protected by water), and
• domestic pig (suid and domesticated).

Of the above, the most puzzling case is beavers, which have remarkably small brains for 'ecosystem engineers' capable of construction/architecture/vegetation management.

Species with encephalisation quotients slightly exceeding 0.5 (in no particular order): anteater, eland, rabbit, rat, mouse, wild boar.

Publicado el junio 25, 2024 01:28 MAÑANA por milewski