Data on braininess in mammals, part 3
My commentary:
Zebras have brains 2.3-fold more massive than those of tapirs and rhinoceroses, relative to body mass allometrically.
I.e. tapirs and rhinoceroses
- have brains 43% of those of zebras, by mass, relative to the allometry of body mass, and
- have considerably less massive brains than Artiodactyla would have at similar body mass.
Perissodactyls, overall, are not much less encephalised than are artiodactyls. However, perissodactyls are heterogeneous in their encephalisation.
Brain mass on average is about 2.5-fold greater in Rodentia and Lagomorpha than in 'basal insectivores'.
In turn, brain mass in Artiodactyla and Carnivora is about 2.5-fold greater than that in Rodentia and Lagomorpha.
Among Carnivora:
- Canidae and Ursidae are generally similar in encephalisation,
- among Ursidae, Helarctos malayanus is remarkably more encephalised than other bears, suggesting that it is in some ways an ecological counterpart for chimpanzees (Pan spp.) in southeast Asia,
- seals, sea lions, and walruses (Phocidae, Otariidae, and Odobenidae) tend to be more encephalised than expected for Carnivora, whereas Mustelidae (other than otters) tend to be less encephalised than expected for Carnivora, and
- the smallest-bodied seals (Phocidae) are considerably more encephalised than the largest-bodied otters (Mustelidae), despite similar body masses and despite the tendency to evolutionary convergence between seals and otters.
OBOUSSIER H AND SCHLIEMANN H (1966) Hirn-Korpergewichtsbeziehungen bei Boviden. Z Saugetierk 31: 464-471.
sex-based data, allocated by me to sex by inference
Taurotragus oryx
female adult (n=1) body mass 400 kg, brain mass 440 g
male adult (n=1) body mass 600 kg, brain mass 530 g
Syncerus caffer (also see https://www.inaturalist.org/posts/96248-individual-variation-in-brain-size-in-the-rocky-mountain-mule-deer-odocoileus-hemionus-hemionus#activity_comment_f8c335e2-8633-4a9f-b8f1-a23021aa769a)
female adult (n=1) body mass 600 kg, brain mass 570 g
male mature adult (n=1) body mass 900 kg, brain mass 640 g
Also see https://journals.co.za/doi/pdf/10.10520/AJA00445096_2421
CRILE AND QUIRING (1940)
Alcelaphus cokii
male adult (n=1) body mass 134 kg, brain mass 275 g
Eudorcas thomsonii
infant (n=1) body mass 2.43 kg, brain mass 54.61 g
male mature (n=1) adult body mass 24.4 kg, brain mass 91.8 g
Madoqua kirkii
male adult (n=1) body mass 4.57 kg, brain mass 37 g
Syncerus caffer (also see https://www.inaturalist.org/posts/96248-individual-variation-in-brain-size-in-the-rocky-mountain-mule-deer-odocoileus-hemionus-hemionus#activity_comment_f8c335e2-8633-4a9f-b8f1-a23021aa769a)
female adult (pregnant) (n=1) body mass 572 kg, brain mass 642 g
male adult (n=1) body mass 759 kg, brain mass 653 g
male adult (n=1) body mass 750 kg, brain mass 640 g
Tragelaphus sylvaticus massaicus
female adult (n=1) body mass 35.4 kg, brain mass 140 g
male mature adult (n=1) body mass 53.1 kg, brain mass 190 g
Axis axis
male mature adult (n=1) body mass 88.5 kg, brain mass 219 g
Odocoileus virginianus
male adult (n=1) body mass 65.1 kg, brain mass 210 g
Rangifer tarandus arcticus
female adult (n=1) body mass 71.7 kg, brain mass 278 g
male mature adults (n=2) body mass mean 128.5 kg, brain mass mean 306 g
male adolescent (n=1) body mass 62.1 kg, brain mass 285 g
Giraffa camelopardalis
male adult (n=1) body mass 1220 kg, brain mass 700 g
Comments
Reference:
Rogers and Kaplan (2003, https://rune.une.edu.au/web/handle/1959.11/2439)
Intelligence in Canis lupus:
Page 147:
"Wolves are...known for their masterful ability to learn by observation. people in the United States who have kept grey wolves in captivity note, time and time again, that they learn to open latches and gates by observing what their keepers do. One observation of the gate latch being opened seems to be sufficient for them to learn. Domestic dogs do not learn this under similar circumstances. Added to this, wolves will wait until the coast is clear before they make an escape. That takes planning ahead, which is another aspect of intelligence. They have also been noted to open the doors of other cages containing wolves before making their escape. perhaps this assistance of the other is typical 'clan' behaviour."
Pages 152-153:
"...failing the opportunity of opening the gate latch to escape, the captive wolf has no alternative other than going over the fence. Some do just this by climbing even several metres of fencing wire."
Intelligence in Canis latrans:
Page 153:
"In their book Dogs: A Startling New Understanding of Canine Origin, Behavior, and Evolution, Raymond and Lorna Coppinger report the difficulty of keeping coyotes in captivity...they were raising coyote pups and border collie pups at the same time. One day they saw a coyote climb the wire-mesh fence and walk along the top rail to reach the cage containing the collies...they deduced that each night the coyotes escaped from their cages to hunt mice in the field and returned to be with the collies during the day."
Page 161:
"Coyotes have been seen hunting in pairs in whuchbine bounds around and rolls in full view of the prey, to distract its attention, while the other remains in hiding until the prey is sufficiently off-guard for the attack to go unnoticed until it is too late."
Page 163:
"Using tools...A captive coyote was seen to use food baits as tools to attract a chicken into his clutches. He saved some of his usual meal and placed several pieces near the fence of his cage. He then took hide as the chickens came pecking for the morsels of food. As one eventually took the piece of food closest to his hiding spot, he pounced and so obtained his preferred food in place of the food pieces that had become tools. This speaks strongly of the intelligence of canids"...
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