An overview of the central nervous system of the elephant through a critical appraisal of the literature published in the XIX and XX centuries

Cozzi, Bruno; Spagnoli, S.; Bruno, Lúcia

doi:10.1016/s0361-9230(00)00456-1

Cited by 45 publications

(44 citation statements)

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“…Furthermore, several lines of indirect evidence suggest that the elephant neocortex is likely to require a great deal of energy on a neuron-specific basis. The elephant neocortex has a relatively low density of very largesized neurons (41,42) with extensive dendritic arborization (16), suggesting that each receives a relatively large number of synapses from interconnecting axons as compared with a large-brained primate (43). Accordingly, the interneuronal space in the elephant neocortex is occupied by a remarkably high density of glial cells (42).…”

Section: The Elephant's Adaptively Evolved Brain and Chemosensory Behmentioning

confidence: 99%

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Phylogenomic analyses reveal convergent patterns of adaptive evolution in elephant and human ancestries

Goodman

Sterner

Islam

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Specific sets of brain-expressed genes, such as aerobic energy metabolism genes, evolved adaptively in the ancestry of humans and may have evolved adaptively in the ancestry of other large-brained mammals. The recent addition of genomes from two afrotherians (elephant and tenrec) to the expanding set of publically available sequenced mammalian genomes provided an opportunity to test this hypothesis. Elephants resemble humans by having large brains and long life spans; tenrecs, in contrast, have small brains and short life spans. Thus, we investigated whether the phylogenomic patterns of adaptive evolution are more similar between elephant and human than between either elephant and tenrec lineages or human and mouse lineages, and whether aerobic energy metabolism genes are especially well represented in the elephant and human patterns. Our analyses encompassed ≈6,000 genes in each of these lineages with each gene yielding extensive coding sequence matches in interordinal comparisons. Each gene's nonsynonymous and synonymous nucleotide substitution rates and dN/dS ratios were determined. Then, from gene ontology information on genes with the higher dN/dS ratios, we identified the more prevalent sets of genes that belong to specific functional categories and that evolved adaptively. Elephant and human lineages showed much slower nucleotide substitution rates than tenrec and mouse lineages but more adaptively evolved genes. In correlation with absolute brain size and brain oxygen consumption being largest in elephants and next largest in humans, adaptively evolved aerobic energy metabolism genes were most evident in the elephant lineage and next most evident in the human lineage.

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Section: The Elephant's Adaptively Evolved Brain and Chemosensory Behmentioning

confidence: 99%

“…Elephants have the largest absolute brain size of any land animal: 5.5 kg in Asian elephants and 6.5 kg in African savannah elephants (16)(17)(18). These values are Ϸ4 times the average brain mass of humans (9,19).…”

mentioning

confidence: 99%

Phylogenomic analyses reveal convergent patterns of adaptive evolution in elephant and human ancestries

Goodman

Sterner

Islam

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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“…It does not, however, give the best indication of 'brain-power': as with any computational system, to assess power it is the actual number of processing units available for use that is important (Byrne, 1996). Elephants have the largest absolute brain size among land animals: up to 5.5 kg in Asian elephants and up to 6.5 kg in African savannah elephants (Cozzi, Spagnoli, & Bruno, 2001;Shoshani, Kupsky, & Marchant, 2006). Although neurons are less densely packed in elephant brains than in primates', elephant brains nevertheless contain as many cortical neurons as do human brains (Roth & Dicke, 2005).…”

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confidence: 99%

“…Although neurons are less densely packed in elephant brains than in primates', elephant brains nevertheless contain as many cortical neurons as do human brains (Roth & Dicke, 2005). Moreover, the pyramidal neurons are larger than in humans and most other species, with a large dendritic tree giving the potential for many more connections, and perhaps hinting at superior learning and memory skills (Cozzi, et al, 2001). There is a considerable body of theory and supportive data to suggest that living in an extensive social network often correlates with, and likely promotes, cognitive sophistication .…”

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confidence: 99%

Elephant cognition in primate perspective

Byrne¹,

Bates²,

Moss

2009

CCBR

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On many of the staple measures of comparative psychology, elephants show no obvious differences from other mammals, such as primates: discrimination learning, memory, spontaneous tool use, etc. However, a range of more naturalistic measures have recently suggested that elephant cognition may be rather different. Wild elephants sub-categorize humans into groups, independently making this classification on the basis of scent or colour. In number discrimination, elephants show no effects of absolute magnitude or relative size disparity in making number judgements. In the social realm, elephants show empathy into the problems faced by others, and give hints of special abilities in cooperation, vocal imitation and perhaps teaching. Field data suggest that the elephant's vaunted reputation for memory may have a factual basis, in two ways. Elephants' ability to remember large-scale space over long periods suggests good cognitive mapping skills. Elephants' skill in keeping track of the current locations of many family members implies that working memory may be unusually developed, consistent with the laboratory finding that their quantity judgements do not show the usual magnitude effects.

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“…Past workers have recognized a deep sylvian fossa, an arched suprasylvia and a coronolateral (or lateral) sulcus, just as in Hyracoidea, but failed to identify a splenial sul- 164 cus in most cases [Elliot Smith, 1902;Friant, 1954aFriant, , b, 1957Anthony, 1972;Cozzi et al, 2001;Shoshani et al, 2006]. In addition they found a sylvian fossa prolongated dorsally by a deep pseudosylvia , a praesylvian sulcus starting from the anterior rhinal fissure and bearing three ramifications, a transverse sulcus called the fissure of Rolando, an antero-temporal sulcus called the postsylvia and a postero-temporal sulcus called the sulcus postlateral.…”

Section: Macroscelidea and Tenrecoidea (Afroinsectivora)mentioning

confidence: 99%

A Memory Already like an Elephant's? The Advanced Brain Morphology of the Last Common Ancestor of Afrotheria (Mammalia)

et al. 2013

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Virtually reconstructed and natural endocranial casts are used in the study of brain evolution through geological time. We here present work investigating the paleoneurological evolution of afrotherian mammals. Using microCT-generated endocasts we show that, with the exception of the subfamilies Macroscelidinae and Tenrecoidea, most Afroinsectiphilia display a more or less gyrencephalic and ventrally expanded neopallium, two derived features that are unexpected for these insectivore-grade afrotherians. This implies that the endocranial cast morphology at the root of the afrotherian clade may have been more advanced than previously thought. The reconstructed endocranial morphology of the Afrotheria's last common ancestor reaches the level of complexity of some early Cenozoic archaic ungulates. Our result gives support to the hypothesis of an ungulate-like ancestral body plan for Afrotheria. It also implies that the a priori ‘primitive' suite of traits evident in the brain of Afroinsectivora, especially in the tenrecs, may have been secondarily acquired. Implications on the overestimation of the divergence age of Afrotheria are discussed.

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An overview of the central nervous system of the elephant through a critical appraisal of the literature published in the XIX and XX centuries

Cited by 45 publications

References 46 publications

Phylogenomic analyses reveal convergent patterns of adaptive evolution in elephant and human ancestries

Phylogenomic analyses reveal convergent patterns of adaptive evolution in elephant and human ancestries

Elephant cognition in primate perspective

A Memory Already like an Elephant's? The Advanced Brain Morphology of the Last Common Ancestor of Afrotheria (Mammalia)

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