1
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Thor S. Indirect neurogenesis in space and time. Nat Rev Neurosci 2024; 25:519-534. [PMID: 38951687 DOI: 10.1038/s41583-024-00833-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/29/2024] [Indexed: 07/03/2024]
Abstract
During central nervous system (CNS) development, neural progenitor cells (NPCs) generate neurons and glia in two different ways. In direct neurogenesis, daughter cells differentiate directly into neurons or glia, whereas in indirect neurogenesis, neurons or glia are generated after one or more daughter cell divisions. Intriguingly, indirect neurogenesis is not stochastically deployed and plays instructive roles during CNS development: increased generation of cells from specific lineages; increased generation of early or late-born cell types within a lineage; and increased cell diversification. Increased indirect neurogenesis might contribute to the anterior CNS expansion evident throughout the Bilateria and help to modify brain-region size without requiring increased NPC numbers or extended neurogenesis. Increased indirect neurogenesis could be an evolutionary driver of the gyrencephalic (that is, folded) cortex that emerged during mammalian evolution and might even have increased during hominid evolution. Thus, selection of indirect versus direct neurogenesis provides a powerful developmental and evolutionary instrument that drives not only the evolution of CNS complexity but also brain expansion and modulation of brain-region size, and thereby the evolution of increasingly advanced cognitive abilities. This Review describes indirect neurogenesis in several model species and humans, and highlights some of the molecular genetic mechanisms that control this important process.
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Affiliation(s)
- Stefan Thor
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia.
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2
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York AR, Sherwood CC, Manger PR, Kaas JH, Mota B, Herculano-Houzel S. Folding of the cerebellar cortex is clade-specific in form but universal in degree. J Comp Neurol 2024; 532:e25616. [PMID: 38634526 DOI: 10.1002/cne.25616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 02/01/2024] [Accepted: 03/26/2024] [Indexed: 04/19/2024]
Abstract
Like the cerebralcortex, the surface of the cerebellum is repeatedly folded. Unlike the cerebralcortex, however, cerebellar folds are much thinner and more numerous; repeatthemselves largely along a single direction, forming accordion-like folds transverseto the mid-sagittal plane; and occur in all but the smallest cerebella. We haveshown previously that while the location of folds in mammalian cerebral cortex isclade-specific, the overall degree of folding strictly follows a universalpower law relating cortical thickness and the exposed and total surface areas predictedfrom the minimization of the effective free energy of an expanding, self-avoidingsurface of a certain thickness. Here we show that this scaling law extends tothe folding of the mid-sagittal sections of the cerebellum of 53 speciesbelonging to six mammalian clades. Simultaneously, we show that each clade hasa previously unsuspected distinctive spatial pattern of folding evident at themid-sagittal surface of the cerebellum. We note, however, that the mammaliancerebellum folds as a multi-fractal object, because of the difference betweenthe outside-in development of the cerebellar cortex around a preexisting coreof already connected white matter, compared to the inside-out development ofthe cerebral cortex with a white matter volume that develops as the cerebralcortex itself gains neurons. We conclude that repeated folding, one of the mostrecognizable features of biology, can arise simply from the interplay betweenthe universal applicability of the physics of self-organization and biological,phylogenetical clade-specific contingency, without the need for invokingselective pressures in evolution.
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Affiliation(s)
- Annaleigh R York
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, USA
| | - Chet C Sherwood
- Department of Anthropology, The George Washington University, Washington, District of Columbia, USA
| | - Paul R Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witswatersrand, Johannesburg, South Africa
| | - Jon H Kaas
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, USA
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee, USA
| | - Bruno Mota
- Institute of Physics, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Suzana Herculano-Houzel
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, USA
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee, USA
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3
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Baričević Z, Pongrac M, Ivaničić M, Hreščak H, Tomljanović I, Petrović A, Cojoc D, Mladinic M, Ban J. SOX2 and SOX9 Expression in Developing Postnatal Opossum ( Monodelphis domestica) Cortex. Biomolecules 2024; 14:70. [PMID: 38254670 PMCID: PMC10813269 DOI: 10.3390/biom14010070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 12/30/2023] [Accepted: 12/31/2023] [Indexed: 01/24/2024] Open
Abstract
(1) Background: Central nervous system (CNS) development is characterized by dynamic changes in cell proliferation and differentiation. Key regulators of these transitions are the transcription factors such as SOX2 and SOX9. SOX2 is involved in the maintenance of progenitor cell state and neural stem cell multipotency, while SOX9, expressed in neurogenic niches, plays an important role in neuron/glia switch with predominant expression in astrocytes in the adult brain. (2) Methods: To validate SOX2 and SOX9 expression patterns in developing opossum (Monodelphis domestica) cortex, we used immunohistochemistry (IHC) and the isotropic fractionator method on fixed cortical tissue from comparable postnatal ages, as well as dissociated primary neuronal cultures. (3) Results: Neurons positive for both neuronal (TUJ1 or NeuN) and stem cell (SOX2) markers were identified, and their presence was confirmed with all methods and postnatal age groups (P4-6, P6-18, and P30) analyzed. SOX9 showed exclusive staining in non-neuronal cells, and it was coexpressed with SOX2. (4) Conclusions: The persistence of SOX2 expression in developing cortical neurons of M. domestica during the first postnatal month implies the functional role of SOX2 during neuronal differentiation and maturation, which was not previously reported in opossums.
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Affiliation(s)
- Zrinko Baričević
- Faculty of Biotechnology and Drug Development, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia; (Z.B.); (M.P.); (M.I.); (H.H.); (I.T.); (A.P.); (M.M.)
| | - Marta Pongrac
- Faculty of Biotechnology and Drug Development, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia; (Z.B.); (M.P.); (M.I.); (H.H.); (I.T.); (A.P.); (M.M.)
| | - Matea Ivaničić
- Faculty of Biotechnology and Drug Development, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia; (Z.B.); (M.P.); (M.I.); (H.H.); (I.T.); (A.P.); (M.M.)
| | - Helena Hreščak
- Faculty of Biotechnology and Drug Development, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia; (Z.B.); (M.P.); (M.I.); (H.H.); (I.T.); (A.P.); (M.M.)
| | - Ivana Tomljanović
- Faculty of Biotechnology and Drug Development, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia; (Z.B.); (M.P.); (M.I.); (H.H.); (I.T.); (A.P.); (M.M.)
| | - Antonela Petrović
- Faculty of Biotechnology and Drug Development, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia; (Z.B.); (M.P.); (M.I.); (H.H.); (I.T.); (A.P.); (M.M.)
| | - Dan Cojoc
- CNR-IOM, Materials Foundry, National Research Council of Italy, 34149 Trieste, Italy;
| | - Miranda Mladinic
- Faculty of Biotechnology and Drug Development, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia; (Z.B.); (M.P.); (M.I.); (H.H.); (I.T.); (A.P.); (M.M.)
| | - Jelena Ban
- Faculty of Biotechnology and Drug Development, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia; (Z.B.); (M.P.); (M.I.); (H.H.); (I.T.); (A.P.); (M.M.)
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4
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Paolino A, Haines EH, Bailey EJ, Black DA, Moey C, García-Moreno F, Richards LJ, Suárez R, Fenlon LR. Non-uniform temporal scaling of developmental processes in the mammalian cortex. Nat Commun 2023; 14:5950. [PMID: 37741828 PMCID: PMC10517946 DOI: 10.1038/s41467-023-41652-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 09/13/2023] [Indexed: 09/25/2023] Open
Abstract
The time that it takes the brain to develop is highly variable across animals. Although staging systems equate major developmental milestones between mammalian species, it remains unclear how distinct processes of cortical development scale within these timeframes. Here, we compare the timing of cortical development in two mammals of similar size but different developmental pace: eutherian mice and marsupial fat-tailed dunnarts. Our results reveal that the temporal relationship between cell birth and laminar specification aligns to equivalent stages between these species, but that migration and axon extension do not scale uniformly according to the developmental stages, and are relatively more advanced in dunnarts. We identify a lack of basal intermediate progenitor cells in dunnarts that likely contributes in part to this timing difference. These findings demonstrate temporal limitations and differential plasticity of cortical developmental processes between similarly sized Therians and provide insight into subtle temporal changes that may have contributed to the early diversification of the mammalian brain.
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Affiliation(s)
- Annalisa Paolino
- The University of Queensland, School of Biomedical Sciences, Brisbane, QLD 4072, Australia
- The University of Queensland, Queensland Brain Institute, Brisbane, QLD 4072, Australia
| | - Elizabeth H Haines
- The University of Queensland, School of Biomedical Sciences, Brisbane, QLD 4072, Australia
- The University of Queensland, Queensland Brain Institute, Brisbane, QLD 4072, Australia
| | - Evan J Bailey
- The University of Queensland, School of Biomedical Sciences, Brisbane, QLD 4072, Australia
- The University of Queensland, Queensland Brain Institute, Brisbane, QLD 4072, Australia
| | - Dylan A Black
- The University of Queensland, Queensland Brain Institute, Brisbane, QLD 4072, Australia
| | - Ching Moey
- The University of Queensland, Queensland Brain Institute, Brisbane, QLD 4072, Australia
| | - Fernando García-Moreno
- Achucarro Basque Center for Neuroscience, Scientific Park of the University of the Basque Country (UPV/EHU), 48940, Leioa, Spain
- IKERBASQUE Foundation, María Díaz de Haro 3, 48013, Bilbao, Spain
| | - Linda J Richards
- The University of Queensland, School of Biomedical Sciences, Brisbane, QLD 4072, Australia
- The University of Queensland, Queensland Brain Institute, Brisbane, QLD 4072, Australia
- Washington University in St Louis School of Medicine, Department of Neuroscience, St Louis, MO, 63108, USA
| | - Rodrigo Suárez
- The University of Queensland, School of Biomedical Sciences, Brisbane, QLD 4072, Australia.
- The University of Queensland, Queensland Brain Institute, Brisbane, QLD 4072, Australia.
| | - Laura R Fenlon
- The University of Queensland, School of Biomedical Sciences, Brisbane, QLD 4072, Australia.
- The University of Queensland, Queensland Brain Institute, Brisbane, QLD 4072, Australia.
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5
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Ocklenburg S, El Basbasse Y, Ströckens F, Müller-Alcazar A. Hemispheric asymmetries and brain size in mammals. Commun Biol 2023; 6:521. [PMID: 37188844 DOI: 10.1038/s42003-023-04894-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 05/02/2023] [Indexed: 05/17/2023] Open
Abstract
Hemispheric asymmetries differ considerably across species, but the neurophysiological base of this variation is unclear. It has been suggested that hemispheric asymmetries evolved to bypass interhemispheric conduction delay when performing time-critical tasks. This implies that large brains should be more asymmetric. We performed preregistered cross-species meta-regressions with brain mass and neuron number as predictors for limb preferences, a behavioral marker of hemispheric asymmetries, in mammals. Brain mass and neuron number showed positive associations with rightward limb preferences but negative associations with leftward limb preferences. No significant associations were found for ambilaterality. These results are only partly in line with the idea that conduction delay is the critical factor that drives the evolution of hemispheric asymmetries. They suggest that larger-brained species tend to shift towards more right-lateralized individuals. Therefore, the need for coordination of lateralized responses in social species needs to be considered in the context of the evolution of hemispheric asymmetries.
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Affiliation(s)
- Sebastian Ocklenburg
- Department of Psychology, MSH Medical School Hamburg, Hamburg, Germany.
- Institute for Cognitive and Affective Neuroscience, MSH Medical School Hamburg, Hamburg, Germany.
- Biopsychology, Institute for Cognitive Neuroscience, Ruhr University Bochum, Bochum, Germany.
| | - Yasmin El Basbasse
- Biopsychology, Institute for Cognitive Neuroscience, Ruhr University Bochum, Bochum, Germany
| | - Felix Ströckens
- C. & O. Vogt Institute for Brain Research, University Hospital Düsseldorf, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Anett Müller-Alcazar
- Department of Psychology, MSH Medical School Hamburg, Hamburg, Germany
- Institute for Cognitive and Affective Neuroscience, MSH Medical School Hamburg, Hamburg, Germany
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6
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Cunha F, Stingo-Hirmas D, Cardoso RF, Wright D, Henriksen R. Neuronal and non-neuronal scaling across brain regions within an intercross of domestic and wild chickens. Front Neuroanat 2022; 16:1048261. [PMID: 36506870 PMCID: PMC9732670 DOI: 10.3389/fnana.2022.1048261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 11/11/2022] [Indexed: 11/26/2022] Open
Abstract
The allometric scaling of the brain size and neuron number across species has been extensively studied in recent years. With the exception of primates, parrots, and songbirds, larger brains have more neurons but relatively lower neuronal densities than smaller brains. Conversely, when considering within-population variability, it has been shown that mice with larger brains do not necessarily have more neurons but rather more neurons in the brain reflect higher neuronal density. To what extent this intraspecific allometric scaling pattern of the brain applies to individuals from other species remains to be explored. Here, we investigate the allometric relationships among the sizes of the body, brain, telencephalon, cerebellum, and optic tectum, and the numbers of neurons and non-neuronal cells of the telencephalon, cerebellum, and optic tectum across 66 individuals originated from an intercross between wild and domestic chickens. Our intercross of chickens generates a population with high variation in brain size, making it an excellent model to determine the allometric scaling of the brain within population. Our results show that larger chickens have larger brains with moderately more neurons and non-neuronal cells. Yet, absolute number of neurons and non-neuronal cells correlated strongly and positively with the density of neurons and non-neuronal cells, respectively. As previously shown in mice, this scaling pattern is in stark contrast with what has been found across different species. Our findings suggest that neuronal scaling rules across species are not a simple extension of the neuronal scaling rules that apply within a species, with important implications for the evolutionary developmental origins of brain diversity.
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7
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Comparative Study of Brain Size Ontogeny: Marsupials and Placental Mammals. BIOLOGY 2022; 11:biology11060900. [PMID: 35741421 PMCID: PMC9219685 DOI: 10.3390/biology11060900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 05/15/2022] [Accepted: 06/08/2022] [Indexed: 11/17/2022]
Abstract
There exists a negative allometry between vertebrate brain size and body size. It has been well studied among placental mammals but less is known regarding marsupials. Consequently, this study explores brain/body ontogenetic growth in marsupials and compares it with placental mammals. Pouch young samples of 43 koalas (Phascolarctos cinereus), 28 possums (Trichosurus vulpecula), and 36 tammar wallabies (Macropus eugenii) preserved in a solution of 10% buffered formalin, as well as fresh juveniles and adults of 43 koalas and 40 possums, were studied. Their brain size/body size allometry was compared to that among humans, rhesus monkeys, dogs, cats, rats, guinea pigs, rabbits, wild pigs, and mice. Two patterns of allometric curves were found: a logarithmic one (marsupials, rabbits, wild pigs, and guinea pigs) and a logistic one (the rest of mammals).
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8
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Thittamranahalli Kariyappa J, Zanoni S, Bongers A, Tong L, Ashwell KWS. Magnetic resonance imaging and diffusion tensor imaging reconstruction of connectomes in a macropod, the quokka (Setonix brachyurus). J Comp Neurol 2022; 530:2188-2214. [PMID: 35417062 DOI: 10.1002/cne.25328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 02/26/2022] [Accepted: 03/15/2022] [Indexed: 11/10/2022]
Abstract
The diversity of the diprotodontids provides an excellent opportunity to study how a basic marsupial cortical plan has been modified for the needs of the mammals living in different habitats. Very little is known about the connections of the cerebral cortex with the deep brain structures (basal ganglia and thalamus) in this evolutionarily significant group of mammals. In this study, we performed mapping of brain regions and connections in a diprotodontid marsupial from data obtained from an excised brain scanned in high-field (9.4 T) microstructural magnetic resonance imaging (MRI) instrument. The analysis was based on two MRI methodologies. First, high-resolution structural scans were used to map MRI visible brain regions from T1w and T2w images. Second, extensive diffusion tensor imaging (DTI) data were obtained to elucidate connectivity between brain areas using deterministic diffusion tracking of neuronal brain fibers. From the data, we were able to identify corticostriate connections between the frontal association and dorsomedial isocortex and the head of the caudate, and between the lateral somatosensory cortex and the putamen. We were also able to follow the olfactory and limbic connections by tracing fibers in the fornix, cingulum, intrabulbar part of the anterior commissure, and lateral olfactory tract. There was segregation of fibers in the anterior commissure such that olfactory connections passed through the rostroventral part and successively more dorsal cortical areas connected through more dorsal parts of the commissure. Our findings confirm a common pattern of cortical connectivity in therian mammals, even where brain expansion has occurred independently in diverse groups.
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Affiliation(s)
| | - Simone Zanoni
- Biological Resources and Imaging Laboratory, The University of New South Wales, Sydney, New South Wales, Australia
| | - Andre Bongers
- Biological Resources and Imaging Laboratory, The University of New South Wales, Sydney, New South Wales, Australia
| | - Lydia Tong
- Taronga Wildlife Hospital, Taronga Zoo, Taronga Conservation Society Australia, Sydney, New South Wales, Australia
| | - Ken W S Ashwell
- Department of Anatomy, School of Medical Sciences, The University of New South Wales, Sydney, New South Wales, Australia
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9
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Abstract
The evolution of brain processing capacity has traditionally been inferred from data on brain size. However, similarly sized brains of distantly related species can differ in the number and distribution of neurons, their basic computational units. Therefore, a finer-grained approach is needed to reveal the evolutionary paths to increased cognitive capacity. Using a new, comprehensive dataset, we analyzed brain cellular composition across amniotes. Compared to reptiles, mammals and birds have dramatically increased neuron numbers in the telencephalon and cerebellum, which are brain parts associated with higher cognition. Astoundingly, a phylogenetic analysis suggests that as few as four major changes in neuron–brain scaling in over 300 million years of evolution pave the way to intelligence in endothermic land vertebrates. Reconstructing the evolution of brain information-processing capacity is paramount for understanding the rise of complex cognition. Comparative studies of brain evolution typically use brain size as a proxy. However, to get a less biased picture of the evolutionary paths leading to high cognitive power, we need to compare brains not by mass but by numbers of neurons, which are their basic computational units. This study reconstructs the evolution of brains across amniotes by directly analyzing neuron numbers by using the largest dataset of its kind and including essential data on reptiles. We show that reptiles have not only small brains relative to body size but also low neuronal densities, resulting in average neuron numbers over 20 times lower than those in birds and mammals of similar body size. Amniote brain evolution is characterized by the following four major shifts in neuron–brain scaling. The most dramatic increases in brain neurons occurred independently with the appearance of birds and mammals, resulting in convergent neuron scaling in the two endotherm lineages. The other two major increases in the number of neurons happened in core land birds and anthropoid primates, which are two groups known for their cognitive prowess. Interestingly, relative brain size is associated with relative neuronal cell density in reptiles, birds, and primates but not in other mammals. This has important implications for studies using relative brain size as a proxy when looking for evolutionary drivers of animal cognition.
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10
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Bryer MAH, Koopman SE, Cantlon JF, Piantadosi ST, MacLean EL, Baker JM, Beran MJ, Jones SM, Jordan KE, Mahamane S, Nieder A, Perdue BM, Range F, Stevens JR, Tomonaga M, Ujfalussy DJ, Vonk J. The evolution of quantitative sensitivity. Philos Trans R Soc Lond B Biol Sci 2022; 377:20200529. [PMID: 34957840 PMCID: PMC8710878 DOI: 10.1098/rstb.2020.0529] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The ability to represent approximate quantities appears to be phylogenetically widespread, but the selective pressures and proximate mechanisms favouring this ability remain unknown. We analysed quantity discrimination data from 672 subjects across 33 bird and mammal species, using a novel Bayesian model that combined phylogenetic regression with a model of number psychophysics and random effect components. This allowed us to combine data from 49 studies and calculate the Weber fraction (a measure of quantity representation precision) for each species. We then examined which cognitive, socioecological and biological factors were related to variance in Weber fraction. We found contributions of phylogeny to quantity discrimination performance across taxa. Of the neural, socioecological and general cognitive factors we tested, cortical neuron density and domain-general cognition were the strongest predictors of Weber fraction, controlling for phylogeny. Our study is a new demonstration of evolutionary constraints on cognition, as well as of a relation between species-specific neuron density and a particular cognitive ability. This article is part of the theme issue ‘Systems neuroscience through the lens of evolutionary theory’.
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Affiliation(s)
- Margaret A H Bryer
- Department of Psychology, Carnegie Mellon University, Pittsburgh, PA 15213, USA.,Department of Psychology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Sarah E Koopman
- School of Psychology and Neuroscience, University of St. Andrews, St Andrews KY16 9AJ, UK
| | - Jessica F Cantlon
- Department of Psychology, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Steven T Piantadosi
- Department of Psychology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Evan L MacLean
- School of Anthropology, University of Arizona, Tucson, AZ 85719, USA.,College of Veterinary Medicine, University of Arizona, Tucson, AZ 85719, USA
| | - Joseph M Baker
- Center for Interdisciplinary Brain Sciences Research, Division of Brain Sciences, Department of Psychiatry and Behavioral Sciences, School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Michael J Beran
- Department of Psychology and Language Research Center, Georgia State University, Atlanta, GA 30302, USA
| | - Sarah M Jones
- Psychology Program, Berea College, Berea, KY 40403, USA
| | - Kerry E Jordan
- Department of Psychology, Utah State University, Logan, UT 84322, USA
| | - Salif Mahamane
- Behavioral and Social Sciences Department, Western Colorado University, Gunnison, CO 81231, USA
| | - Andreas Nieder
- Animal Physiology Unit, Institute of Neurobiology, University of Tübingen, Tübingen 72076, Germany
| | - Bonnie M Perdue
- Department of Psychology, Agnes Scott College, Decatur, GA 30030, USA
| | - Friederike Range
- Domestication Lab, Konrad Lorenz Institute of Ethology, Department of Interdisciplinary Life Sciences, University of Veterinary Medicine Vienna, Savoyenstrasse 1a, Vienna 1160, Austria
| | - Jeffrey R Stevens
- Department of Psychology and Center for Brain, Biology and Behavior, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | | | - Dorottya J Ujfalussy
- MTA-ELTE Comparative Ethology Research Group, Eötvös Loránd University of Sciences (ELTE), Budapest 1117, Hungary.,Department of Ethology, Eötvös Loránd University of Sciences (ELTE), Budapest 1117, Hungary
| | - Jennifer Vonk
- Department of Psychology, Oakland University, Rochester, MI 48309, USA
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11
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Massen JJM, Hartlieb M, Martin JS, Leitgeb EB, Hockl J, Kocourek M, Olkowicz S, Zhang Y, Osadnik C, Verkleij JW, Bugnyar T, Němec P, Gallup AC. Brain size and neuron numbers drive differences in yawn duration across mammals and birds. Commun Biol 2021; 4:503. [PMID: 33958700 PMCID: PMC8102614 DOI: 10.1038/s42003-021-02019-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 03/24/2021] [Indexed: 02/02/2023] Open
Abstract
Recent studies indicate that yawning evolved as a brain cooling mechanism. Given that larger brains have greater thermolytic needs and brain temperature is determined in part by heat production from neuronal activity, it was hypothesized that animals with larger brains and more neurons would yawn longer to produce comparable cooling effects. To test this, we performed the largest study on yawning ever conducted, analyzing 1291 yawns from 101 species (55 mammals; 46 birds). Phylogenetically controlled analyses revealed robust positive correlations between yawn duration and (1) brain mass, (2) total neuron number, and (3) cortical/pallial neuron number in both mammals and birds, which cannot be attributed solely to allometric scaling rules. These relationships were similar across clades, though mammals exhibited considerably longer yawns than birds of comparable brain and body mass. These findings provide further evidence suggesting that yawning is a thermoregulatory adaptation that has been conserved across amniote evolution.
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Affiliation(s)
- Jorg J M Massen
- Animal Behaviour and Cognition, Department of Biology, Utrecht University, Utrecht, The Netherlands.
| | - Margarita Hartlieb
- Department of Behavioral & Cognitive Biology, University of Vienna, Vienna, Austria
| | - Jordan S Martin
- Human Ecology Group, Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland
| | - Elisabeth B Leitgeb
- Department of Behavioral & Cognitive Biology, University of Vienna, Vienna, Austria
| | - Jasmin Hockl
- Department of Behavioral & Cognitive Biology, University of Vienna, Vienna, Austria
| | - Martin Kocourek
- Department of Zoology, Charles University, Prague, Czech Republic
| | - Seweryn Olkowicz
- Department of Zoology, Charles University, Prague, Czech Republic
| | - Yicheng Zhang
- Department of Zoology, Charles University, Prague, Czech Republic
| | - Christin Osadnik
- Department of General Zoology, University of Duisburg-Essen, Essen, Germany
| | - Jorrit W Verkleij
- Animal Behaviour and Cognition, Department of Biology, Utrecht University, Utrecht, The Netherlands
| | - Thomas Bugnyar
- Department of Behavioral & Cognitive Biology, University of Vienna, Vienna, Austria
| | - Pavel Němec
- Department of Zoology, Charles University, Prague, Czech Republic
| | - Andrew C Gallup
- Psychology Program, Department of Social and Behavioral Sciences, SUNY Polytechnic Institute, Utica, NY, USA.
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12
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Weisbecker V, Rowe T, Wroe S, Macrini TE, Garland KLS, Travouillon KJ, Black K, Archer M, Hand SJ, Berlin JC, Beck RMD, Ladevèze S, Sharp AC, Mardon K, Sherratt E. Global elongation and high shape flexibility as an evolutionary hypothesis of accommodating mammalian brains into skulls. Evolution 2021; 75:625-640. [PMID: 33483947 DOI: 10.1111/evo.14163] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 12/07/2020] [Accepted: 12/13/2020] [Indexed: 12/26/2022]
Abstract
Little is known about how the large brains of mammals are accommodated into the dazzling diversity of their skulls. It has been suggested that brain shape is influenced by relative brain size, that it evolves or develops according to extrinsic or intrinsic mechanical constraints, and that its shape can provide insights into its proportions and function. Here, we characterize the shape variation among 84 marsupial cranial endocasts of 57 species including fossils, using three-dimensional geometric morphometrics and virtual dissections. Statistical shape analysis revealed four main patterns: over half of endocast shape variation ranges from elongate and straight to globular and inclined; little allometric variation with respect to centroid size, and none for relative volume; no association between locomotion and endocast shape; limited association between endocast shape and previously published histological cortex volumes. Fossil species tend to have smaller cerebral hemispheres. We find divergent endocast shapes in closely related species and within species, and diverse morphologies superimposed over the main variation. An evolutionarily and individually malleable brain with a fundamental tendency to arrange into a spectrum of elongate-to-globular shapes-possibly mostly independent of brain function-may explain the accommodation of brains within the enormous diversity of mammalian skull form.
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Affiliation(s)
- Vera Weisbecker
- College of Science and Engineering, Flinders University, Bedford Park, SA, 5042, Australia.,School of Biological Sciences, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Timothy Rowe
- Department of Geological Sciences, The University of Texas at Austin, Austin, Texas, 78712
| | - Stephen Wroe
- School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia
| | - Thomas E Macrini
- Department of Biological Sciences, St. Mary's University, San Antonio, Texas, 78228
| | | | - Kenny J Travouillon
- Collections and Research, Western Australian Museum, Welshpool, WA, 6986, Australia
| | - Karen Black
- Earth and Sustainability Science Research Center, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Michael Archer
- Earth and Sustainability Science Research Center, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Suzanne J Hand
- Earth and Sustainability Science Research Center, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Jeri C Berlin
- Department of Geological Sciences, The University of Texas at Austin, Austin, Texas, 78712
| | - Robin M D Beck
- School of Science, Engineering and Environment, University of Salford, Salford, M5 4WT, United Kingdom
| | - Sandrine Ladevèze
- CR2P UMR 7207, CNRS/MNHN/Sorbonne Université, Muséum National d'Histoire Naturelle, Paris, F-75005, France
| | - Alana C Sharp
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, L7 8TX, United Kingdom
| | - Karine Mardon
- Centre of Advanced Imaging, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Emma Sherratt
- School of Biological Sciences, The University of Adelaide, Adelaide, SA, 5005, Australia
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13
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Herculano-Houzel S, da Cunha FB, Reed JL, Kaswera-Kyamakya C, Gillissen E, Manger PR. Microchiropterans have a diminutive cerebral cortex, not an enlarged cerebellum, compared to megachiropterans and other mammals. J Comp Neurol 2020; 528:2978-2993. [PMID: 32656795 DOI: 10.1002/cne.24985] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 06/14/2020] [Accepted: 06/16/2020] [Indexed: 11/11/2022]
Abstract
Small echolocating bats are set apart from most other mammals by their relatively large cerebellum, a feature that has been associated to echolocation, as it is presumed to indicate a relatively enlarged number of neurons in the cerebellum in comparison to other brain structures. Here we quantify the neuronal composition of the cerebral cortex, cerebellum and remaining brain structures of seven species of large Pteropodid bats (formerly classified as megachiropterans), one of which echolocates, and six species of small bats (formerly classified as microchiropterans), all of which echolocate. This chiropteran data is compared to 60 mammalian species in our dataset to determine whether the relatively large cerebellum of the small echolocating bats, and possibly that of the echolocating Pteropodid, contains a relatively enlarged number of neurons. We find no evidence that the distribution of neurons differs between microchiropterans and megachiropterans, but our data indicate that microchiropterans, like the smallest shrew in our dataset, have diminutive cerebral cortices, which makes the cerebellum appear relatively large. We propose that, in agreement with the diminutive brain size of the earliest fossil mammals, this is a plesiomorphic, not a derived, feature of microchiropteran brains. The results of this study also reveal important neural characteristics related to the phylogenetic affinities and relationships of the chiropterans.
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Affiliation(s)
- Suzana Herculano-Houzel
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, USA.,Department Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee, USA
| | - Felipe Barros da Cunha
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,University of Lethbridge, Lethbridge, Canada
| | - Jamie L Reed
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, USA
| | | | - Emmanuel Gillissen
- Department of African Zoology, Royal Museum for Central Africa, Tervuren, Belgium.,Laboratory of Histology and Neuropathology, Université Libre de Bruxelles, Brussels, Belgium.,Department of Anthropology, University of Arkansas, Fayetteville, Arkansas, USA
| | - Paul R Manger
- School of Anatomical Sciences, University of the Witwatersrand, South Africa
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14
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Bhagwandin A, Debipersadh U, Kaswera-Kyamakya C, Gilissen E, Rockland KS, Molnár Z, Manger PR. Distribution, number, and certain neurochemical identities of infracortical white matter neurons in the brains of three megachiropteran bat species. J Comp Neurol 2020; 528:3023-3038. [PMID: 32103488 DOI: 10.1002/cne.24894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 02/06/2020] [Accepted: 02/24/2020] [Indexed: 12/13/2022]
Abstract
A large population of infracortical white matter neurons, or white matter interstitial cells (WMICs), are found within the subcortical white matter of the mammalian telencephalon. We examined WMICs in three species of megachiropterans, Megaloglossus woermanni, Casinycteris argynnis, and Rousettus aegyptiacus, using immunohistochemical and stereological techniques. Immunostaining for neuronal nuclear marker (NeuN) revealed substantial numbers of WMICs in each species-M. woermanni 124,496 WMICs, C. argynnis 138,458 WMICs, and the larger brained R. aegyptiacus having an estimated WMIC population of 360,503. To examine the range of inhibitory neurochemical types we used antibodies against parvalbumin, calbindin, calretinin, and neural nitric oxide synthase (nNOS). The calbindin and nNOS immunostained neurons were the most commonly observed, while those immunoreactive for calretinin and parvalbumin were sparse. The proportion of WMICs exhibiting inhibitory neurochemical profiles was ~26%, similar to that observed in previously studied primates. While for the most part the WMIC population in the megachiropterans studied was similar to that observed in other mammals, the one feature that differed was the high proportion of WMICs immunoreactive to calbindin, whereas in primates (macaque monkey, lar gibbon and human) the highest proportion of inhibitory WMICs contain calretinin. Interestingly, there appears to be an allometric scaling of WMIC numbers with brain mass. Further quantitative comparative work across more mammalian species will reveal the developmental and evolutionary trends associated with this infrequently studied neuronal population.
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Affiliation(s)
- Adhil Bhagwandin
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Johannesburg, South Africa
- Division of Clinical Anatomy and Biological Anthropology, Department of Human Biology, University of Cape Town, Cape Town, South Africa
| | - Ulsana Debipersadh
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Johannesburg, South Africa
| | | | - Emmanuel Gilissen
- Department of African Zoology, Royal Museum for Central Africa, Tervuren, Belgium
- Laboratory of Histology and Neuropathology, Université Libre de Bruxelles, Brussels, Belgium
- Department of Anthropology, University of Arkansas, Fayetteville, Arkansas, USA
| | - Kathleen S Rockland
- Department of Anatomy and Neurobiology, Boston University, School of Medicine, Boston, Massachusetts, USA
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Paul R Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Johannesburg, South Africa
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15
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Numerical Analysis of the Cerebral Cortex in Diprotodontids (Marsupialia; Australidelphia) and Comparison with Eutherian Brains. ZOOLOGY 2020; 143:125845. [DOI: 10.1016/j.zool.2020.125845] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 09/09/2020] [Accepted: 09/11/2020] [Indexed: 11/22/2022]
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16
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Similar Microglial Cell Densities across Brain Structures and Mammalian Species: Implications for Brain Tissue Function. J Neurosci 2020; 40:4622-4643. [PMID: 32253358 DOI: 10.1523/jneurosci.2339-19.2020] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 12/10/2019] [Accepted: 01/05/2020] [Indexed: 12/30/2022] Open
Abstract
Microglial cells play essential volume-related actions in the brain that contribute to the maturation and plasticity of neural circuits that ultimately shape behavior. Microglia can thus be expected to have similar cell sizes and even distribution both across brain structures and across species with different brain sizes. To test this hypothesis, we determined microglial cell densities (the inverse of cell size) using immunocytochemistry to Iba1 in samples of free cell nuclei prepared with the isotropic fractionator from brain structures of 33 mammalian species belonging to males and females of five different clades. We found that microglial cells constitute ∼7% of non-neuronal cells in different brain structures as well as in the whole brain of all mammalian species examined. Further, they vary little in cell density compared with neuronal cell densities within the cerebral cortex, across brain structures, across species within the same clade, and across mammalian clades. As a consequence, we find that one microglial cell services as few as one and as many as 100 neurons in different brain regions and species, depending on the local neuronal density. We thus conclude that the addition of microglial cells to mammalian brains is governed by mechanisms that constrain the size of these cells and have remained conserved over 200 million years of mammalian evolution. We discuss the probable consequences of such constrained size for brain function in health and disease.SIGNIFICANCE STATEMENT Microglial cells are resident macrophages of the CNS, with key functions in recycling synapses and maintaining the local environment in health and disease. We find that microglial cells occur in similar densities in the brains of different species and in the different structures of each individual brain, which indicates that these cells maintain a similar average size in mammalian evolution, suggesting in turn that the volume monitored by each microglial cell remains constant across mammals. Because the density of neurons is highly variable across the same brain structures and species, our finding implies that microglia-dependent functional recovery may be particularly difficult in those brain structures and species with high neuronal densities and therefore fewer microglial cells per neuron.
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17
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Ashwell KW. Quantitative analysis of cerebellar morphology in monotreme, metatherian and eutherian mammals. ZOOLOGY 2020; 139:125753. [DOI: 10.1016/j.zool.2020.125753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/24/2020] [Accepted: 01/27/2020] [Indexed: 11/25/2022]
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18
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Němec P, Osten P. The evolution of brain structure captured in stereotyped cell count and cell type distributions. Curr Opin Neurobiol 2020; 60:176-183. [PMID: 31945723 PMCID: PMC7191610 DOI: 10.1016/j.conb.2019.12.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/23/2019] [Accepted: 12/24/2019] [Indexed: 12/13/2022]
Abstract
The stereotyped features of brain structure, such as the distribution, morphology and connectivity of neuronal cell types across brain areas, are those most likely to explain the remarkable capacity of the brain to process information and govern behaviors. Recent advances in anatomical methods, including the simple but versatile isotropic fractionator and several whole-brain labeling, clearing and microscopy methods, have opened the door to an exciting new era in comparative brain anatomy, one that has the potential to transform our understanding of the brain structure-function relationship by representing the evolution of brain complexity in quantitative anatomical features shared across species and species-specific or clade-specific. Here we discuss these methods and their application to mapping brain cell count and cell type distributions-two particularly powerful neural correlates of vertebrate cognitive and behavioral capabilities.
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Affiliation(s)
- Pavel Němec
- Department of Zoology, Faculty of Science, Charles University, Vinicna 7, 12844 Prague, Czech Republic.
| | - Pavel Osten
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11743, USA.
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19
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Marhounová L, Kotrschal A, Kverková K, Kolm N, Němec P. Artificial selection on brain size leads to matching changes in overall number of neurons. Evolution 2019; 73:2003-2012. [PMID: 31339177 PMCID: PMC6772110 DOI: 10.1111/evo.13805] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 06/13/2019] [Accepted: 06/19/2019] [Indexed: 12/16/2022]
Abstract
Neurons are the basic computational units of the brain, but brain size is the predominant surrogate measure of brain functional capacity in comparative and cognitive neuroscience. This approach is based on the assumption that larger brains harbor higher numbers of neurons and their connections, and therefore have a higher information-processing capacity. However, recent studies have shown that brain mass may be less strongly correlated with neuron counts than previously thought. Till now, no experimental test has been conducted to examine the relationship between evolutionary changes in brain size and the number of brain neurons. Here, we provide such a test by comparing neuron number in artificial selection lines of female guppies (Poecilia reticulata) with >15% difference in relative brain mass and numerous previously demonstrated cognitive differences. Using the isotropic fractionator, we demonstrate that large-brained females have a higher overall number of neurons than small-brained females, but similar neuronal densities. Importantly, this difference holds also for the telencephalon, a key region for cognition. Our study provides the first direct experimental evidence that selection for brain mass leads to matching changes in number of neurons and shows that brain size evolution is intimately linked to the evolution of neuron number and cognition.
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Affiliation(s)
- Lucie Marhounová
- Department of Zoology, Faculty of ScienceCharles University12844PragueCzech Republic
| | - Alexander Kotrschal
- Behavioural Ecology GroupDepartment of Animal Sciences6708wdWageningenNetherlands
- Department of Zoology/EthologyStockholm University10691StockholmSweden
| | - Kristina Kverková
- Department of Zoology, Faculty of ScienceCharles University12844PragueCzech Republic
| | - Niclas Kolm
- Department of Zoology/EthologyStockholm University10691StockholmSweden
| | - Pavel Němec
- Department of Zoology, Faculty of ScienceCharles University12844PragueCzech Republic
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20
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Herculano-Houzel S. Life history changes accompany increased numbers of cortical neurons: A new framework for understanding human brain evolution. PROGRESS IN BRAIN RESEARCH 2019; 250:179-216. [PMID: 31703901 DOI: 10.1016/bs.pbr.2019.06.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Narratives of human evolution have focused on cortical expansion and increases in brain size relative to body size, but considered that changes in life history, such as in age at sexual maturity and thus the extent of childhood and maternal dependence, or maximal longevity, are evolved features that appeared as consequences of selection for increased brain size, or increased cognitive abilities that decrease mortality rates, or due to selection for grandmotherly contribution to feeding the young. Here I build on my recent finding that slower life histories universally accompany increased numbers of cortical neurons across warm-blooded species to propose a simpler framework for human evolution: that slower development to sexual maturity and increased post-maturity longevity are features that do not require selection, but rather inevitably and immediately accompany evolutionary increases in numbers of cortical neurons, thus fostering human social interactions and cultural and technological evolution as generational overlap increases.
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Affiliation(s)
- Suzana Herculano-Houzel
- Department of Psychology, Department of Biological Sciences, Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, United States.
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21
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Mota B, Dos Santos SE, Ventura-Antunes L, Jardim-Messeder D, Neves K, Kazu RS, Noctor S, Lambert K, Bertelsen MF, Manger PR, Sherwood CC, Kaas JH, Herculano-Houzel S. White matter volume and white/gray matter ratio in mammalian species as a consequence of the universal scaling of cortical folding. Proc Natl Acad Sci U S A 2019; 116:15253-15261. [PMID: 31285343 PMCID: PMC6660724 DOI: 10.1073/pnas.1716956116] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Because the white matter of the cerebral cortex contains axons that connect distant neurons in the cortical gray matter, the relationship between the volumes of the 2 cortical compartments is key for information transmission in the brain. It has been suggested that the volume of the white matter scales universally as a function of the volume of the gray matter across mammalian species, as would be expected if a global principle of wiring minimization applied. Using a systematic analysis across several mammalian clades, here we show that the volume of the white matter does not scale universally with the volume of the gray matter across mammals and is not optimized for wiring minimization. Instead, the ratio between volumes of gray and white matter is universally predicted by the same equation that predicts the degree of folding of the cerebral cortex, given the clade-specific scaling of cortical thickness, such that the volume of the gray matter (or the ratio of gray to total cortical volumes) divided by the square root of cortical thickness is a universal function of total cortical volume, regardless of the number of cortical neurons. Thus, the very mechanism that we propose to generate cortical folding also results in compactness of the white matter to a predictable degree across a wide variety of mammalian species.
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Affiliation(s)
- Bruno Mota
- Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21941-909, Brazil
| | | | | | - Débora Jardim-Messeder
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21941-901, Brazil
| | - Kleber Neves
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21941-901, Brazil
| | - Rodrigo S Kazu
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21941-901, Brazil
- Department of Psychology, University of Sheffield, Reading RG6 6AH, United Kingdom
| | - Stephen Noctor
- Department of Psychiatry and Behavioral Sciences, University of California, Davis, CA 95616
| | - Kelly Lambert
- Department of Psychology, University of Richmond, Richmond, VA 23173
| | - Mads F Bertelsen
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, 2000 Copenhagen, Denmark
| | - Paul R Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Braamfontein 2000, Johannesburg, South Africa
| | - Chet C Sherwood
- Department of Anthropology, The George Washington University, Washington, DC 20052
- Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, DC 20052
| | - Jon H Kaas
- Department of Psychology, Vanderbilt University, Nashville, TN 37203;
| | - Suzana Herculano-Houzel
- Department of Psychology, Vanderbilt University, Nashville, TN 37203;
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37212
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232
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22
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Herculano-Houzel S. Longevity and sexual maturity vary across species with number of cortical neurons, and humans are no exception. J Comp Neurol 2018; 527:1689-1705. [PMID: 30350858 DOI: 10.1002/cne.24564] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 08/23/2018] [Accepted: 10/08/2018] [Indexed: 01/04/2023]
Abstract
Maximal longevity of endotherms has long been considered to increase with decreasing specific metabolic rate, and thus with increasing body mass. Using a dataset of over 700 species, here I show that maximal longevity, age at sexual maturity, and postmaturity longevity across bird and mammalian species instead correlate primarily, and universally, with the number of cortical brain neurons. Correlations with metabolic rate and body mass are entirely explained by clade-specific relationships between these variables and numbers of cortical neurons across species. Importantly, humans reach sexual maturity and subsequently live just as long as expected for their number of cortical neurons, which eliminates the basis for earlier theories of protracted childhood and prolonged post-menopause longevity as derived human characteristics. Longevity might increase together with numbers of cortical neurons through their impact on three main factors: delay of sexual maturity, which postpones the onset of aging; lengthening of the period of viable physiological integration and adaptation, which increases postmaturity longevity; and improved cognitive capabilities that benefit survival of the self and of longer-lived progeny, and are conducive to prolonged learning and cultural transmission through increased generational overlap. Importantly, the findings indicate that theories of aging and neurodegenerative diseases should take absolute time lived besides relative "age" into consideration.
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Affiliation(s)
- Suzana Herculano-Houzel
- Department of Psychology, Vanderbilt University, Nashville, Tennessee.,Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee.,Brain Institute, Vanderbilt University, Nashville, Tennessee
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23
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Jardim-Messeder D, Lambert K, Noctor S, Pestana FM, de Castro Leal ME, Bertelsen MF, Alagaili AN, Mohammad OB, Manger PR, Herculano-Houzel S. Dogs Have the Most Neurons, Though Not the Largest Brain: Trade-Off between Body Mass and Number of Neurons in the Cerebral Cortex of Large Carnivoran Species. Front Neuroanat 2017; 11:118. [PMID: 29311850 PMCID: PMC5733047 DOI: 10.3389/fnana.2017.00118] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 11/27/2017] [Indexed: 12/27/2022] Open
Abstract
Carnivorans are a diverse group of mammals that includes carnivorous, omnivorous and herbivorous, domesticated and wild species, with a large range of brain sizes. Carnivory is one of several factors expected to be cognitively demanding for carnivorans due to a requirement to outsmart larger prey. On the other hand, large carnivoran species have high hunting costs and unreliable feeding patterns, which, given the high metabolic cost of brain neurons, might put them at risk of metabolic constraints regarding how many brain neurons they can afford, especially in the cerebral cortex. For a given cortical size, do carnivoran species have more cortical neurons than the herbivorous species they prey upon? We find they do not; carnivorans (cat, mongoose, dog, hyena, lion) share with non-primates, including artiodactyls (the typical prey of large carnivorans), roughly the same relationship between cortical mass and number of neurons, which suggests that carnivorans are subject to the same evolutionary scaling rules as other non-primate clades. However, there are a few important exceptions. Carnivorans stand out in that the usual relationship between larger body, larger cortical mass and larger number of cortical neurons only applies to small and medium-sized species, and not beyond dogs: we find that the golden retriever dog has more cortical neurons than the striped hyena, African lion and even brown bear, even though the latter species have up to three times larger cortices than dogs. Remarkably, the brown bear cerebral cortex, the largest examined, only has as many neurons as the ten times smaller cat cerebral cortex, although it does have the expected ten times as many non-neuronal cells in the cerebral cortex compared to the cat. We also find that raccoons have dog-like numbers of neurons in their cat-sized brain, which makes them comparable to primates in neuronal density. Comparison of domestic and wild species suggests that the neuronal composition of carnivoran brains is not affected by domestication. Instead, large carnivorans appear to be particularly vulnerable to metabolic constraints that impose a trade-off between body size and number of cortical neurons.
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Affiliation(s)
- Débora Jardim-Messeder
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Kelly Lambert
- Department of Psychology, University of Richmond, Richmond, VA, United States
| | - Stephen Noctor
- Department of Psychiatry and Behavioral Sciences, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Fernanda M Pestana
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Mads F Bertelsen
- Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, Denmark
| | - Abdulaziz N Alagaili
- KSU Mammals Research Chair, Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Osama B Mohammad
- KSU Mammals Research Chair, Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Paul R Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Suzana Herculano-Houzel
- Department of Psychology, Vanderbilt University, Nashville, TN, United States.,Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States.,Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, United States
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24
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