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Pestana C, de Sousa AA, Todorov OS, Beaudet A, Benoit J. Evolutionary history of hominin brain size and phylogenetic comparative methods. PROGRESS IN BRAIN RESEARCH 2023; 275:217-232. [PMID: 36841569 DOI: 10.1016/bs.pbr.2022.12.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
An absolutely and relatively large brain has traditionally been viewed as a distinctive characteristic of the Homo genus, with anatomically modern humans presented at the apex of a long line of progressive increases in encephalization. Many studies continue to focus attention on increasing brain size in the Homo genus, while excluding measures of absolute and relative brain size of more geologically recent, smaller brained, hominins such as Homo floresiensis, and Homo naledi and smaller brained Homo erectus specimens. This review discusses the benefits of using phylogenetic comparative methods to trace the diverse changes in hominin brain evolution and the drawbacks of not doing so.
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Affiliation(s)
- Christopher Pestana
- Evolutionary Studies Institute, School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | | | - Orlin S Todorov
- School of Natural Sciences, Macquarie University, Sydney, NSW, Australia
| | - Amélie Beaudet
- Department of Archaeology, University of Cambridge, Cambridge, United Kingdom; School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Johannesburg, South Africa; Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Julien Benoit
- Evolutionary Studies Institute, School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
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Lyras GA. Brain Changes during Phyletic Dwarfing in Elephants and Hippos. BRAIN, BEHAVIOR AND EVOLUTION 2019; 92:167-181. [PMID: 30943507 DOI: 10.1159/000497268] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/27/2019] [Indexed: 11/19/2022]
Abstract
Of all known insular mammals, hippos and elephants present the extremes of body size decrease, reducing to 4 and a mere 2% of their ancestral mainland size, respectively. Despite the numerous studies on these taxa, what happens to their relative brain size during phyletic dwarfing is not well known, and results are sometimes conflicting. For example, relative brain size increase has been noted in the Sicilian dwarf elephant, Palaeoloxodon falconeri, whereas relative brain size decrease has been postulated for Malagasy dwarf hippos. Here, I perform an analysis of brain, skull, and body size of 3 insular elephants (Palaeoloxodon "mnaidriensis," P. tiliensis, and P. falconeri) and 3 insular hippos (Hippopotamus madagascariensis, H. lemerlei, and H. minor) to address this issue and to test whether relative brain size in phyletic dwarf species can be predicted. The results presented here show that the encephalization of all insular elephants and hippos is higher than that of their continental relatives. P. falconeri in particular has an enormous encephalization increase, which has so far not been reported in any other insular mammal. Insular brain size cannot be reliably predicted using either static allometric or ontogenetic scaling models. The results of this study indicate that insular dwarf species follow brain-body allometric relationships different from the expected patterns seen for their mainland relatives.
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Affiliation(s)
- George A Lyras
- Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, Athens, Greece,
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Sayol F, Downing PA, Iwaniuk AN, Maspons J, Sol D. Predictable evolution towards larger brains in birds colonizing oceanic islands. Nat Commun 2018; 9:2820. [PMID: 30065283 PMCID: PMC6068123 DOI: 10.1038/s41467-018-05280-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 06/11/2018] [Indexed: 11/27/2022] Open
Abstract
Theory and evidence suggest that some selective pressures are more common on islands than in adjacent mainland habitats, leading evolution to follow predictable trends. The existence of predictable evolutionary trends has nonetheless been difficult to demonstrate, mainly because of the challenge of separating in situ evolution from sorting processes derived from colonization events. Here we use brain size measurements of >1900 avian species to reveal the existence of one such trend: increased brain size in island dwellers. Based on sister-taxa comparisons and phylogenetic ancestral trait estimations, we show that species living on islands have relatively larger brains than their mainland relatives and that these differences mainly reflect in situ evolution rather than varying colonization success. Our findings reinforce the view that in some instances evolution may be predictable, and yield insight into why some animals evolve larger brains despite substantial energetic and developmental costs.
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Affiliation(s)
- Ferran Sayol
- CREAF, Bellaterra (Cerdanyola del Vallès), 08193, Barcelona, Catalonia, Spain.
| | - Philip A Downing
- Department of Biology, Molecular Ecology and Evolution Laboratory, Lund University, 223 62, Lund, Sweden
| | - Andrew N Iwaniuk
- Department of Neuroscience, Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, AB, T1K 3M4, Canada
| | - Joan Maspons
- CREAF, Bellaterra (Cerdanyola del Vallès), 08193, Barcelona, Catalonia, Spain
| | - Daniel Sol
- CREAF, Bellaterra (Cerdanyola del Vallès), 08193, Barcelona, Catalonia, Spain.
- CSIC, Bellaterra (Cerdanyola del Vallès), 08913, Barcelona, Catalonia, Spain.
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van den Hoek Ostende LW. Cladistics and insular evolution, an unfortunate marriage? Another tangle in theDeinogalerixanalysis of Borrani et al. (2017). Cladistics 2018; 34:708-713. [DOI: 10.1111/cla.12238] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/28/2018] [Indexed: 11/25/2022] Open
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Diniz-Filho JAF, Raia P. Island Rule, quantitative genetics and brain-body size evolution in Homo floresiensis. Proc Biol Sci 2017; 284:20171065. [PMID: 28637851 PMCID: PMC5489739 DOI: 10.1098/rspb.2017.1065] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 05/23/2017] [Indexed: 12/23/2022] Open
Abstract
Colonization of islands often activate a complex chain of adaptive events that, over a relatively short evolutionary time, may drive strong shifts in body size, a pattern known as the Island Rule. It is arguably difficult to perform a direct analysis of the natural selection forces behind such a change in body size. Here, we used quantitative evolutionary genetic models, coupled with simulations and pattern-oriented modelling, to analyse the evolution of brain and body size in Homo floresiensis, a diminutive hominin species that appeared around 700 kya and survived up to relatively recent times (60-90 kya) on Flores Island, Indonesia. The hypothesis of neutral evolution was rejected in 97% of the simulations, and estimated selection gradients are within the range found in living natural populations. We showed that insularity may have triggered slightly different evolutionary trajectories for body and brain size, which means explaining the exceedingly small cranial volume of H. floresiensis requires additional selective forces acting on brain size alone. Our analyses also support previous conclusions that H. floresiensis may be most likely derived from an early Indonesian H. erectus, which is coherent with currently accepted biogeographical scenario for Homo expansion out of Africa.
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Affiliation(s)
- José Alexandre Felizola Diniz-Filho
- Departamento de Ecologia e PPG em Ecologia and Evolução, Universidade Federal de Goiás, Instituto de Ciências Biológicas, Goiania, GO, Brazil
| | - Pasquale Raia
- Dipartimento di Scienze della Terra, dell'Ambiente e delle Risorse, Università di Napoli Federico II, Napoli, Italy
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Mondal M, Casals F, Xu T, Dall'Olio GM, Pybus M, Netea MG, Comas D, Laayouni H, Li Q, Majumder PP, Bertranpetit J. Genomic analysis of Andamanese provides insights into ancient human migration into Asia and adaptation. Nat Genet 2016; 48:1066-70. [DOI: 10.1038/ng.3621] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 06/17/2016] [Indexed: 12/19/2022]
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Balzeau A, Charlier P. What do cranial bones of LB1 tell us about Homo floresiensis? J Hum Evol 2016; 93:12-24. [PMID: 27086053 DOI: 10.1016/j.jhevol.2015.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 11/04/2015] [Accepted: 12/09/2015] [Indexed: 12/01/2022]
Abstract
Cranial vault thickness (CVT) of Liang Bua 1, the specimen that is proposed to be the holotype of Homo floresiensis, has not yet been described in detail and compared with samples of fossil hominins, anatomically modern humans or microcephalic skulls. In addition, a complete description from a forensic and pathological point of view has not yet been carried out. It is important to evaluate scientifically if features related to CVT bring new information concerning the possible pathological status of LB1, and if it helps to recognize affinities with any hominin species and particularly if the specimen could belong to the species Homo sapiens. Medical examination of the skull based on a micro-CT examination clearly brings to light the presence of a sincipital T (a non-metrical variant of normal anatomy), a scar from an old frontal trauma without any evident functional consequence, and a severe bilateral hyperostosis frontalis interna that may have modified the anterior morphology of the endocranium of LB1. We also show that LB1 displays characteristics, related to the distribution of bone thickness and arrangements of cranial structures, that are plesiomorphic traits for hominins, at least for Homo erectus s.l. relative to Homo neanderthalensis and H. sapiens. All the microcephalic skulls analyzed here share the derived condition of anatomically modern H. sapiens. Cranial vault thickness does not help to clarify the definition of the species H. floresiensis but it also does not support an attribution of LB1 to H. sapiens. We conclude that there is no support for the attribution of LB1 to H. sapiens as there is no evidence of systemic pathology and because it does not have any of the apomorphic traits of our species.
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Affiliation(s)
- Antoine Balzeau
- Équipe de Paléontologie Humaine, UMR 7194 du CNRS, Département de Préhistoire, Muséum National d'Histoire Naturelle, Paris, France; Department of African Zoology, Royal Museum for Central Africa, B-3080 Tervuren, Belgium.
| | - Philippe Charlier
- Section of Medical and Forensic Anthropology, UFR of Health Sciences (UVSQ/Paris-Descartes University, AP-HP), Montigny-Le-Bretonneux, France
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Kaifu Y, Kono RT, Sutikna T, Saptomo EW, Jatmiko, Due Awe R. Unique Dental Morphology of Homo floresiensis and Its Evolutionary Implications. PLoS One 2015; 10:e0141614. [PMID: 26624612 PMCID: PMC4651360 DOI: 10.1371/journal.pone.0141614] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 10/09/2015] [Indexed: 01/12/2023] Open
Abstract
Homo floresiensis is an extinct, diminutive hominin species discovered in the Late Pleistocene deposits of Liang Bua cave, Flores, eastern Indonesia. The nature and evolutionary origins of H. floresiensis' unique physical characters have been intensively debated. Based on extensive comparisons using linear metric analyses, crown contour analyses, and other trait-by-trait morphological comparisons, we report here that the dental remains from multiple individuals indicate that H. floresiensis had primitive canine-premolar and advanced molar morphologies, a combination of dental traits unknown in any other hominin species. The primitive aspects are comparable to H. erectus from the Early Pleistocene, whereas some of the molar morphologies are more progressive even compared to those of modern humans. This evidence contradicts the earlier claim of an entirely modern human-like dental morphology of H. floresiensis, while at the same time does not support the hypothesis that H. floresiensis originated from a much older H. habilis or Australopithecus-like small-brained hominin species currently unknown in the Asian fossil record. These results are however consistent with the alternative hypothesis that H. floresiensis derived from an earlier Asian Homo erectus population and experienced substantial body and brain size dwarfism in an isolated insular setting. The dentition of H. floresiensis is not a simple, scaled-down version of earlier hominins.
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Affiliation(s)
- Yousuke Kaifu
- Department of Anthropology, National Museum of Nature and Science, Tokyo, Japan
- Department of Biological Sciences, The University of Tokyo, Tokyo, Japan
| | - Reiko T. Kono
- Department of Anthropology, National Museum of Nature and Science, Tokyo, Japan
| | - Thomas Sutikna
- Centre for Archaeological Science, University of Wollongong, Wollongong, Australia
- The National Research and Development Centre for Archaeology, Jakarta, Indonesia
| | - Emanuel Wahyu Saptomo
- Centre for Archaeological Science, University of Wollongong, Wollongong, Australia
- The National Research and Development Centre for Archaeology, Jakarta, Indonesia
| | - Jatmiko
- Centre for Archaeological Science, University of Wollongong, Wollongong, Australia
- The National Research and Development Centre for Archaeology, Jakarta, Indonesia
| | - Rokus Due Awe
- Centre for Archaeological Science, University of Wollongong, Wollongong, Australia
- The National Research and Development Centre for Archaeology, Jakarta, Indonesia
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A Brief Overview of the Last 10 Years of Major Late Pleistocene Discoveries in the Old World: Homo floresiensis, Neanderthal, and Denisovan. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/581689] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In the last ten years, new fossil, archaeological, and genetic data have significantly altered our understanding of the peopling of the Old World in the Late Pleistocene. Scholars have long been challenged to define humanity’s place in evolution and to trace our phylogeny. Differences in the skeletal morphology of hominin fossils have often led to the naming of distinct new species, but recent genetic findings have challenged the traditional perspective by demonstrating that modern human DNA contains genes inherited from Neanderthals and Denisovans, thus questioning their status as separate species. The recent discovery of Homo floresiensis from Flores Island has also raised interesting queries about how much genetic and morphological diversity was present during the Late Pleistocene. This paper discusses the nature and implications of the evidence with respect to Homo floresiensis, Neanderthals, and Denisovans and briefly reviews major Late Pleistocene discoveries from the last ten years of research in the Old World and their significance to the study of human evolution.
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Affiliation(s)
- Maria Rita Palombo
- Dipartimento di Scienze della Terra Sapienza Università di Roma Rome; Italy
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