1
|
Comparative anatomy and 3D geometric morphometrics of the El Sidrón atlases (C1). J Hum Evol 2020; 149:102897. [PMID: 33137550 DOI: 10.1016/j.jhevol.2020.102897] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 09/22/2020] [Accepted: 09/24/2020] [Indexed: 12/28/2022]
Abstract
The first cervical vertebra (atlas, C1) is an important element of the vertebral column because it connects the cranial base with the cervical column, thus helping to maintain head posture and contributing to neck mobility. However, few atlases are preserved in the fossil record because of the fragility of this vertebra. Consequently, only eight well-preserved atlases from adult Neandertals have been recovered and described. Here, we present nine new atlas remains from the El Sidrón Neandertal site (Asturias, Spain), two of which (SD-1643 and SD-1605/1595) are sufficiently well preserved to allow for a detailed comparative and three-dimensional geometric morphometric analysis. We compared standard linear measurements of SD-1643 and SD-1605/1595 with those of other Neandertal atlases and carried out three-dimensional geometric morphometric analyses to compare size and shape of SD-1643 and SD-1605/1595 with those of 28 Pan (Pan troglodytes and Pan paniscus), a broad comparative sample of 55 anatomically modern humans from African and European populations, and other fossil hominins (Neandertals, Homo antecessor, Paranthropus boisei). The El Sidrón atlas fossils show typical features of the Neandertal atlas morphology, such as caudal projection of the anterior tubercle, gracility of both the posterior tubercle and the tuberosity for the insertion of the transverse ligament, and an anteroposteriorly elongated neural canal. Furthermore, when compared with atlases from the other taxa, Neandertals exhibit species-specific features of atlas morphology including a relatively lower lateral mass height, relatively narrower transverse foramina, and flatter and more horizontally oriented articular facets. Some of these features fit with previous suggestions of shorter overall length of the cervical spine and potential differences in craniocervical posture and mobility. Our results may support a different spinopelvic alignment in this species, as the atlas morphology suggests reduced cervical lordosis.
Collapse
|
2
|
Seymour RS, Bosiocic V, Snelling EP, Chikezie PC, Hu Q, Nelson TJ, Zipfel B, Miller CV. Cerebral blood flow rates in recent great apes are greater than in Australopithecus species that had equal or larger brains. Proc Biol Sci 2019; 286:20192208. [PMID: 31718497 DOI: 10.1098/rspb.2019.2208] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Brain metabolic rate (MR) is linked mainly to the cost of synaptic activity, so may be a better correlate of cognitive ability than brain size alone. Among primates, the sizes of arterial foramina in recent and fossil skulls can be used to evaluate brain blood flow rate, which is proportional to brain MR. We use this approach to calculate flow rate in the internal carotid arteries (Q˙ICA), which supply most of the primate cerebrum. Q˙ICA is up to two times higher in recent gorillas, chimpanzees and orangutans compared with 3-million-year-old australopithecine human relatives, which had equal or larger brains. The scaling relationships between Q˙ICA and brain volume (Vbr) show exponents of 1.03 across 44 species of living haplorhine primates and 1.41 across 12 species of fossil hominins. Thus, the evolutionary trajectory for brain perfusion is much steeper among ancestral hominins than would be predicted from living primates. Between 4.4-million-year-old Ardipithecus and Homo sapiens, Vbr increased 4.7-fold, but Q˙ICA increased 9.3-fold, indicating an approximate doubling of metabolic intensity of brain tissue. By contrast, Q˙ICA is proportional to Vbr among haplorhine primates, suggesting a constant volume-specific brain MR.
Collapse
Affiliation(s)
- Roger S Seymour
- School of Biological Sciences, Faculty of Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Vanya Bosiocic
- School of Biological Sciences, Faculty of Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Edward P Snelling
- Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa.,Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg 2193, South Africa
| | - Prince C Chikezie
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg 2193, South Africa
| | - Qiaohui Hu
- School of Biological Sciences, Faculty of Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Thomas J Nelson
- School of Biological Sciences, Faculty of Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Bernhard Zipfel
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg 2193, South Africa
| | - Case V Miller
- Vertebrate Palaeontology Laboratory, Department of Earth Sciences, University of Hong Kong, Pok Fu Lam, Hong Kong
| |
Collapse
|
3
|
Yu E, Ashwell KWS, Shulruf B. Quantitative analysis of arterial supply to the developing brain in tetrapod vertebrates. Anat Rec (Hoboken) 2019; 303:2309-2329. [PMID: 31680454 DOI: 10.1002/ar.24317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 09/01/2019] [Accepted: 10/03/2019] [Indexed: 11/05/2022]
Abstract
Understanding the metabolic cost of building developing tetrapod brains is critically important to explaining the more than 10-fold differences in encephalization of adult tetrapods that have emerged during evolution. The exact metabolic costs of developing the variety of tetrapod brains are impossible to determine, but one can compare cerebral artery caliber (internal radius raised to the fourth power-r4 ) across developing tetrapod vertebrate groups as a proxy of cerebral arterial flow, the delivery of nutrients during embryogenesis and early postnatal development, and hence the metabolic costs of brain development. In this study, r4 of aortic outflow and cerebral inflow arteries, as well as aortic wall thickness as a proxy of arterial pressure, were measured and compared between developing representatives of all four tetrapod classes (mammals, birds, reptiles, and amphibians). We found a clear endotherm/ectotherm dichotomy in aortic outflow and cerebral inflow between developing mammals and birds on the one hand, and developing reptiles and amphibians on the other. We did not find strong evidence for functionally significant differences in cerebral arterial caliber between groups at the order level (i.e., within birds, reptiles or amphibians). In particular, we did not find evidence in favor of increased blood supply to the brain for more behaviorally complex and encephalized avian species.
Collapse
Affiliation(s)
- Eamon Yu
- Department of Anatomy, School of Medical Sciences, The University of New South Wales, 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
| | - Boaz Shulruf
- Medical Education, The University of New South Wales, Sydney, New South Wales, Australia
| |
Collapse
|
4
|
Seymour RS, Hu Q, Snelling EP, White CR. Interspecific scaling of blood flow rates and arterial sizes in mammals. ACTA ACUST UNITED AC 2019; 222:jeb.199554. [PMID: 30877224 DOI: 10.1242/jeb.199554] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 03/07/2019] [Indexed: 01/16/2023]
Abstract
This meta-study investigated the relationships between blood flow rate (Q̇; cm3 s-1), wall shear stress (τw; dyn cm-2) and lumen radius (r i; cm) in 20 named systemic arteries of nine species of mammals, ranging in mass from 23 g mice to 652 kg cows, at rest. In the dataset, derived from 50 studies, lumen radius varied between 3.7 µm in a cremaster artery of a rat and 11.2 mm in the aorta of a human. The 92 logged data points of [Formula: see text] and r i are described by a single second-order polynomial curve with the equation: [Formula: see text] The slope of the curve increased from approximately 2 in the largest arteries to approximately 3 in the smallest ones. Thus, da Vinci's rule ([Formula: see text]) applies to the main arteries and Murray's law ([Formula: see text]) applies to the microcirculation. A subset of the data, comprising only cephalic arteries in which [Formula: see text] is fairly constant, yielded the allometric power equation: [Formula: see text] These empirical equations allow calculation of resting perfusion rates from arterial lumen size alone, without reliance on theoretical models or assumptions on the scaling of wall shear stress in relation to body mass. As expected, [Formula: see text] of individual named arteries is strongly affected by body mass; however, [Formula: see text] of the common carotid artery from six species (mouse to horse) is also sensitive to differences in whole-body basal metabolic rate, independent of the effect of body mass.
Collapse
Affiliation(s)
- Roger S Seymour
- School of Biological Sciences, Faculty of Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Qiaohui Hu
- School of Biological Sciences, Faculty of Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Edward P Snelling
- Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Gauteng 0110, South Africa.,Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Gauteng 2193, South Africa
| | - Craig R White
- Centre for Geometric Biology, School of Biological Sciences, Faculty of Science, Monash University, Clayton, VIC 3800, Australia
| |
Collapse
|
5
|
Boyer DM, Harrington AR. New estimates of blood flow rates in the vertebral artery of euarchontans and their implications for encephalic blood flow scaling: A response to Seymour and Snelling (2018). J Hum Evol 2018; 128:93-98. [PMID: 30454907 DOI: 10.1016/j.jhevol.2018.10.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 10/01/2018] [Accepted: 10/03/2018] [Indexed: 10/27/2022]
Affiliation(s)
- Doug M Boyer
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA.
| | - Arianna R Harrington
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA
| |
Collapse
|