G A Macho
Biographic Data
| ID | 1169 |
|---|---|
| NAME | G A Macho |
| GIVEN NAMES | G A |
| FAMILY NAME | Macho |
| SIGNATURE | MACHO G A |
| AFFILIATIONS | University of Liverpool |
| ORCID | 0000-0002-2355-2858 |
| VERIFIED | Yes |
| TOTAL WORKS | 32 |
| TOTAL CITATIONS | 455 |
| AUTHOR COUNT | 32 |
| EDITOR COUNT | 0 |
| FIRST PUBLICATION YEAR | 1986 |
| LATEST PUBLICATION YEAR | 2022 |
| H-INDEX | 11 |
Do rates of dental wear in extant African great apes inform the time of weaning
The Implications of Morphology, Mechanics, and Microstructure of Teeth for Understanding Dietary Drivers in Human Evolution
Hominins evolved in mosaic to open habitats that experienced seasonal and larger timescale fluctuations in resources. Yet they were able to thrive and to evolve large brains that require a constant supply of high-quality foods. Analyses of overall tooth morphology and enamel microstructure indicate that mid-Pliocene hominins broadened their dietary niches and incorporated increasing amounts of abrasive foods; they probably underwent a shift towar…
General Principles of Evolutionary Morphology
Pliocene hominin biogeography and ecology
General Principles of Evolutionary Morphology
Kinematic parameters inferred from enamel microstructure: New insights into the diet of Australopithecus anamensis
Small-scale environmental fluctuations and their possible effects on cognitive evolution and migration of Homo
Dietary adaptations of South African australopiths: Inference From Enamel Prism Attitude
General Principles of Evolutionary Morphology
Effect of prism orientation and loading direction on contact stresses in prismatic enamel of primates: Implications for interpreting wear patterns
The ability of prisms to effectively dissipate contact stress at the surface will influence wear rates in teeth. The aim of this investigation was to begin to quantify the effect of prism orientation on surface stresses. Seven finite element models of enamel microstructure were created, each model differing in the angulation of prism orientation with regard to the wear surface. For validation purposes, the mechanical behavior of the model was com…
Age changes in bone microstructure: Do They Occur Uniformly
Age estimations based on conventional multifactorial methods were compared with trends observed in the internal morphology of bones obtained from high-resolution μCT. Specifically, average trabecular thickness and number of trabeculae/mm transect were determined in the non-load-bearing capitate (hand) and the load-bearing navicular (foot). The μCT findings reveal age-related trends but—surprisingly—these correspond only loosely with the ages assi…
Enamel microstructure-a truly three-dimensional structure
Primate molar crown formation times and life history evolution revisited
Comparative studies have convincingly demonstrated that the pattern and timing of tooth emergence are highly correlated with life‐history variables and brain size. Conversely, a firm relationship between molar formation time and life‐history variables has not yet been established. It seems counterintuitive that one aspect of dental development should be correlated with life‐history variables, whereas the other should not. In order to shed light o…
Effects of loading on the biochemical behavior of molars ofHomo,Pan, andPongo
In a previous study, we found systematic differences in the biomechanical behavior of modern human molars using finite element stress analyses (FESA), which led us to propose that molars are adapted to differently-directed loads depending on their position within the mouth (Spears and Macho [1998] Am. J. Phys. Anthropol. 106:467-482). While the FESA results thus derived have not been verified experimentally, such an interpretation seemed reasonab…
Did knuckle walking evolve twice
Effects of loading on the biochemical behavior of molars of Homo, Pan, and Pongo
In a previous study, we found systematic differences in the biomechanical behavior of modern human molars using finite element stress analyses (FESA), which led us to propose that molars are adapted to differently-directed loads depending on their position within the mouth (Spears and Macho [1998] Am. J. Phys. Anthropol. 106:467–482 ). While the FESA results thus derived have not been verified experimentally, such an interpretation seemed reasona…
Biomechanical behaviour of modern human molars: Implications for interpreting the fossil record
Finite-element models of 29 intact molars were created and subjected to cleavage-type loads in order to assess differences in the biomechanical behaviour of molars. A simulated food particle, which was one-third the size of the intercuspal distance and had the properties of a Mezzettia seed, was pushed onto the occlusal basin of these models at various angles, resulting in either both or one particular cusp being preferentially loaded. In all cas…
Biomechanical behaviour of modern human molars: Implications for interpreting the fossil record
Finite-element models of 29 intact molars were created and subjected to cleavage-type loads in order to assess differences in the biomechanical behaviour of molars. A simulated food particle, which was one-third the size of the intercuspal distance and had the properties of a Mezzettia seed, was pushed onto the occlusal basin of these models at various angles, resulting in either both or one particular cusp being preferentially loaded. In all cas…
Climatic effects on dental development ofTheropithecus oswaldi from Koobi Fora and Olorgesailie
The role of time and timing in hominid dental evolution
Exactly when during evolution hominids acquired their extended extra‐uterine growth period is a contentious issue. In order to shed light on the tempo and mode of ontogenetic changes during hominid evolution, research has focused on the pattern and, to a lesser extent, the rate of growth observed in the developing dentition of extant and extinct hominoid taxa. From these data, the absolute timing of events has often been inferred, either implicit…
Enamel thickness and the helicoidal occlusal plane
In the present study 38 unworn maxillary molars (M 1 = 16, M 2 = 12, M 3 = 10) of modern humans from a Slavic necropolis were sectioned through the mesial cusps in a plane perpendicular to the cervical margin of the crown. Five slightly worn M 1 s and one slightly worn M 3 were also used thus increasing the total sample to 44, but measurements made on the worn areas were coded as missing values. Seven measurements of enamel thickness as well as t…
Linear measurements of cortical bone and dental enamel by computed tomography: Applications and problems
This paper explores the potential of high‐resolution computed tomography (CT) as a morphometric tool in paleoanthropology. The accuracy of linear measurements of enamel thickness and cortical bone thickness taken from CT scans is evaluated by making comparison with measurements taken directly from physical sections. The measurements of cortical bone are taken on extant and fossil specimens with and without attached matrix, and the dental specimen…
Histological reconstruction of dental development and age at death of a juvenile Paranthropus robustus specimen, SK 63, from Swartkrans, South Africa
There has been disagreement about whether the earliest hominids grew in a similar manner to great apes or modern humans. This has important biological implications, since it may have been inappropriate to apply modern human developmental standards to early hominids. The aim of the present study was to combine data from replicas of tooth surfaces, computed tomographic (CT) scans, and radiographs with data from a histological section of the canine …
Enamel thickness of human maxillary molars reconsidered
Forty‐four modern human maxillary molars (M 1 = 21, M 2 = 12, and M 3 = 11) were sectioned through the mesial cusps in a plane perpendicular to the cervical margin of the crown. Eight measurements of enamel thickness as well as bucco‐lingual (BL) and mesio‐distal (MD) diameters were recorded for each tooth in order to investigate differences in these dimensions between tooth categories. Uni‐ and multi‐variate analyses revealed first maxillary mol…
Computed tomography and intercuspal angulation of maxillary molars of Plio-Pleistocene hominids from Sterkfontein, Swartkrans and Kromdraai (South Africa): An exploratory study
Linear measurements of cortical bone and dental enamel by computed tomography: Applications and problems
This paper explores the potential of high‐resolution computed tomography (CT) as a morphometric tool in paleoanthropology. The accuracy of linear measurements of enamel thickness and cortical bone thickness taken from CT scans is evaluated by making comparison with measurements taken directly from physical sections. The measurements of cortical bone are taken on extant and fossil specimens with and without attached matrix, and the dental specimen…
Histological reconstruction of dental development and age at death of a juvenile Paranthropus robustus specimen, SK 63, from Swartkrans, South Africa
There has been disagreement about whether the earliest hominids grew in a similar manner to great apes or modern humans. This has important biological implications, since it may have been inappropriate to apply modern human developmental standards to early hominids. The aim of the present study was to combine data from replicas of tooth surfaces, computed tomographic (CT) scans, and radiographs with data from a histological section of the canine …
Enamel thickness of human maxillary molars reconsidered
Forty‐four modern human maxillary molars (M 1 = 21, M 2 = 12, and M 3 = 11) were sectioned through the mesial cusps in a plane perpendicular to the cervical margin of the crown. Eight measurements of enamel thickness as well as bucco‐lingual (BL) and mesio‐distal (MD) diameters were recorded for each tooth in order to investigate differences in these dimensions between tooth categories. Uni‐ and multi‐variate analyses revealed first maxillary mol…
Climatic effects on dental development ofTheropithecus oswaldi from Koobi Fora and Olorgesailie
Enamel thickness and the helicoidal occlusal plane
In the present study 38 unworn maxillary molars (M 1 = 16, M 2 = 12, M 3 = 10) of modern humans from a Slavic necropolis were sectioned through the mesial cusps in a plane perpendicular to the cervical margin of the crown. Five slightly worn M 1 s and one slightly worn M 3 were also used thus increasing the total sample to 44, but measurements made on the worn areas were coded as missing values. Seven measurements of enamel thickness as well as t…
Did knuckle walking evolve twice
Computed tomography and enamel thickness of maxillary molars of Plio‐Pleistocene hominids from Sterkfontein, Swartkrans, and Kromdraai (South Africa): An exploratory study
This paper is one in a series which explores the possibility of using the non‐destructive CT technique to identify patterns in tooth enamel distribution and structure of hominid molars from Plio‐Pleistocene sites in South Africa, notably Swartkrans, Sterkfontein, and Kromdraai. Whereas previous investigators have emphasised gross differences in absolute and relative or average enamel thickness between hominid taxa, the present study highlights di…
Reduction of maxillary molars in Homo sapiens sapiens: A different perspective
Crown and cusp areas, and buccolingual and mesiodistal diameters of maxillary molars of complete upper tooth rows (30 males, 30 females) were analysed in order to quantify changes in size and shape from the first to the third molar. Uni‐ and multivariate analyses revealed the mesial cusps, in particular the protocone (mesiolingual cusp), to be more stable than the other cusps. Although there is a gradient in size from the first to third molar, sh…
The role of time and timing in hominid dental evolution
Exactly when during evolution hominids acquired their extended extra‐uterine growth period is a contentious issue. In order to shed light on the tempo and mode of ontogenetic changes during hominid evolution, research has focused on the pattern and, to a lesser extent, the rate of growth observed in the developing dentition of extant and extinct hominoid taxa. From these data, the absolute timing of events has often been inferred, either implicit…
Dietary adaptations of South African australopiths: Inference From Enamel Prism Attitude
Enamel microstructure-a truly three-dimensional structure
Effect of prism orientation and loading direction on contact stresses in prismatic enamel of primates: Implications for interpreting wear patterns
The ability of prisms to effectively dissipate contact stress at the surface will influence wear rates in teeth. The aim of this investigation was to begin to quantify the effect of prism orientation on surface stresses. Seven finite element models of enamel microstructure were created, each model differing in the angulation of prism orientation with regard to the wear surface. For validation purposes, the mechanical behavior of the model was com…
Kinematic parameters inferred from enamel microstructure: New insights into the diet of Australopithecus anamensis
Age changes in bone microstructure: Do They Occur Uniformly
Age estimations based on conventional multifactorial methods were compared with trends observed in the internal morphology of bones obtained from high-resolution μCT. Specifically, average trabecular thickness and number of trabeculae/mm transect were determined in the non-load-bearing capitate (hand) and the load-bearing navicular (foot). The μCT findings reveal age-related trends but—surprisingly—these correspond only loosely with the ages assi…
Pliocene hominin biogeography and ecology
Evidence of a healed compression fracture in a Plio-Pleistocene hominid talus from Sterkfontein, South Africa
The object of this communication is to draw attention to the appearance of this fossil talus Stw 363, which carries a densely adherent fragment on its posterosuperior aspect. We have endeavoured to verify that this bony fragment could be the posterior half of the fractured calcaneus resulting from a fall on to the animal's left foot. Furthermore, it is suggested that this animal survived long enough for this fracture to unite by bone to the poste…
Cephalometric and craniometric age changes in adult humans
Thirty-three cephalometric and craniometric measurements were made on lateral radiographs of 154 males and 199 females, aged 21-83 years, from Vienna, Austria. The measurements were studied in age-groups by univariate and multivariate analyses. The results showed that the height dimensions of the face and viscerocranium increase up to the fourth decade but then decrease, while the height dimensions of the neurocranium decrease progressively with …
Is sexual dimorphism in the femur a "population specific phenomenon"?
The patterns of sexual dimorphism as well as the differences in amount between the populations were studied on a sample of 162 male and 159 female left femora, which were classified as Zulu, Sotho, Xosa and South Africans of European extraction. Multivariate analyses revealed that even adjacent African tribes exhibit a different pattern of sexual dimorphism, but there were similarities between Zulu and European femora. Furthermore, relative size …
Anthropological evaluation of left-right differences in the femur of southern African populations
Bilateral asymmetries were tested on a series of anthropological measurements recorded from 566 femora of 161 males and 122 females of southern African populations. Uni- and multivariate statistics revealed that there is a high degree of side differences apparent in the morphological features of the femur, and close to 75% of all femora could be correctly assigned to their respective sides. While most dimensions were greater on the left side, ant…
Morphological asymmetries in Southern African populations. Further evidence for lateralization
Both femora of 364 individuals of southern African tribes and South Africans of European origin were analysed for population and side differences. Emphasis was placed on multivariate analyses, although uni-and bivariate statistics were also employed and discussed. While the latter analyses did not provide conclusive results, all multivariate tests were highly significant and demonstrated that differences between samples were predominantly due to …
Computed tomography and intercuspal angulation of maxillary molars of Plio-Pleistocene hominids from Sterkfontein, Swartkrans and Kromdraai (South Africa): An exploratory study
Computed tomography and enamel thickness of maxillary molars of Plio‐Pleistocene hominids from Sterkfontein, Swartkrans, and Kromdraai (South Africa): An exploratory study
This paper is one in a series which explores the possibility of using the non‐destructive CT technique to identify patterns in tooth enamel distribution and structure of hominid molars from Plio‐Pleistocene sites in South Africa, notably Swartkrans, Sterkfontein, and Kromdraai. Whereas previous investigators have emphasised gross differences in absolute and relative or average enamel thickness between hominid taxa, the present study highlights di…
Reduction of maxillary molars in Homo sapiens sapiens: A different perspective
Crown and cusp areas, and buccolingual and mesiodistal diameters of maxillary molars of complete upper tooth rows (30 males, 30 females) were analysed in order to quantify changes in size and shape from the first to the third molar. Uni‐ and multivariate analyses revealed the mesial cusps, in particular the protocone (mesiolingual cusp), to be more stable than the other cusps. Although there is a gradient in size from the first to third molar, sh…
Evidence of a healed compression fracture in a Plio-Pleistocene hominid talus from Sterkfontein, South Africa
The object of this communication is to draw attention to the appearance of this fossil talus Stw 363, which carries a densely adherent fragment on its posterosuperior aspect. We have endeavoured to verify that this bony fragment could be the posterior half of the fractured calcaneus resulting from a fall on to the animal's left foot. Furthermore, it is suggested that this animal survived long enough for this fracture to unite by bone to the poste…
Linear measurements of cortical bone and dental enamel by computed tomography: Applications and problems
This paper explores the potential of high‐resolution computed tomography (CT) as a morphometric tool in paleoanthropology. The accuracy of linear measurements of enamel thickness and cortical bone thickness taken from CT scans is evaluated by making comparison with measurements taken directly from physical sections. The measurements of cortical bone are taken on extant and fossil specimens with and without attached matrix, and the dental specimen…
Histological reconstruction of dental development and age at death of a juvenile Paranthropus robustus specimen, SK 63, from Swartkrans, South Africa
There has been disagreement about whether the earliest hominids grew in a similar manner to great apes or modern humans. This has important biological implications, since it may have been inappropriate to apply modern human developmental standards to early hominids. The aim of the present study was to combine data from replicas of tooth surfaces, computed tomographic (CT) scans, and radiographs with data from a histological section of the canine …
Enamel thickness of human maxillary molars reconsidered
Forty‐four modern human maxillary molars (M 1 = 21, M 2 = 12, and M 3 = 11) were sectioned through the mesial cusps in a plane perpendicular to the cervical margin of the crown. Eight measurements of enamel thickness as well as bucco‐lingual (BL) and mesio‐distal (MD) diameters were recorded for each tooth in order to investigate differences in these dimensions between tooth categories. Uni‐ and multi‐variate analyses revealed first maxillary mol…
Enamel thickness and the helicoidal occlusal plane
In the present study 38 unworn maxillary molars (M 1 = 16, M 2 = 12, M 3 = 10) of modern humans from a Slavic necropolis were sectioned through the mesial cusps in a plane perpendicular to the cervical margin of the crown. Five slightly worn M 1 s and one slightly worn M 3 were also used thus increasing the total sample to 44, but measurements made on the worn areas were coded as missing values. Seven measurements of enamel thickness as well as t…
The role of time and timing in hominid dental evolution
Exactly when during evolution hominids acquired their extended extra‐uterine growth period is a contentious issue. In order to shed light on the tempo and mode of ontogenetic changes during hominid evolution, research has focused on the pattern and, to a lesser extent, the rate of growth observed in the developing dentition of extant and extinct hominoid taxa. From these data, the absolute timing of events has often been inferred, either implicit…
Climatic effects on dental development ofTheropithecus oswaldi from Koobi Fora and Olorgesailie
Biomechanical behaviour of modern human molars: Implications for interpreting the fossil record
Finite-element models of 29 intact molars were created and subjected to cleavage-type loads in order to assess differences in the biomechanical behaviour of molars. A simulated food particle, which was one-third the size of the intercuspal distance and had the properties of a Mezzettia seed, was pushed onto the occlusal basin of these models at various angles, resulting in either both or one particular cusp being preferentially loaded. In all cas…
Biomechanical behaviour of modern human molars: Implications for interpreting the fossil record
Finite-element models of 29 intact molars were created and subjected to cleavage-type loads in order to assess differences in the biomechanical behaviour of molars. A simulated food particle, which was one-third the size of the intercuspal distance and had the properties of a Mezzettia seed, was pushed onto the occlusal basin of these models at various angles, resulting in either both or one particular cusp being preferentially loaded. In all cas…
Effects of loading on the biochemical behavior of molars ofHomo,Pan, andPongo
In a previous study, we found systematic differences in the biomechanical behavior of modern human molars using finite element stress analyses (FESA), which led us to propose that molars are adapted to differently-directed loads depending on their position within the mouth (Spears and Macho [1998] Am. J. Phys. Anthropol. 106:467-482). While the FESA results thus derived have not been verified experimentally, such an interpretation seemed reasonab…
Did knuckle walking evolve twice
Effects of loading on the biochemical behavior of molars of Homo, Pan, and Pongo
In a previous study, we found systematic differences in the biomechanical behavior of modern human molars using finite element stress analyses (FESA), which led us to propose that molars are adapted to differently-directed loads depending on their position within the mouth (Spears and Macho [1998] Am. J. Phys. Anthropol. 106:467–482 ). While the FESA results thus derived have not been verified experimentally, such an interpretation seemed reasona…
Primate molar crown formation times and life history evolution revisited
Comparative studies have convincingly demonstrated that the pattern and timing of tooth emergence are highly correlated with life‐history variables and brain size. Conversely, a firm relationship between molar formation time and life‐history variables has not yet been established. It seems counterintuitive that one aspect of dental development should be correlated with life‐history variables, whereas the other should not. In order to shed light o…
Enamel microstructure-a truly three-dimensional structure
Effect of prism orientation and loading direction on contact stresses in prismatic enamel of primates: Implications for interpreting wear patterns
The ability of prisms to effectively dissipate contact stress at the surface will influence wear rates in teeth. The aim of this investigation was to begin to quantify the effect of prism orientation on surface stresses. Seven finite element models of enamel microstructure were created, each model differing in the angulation of prism orientation with regard to the wear surface. For validation purposes, the mechanical behavior of the model was com…
Age changes in bone microstructure: Do They Occur Uniformly
Age estimations based on conventional multifactorial methods were compared with trends observed in the internal morphology of bones obtained from high-resolution μCT. Specifically, average trabecular thickness and number of trabeculae/mm transect were determined in the non-load-bearing capitate (hand) and the load-bearing navicular (foot). The μCT findings reveal age-related trends but—surprisingly—these correspond only loosely with the ages assi…
General Principles of Evolutionary Morphology
Small-scale environmental fluctuations and their possible effects on cognitive evolution and migration of Homo
Biology (25 works) · Pleistocene-Era Hominins and Archaeology (21 works) · Medicine (17 works) · Forensic Anthropology and Bioarchaeology Studies (15 works) · Molar (14 works) · Enamel paint (12 works) · Paleontology (12 works) · Anatomy (11 works) · Dentistry (11 works) · Evolution and Paleontology Studies (11 works)