Browse
Submit Data
Databases
API
Help

Dataset Information

30 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Sexual dimorphism in Australopithecus afarensis was similar to that of modern humans.

ABSTRACT: The substantial fossil record for Australopithecus afarensis includes both an adult partial skeleton [Afar Locality (A.L.) 288-1, "Lucy"] and a large simultaneous death assemblage (A.L. 333). Here we optimize data derived from both to more accurately estimate skeletal size dimorphism. Postcranial ratios derived from A.L. 288-1 enable a significant increase in sample size compared with previous studies. Extensive simulations using modern humans, chimpanzees, and gorillas confirm that this technique is accurate and that skeletal size dimorphism in A. afarensis was most similar to that of contemporary Homo sapiens. These data eliminate some apparent discrepancies between the canine and skeletal size dimorphism in hominoids, imply that the species was not characterized by substantial sexual bimaturation, and greatly increase the probability that the reproductive strategy of A. afarensis was principally monogamy.

SUBMITTER: Reno PL

PROVIDER: S-EPMC170931 | biostudies-literature | 2003 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Sexual dimorphism in Australopithecus afarensis was similar to that of modern humans.

Reno Philip L PL Meindl Richard S RS McCollum Melanie A MA Lovejoy C Owen CO

Proceedings of the National Academy of Sciences of the United States of America 20030723 16

The substantial fossil record for Australopithecus afarensis includes both an adult partial skeleton [Afar Locality (A.L.) 288-1, "Lucy"] and a large simultaneous death assemblage (A.L. 333). Here we optimize data derived from both to more accurately estimate skeletal size dimorphism. Postcranial ratios derived from A.L. 288-1 enable a significant increase in sample size compared with previous studies. Extensive simulations using modern humans, chimpanzees, and gorillas confirm that this techniq ...[more]

PMID: 12878734

Similar Datasets

Homoplasy in the evolution of modern human-like joint proportions in Australopithecus afarensis.

Project description:The evolution of bipedalism and reduced reliance on arboreality in hominins resulted in larger lower limb joints relative to the joints of the upper limb. The pattern and timing of this transition, however, remains unresolved. Here, we find the limb joint proportions of Australopithecus afarensis, Homo erectus, and Homo naledi to resemble those of modern humans, whereas those of A. africanus, Australopithecus sediba, Paranthropus robustus, Paranthropus boisei, Homo habilis, and Homo floresiensis are more ape-like. The homology of limb joint proportions in A. afarensis and modern humans can only be explained by a series of evolutionary reversals irrespective of differing phylogenetic hypotheses. Thus, the independent evolution of modern human-like limb joint proportions in A. afarensis is a more parsimonious explanation. Overall, these results support an emerging perspective in hominin paleobiology that A. afarensis was the most terrestrially adapted australopith despite the importance of arboreality throughout much of early hominin evolution.

| S-EPMC8116054 | biostudies-literature

From Lucy to Kadanuumuu: balanced analyses of Australopithecus afarensis assemblages confirm only moderate skeletal dimorphism.

Project description:Sexual dimorphism in body size is often used as a correlate of social and reproductive behavior in Australopithecus afarensis. In addition to a number of isolated specimens, the sample for this species includes two small associated skeletons (A.L. 288-1 or "Lucy" and A.L. 128/129) and a geologically contemporaneous death assemblage of several larger individuals (A.L. 333). These have driven both perceptions and quantitative analyses concluding that Au. afarensis was markedly dimorphic. The Template Method enables simultaneous evaluation of multiple skeletal sites, thereby greatly expanding sample size, and reveals that A. afarensis dimorphism was similar to that of modern humans. A new very large partial skeleton (KSD-VP-1/1 or "Kadanuumuu") can now also be used, like Lucy, as a template specimen. In addition, the recently developed Geometric Mean Method has been used to argue that Au. afarensis was equally or even more dimorphic than gorillas. However, in its previous application Lucy and A.L. 128/129 accounted for 10 of 11 estimates of female size. Here we directly compare the two methods and demonstrate that including multiple measurements from the same partial skeleton that falls at the margin of the species size range dramatically inflates dimorphism estimates. Prevention of the dominance of a single specimen's contribution to calculations of multiple dimorphism estimates confirms that Au. afarensis was only moderately dimorphic.

| S-EPMC4419524 | biostudies-literature

Morphological correlates of distal fibular morphology with locomotion in great apes, humans, and Australopithecus afarensis.

Project description:ObjectivesRecent studies highlighted the importance of the fibula to further our understanding of locomotor adaptations in fossil hominins. In this study, we present a three-dimensional geometric morphometric (3D-GM) investigation of the distal fibula in extant hominids and Australopithecus afarensis with the aim of pointing out morphological correlations to arboreal behavior.MethodsThree-dimensional surface meshes of the distal fibula were obtained using computer tomography for 40 extant hominid specimens and laser scanner for five A. afarensis specimens. Distal fibula morphology was quantified positioning 11 fixed landmarks, 40 curve semilandmarks, and 20 surface landmarks on each specimen. A generalized Procrustes analysis (GPA) was carried out on all landmark coordinates followed by Procrustes ANOVA. Principal component analysis (PCA) was performed on the GPA-aligned shape coordinates. Kruskal-Wallis tests and Mann-Whitney test were performed on scores along PCs.ResultsGreat apes are characterized by a shorter subcutaneous triangular surface (STS), more downward facing fibulotalar articular facets, more anteriorly facing lateral malleolus and wider/deeper malleolar fossa than humans. Within great apes, orangutans are characterized by more medially facing fibulotalar articular facets. Australopithecus afarensis shows a unique distal fibular morphology with several traits that are generally associated more to arboreality and less to bipedalism such as a short STS, a more anteriorly facing, laterally pointing malleolus and deeper and larger malleolar fossa.ConclusionsThe distal fibula morphology is indicative of locomotor patterns within extant hominids. The 3D-GM method presented here can be successfully used to further our understanding of arboreal adaptations in fossil hominins.

| S-EPMC9314891 | biostudies-literature

An early Australopithecus afarensis postcranium from Woranso-Mille, Ethiopia.

Project description:Only one partial skeleton that includes both forelimb and hindlimb elements has been reported for Australopithecus afarensis. The diminutive size of this specimen (A.L. 288-1 ["Lucy"]) has hampered our understanding of the paleobiology of this species absent the potential impact of allometry. Here we describe a large-bodied (i.e., well within the range of living Homo) specimen that, at 3.58 Ma, also substantially antedates A.L. 288-1. It provides fundamental evidence of limb proportions, thoracic form, and locomotor heritage in Australopithecus afarensis. Together, these characteristics further establish that bipedality in Australopithecus was highly evolved and that thoracic form differed substantially from that of either extant African ape.

| S-EPMC2901440 | biostudies-literature

High-resolution vegetation and climate change associated with Pliocene Australopithecus afarensis.

Project description:Plio-Pleistocene global climate change is believed to have had an important influence on local habitats and early human evolution in Africa. Responses of hominin lineages to climate change have been difficult to test, however, because this procedure requires well documented evidence for connections between global climate and hominin environment. Through high-resolution pollen data from Hadar, Ethiopia, we show that the hominin Australopithecus afarensis accommodated to substantial environmental variability between 3.4 and 2.9 million years ago. A large biome shift, up to 5 degrees C cooling, and a 200- to 300-mm/yr rainfall increase occurred just before 3.3 million years ago, which is consistent with a global marine delta(18)O isotopic shift.

| S-EPMC514445 | biostudies-literature

Gorilla-like anatomy on Australopithecus afarensis mandibles suggests Au. afarensis link to robust australopiths.

Project description:Mandibular ramus morphology on a recently discovered specimen of Australopithecus afarensis closely matches that of gorillas. This finding was unexpected given that chimpanzees are the closest living relatives of humans. Because modern humans, chimpanzees, orangutans, and many other primates share a ramal morphology that differs from that of gorillas, the gorilla anatomy must represent a unique condition, and its appearance in fossil hominins must represent an independently derived morphology. This particular morphology appears also in Australopithecus robustus. The presence of the morphology in both the latter and Au. afarensis and its absence in modern humans cast doubt on the role of Au. afarensis as a modern human ancestor. The ramal anatomy of the earlier Ardipithecus ramidus is virtually that of a chimpanzee, corroborating the proposed phylogenetic scenario.

| S-EPMC1871826 | biostudies-other

The influence of life history and sexual dimorphism on entheseal changes in modern humans and African great apes.

Project description:Entheseal changes have been widely studied with regard to their correlation to biomechanical stress and their usefulness for biocultural reconstructions. However, anthropological and medical studies have demonstrated the marked influence of both age and sex on the development of these features. Studies of entheseal changes are mostly aimed in testing functional hypotheses and are mostly focused on modern humans, with few data available for non-human primates. The lack of comparative studies on the effect of age and sex on entheseal changes represent a gap in our understanding of the evolutionary basis of both development and degeneration of the human musculoskeletal system. The aim of the present work is to compare age trajectories and patterns of sexual dimorphism in entheseal changes between modern humans and African great apes. To this end we analyzed 23 postcranial entheses in a human contemporary identified skeletal collection (N = 484) and compared the results with those obtained from the analysis of Pan (N = 50) and Gorilla (N = 47) skeletal specimens. Results highlight taxon-specific age trajectories possibly linked to differences in life history schedules and phyletic relationships. Robusticity trajectories separate Pan and modern humans from Gorilla, whereas enthesopathic patterns are unique in modern humans and possibly linked to their extended potential lifespan. Comparisons between sexes evidence a decreasing dimorphism in robusticity from Gorilla, to modern humans to Pan, which is likely linked to the role played by size, lifespan and physical activity on robusticity development. The present study confirms previous hypotheses on the possible relevance of EC in the study of life history, pointing moreover to their usefulness in evolutionary studies.

| S-EPMC4175998 | biostudies-literature

Diet of Australopithecus afarensis from the Pliocene Hadar Formation, Ethiopia.

Project description:The enhanced dietary flexibility of early hominins to include consumption of C4/crassulacean acid metabolism (CAM) foods (i.e., foods derived from grasses, sedges, and succulents common in tropical savannas and deserts) likely represents a significant ecological and behavioral distinction from both extant great apes and the last common ancestor that we shared with great apes. Here, we use stable carbon isotopic data from 20 samples of Australopithecus afarensis from Hadar and Dikika, Ethiopia (>3.4-2.9 Ma) to show that this species consumed a diet with significant C4/CAM foods, differing from its putative ancestor Au. anamensis. Furthermore, there is no temporal trend in the amount of C4/CAM food consumption over the age of the samples analyzed, and the amount of C4/CAM food intake was highly variable, even within a single narrow stratigraphic interval. As such, Au. afarensis was a key participant in the C4/CAM dietary expansion by early australopiths of the middle Pliocene. The middle Pliocene expansion of the eastern African australopith diet to include savanna-based foods represents a shift to use of plant food resources that were already abundant in hominin environments for at least 1 million y and sets the stage for dietary differentiation and niche specialization by subsequent hominin taxa.

| S-EPMC3696813 | biostudies-other

<i>Australopithecus afarensis</i> endocasts suggest ape-like brain organization and prolonged brain growth.

Project description:Human brains are three times larger, are organized differently, and mature for a longer period of time than those of our closest living relatives, the chimpanzees. Together, these characteristics are important for human cognition and social behavior, but their evolutionary origins remain unclear. To study brain growth and organization in the hominin species Australopithecus afarensis more than 3 million years ago, we scanned eight fossil crania using conventional and synchrotron computed tomography. We inferred key features of brain organization from endocranial imprints and explored the pattern of brain growth by combining new endocranial volume estimates with narrow age at death estimates for two infants. Contrary to previous claims, sulcal imprints reveal an ape-like brain organization and no features derived toward humans. A comparison of infant to adult endocranial volumes indicates protracted brain growth in A. afarensis, likely critical for the evolution of a long period of childhood learning in hominins.

| S-EPMC7112758 | biostudies-literature

Exploring sexual dimorphism of the modern human talus through geometric morphometric methods.

Project description:Sex determination is a pivotal step in forensic and bioarchaeological fields. Generally, scholars focus on metric or qualitative morphological features, but in the last few years several contributions have applied geometric-morphometric (GM) techniques to overcome limitations of traditional approaches. In this study, we explore sexual dimorphism in modern human tali from three early 20th century populations (Sassari and Bologna, Italy; New York, USA) at intra- and interspecific population levels using geometric morphometric (GM) methods. Statistical analyses were performed using shape, form, and size variables. Our results do not show significant differences in shape between males and females, either considering the pooled sample or the individual populations. Differences in talar morphology due to sexual dimorphism are mainly related to allometry, i.e. size-related changes of morphological traits. Discriminant function analysis using form space Principal Components and centroid size correctly classify between 87.7% and 97.2% of the individuals. The result is similar using the pooled sample or the individual population, except for a diminished outcome for the New York group (from 73.9% to 78.2%). Finally, a talus from the Bologna sample (not included in the previous analysis) with known sex was selected to run a virtual resection, followed by two digital reconstructions based on the mean shape of both the pooled sample and the Bologna sample, respectively. The reconstructed talus was correctly classified with a Ppost between 99.9% and 100%, demonstrating that GM is a valuable tool to cope with fragmentary tali, which is a common occurrence in forensic and bioarchaeological contexts.

| S-EPMC7021319 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data