Lucy's Flat Feet: The Relationship between the Ankle and Rearfoot Arching in Early Hominins

BACKGROUND. In the Plio-Pleistocene, the hominin foot evolved from a grasping appendage to a stiff, propulsive lever. Central to this transition was the development of the longitudinal arch, a structure that helps store elastic energy and stiffen the foot during bipedal locomotion. Direct evidence for arch evolution, however, has been somewhat elusive given the failure of soft-tissue to fossilize. Paleoanthropologists have relied on footprints and bony correlates of arch development, though little consensus has emerged as to when the arch evolved. METHODOLOGY/PRINCIPAL FINDINGS. Here, we present evidence from radiographs of modern humans (n=261) that the set of the distal tibia in the sagittal plane, henceforth referred to as the tibial arch angle, is related to rearfoot arching. Non-human primates have a posteriorly directed tibial arch angle, while most humans have an anteriorly directed tibial arch angle. Those humans with a posteriorly directed tibial arch angle (8%) have significantly lower talocalcaneal and talar declination angles, both measures of an asymptomatic flatfoot. Application of these results to the hominin fossil record reveals that a well developed rearfoot arch had evolved in Australopithecus afarensis. However, as in humans today, Australopithecus populations exhibited individual variation in foot morphology and arch development, and "Lucy" (A.L. 288-1), a 3.18 Myr-old female Australopithecus, likely possessed asymptomatic flat feet. Additional distal tibiae from the Plio-Pleistocene show variation in tibial arch angles, including two early Homo tibiae that also have slightly posteriorly directed tibial arch angles. CONCLUSIONS/SIGNIFICANCE. This study finds that the rearfoot arch was present in the genus Australopithecus. However, the female Australopithecus afarensis "Lucy" has an ankle morphology consistent with non-pathological flat-footedness. This study suggests that, as in humans today, there was variation in arch development in Plio-Pleistocene hominins.Leakey Foundatio

Morphological Variability in Paleoanthropology: New Approaches, New Issues?

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Walking with hominins: from the reconstruction of a plausible anatomical model to gait energetics in Neandertals. Methodological aspects

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Bipedal vs. quadrupedall hind limb and foot kinematics in a captive sample of olive baboons (Papio anubis): setup and preliminary results

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Bipedal vs. quadrupedall hind limb and foot kinematics in a captive sample of olive baboons (Papio anubis): setup and preliminary results

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Techno−Typologie des assemblages lithiques. Garm Roud 2, un site de plein air au paléolithique supérieur (Baliran, Amol, Mazandarn).

International audienceIntroduction - Iranian plateau with its outstanding geographical and climatic conditions has been considered a key region in the study of Pleistocene human societies. So far numerous Paleolithic sites have been discovered throughout Iran; however, our knowledge concerning the Upper Paleolithic occupations was limited to Zagros region. The Upper Paleolithic occupations of northern Alborz Mountains and southern Caspian Sea has been remained unknown. In this context, the discovery of the open air site of Garmrud 2 by the French-Iranian Paleoanthropological Project (FIPP) in 2005 was a major breakthrough in case of filling the mentioned gaps between older Paleolithic materials and those of Mesolithic from the southeastern of the Caspian Sea (e.g., Komishan, Huto, Kamarband, Al Tepe). Materilas and Methods The southeastern of the Caspian Sea is a strategic region for those interested in prehistoric human movements and dispersions. This regain is one of the proposed migratory corridors for prehistoric societies. The studied area is located between two geographical barriers: in the north is located the Caspian Sea and in the south of the Alborz Mountains. Between these barriers, there are Mazandaran and Gilan Plains with high rate of precipitations and numerous permanent and seasonal rivers. Such geographical conditions have made these plains so fertile, and attracted human societies since prehistoric times. Even today this area represents one of the densest human populations in Iran.Results and Discussion - First, it was Carlton S. Coon who conducted several field missions at the southeastern of the Caspian Sea leading to the discovery and excavation of two famous caves of Huto and Kamarband (Coon, 1951, 1952). Later Charles McBurney from University of Cambridge followed Coon’s footsteps and excavated sites of Key-Aram I and Al Tepe (Ali Tepe). In most recent years, another Mesolithic site (Komishan Cave) was excavated in the region (Vahdati Nasab et al., 2011). The astonishing point conserving these sites chronology is the fact that none belonged to the Upper Paleolithic (Key-Aram I consist of Middle Paleolithic and Mousterian materials and the rest was assigned to the Mesolithic period). For some reasons it was believed that the Upper Paleolithic is the lost period in the north and northeastern of Alborz. Similar scenarios have been observed in Turkmenistan and Tajikistan, which provoked some researchers to claim due to some climatic obstacles of these geographical regions were abandoned during the Upper Paleolithic period. That is why the discovery of a well dated site of Garm Rud 2 could shed light on some of the key aspects of this enigma. This site, which is situated at the river cut of Garm Rud River nearby the Baliran village in Amol, has witnessed three consecutive excavations producing immense amount of data in form of lithic, bones, and shells. The absolute calibrated dating of 33878±3300 plus dominance of balde/ bladelet knapping technologies leave no room for any doubt to associate Garm Rud 2 with the Upper Paleolithic period. Evidence of fauna remains in close association with lithic materials indicates that Garm Rud 2 was a butchering station, which was occupied for a brief time period. Lithic assemblages of the first excavation season were the subject of this research. In this regard, only 2.6% of the assemblage belongs to core/core fragments. Such fact plus low quantity of cortical pieces indicate that the initial preparation stages were taken place somewhere outside of the site. Bladelets are in largest quantity followed by flakes with no secondary edge work and blades. Considerable number of flake debitage implies that they have been byproducts of bladelet/blade production sequences.Conclusion - In case of comparative studies, Garm Rud 2 represents close affinities with the two Upper Paleolithic open air sites of Sefid-Ab and Delazian both located at the southern hills of Alborz Mountains. At the same time it deviates significantly from the Upper Paleolithic cave site of Yafteh in Zagros. Prior to apply any stylistic explanations, the geomorphological formations of these sites must be taken into considerations. In addition, the site formation and usage of the sites must be taken into account. Yafteh is a Karstic cave in Zagros, which based on its strategic location and abundance number of lithic/fauna materials had been a base camp during the beginning of the Upper Paleolithic period. On the other hand, as it was mentioned earlier Garm Rud 2 was a butchering station with short occupation period; therefore, comparing lithic techno-typologies of Yafteh and Garm Rud 2 might not provide comprehensive results. Up until present Garm Rud 2 is the only well dated Upper Paleolithic settlement at the north of Iranian plateau

In what manner do quadrupedal primates walk on two legs ? Preliminary results on Olive Baboons (Papio anubis)

International audienceOlive baboons (Papio anubis) are typically described as highly ­specialized for quadrupedal locomotion. Yet, they regularly and spontaneously walk bipedally as well. In what manner do they do this, when compared to other primates and humans? This question is of interest with regard to the origin of bipedalism in hominids. As a first step in understanding bipedal locomotion in baboons, we here present novel kinematic data, achieved using a custom-built setup that allows to measure individual locomotor parameters in a population of 55-60 captive olive baboons housed at the Primatology Station of the National Centre for Scientific Research (CNRS, France) using a high-speed digital recording system (100 fps) and a walkway (Podium). Within our population, we observed bipedality mainly in infant and subadult individuals: we present the sagittal motion parameters that we collected on a sample of 10 males and females of ages between 6 months and 5.5 years. As far as angular trajectories of the trunk and the lower limb joints are concerned, olive baboons walk bipedally in a rather stereotyped, compliant manner with a semiplantigrade stance phase, a trunk that is slightly tilted forward and immobile forelimbs kept forward in a parasagittal plane. Some small variations can be depicted, especially in the younger individuals of the sample. Among other "quadrupedal" primates of which the bipedal locomotion has been kinematically analyzed, the kinematics of bipedal walking of Papio anubis more closely resembles those described in Macaca fuscata. In the broader framework of our study, numerous transversal and longitudinal analyses are in progress on data as varied as noninvasive anatomical investigations, kinematics, kinetics, and paedobarography

The Late Pleistocene in the Northern fringes of Iranian Central Desert and the Formation of Archaeological Sites; Case Study: Mirak, Semnan

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