scholarly journals The African ape-like foot of Ardipithecus ramidus and its implications for the origin of bipedalism

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Thomas Cody Prang
Keyword(s):  
Modern Human ◽  
Bipedal Locomotion ◽  
Early Form ◽  
Large Sample ◽  
Ancestral Condition ◽  
Ancestral Form ◽  
Human Foot ◽  
African Apes ◽  
Anthropoid Primates ◽  
Foot Morphology

The ancestral condition from which humans evolved is critical for understanding the adaptive origin of bipedal locomotion. The 4.4 million-year-old hominin partial skeleton attributed to Ardipithecus ramidus preserves a foot that purportedly shares morphometric affinities with monkeys, but this interpretation remains controversial. Here I show that the foot of Ar. ramidus is most similar to living chimpanzee and gorilla species among a large sample of anthropoid primates. The foot morphology of Ar. ramidus suggests that the evolutionary precursor of hominin bipedalism was African ape-like terrestrial quadrupedalism and climbing. The elongation of the midfoot and phalangeal reduction in Ar. ramidus relative to the African apes is consistent with hypotheses of increased propulsive capabilities associated with an early form of bipedalism. This study provides evidence that the modern human foot was derived from an ancestral form adapted to terrestrial plantigrade quadrupedalism.

Seven Steps in the Evolution of the Human Imagination

2007 ◽  
Author(s):  
STEVEN MITHEN
Keyword(s):  
Cultural Change ◽  
Homo Sapiens ◽  
Brain Size ◽  
Modern Human ◽  
Clear Picture ◽  
Modern Humans ◽  
Creative Imagination ◽  
African Apes ◽  
Ways Of Thinking ◽  
Forms Of Knowledge

The modern human is a product of six million years of evolution wherein it is assumed that the ancestor of man resembles that of a chimpanzee. This assumption is based on the similarities of the ape-like brain size and post-cranial characteristics of the earliest hominid species to chimpanzees. Whilst it is unclear whether chimpanzees share the same foresight and contemplation of alternatives as with humans, it is nevertheless clear that chimpanzees lack creative imagination — an aspect of modern human imagination that sets humanity apart from its hominid ancestors. Creative imagination pertains to the ability to combine different forms of knowledge and ways of thinking to form creative and novel ideas. This chapter discusses seven critical steps in the evolution of the human imagination. These steps provide a clear picture of the gradual emergence of creative imagination in humans from their primitive origins as Homo sapiens some 200,000 years ago. This chronological evolution of the imaginative mind of humans involves both biological and cultural change that began soon after the divergence of the two lineages that led to modern humans and African apes.

scholarly journals Evolution and function of the hominin forefoot

2018 ◽  
Vol 115 (35) ◽  
pp. 8746-8751 ◽  
Author(s):  
Peter J. Fernández ◽  
Carrie S. Mongle ◽  
Louise Leakey ◽  
Daniel J. Proctor ◽  
Caley M. Orr ◽  
...  
Keyword(s):  
Soft Tissues ◽  
Common Ancestor ◽  
Bipedal Locomotion ◽  
Last Common Ancestor ◽  
Primary Role ◽  
Anthropoid Primates ◽  
And Function ◽  
Metatarsophalangeal Joints ◽  
Selection Of

The primate foot functions as a grasping organ. As such, its bones, soft tissues, and joints evolved to maximize power and stability in a variety of grasping configurations. Humans are the obvious exception to this primate pattern, with feet that evolved to support the unique biomechanical demands of bipedal locomotion. Of key functional importance to bipedalism is the morphology of the joints at the forefoot, known as the metatarsophalangeal joints (MTPJs), but a comprehensive analysis of hominin MTPJ morphology is currently lacking. Here we present the results of a multivariate shape and Bayesian phylogenetic comparative analyses of metatarsals (MTs) from a broad selection of anthropoid primates (including fossil apes and stem catarrhines) and most of the early hominin pedal fossil record, including the oldest hominin for which good pedal remains exist, Ardipithecus ramidus. Results corroborate the importance of specific bony morphologies such as dorsal MT head expansion and “doming” to the evolution of terrestrial bipedalism in hominins. Further, our evolutionary models reveal that the MT1 of Ar. ramidus shifts away from the reconstructed optimum of our last common ancestor with apes, but not necessarily in the direction of modern humans. However, the lateral rays of Ar. ramidus are transformed in a more human-like direction, suggesting that they were the digits first recruited by hominins into the primary role of terrestrial propulsion. This pattern of evolutionary change is seen consistently throughout the evolution of the foot, highlighting the mosaic nature of pedal evolution and the emergence of a derived, modern hallux relatively late in human evolution.

scholarly journals The hominid ilium is shaped by a synapomorphic growth mechanism that is unique within primates

2019 ◽  
Vol 116 (28) ◽  
pp. 13915-13920
Author(s):  
Dexter Zirkle ◽  
C. Owen Lovejoy
Keyword(s):  
Growth Mechanism ◽  
Bipedal Locomotion ◽  
Anterior Inferior Iliac Spine ◽  
African Apes ◽  
Secondary Center

The human ilium is significantly shorter and broader than those of all other primates. In addition, it exhibits an anterior inferior iliac spine (AIIS) that emerges via a secondary center of ossification, which is unique to hominids (i.e., all taxa related to the human clade following their phyletic separation from the African apes). Here, we track the ontogeny of human and other primate ossa coxae. The human pattern is unique, from anlage to adulthood, and fusion of its AIIS is the capstone event in a repositioning of the anterior gluteals that maximizes control of pelvic drop during upright walking. It is therefore a hominid synapomorphy that can be used to assess the presence and age of bipedal locomotion in extinct taxa.

scholarly journals Dimorphism and integration in the pelves of anthropoid primates

2016 ◽  
Author(s):  
◽  
Elizabeth A. Moffett
Keyword(s):  
Sexual Dimorphism ◽  
Modern Human ◽  
Morphological Integration ◽  
Past Century ◽  
Birth Canal ◽  
Pelvic Morphology ◽  
The Past ◽  
Anthropoid Primates ◽  
Selection For ◽  
Pelvic Sexual Dimorphism

The link between obstetric demand (natural selection for birth) and pelvic morphology in anthropoids has remained ambiguous for the past century. Though it is assumed that the dramatic sexual dimorphism seen in modern human pelves is due to obstetric demand, this does not explain why other primates that give birth to relatively small neonates also exhibit pelvic dimorphism. This thesis explores the correlation between obstetric demand and dimorphism and morphological integration in anthropoid pelves. Dimorphism in birth canal and non-obstetric pelvic morphology is present across most primates regardless of obstetric demand, but those primates that give birth to relatively large babies have the most pelvic sexual dimorphism. Sexual dimorphism in sacral breadth is likewise most apparent in species that give birth to large neonates relative to the maternal birth canal. In species that give birth to large neonates, females also have higher magnitudes of integration in birth canal morphology compared to males, but this is not true in species that give birth to small neonates. This study demonstrates a clear link between obstetric demand, pelvic dimorphism, and the magnitudes of pelvic integration in anthropoid primates.

A Review of Current Concepts on the Evolution of the Human Foot

Foot & Ankle ◽  
1982 ◽  
Vol 2 (5) ◽  
pp. 284-290 ◽  
Author(s):  
Jeffery T. Laitman ◽  
William L. Jaffe
Keyword(s):  
Bipedal Locomotion ◽  
Early Eocene ◽  
Human Foot ◽  
Recent Advances ◽  
Postcranial Remains

This paper reviews a number of recent advances in understanding the evolution of the human foot. The foot has gradually changed from the grasping and clinging organ of early Eocene and Miocene and Miocene primate ancestors to the specialized weightbearing structure of modern. Recent studies have indicated that postcranial remains conmensurate with the requirements of bipedal locomotion may have been present as far back as 3½ million years ago in the forerunners of modern man known as the australopithecines. Subsequent modifications appear to be refinements to increase the efficiency of weight transmission in habitual bipedallsm.

scholarly journals Tracing the origin and geographic distribution of an ancestral form of the modern human Y chromosome

2001 ◽  
Vol 74 (1) ◽  
Author(s):  
CLAUDIO M BRAVI ◽  
GRACIELA BAILLIET ◽  
VERÓNICA L MARTÍNEZ-MARIGNAC ◽  
NESTOR O BIANCHI
Keyword(s):  
Y Chromosome ◽  
Geographic Distribution ◽  
Modern Human ◽  
Ancestral Form ◽  
Human Y Chromosome

The Evolutionary Basis of Some Clinical Disorders of the Human Foot: A Comparative Survey of the Living Primates

Foot & Ankle ◽  
1983 ◽  
Vol 3 (6) ◽  
pp. 322-341 ◽  
Author(s):  
Todd R. Olson ◽  
Michael R. Seidel
Keyword(s):  
Anatomical Variation ◽  
Clinical Manifestations ◽  
Modern Human ◽  
Bipedal Walking ◽  
Structural Basis ◽  
Erect Posture ◽  
Human Foot ◽  
Initial Stage ◽  
History Of ◽  
The Comparative Study

The living primates are a highly diverse group of essentially arboreal animals whose feet are variously adapted for grasping, climbing, and leaping in trees. One of the most remarkable aspects of the anatomical variation in the feet of the extant primates is that this diversity can be arranged in a graduated sequence ranging from the primitive transtarsal-opposition type of grasping foot found in the lemurs, through the specialized transmeta-tarsal-adduction type that characterizes the higher primates, to'the unique nongrasping foot of humans. The comparative study of this graded series makes it possible, without recourse to the fossil record, to appreciate the adaptive and functional stages through which the human foot passed in its evolution. It is hypothesized that the initial stage of human erect posture was characterized by a foot which was adapted to both hallucial grasping and short distance bipedal walking. In many respects, the structure of the foot of this primitive human was probably similar to that of the living highland gorilla. When compared with the feet of our closest living relatives, the African apes, the human foot is characterized by two major evolutionary specializations: the longitudinal and transverse arches, and the parallel first and second metatarsals. These two morphological adaptations, together with several associated specializations, are the structural basis of the bipedal human foot. Reconstructing the evolutionary and adaptive history of these specializations creates a better understanding of some of the more common clinical podiatric disorders. The modern human foot is structurally so well adapted to prolonged bipedal walking and standing that even slight deviations from its evolutionarily established pattern will produce debilitating clinical manifestations. In most cases, successful treatment of such disorders involves restoration of the foot's basic adaptive configuration.

The Development of the Human Foot As a Résumé of Its Evolution

Foot & Ankle ◽  
1983 ◽  
Vol 3 (6) ◽  
pp. 305-321 ◽  
Author(s):  
Edmund S. Crelin
Keyword(s):  
Modern Human ◽  
Human Beings ◽  
Functional Changes ◽  
Human Foot ◽  
Evolutionary View ◽  
Hind Foot

The changes the human foot undergoes during its development are described as indications of structural and functional changes which might have occurred during the evolution of the vertebrate hind foot. The human foot, when compared to other vertebrate feet, appears to be a relatively minor modification of the plantigrade hind foot of the shrew-like insectivores that gave rise to all of the mammals. There is no developmental evidence to indicate that the first toe of the human foot was ever prehensile. Thus, the generally accepted evolutionary view, which depicts the feet of the early ancestors of modern human beings as having ape-like prehensile first toes, is seriously questioned.

scholarly journals Comparative radiographic analysis of three-dimensional innate mobility of the foot bones under axial loading of humans and African great apes

2021 ◽  
Vol 8 (11) ◽  
Author(s):  
Takuo Negishi ◽  
Kohta Ito ◽  
Koh Hosoda ◽  
Takeo Nagura ◽  
Tomohiko Ota ◽  
...  
Keyword(s):  
Weight Bearing ◽  
Three Dimensional ◽  
Axial Loading ◽  
Great Apes ◽  
Bipedal Locomotion ◽  
Human Foot ◽  
Foot Bones ◽  
Coupling Motion ◽  
African Great Apes ◽  
The Difference

The human foot is considered to be morphologically adapted for habitual bipedal locomotion. However, how the mobility and mechanical interaction of the human foot with the ground under a weight-bearing condition differ from those of African great apes is not well understood. We compared three-dimensional (3D) bone kinematics of cadaver feet under axial loading of humans and African great apes using a biplanar X-ray fluoroscopy system. The calcaneus was everted and the talus and tibia were internally rotated in the human foot, but such coupling motion was much smaller in the feet of African great apes, possibly due to the difference in morphology of the foot bones and articular surfaces. This study also found that the changes in the length of the longitudinal arch were larger in the human foot than in the feet of chimpanzees and gorillas, indicating that the human foot is more deformable, possibly to allow storage and release of the elastic energy during locomotion. The coupling motion of the calcaneus and the tibia, and the larger capacity to be flattened due to axial loading observed in the human foot are possibly morphological adaptations for habitual bipedal locomotion that has evolved in the human lineage.

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