In this article, I advance a novel hypothesis on the evolution of hominin bipedalism. I begin by arguing extensively for how the transition to bipedalism must have been problematic for hominins during the Neogene. Due to this and the fact that no other primate has made the unusual switch to bipedalism, it seems likely that the selection pressure towards bipedalism was unusually strong. With this in mind, I briefly lay out some of the most promising hypotheses on the evolutionary origin (...) of hominin bipedalism and show how most, if not all, fail in the face of the need for an unusually strong selection pressure. For example, some hypotheses maintain that hominins became bipedal so they could use their hands for carrying infants, food, or other valuable objects. But extant apes are able to carry objects in one of their front limbs (while walking with the other three), and thus it does not seem plausible that our hominin ancestors went through the troublesome transition to bipedalism just so they could carry objects a little more efficiently. After I show that past hypotheses are wanting in the face of this challenge, I argue that there is only one selection pressure powerful enough to instigate a strange and problematic evolutionary adaptation like bipedalism, and that is sexual selection. Specifically, from the fact that bipedal locomotion is an important strategy for intimidating others and ascending the dominance hierarchy in extant apes, I argue that for no particular selective reason bipedal locomotion became a signal for high fitness (much as a large and intricate tail became a signal for high fitness for peahens), and this led to the trait being continuously reinforced in spite of all its deleterious fitness consequences. (shrink)

The kinship theory of genomic imprinting predicts that imprinted genes affect parent–child and child–child interactions. During prenatal and neonatal stages, patrigenes promote selfish and matrigenes altruistic behavior. Models predict that this imprinted gene expression pattern is reversed starting with the juvenile stage. This article explores possible effects of imprinted genes on nonverbal and simple and complex linguistic behaviors before and after the reversal. A hypothesis is discussed that is based on the observation language evolved as a new form of communicative (...) behavior. Inclusive fitness theory is used for explaining how and why new forms of communicative behaviors evolved as an extension of behaviors and gestures displayed by our predecessors. The hypothesis is elaborated through discussing a scenario of early language evolution. This scenario is used for explaining early stages in child development and for discussing possible effects of patrigenes and matrigenes on the development of children’s communicative behaviors. (shrink)

This paper presents a new line of inquiry into when and how music as a semiotic system was born. Ten principal expressive aspects of music retain specific structural patterns to signify a certain affective state, which distinguishes the tonal organization of music from the phonetic and prosodic organization of natural languages. Therefore, the question of music’s origin can be answered by establishing the point in human history, at which expressive aspects might have been abstracted from the instinct-driven primate calls and (...) used to express human psycho-emotional states. Etic analysis of acoustic parameters is the prime means of cross-comparison of the typical patterns of expression of the same basic emotions in human music versus animal vocal communication. A new method of such analysis is proposed here. Formation of such expressive aspects as meter, tempo, melodic intervals, and articulation can be explained by the influence of bipedal locomotion, breathing cycle, and heartbeat, long before Homo sapiens. However, two aspects, rhythm and melodic contour, most crucial for music as we know it, lack proxies in the Paleolithic lifestyle. The available ethnographic and developmental data leads one to believe that rhythmic and directional patterns of melody became involved in conveying emotion-related information as a result of frequent switching from one call-type to another within the limited repertory of calls adopted for ongoing caretaking of human youngsters and domestic animals. The efficacy of rhythm and pitch contour in affective communication must have been discovered spontaneously in new important cultural activities. The most likely scenario for music to have become fully semiotically functional is the formation of cross-specific communication between humans and domesticated animals during the Neolithic demographic explosion. The model of such communication can be found in the surviving tradition of Scandinavian pastoral music. This article discusses the most likely ways in which such music evolved. (shrink)

Recent studies with human infants and nonhuman primates reveal that posture interacts with the expression and stability of handedness. Converging results demonstrate that quadrupedal locomotion hinders the expression of handedness, whereas bipedal posture enhances preferred hand use. From an evolutionary perspective, these findings suggest that right-handedness may have emerged first, following the adoption of bipedal locomotion, with speech emerging later.

A converging pattern of evidence from laughter, tickling, and motherese suggests that bipedal locomotion plays a critical and unanticipated role in vocal evolution. Bipedalism frees the thorax of its support role during quadrupedal locomotion, which permits the uncoupling of breathing and striding necessary for the subsequent selection for vocal virtuosity and speech.

: Using Judith Butler's notion that bodies are materialized via performances, "resignifying" disability involves a "democratizing contestation" of staircases because they exclude those in wheelchairs. Paleoanthropologist Maxine Sheets-Johnstone shows how consistent bipedal locomotion, together with the knowledge that we will die (upon which mutuality is based), are ingredients of our pan-hominid speciation, not contingent constructions. As axiologically important as contestation is, it forecloses the possibility of achieving a mutuality with others, that is wonderfully possible.

Using Judith Butler's notion that bodies are materialized via performances, “resig-nifying” disability involves a “democratizing contestation” of staircases because they exclude those in wheelchairs. Paleoanthropologist Maxine Sheets-Johnstone shows how consistent bipedal locomotion, together with the knowledge that we will die, are ingredients of our pan-hominid speciation, not contingent constructions. As axiologically important as contestation is, it forecloses the possibility of achieving a mutuality with others that is wonderfully possible.

I selectively and critically review the state of knowledge about human evolution and the place of humans vis-à-vis living apes, with emphasis on bipedal posture and locomotion, expansion of the brain and associated cognitive capacities, speech, tool behavior, culture, and society. I end with a personal perspective on God and Heaven.

In this paper I present a case study of mathematical explanation in science that is new to the philosophical literature, and that arises in the context of estimating the energetic costs of running in bipedal animals. I refer to this as the Bipedal Gait Costs explanation. I argue that it is important for examples of applied mathematics to be driven not just by philosophical and mathematical concerns but also by scientific concerns. After a detailed presentation of the BGC (...) case study, I discuss ways in which it is different from standard examples of MES. One distinctive aspect of BGC is that substantive mathematics occurs at two different levels. I argue for a distinction to be drawn between the mathematical modeling that occurs at one level, which is non-explanatory, and the mathematical theorem which is applied to results gleaned from these models, which is explanatory. I conclude by drawing some connections with broader indispensability-based arguments for platonism in the philosophy of mathematics. (shrink)

With the discovery of Australopithecus, the concepts of bipedalism, the emergence of the open savannas, and the separation of pongids and hominids (bipedal-savanna-cladogeny; the BSC model) were integrated in an attempt to interpret the keys to the emergence of man. However, palæoclimatology, palaeoecology, and the morphology of A. ramidus and A. afarensis show that early hominids were better adapted to the tropical forest. Consequently, the BSC model is no longer valid, even though the relationship between open savannas and bipedalism (...) can still be invoked to explain cladogeny between Paranthropus and Homo. That the BSC model is still thriving could be due to preconceived ideas as to what constitutes a human being — ideas that are projected into the past to explain our origins. (shrink)

Previous studies have shown that the motion intention recognition for lower limb prosthesis mainly focused on the identification of performed gait. However, the bionic prosthesis needs to know the next movement at the beginning of a new gait, especially in complex operation environments. In this paper, an upcoming locomotion prediction scheme via multilevel classifier fusion was proposed for the complex operation. At first, two motion states, including steady state and transient state, were defined. Steady-state recognition was backtracking of a (...) completed gait, which would be used as prior knowledge of motion prediction. In steady-state recognition, surface electromyographic and inertial sensors were fused to improve recognition accuracy; five typical locomotion modes were recognized by random forest classifier with over 97.8% accuracy. The transient state was defined as an observation period at the initial stage of upcoming movement, in which only the sEMG signal was recorded due to the limitation of sliding window length. LightGBM classifier was validated to outperform other methods in the accuracy and prediction time of transient-state recognition. Finally, a simplified HMM model based on prior knowledge and observation result was constructed to predict upcoming locomotion. The results indicated that the locomotion prediction was over 91% accuracy. The proposed scheme implements the locomotion prediction at the initial stage of each gait and provides critical information for the gait control of lower limb prosthesis. (shrink)

The thoughts presented here never appeared in research proposals, but nevertheless grew at the Stanford University Artificial Intelligence Laboratory over the years 1971 through 1980 under support from the National Institutes of Health, the Defense Advanced Research Projects Agency, the National Science Foundation and the National Aeronautics and Space Administration, and more recently at the Carnegie-Mellon University Robotics Institute under Office of Naval Research contract number N00014-81-K-0503.

Three-legged animals do not exist today and such an animal is not found in the fossil record. Which constraints operate to result in the lack of a triped phenotype? Consideration of animal locomotion and robotic studies suggests that physical constraints would not prevent a triped from being functional or advantageous. As is reviewed here, the strongest constraint on the evolution of a triped is phylogenetic: namely, the early genetic adoption of a bilaterally symmetrical body plan occurring before the advent (...) of limbs. Presumably, this would greatly constrain any three-legged animal from ever evolving. Tripedalism is employed only by a few animals, but many use a tripod stance while engaged in a variety of activities. Because terms are often used interchangeably in the literature, a standardization of locomotion terminology is proposed. Understanding the constraints behind “forbidden” phenotypes forces us to confront gaps in our evolutionary understanding of which we may be unaware. (shrink)

Face à la défense aristotélicienne de l'esclavage, il faut, dit-on "sauver l'honneur des philosophes". Objectif: dévoiler le coût de cette entreprise dans un contexte où l'on préconise de plus en plus le recours à Aristote pour surmonter les impasses imputées à la pensée éthico-politique contemporaine. Au delà de sa portée historique, cet ouvrage interroge l'image actuelle du philosophe grec véhiculée par ses commentateurs francophones (1932-1999) et la pertinence attribuée à son message.

Malgré leurs divergences, les interprètes sont en général d’accord sur le fait que pour Aristote, le lieu est bidimensionnel et peu significatif du point de vue de l’ontologie. Dernièrement, ces présupposés ont cependant été remis en question par Casey et Lang. Dans cet article, c’est la position traditionnelle qui est défendue, et j’argumente en faveur de l’idée qu’Aristote développe sa théorie du lieu à partir du point de vue d’une mécanique du mouvement spatial et des outils nécessaires à un corps (...) organique pour son mouvement dans l’espace – et non à partir d’une théorie de la localisation des corps. Pour finir, la méthodologie aristotélicienne est comparée avec la physique contemporaine depuis Descartes. (shrink)

Shape and locomotion of tissue cells depend on the interaction of elements of the cytoskeleton, adhesion to the substrate and an intracellular hydrostatic pressure. The existence of this pressure becomes obvious from increase in cell volume on cessation of contractile forces and from observations with ultrasound acoustic microscopy. Wherever such an internal pressure is established, it is involved in generation of shape and driving force of cell locomotion. Therefore each hypothesis on cell shape and locomotion must consider (...) this property of a living cell. Apparently different types of locomotion depend on differences in substrate adhesion and/or cytoskeleton organisation. (shrink)

This paper presents a bioinspired lower extremity exoskeleton robot. The proposed exoskeleton robot can be adjusted in structure to meet the wearer’s height of 150–185 cm and has a good gait stability. In the gait control part, a method of identifying different locomotion modes is proposed; five common locomotion modes are considered in this paper, including sitting down, standing up, level-ground walking, ascending stairs, and descending stairs. The identification is depended on angle information of the hip, knee, and (...) ankle joints. A deep locomotion mode identification model based on long-short term memory architecture is proposed in this paper for exploiting the angle data. We conducted two experiments to verify the effectiveness of the proposed method. Experimental results show that the DLMIM is capable of learning inherent characteristics of joint angles and achieves more accurate identification than the other models. The last experiment demonstrates that the DLMIM can recognize transitions between different locomotion modes in time and the real-time performance varies with each individual. (shrink)

Performance and control of upright bipedal posture requires a constant and dynamic integration of relative contributions of different sensory inputs (i. e., sensory reweighting) to enable effective adaptations as individuals face environmental changes and perturbations. Children with gymnastic experience showed balance performance closer to that of adults during and after proprioceptive alteration than children without gymnastic experience when their center of pressure (COP) was analyzed. However, a particular COP sway can be achieved through performing and coordinating different postural movements. (...) The aim of this study was to assess how children and adults of different gymnastic experience perform and control postural movements while they have to adjust balance during and after bilateral tendon vibration. All participants were equipped with spherical markers attached to their skin and two vibrators strapped over the Achilles tendons. Bipedal stance was performed in three 45-s trials in two visual conditions (eyes open, EO, and eyes closed, EC) ordered randomly in which vibration lasted 10 s. Posture movements were analyzed by a principal component analysis (PCA) calculated on normalized and weighted markers coordinates. The relative standard deviation of each principal movement component (principal position, PP-rSTD) quantified its contribution to the whole postural movements, i.e., quantified the coordinative structure. The first (principal velocities, PV-rSTD) and second (principal accelerations, PA-rSTD) time-derivatives characterized the rate-dependent sensory information associated with and the neuromuscular control of the postural movements, respectively. Children without gymnastic experience showed a different postural coordinative structure and different sensory-motor control characteristics. They used less ankle movements in the anterior-posterior direction but increased ankle movements in medio-lateral direction, presented larger hip and trunk velocities, and exhibited more hip actions. Gymnastic experience during childhood seemed to benefit the development of proprioceptive reweighting processes in children, leading to a more mature form of coordinating and controlling posture similarly to adults. (shrink)

This paper focuses on an understudied aspect of Hobbes's natural philosophy: his approach to the domain of life. I concentrate on the role assigned by Hobbes to the heart, which occupies a central role in both his account of human physiology and of the origin of animal locomotion. With this, I have three goals in mind. First, I aim to offer a cross-section of Hobbes's effort to provide a mechanistic picture of human life. Second, I aim to contextualize Hobbes's (...) views in the seventeenth-century debates on human physiology and animal locomotion. In particular, I will compare Hobbes's views with the theories put forth by Harvey, Descartes, the Galenic, and Peripatetic traditions. Also, I will show that Hobbes was receptive to advances within contemporary English physiology and chemistry. Third, by means of a comparison with Descartes, I advance some hypothesis to explain why Hobbes indentified the heart, and not the brain (as was increasingly com... (shrink)

Bipedalism is one of the criteria that paleoanthropologists use in order to interpret the fossil record and to determine if a specimen belongs to the human lineage. In the context of such interpretations, bipedalism is considered to be a unique characteristic of this lineage that also marks its origin. This conception has largely remained unchallenged over the last decades, in spite of fossil discoveries that led to the emergence of bipedalism in the human lineage being shifted back by several millions (...) of years. In this paper, I analyze the uses of this criterion in paleoanthropology and demonstrate that interpretative biases (such as underdetermined inferences and circular reasoning) are at play in interpretations of hominin remains. By discussing Darwin’s hypotheses about the evolution of bipedalism, I identify major theoretical issues that need to be addressed in the current debates on hominin evolution. First, the assumption that “man alone has become a biped” (Darwin in The descent of man, and selection in relation to sex, John Murray, London, 1871) is analyzed in the light of recent empirical data. Three major issues are discussed: the definition of “man”, i.e. “human”, the uniqueness of human bipedalism, and the equivocal meaning of being a “biped”. Then, I highlight some of Darwin’s remarks that may be helpful for current debates in paleoanthropology, regarding natural selection in locomotor evolution, as well as taxonomic and phylogenetic significance of functional features. Finally, I analyze two examples of how fossil discoverers referred to Darwin in the recent years and discuss his role as an intellectual support. (shrink)

Bipedalism is one of the criteria that paleoanthropologists use in order to interpret the fossil record and to determine if a specimen belongs to the human lineage. In the context of such interpretations, bipedalism is considered to be a unique characteristic of this lineage that also marks its origin. This conception has largely remained unchallenged over the last decades, in spite of fossil discoveries that led to the emergence of bipedalism in the human lineage being shifted back by several millions (...) of years. In this paper, I analyze the uses of this criterion in paleoanthropology and demonstrate that interpretative biases are at play in interpretations of hominin remains. By discussing Darwin’s hypotheses about the evolution of bipedalism, I identify major theoretical issues that need to be addressed in the current debates on hominin evolution. First, the assumption that “man alone has become a biped” is analyzed in the light of recent empirical data. Three major issues are discussed: the definition of “man”, i.e. “human”, the uniqueness of human bipedalism, and the equivocal meaning of being a “biped”. Then, I highlight some of Darwin’s remarks that may be helpful for current debates in paleoanthropology, regarding natural selection in locomotor evolution, as well as taxonomic and phylogenetic significance of functional features. Finally, I analyze two examples of how fossil discoverers referred to Darwin in the recent years and discuss his role as an intellectual support. (shrink)

The bacterial pathogen Listeria monocytogenes displays the remarkable ability to reorganize the actin cytoskeleton within host cells as a means for promoting cell‐to‐cell transfer of the pathogen, in a manner that evades humoral immunity. In a series of events commencing with the biosynthesis of the bacterial surface protein ActA, host cell actin and many actin‐associated protein self‐assemble to from rocket‐tail structures that continually grow at sites proximal to the bacterium and depolymerize distally. Widespread interest in the underlying molecular mechanism of (...) Listeria locomotion stems from the likelihood that the dynamic remodeling of the host cell actin cytoskeleton at the cell's leading edge involves mechanistically analogous interactions. Recent advances in our understanding of these fundamental cytoskeletal rearrangements have been achieved through a clearer recognition of the central role of oligo‐proline sequence repeats present in ActA, and these findings provide a basis for inferring the role of analogous host cell proteins in the force‐producing and position‐securing steps in pseudopod and lamellipod formation at the peripheral membrane. (shrink)

The lambda model predicts that the command received by each motor nucleus during locomotion is specific for the joint at which its muscle acts and is independent of external conditions. However, investigation of the commands received by motor nuclei during fictive locomotion and of the sensitivity of these commands to feedback from the limb during locomotion indicates that neither condition is satisfied.