scholarly journals Repetition Without Repetition: A Comparison of the Laetoli G1, Ileret, Namibian Holocene and Modern Human Footprints Using Pedobarographic Statistical Parametric Mapping

2021 ◽  
pp. 41-65
Author(s):  
Juliet McClymont ◽  
Robin H. Crompton
Keyword(s):  
Homo Sapiens ◽  
Statistical Parametric Mapping ◽  
Population Level ◽  
Modern Human ◽  
Foot Pressure ◽  
Motor Patterns ◽  
Experimental Conditions ◽  
Movement Characteristic ◽  
Foot Function ◽  
Small Sample Sizes

AbstractIt is traditionally held that early hominins of the genus Australopithecus had a foot transitional in function between that of the other great apes and our own but that the appearance of genus Homo was marked by evolution of an essentially biomechanically modern foot, as well as modern body proportions. Here, we report the application of whole foot, pixel-wise topological statistical analysis, to compare four populations of footprints from across evolutionary time: Australopithecus at Laetoli (3.66 Ma, Tanzania), early African Homo from Ileret (1.5 Ma, Kenya) and recent modern (presumptively habitually barefoot) pastoralist Homo sapiens from Namibia (Holocene), with footprints from modern Western humans. Contrary to some previous analyses, we find that only limited areas of the footprints show any statistically significant difference in footprint depth (used here as an analogy for plantar pressure). A need for this comparison was highlighted by recent studies using the same statistical approach, to examine variability in the distribution of foot pressure in modern Western humans. This study revealed very high intra-variability (mean square error) step-to-step in over 500 steps. This result exemplifies the fundamental movement characteristic of dynamic biological systems, whereby regardless of the repetition in motor patterns for stepping, and even when constrained by experimental conditions, each step is unique or non-repetitive; hence, repetition without repetition. Thus, the small sample sizes predominant in the fossil and ichnofossil record do not reveal the fundamental neurobiological driver of locomotion (variability), essentially limiting our ability to make reliable interpretations which might be extrapolated to interpret hominin foot function at a population level. However, our need for conservatism in our conclusions does not equate with a conclusion that there has been functional stasis in the evolution of the hominin foot.

scholarly journals 3D enamel profilometry reveals faster growth but similar stress severity in Neanderthal versus Homo sapiens teeth

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kate McGrath ◽  
Laura Sophia Limmer ◽  
Annabelle-Louise Lockey ◽  
Debbie Guatelli-Steinberg ◽  
Donald J. Reid ◽  
...  
Keyword(s):  
Life Stress ◽  
Early Life ◽  
Homo Sapiens ◽  
Normal Growth ◽  
Population Level ◽  
Growth Patterns ◽  
Upper Paleolithic ◽  
Tooth Surface ◽  
Growth Increments ◽  
Anterior Teeth

AbstractEarly life stress disrupts growth and creates horizontal grooves on the tooth surface in humans and other mammals, yet there is no consensus for their quantitative analysis. Linear defects are considered to be nonspecific stress indicators, but evidence suggests that intermittent, severe stressors create deeper defects than chronic, low-level stressors. However, species-specific growth patterns also influence defect morphology, with faster-growing teeth having shallower defects at the population level. Here we describe a method to measure the depth of linear enamel defects and normal growth increments (i.e., perikymata) from high-resolution 3D topographies using confocal profilometry and apply it to a diverse sample of Homo neanderthalensis and H. sapiens anterior teeth. Debate surrounds whether Neanderthals exhibited modern human-like growth patterns in their teeth and other systems, with some researchers suggesting that they experienced more severe childhood stress. Our results suggest that Neanderthals have shallower features than H. sapiens from the Upper Paleolithic, Neolithic, and medieval eras, mirroring the faster growth rates in Neanderthal anterior teeth. However, when defect depth is scaled by perikymata depth to assess their severity, Neolithic humans have less severe defects, while Neanderthals and the other H. sapiens groups show evidence of more severe early life growth disruptions.

scholarly journals Behavioral Triggers of Skin Conductance Responses and Their Neural Correlates in the Primate Amygdala

2009 ◽  
Vol 101 (4) ◽  
pp. 1749-1754 ◽  
Author(s):  
Christopher M. Laine ◽  
Kevin M. Spitler ◽  
Clayton P. Mosher ◽  
Katalin M. Gothard
Keyword(s):  
Skin Conductance ◽  
Single Unit ◽  
Population Level ◽  
Emotional Reaction ◽  
Neural Population ◽  
Experimental Conditions ◽  
Indirect Measure ◽  
Skin Conductance Responses ◽  
The Right ◽  
Sympathetic Arousal

The amygdala plays a crucial role in evaluating the emotional significance of stimuli and in transforming the results of this evaluation into appropriate autonomic responses. Lesion and stimulation studies suggest involvement of the amygdala in the generation of the skin conductance response (SCR), which is an indirect measure of autonomic activity that has been associated with both emotion and attention. It is unclear if this involvement marks an emotional reaction to an external stimulus or sympathetic arousal regardless of its origin. We recorded skin conductance in parallel with single-unit activity from the right amygdala of two rhesus monkeys during a rewarded image viewing task and while the monkeys sat alone in a dimly lit room, drifting in and out of sleep. In both experimental conditions, we found similar SCR-related modulation of activity at the single-unit and neural population level. This suggests that the amygdala contributes to the production or modulation of SCRs regardless of the source of sympathetic arousal.

Language and life history: A new perspective on the development and evolution of human language

2006 ◽  
Vol 29 (3) ◽  
pp. 259-280 ◽  
Author(s):  
John L. Locke ◽  
Barry Bogin
Keyword(s):  
Life History ◽  
Adult Development ◽  
Homo Sapiens ◽  
Human Life ◽  
Modern Human ◽  
Linguistic Knowledge ◽  
Human Language ◽  
Juvenile Period ◽  
Development Of Language ◽  
New Perspective

It has long been claimed that Homo sapiens is the only species that has language, but only recently has it been recognized that humans also have an unusual pattern of growth and development. Social mammals have two stages of pre-adult development: infancy and juvenility. Humans have two additional prolonged and pronounced life history stages: childhood, an interval of four years extending between infancy and the juvenile period that follows, and adolescence, a stage of about eight years that stretches from juvenility to adulthood. We begin by reviewing the primary biological and linguistic changes occurring in each of the four pre-adult ontogenetic stages in human life history. Then we attempt to trace the evolution of childhood and juvenility in our hominin ancestors. We propose that several different forms of selection applied in infancy and childhood; and that, in adolescence, elaborated vocal behaviors played a role in courtship and intrasexual competition, enhancing fitness and ultimately integrating performative and pragmatic skills with linguistic knowledge in a broad faculty of language. A theoretical consequence of our proposal is that fossil evidence of the uniquely human stages may be used, with other findings, to date the emergence of language. If important aspects of language cannot appear until sexual maturity, as we propose, then a second consequence is that the development of language requires the whole of modern human ontogeny. Our life history model thus offers new ways of investigating, and thinking about, the evolution, development, and ultimately the nature of human language.

scholarly journals Recent origin of low trabecular bone density in modern humans

2014 ◽  
Vol 112 (2) ◽  
pp. 366-371 ◽  
Author(s):  
Habiba Chirchir ◽  
Tracy L. Kivell ◽  
Christopher B. Ruff ◽  
Jean-Jacques Hublin ◽  
Kristian J. Carlson ◽  
...  
Keyword(s):  
Body Size ◽  
Trabecular Bone ◽  
Homo Sapiens ◽  
Modern Human ◽  
Homo Erectus ◽  
Lower Limbs ◽  
Modern Humans ◽  
Human Skeleton ◽  
Trabecular Density ◽  
Fossil Hominins

Humans are unique, compared with our closest living relatives (chimpanzees) and early fossil hominins, in having an enlarged body size and lower limb joint surfaces in combination with a relatively gracile skeleton (i.e., lower bone mass for our body size). Some analyses have observed that in at least a few anatomical regions modern humans today appear to have relatively low trabecular density, but little is known about how that density varies throughout the human skeleton and across species or how and when the present trabecular patterns emerged over the course of human evolution. Here, we test the hypotheses that (i) recent modern humans have low trabecular density throughout the upper and lower limbs compared with other primate taxa and (ii) the reduction in trabecular density first occurred in early Homo erectus, consistent with the shift toward a modern human locomotor anatomy, or more recently in concert with diaphyseal gracilization in Holocene humans. We used peripheral quantitative CT and microtomography to measure trabecular bone of limb epiphyses (long bone articular ends) in modern humans and chimpanzees and in fossil hominins attributed to Australopithecus africanus, Paranthropus robustus/early Homo from Swartkrans, Homo neanderthalensis, and early Homo sapiens. Results show that only recent modern humans have low trabecular density throughout the limb joints. Extinct hominins, including pre-Holocene Homo sapiens, retain the high levels seen in nonhuman primates. Thus, the low trabecular density of the recent modern human skeleton evolved late in our evolutionary history, potentially resulting from increased sedentism and reliance on technological and cultural innovations.

scholarly journals Effects of additional load at different heights on gait initiation: A statistical parametric mapping of center of pressure and center of mass behavior

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0242892
Author(s):  
Marcus Fraga Vieira ◽  
Fábio Barbosa Rodrigues ◽  
Alfredo de Oliveira Assis ◽  
Eduardo de Mendonça Mesquita ◽  
Thiago Santana Lemes ◽  
...  
Keyword(s):  
Time Series ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Statistical Parametric Mapping ◽  
Gait Initiation ◽  
Experimental Conditions ◽  
Distributed Load ◽  
Uniformly Distributed Load ◽  
Reaction Forces ◽  
Controlled Object

The purpose of this study was to investigate the effects of different vertical positions of an asymmetrical load on the anticipatory postural adjustments phase of gait initiation. Sixty-eight college students (32 males, 36 females; age: 23.65 ± 3.21 years old; weight: 69.98 ± 8.15 kg; height: 1.74 ± 0.08 m) were enrolled in the study. Ground reaction forces and moments were collected using two force platforms. The participants completed three trials under each of the following random conditions: no-load (NL), waist uniformly distributed load (WUD), shoulder uniformly distributed load (SUD), waist stance foot load (WST), shoulder stance foot load (SST), waist swing foot load (WSW), and shoulder swing foot load (SSW). The paired Hotelling’s T-square test was used to compare the experimental conditions. The center of pressure (COP) time series were significantly different for the SUD vs. NL, SST vs. NL, WST vs. NL, and WSW vs. NL comparisons. Significant differences in COP time series were observed for all comparisons between waist vs. shoulder conditions. Overall, these differences were greater when the load was positioned at the shoulders. For the center of mass (COM) time series, significant differences were found for the WUD vs. NL and WSW vs. NL conditions. However, no differences were observed with the load positioned at the shoulders. In conclusion, only asymmetrical loading at the waist produced significant differences, and the higher the extra load, the greater the effects on COP behavior. By contrast, only minor changes were observed in COM behavior, suggesting that the changes in COP (the controller) behavior are adjustments to maintain the COM (controlled object) unaltered.

scholarly journals Autistic Spectrum Disorder in Prehistory

2011 ◽  
Vol 21 (3) ◽  
pp. 357-364 ◽  
Author(s):  
Catriona Pickard ◽  
Ben Pickard ◽  
Clive Bonsall
Keyword(s):  
Population Level ◽  
Human Mind ◽  
Modern Human ◽  
Human Behaviour ◽  
Specific Reference ◽  
Autistic Spectrum ◽  
Evolutionary Advantage ◽  
New Ideas ◽  
Spectrum Disorders ◽  
Neuropsychiatric Conditions

Individuals with ‘extraordinary’ or ‘different’ minds have been suggested to be central to invention and the spread of new ideas in prehistory, shaping modern human behaviour and conferring an evolutionary advantage at population level. In this article the potential for neuropsychiatric conditions such as autistic spectrum disorders to provide this difference is explored, and the ability of the archaeological record to provide evidence of human behaviour is discussed. Specific reference is made to recent advances in the genetics of these conditions, which suggest that neuropsychiatric disorders represent a non-advantageous, pathological extreme of the human mind and are likely a by-product rather than a cause of human cognitive evolution.

Aterian

2021 ◽  
Author(s):  
Elena A.A. Garcea
Keyword(s):  
Behavioral Plasticity ◽  
Homo Sapiens ◽  
Atlantic Coast ◽  
Modern Human ◽  
Middle Stone Age ◽  
Nile Valley ◽  
Mobility Patterns ◽  
North African ◽  
Behavioral Experiments ◽  
Wide Range

The Aterian is a North African late Middle Stone Age techno-complex. It is spread from the Atlantic coast in Morocco to the Middle Nile Valley in Sudan and from the Mediterranean hinterland to the Southern Sahara. Chronologically, it covers the period between c. 145,000 years bp and 29,000 bp, spanning across discontinuous, alternating dry (end of MIS 6 and MIS 4) and humid (MIS 5 and MIS 3) climatic phases. Few, but significant human remains indicate that the makers of the Aterian complex belong to early Homo sapiens. Their osteological features show affinities with the early anatomically modern human record in the Levant (Skhul and Qafzeh), suggesting that Aterian groups may have taken part in the initial dispersals out of Africa by Homo sapiens. Toolkits consist of a variety of implements not only made of stone but also of bone (points, spatulas, knives, and retouchers). They include tools that were lacking in earlier or other North African contemporary contexts, namely bifacial foliates, blades, perforators, burins, endscrapers, and particularly tanged pieces. Overemphasis on tanged tools often obscured the complexity of the Aterian, which instead displays a wide range of cultural and behavioral innovations. New mobility patterns and intra-site organization, as well as early symbolism with the use of Nassariidae shells and ochre, corroborate early fully complex behavior by these populations. Given the broad geographic and chronological extension of the Aterian, differences are evident at both local and regional scales. They suggest the development of a flexible and variable techno-complex mirroring considerable adaptive cognitive and behavioral plasticity derived from nonlinear processes. Such diversified behavioral experiments result from multiple and noncumulative trajectories due to different internal and external stimuli but are still part of a single cultural entity.

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 Upper Pleistocene Human Dispersals out of Africa: A Review of the Current State of the Debate

2011 ◽  
Vol 2011 ◽  
pp. 1-17 ◽  
Author(s):  
Amanuel Beyin
Keyword(s):  
Early Modern ◽  
Homo Sapiens ◽  
Modern Human ◽  
Middle Stone Age ◽  
Eastern Africa ◽  
Last Interglacial ◽  
Upper Pleistocene ◽  
Current State ◽  
Human Colonization ◽  
Source Populations

Although there is a general consensus on African origin of early modern humans, there is disagreement about how and when they dispersed to Eurasia. This paper reviews genetic and Middle Stone Age/Middle Paleolithic archaeological literature from northeast Africa, Arabia, and the Levant to assess the timing and geographic backgrounds of Upper Pleistocene human colonization of Eurasia. At the center of the discussion lies the question of whether eastern Africa alone was the source of Upper Pleistocene human dispersals into Eurasia or were there other loci of human expansions outside of Africa? The reviewed literature hints at two modes of early modern human colonization of Eurasia in the Upper Pleistocene: (i) from multiple Homo sapiens source populations that had entered Arabia, South Asia, and the Levant prior to and soon after the onset of the Last Interglacial (MIS-5), (ii) from a rapid dispersal out of East Africa via the Southern Route (across the Red Sea basin), dating to ~74–60 kya.

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