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  1. Article ; Online: Forest terrains influence walking kinematics among indigenous Tsimane of the Bolivian Amazon

    Nicholas B. Holowka / Thomas S. Kraft / Ian J. Wallace / Michael Gurven / Vivek V. Venkataraman

    Evolutionary Human Sciences, Vol

    2022  Volume 4

    Abstract: Laboratory-based studies indicate that a major evolutionary advantage of bipedalism is enabling humans to walk with relatively low energy expenditure. However, such studies typically record subjects walking on even surfaces or treadmills that do not ... ...

    Abstract Laboratory-based studies indicate that a major evolutionary advantage of bipedalism is enabling humans to walk with relatively low energy expenditure. However, such studies typically record subjects walking on even surfaces or treadmills that do not represent the irregular terrains our species encounters in natural environments. To date, few studies have quantified walking kinematics on natural terrains. Here we used high-speed video to record marker-based kinematics of 21 individuals from a Tsimane forager–horticulturalist community in the Bolivian Amazon walking on three different terrains: a dirt field, a forest trail and an unbroken forest transect. Compared with the field, in the unbroken forest participants contacted the ground with more protracted legs and flatter foot postures, had more inclined trunks, more flexed hips and knees, and raised their feet higher during leg swing. In contrast, kinematics were generally similar between trail and field walking. These results provide preliminary support for the idea that irregular natural surfaces like those in forests cause humans to alter their walking kinematics, such that travel in these environments could be more energetically expensive than would be assumed from laboratory-based data. These findings have important implications for the evolutionary energetics of human foraging in environments with challenging terrains.
    Keywords Locomotor ecology ; bipedalism ; barefoot walking ; forager–horticulturalist ; Human evolution ; GN281-289 ; Evolution ; QH359-425
    Subject code 629
    Language English
    Publishing date 2022-01-01T00:00:00Z
    Publisher Cambridge University Press
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Foot strength and stiffness are related to footwear use in a comparison of minimally- vs. conventionally-shod populations

    Nicholas B. Holowka / Ian J. Wallace / Daniel E. Lieberman

    Scientific Reports, Vol 8, Iss 1, Pp 1-

    2018  Volume 12

    Abstract: Abstract The longitudinal arch (LA) helps stiffen the foot during walking, but many people in developed countries suffer from flat foot, a condition characterized by reduced LA stiffness that can impair gait. Studies have found this condition is rare in ... ...

    Abstract Abstract The longitudinal arch (LA) helps stiffen the foot during walking, but many people in developed countries suffer from flat foot, a condition characterized by reduced LA stiffness that can impair gait. Studies have found this condition is rare in people who are habitually barefoot or wear minimal shoes compared to people who wear conventional modern shoes, but the basis for this difference remains unknown. Here we test the hypothesis that the use of shoes with features that restrict foot motion (e.g. arch supports, toe boxes) is associated with weaker foot muscles and reduced foot stiffness. We collected data from minimally-shod men from northwestern Mexico and men from urban/suburban areas in the United States who wear ‘conventional’ shoes. We measured dynamic LA stiffness during walking using kinematic and kinetic data, and the cross-sectional areas of three intrinsic foot muscles using ultrasound. Compared to conventionally-shod individuals, minimally-shod individuals had higher and stiffer LAs, and larger abductor hallucis and abductor digiti minimi muscles. Additionally, abductor hallucis size was positively associated with LA stiffness during walking. Our results suggest that use of conventional modern shoes is associated with weaker intrinsic foot muscles that may predispose individuals to reduced foot stiffness and potentially flat foot.
    Keywords Medicine ; R ; Science ; Q
    Language English
    Publishing date 2018-02-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Heel impact forces during barefoot versus minimally shod walking among Tarahumara subsistence farmers and urban Americans

    Ian J. Wallace / Elizabeth Koch / Nicholas B. Holowka / Daniel E. Lieberman

    Royal Society Open Science, Vol 5, Iss

    2018  Volume 3

    Abstract: Despite substantial recent interest in walking barefoot and in minimal footwear, little is known about potential differences in walking biomechanics when unshod versus minimally shod. To test the hypothesis that heel impact forces are similar during ... ...

    Abstract Despite substantial recent interest in walking barefoot and in minimal footwear, little is known about potential differences in walking biomechanics when unshod versus minimally shod. To test the hypothesis that heel impact forces are similar during barefoot and minimally shod walking, we analysed ground reaction forces recorded in both conditions with a pedography platform among indigenous subsistence farmers, the Tarahumara of Mexico, who habitually wear minimal sandals, as well as among urban Americans wearing commercially available minimal sandals. Among both the Tarahumara (n = 35) and Americans (n = 30), impact peaks generated in sandals had significantly (p < 0.05) higher force magnitudes, slower loading rates and larger vertical impulses than during barefoot walking. These kinetic differences were partly due to individuals' significantly greater effective mass when walking in sandals. Our results indicate that, in general, people tread more lightly when walking barefoot than in minimal footwear. Further research is needed to test if the variations in impact peaks generated by walking barefoot or in minimal shoes have consequences for musculoskeletal health.
    Keywords ground reaction force ; heel strike ; huaraches ; impact peak ; minimal shoes ; rarámuri ; Science ; Q
    Subject code 306
    Language English
    Publishing date 2018-01-01T00:00:00Z
    Publisher The Royal Society
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article: Structural analysis of the femoral diaphyses of an early modern human from Tianyuan Cave, China

    Wei, Pianpian / Charles M. Musiba / Ian J. Wallace / Tea Jashashvili / Wu Liu

    Quaternary international. 2017 Apr. 01, v. 434

    2017  

    Abstract: The Tianyuan 1 skeleton is among the oldest fossil specimens of our species from East Asia. Important in the original assessment of the skeleton as belonging to a modern human was its femoral structure, particularly its well-developed pilasters. Also ... ...

    Abstract The Tianyuan 1 skeleton is among the oldest fossil specimens of our species from East Asia. Important in the original assessment of the skeleton as belonging to a modern human was its femoral structure, particularly its well-developed pilasters. Also noteworthy were its large femoral diaphyseal second moments of area, which were interpreted as evidence of a physically demanding lifestyle, and pathological bone growths on the posterior femoral shafts. Here, we build on previous studies of femoral morphology in Tianyuan 1 by analyzing its diaphyseal structure using micro-computed tomography coupled with a novel method of visualizing cortical bone thickness distributions along the shaft with color maps. Additionally, we calculate diaphyseal second moments of area in Tianyuan 1 with and without its pathological bone additions in order to evaluate whether these growths are the cause of its apparently high diaphyseal robusticity. Diaphyseal color maps and second moments of area of Tianyuan 1 femora are compared to those of three recent (Holocene) human comparative samples, as well as samples of Pleistocene humans. The results show that in terms of cortical thickness distribution, Tianyuan 1 femoral diaphyses are strikingly similar to those of recent humans, as well as Pleistocene early modern humans, yet distinct from the diaphyses of Neandertals. This provides additional support for the modern human status of Tianyuan 1. Analyses of second moments of area reveal that Tianyuan 1 is best classified as a Pleistocene early modern human rather than as a member of any of the recent samples when pathological bone additions are included in area moment calculations. Interestingly, however, once pathological growths are virtually removed, Tianyuan 1 cannot be assigned with confidence to any comparative group. This suggests that the relatively high anteroposterior femoral diaphyseal strength mid-distally in Tianyuan 1 is to some degree a product of its pathological condition.
    Keywords color ; femur ; fossils ; humans ; lifestyle ; micro-computed tomography ; skeleton ; China
    Language English
    Dates of publication 2017-0401
    Size p. 48-56.
    Publishing place Elsevier Ltd
    Document type Article
    ISSN 1040-6182
    DOI 10.1016/j.quaint.2015.10.099
    Database NAL-Catalogue (AGRICOLA)

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  5. Article ; Online: Applying an evolutionary mismatch framework to understand disease susceptibility.

    Amanda J Lea / Andrew G Clark / Andrew W Dahl / Orrin Devinsky / Angela R Garcia / Christopher D Golden / Joseph Kamau / Thomas S Kraft / Yvonne A L Lim / Dino J Martins / Donald Mogoi / Päivi Pajukanta / George H Perry / Herman Pontzer / Benjamin C Trumble / Samuel S Urlacher / Vivek V Venkataraman / Ian J Wallace / Michael Gurven /
    Daniel E Lieberman / Julien F Ayroles

    PLoS Biology, Vol 21, Iss 9, p e

    2023  Volume 3002311

    Abstract: Noncommunicable diseases (NCDs) are on the rise worldwide. Obesity, cardiovascular disease, and type 2 diabetes are among a long list of "lifestyle" diseases that were rare throughout human history but are now common. The evolutionary mismatch hypothesis ...

    Abstract Noncommunicable diseases (NCDs) are on the rise worldwide. Obesity, cardiovascular disease, and type 2 diabetes are among a long list of "lifestyle" diseases that were rare throughout human history but are now common. The evolutionary mismatch hypothesis posits that humans evolved in environments that radically differ from those we currently experience; consequently, traits that were once advantageous may now be "mismatched" and disease causing. At the genetic level, this hypothesis predicts that loci with a history of selection will exhibit "genotype by environment" (GxE) interactions, with different health effects in "ancestral" versus "modern" environments. To identify such loci, we advocate for combining genomic tools in partnership with subsistence-level groups experiencing rapid lifestyle change. In these populations, comparisons of individuals falling on opposite extremes of the "matched" to "mismatched" spectrum are uniquely possible. More broadly, the work we propose will inform our understanding of environmental and genetic risk factors for NCDs across diverse ancestries and cultures.
    Keywords Biology (General) ; QH301-705.5
    Subject code 501
    Language English
    Publishing date 2023-09-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Exercise-induced bone formation is poorly linked to local strain magnitude in the sheep tibia.

    Ian J Wallace / Brigitte Demes / Carrie Mongle / Osbjorn M Pearson / John D Polk / Daniel E Lieberman

    PLoS ONE, Vol 9, Iss 6, p e

    2014  Volume 99108

    Abstract: Functional interpretations of limb bone structure frequently assume that diaphyses adjust their shape by adding bone primarily across the plane in which they are habitually loaded in order to minimize loading-induced strains. Here, to test this ... ...

    Abstract Functional interpretations of limb bone structure frequently assume that diaphyses adjust their shape by adding bone primarily across the plane in which they are habitually loaded in order to minimize loading-induced strains. Here, to test this hypothesis, we characterize the in vivo strain environment of the sheep tibial midshaft during treadmill exercise and examine whether this activity promotes bone formation disproportionately in the direction of loading in diaphyseal regions that experience the highest strains. It is shown that during treadmill exercise, sheep tibiae were bent in an anteroposterior direction, generating maximal tensile and compressive strains on the anterior and posterior shaft surfaces, respectively. Exercise led to significantly increased periosteal bone formation; however, rather than being biased toward areas of maximal strains across the anteroposterior axis, exercise-related osteogenesis occurred primarily around the medial half of the shaft circumference, in both high and low strain regions. Overall, the results of this study demonstrate that loading-induced bone growth is not closely linked to local strain magnitude in every instance. Therefore, caution is necessary when bone shaft shape is used to infer functional loading history in the absence of in vivo data on how bones are loaded and how they actually respond to loading.
    Keywords Medicine ; R ; Science ; Q
    Subject code 796
    Language English
    Publishing date 2014-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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