DD'eDeN aka note/nickname/alas_my_loves wrote:
Unique foot posture in Neanderthals reflects their body mass and high mechanical stress
Rita Sorrentino cs 2021 JHE 161:1030
Hn foot-bone proportions & morphology are mostly indistinguishable from Hs, except several distinct Hn features in the talus.
The bio-mechanical implications of these distinct talar features remain contentious, fueling debate around the adaptive meaning of this distinctiveness.
We test phylogenetic & behavioral factors as possible contributors:
we compare 10 Hn & 81 Hs tali (UP & Holocene hunter-gatherers, agriculturalists & post-industrial group) + the Clark Howell talus (Omo, Ethiopia).
Variation in external talar structures was assessed through geometric morphometric methods,
bone volume fraction & degree of anisotropy were quantified in a subsample (n=45).
Co-variation between point clouds of site-specific trabecular variables & surface landmark coordinates was assessed.
Results:
Hn talar external & internal morphologies were distinct from Hs groups,
but shape did not significantly co-vary with either bone volume fraction, or degree of anisotropy,
this suggests limited covariation between external & internal talar structures.
Hn external talar morphology reflects ancestral retentions + various adaptations to high levels of mobility correlated to their presumably unshod hunter-gatherer lifestyle.
This pairs with their high site-specific trabecular bone volume fraction & anisotropy, suggesting intense & consistently oriented locomotor loading resp.
Hn (vs Hs) exhibit differences in the talo-crural joint, potentially attributable to
- cultural & locomotor behavior dissimilarity,
- a talo-navicular joint that mixes ancestral & functional traits,
- a derived subtalar joint that suggests a predisposition for a pronated foot during stance phase.
Overall,
- Hn talar variation is attributable to mobility strategy & phylogenesis,
- Hs talar variation results from the same factors + footwear.
Our results suggest that greater Hn body mass and/or higher mechanical stress uniquely led to their habitually pronated foot posture.
https://pubmed.ncbi.nlm.nih.gov/34749003/
Abstract
Neanderthal foot bone proportions and morphology are mostly
indistinguishable from those of Homo sapiens, with the exception of
several distinct Neanderthal features in the talus. The biomechanical implications of these distinct talar features remain contentious, fueling debate around the adaptive meaning of this distinctiveness. With the
aim of clarifying this controversy, we test phylogenetic and behavioral
factors as possible contributors, comparing tali of 10 Neanderthals and
81 H. sapiens (Upper Paleolithic and Holocene hunter-gatherers, agriculturalists, and postindustrial group) along with the Clark Howell
talus (Omo, Ethiopia). Variation in external talar structures was assessed through geometric morphometric methods, while bone volume fraction
and degree of anisotropy were quantified in a subsample (n = 45). Finally, covariation between point clouds of site-specific trabecular variables and surface landmark coordinates was assessed. Our results show that
although Neanderthal talar external and internal morphologies were
distinct from those of H. sapiens groups, shape did not significantly covary with either bone volume fraction or degree of anisotropy, suggesting
limited covariation between external and internal talar structures.
Neanderthal external talar morphology reflects ancestral retentions, along
with various adaptations to high levels of mobility correlated to their presumably unshod hunter-gatherer lifestyle. This pairs with their high site-specific trabecular bone volume fraction and anisotropy, suggesting intense and consistently oriented locomotor loading, respectively. Relative
to H.sapiens, Neanderthals exhibit differences in the talocrural joint that
are potentially attributable to cultural and locomotor behavior
dissimilarity,
a talonavicular joint that mixes ancestral and functional traits, and a
derived
subtalar joint that suggests a predisposition for a pronated foot during
stance
phase. Overall, Neanderthal talar variation is attributable to mobility strategy
and phylogenesis, while H. sapiens talar variation results from the same factors
plus footwear. Our results suggest that greater Neanderthal body mass and/or higher mechanical stress uniquely led to their habitually pronated foot posture.
Will look at this more fully in the near future.
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