https://royalsocietypublishing.org/doi/epdf/10.1098/rsos.241879
Bite force production and theorigin of Homo
The divergence of Homo from gracile
australopiths has been described as a trend
of decreasing dentognathic size and
robusticity, precipitated by stone tool use
and/or a shift to softer foods, including meat.
Yet, mechanical evidence supporting this
narrative is sparse, and isotopic and
archaeological data have led to the suggestion
that a shift away from a gracile
australopith-like diet would not have
occurred in the most basal members of Homo but
rather only with the appearance of Homo
erectus, implying that the origin of our genus
is not rooted in dietary change. Here, we
provide mechanical evidence that Homo habilis
exhibits an australopith-like pattern of facial
strain during biting but, unlike most
australopiths, was not suited for a diet that
required forceful processing by the molar teeth.
Homo habilis was at elevated risk of distractive
jaw joint forces during those bites,
constraining muscle recruitment so as to avoid
generating uncomfortable/dangerous levels of
tension in the joint. Modern humans have similar
limitations. This suggests that selection on
skeletal traits favouring forceful postcanine
processing was relaxed by the earliest stages
in the evolution of our genus, implying that
dietary or food processing changes played an
important role in the emergence of Homo.
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