From Newsgroup: sci.anthropology.paleo
Evaluating the Evolvability of Paranthropus Cranial Morphology in
Relation to Feeding Biomechanics
ABSTRACT
Objective
Although disagreement persists as to the precise nature of the diet of Paranthropus, there is a consensus that the food resources consumed by Paranthropus were in some way mechanically challenging to process (i.e.,
by being "hard" and/or "tough"). While the highly derived feeding
apparatus of Paranthropus likely conferred biomechanical performance advantages while consuming certain types of foods, it may also have
limited the ability of these early hominins to respond to selection and
evolve rapidly toward new adaptive peaks (i.e., reduced their evolvability).
Materials and Methods
We employed viability selection modeling to test this hypothesis.
Viability selection simulations were performed using Paranthropus boisei
(OH 5), Australopithecus afarensis (A.L. 444-2), and Homo habilis
(KNM-ER 1813) specimens. We simulated the generation-to-generation
evolution of biomechanically informative linear dimensions in a
population where an individual's probability of survival (i.e.,
viability) was determined by its distance to a predetermined adaptive
peak. The number of generations required for an evolving population to
reach a new adaptive peak was used as a measure of evolvability.
Results
The results showed that the mean number of generations from P. boisei to
H. habilis was larger than in the reverse direction when modeled using
either chimpanzee or human estimates of population variance/covariance.
It took longer for P. boisei to evolve toward Au. afarensis than in the reverse direction, but only with the chimpanzee estimates of population variance/covariance.
Discussion
The results suggest that P. boisei faced limitations in cranial
evolvability, particularly if selection favored a cranial morphology
similar to H. habilis.
Open access:
https://doi.org/10.1002/ajpa.70136 https://onlinelibrary.wiley.com/doi/10.1002/ajpa.70136
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