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A New Computational Method for Simulation and Optimization of Hominin Gait

Tom Erez, William D. Smart, and Herman Pontzer.
In "American Association of Physical Anthropologists Annual Meeting", Chicago, IL, April 2009.


This is the abstract of a talk given at the annual meeting of the American Association of Physical Anthropologists. There's no associated paper for this version.

The evolution of hominin bipedalism required changes in both morphology and neural control, with dynamic interaction with the environment playing a crucial role. While several gait simulation models have recently been proposed to investigate bipedalism in early hominins, computational constraints have prevented these studies from incorporating reactive neural control strategies which account for variability in limb position ("feedback control"). Instead, the neural activity in these models depends only on time, and does not account for pose variability due to non-uniform environment. This severely limits the range of models that can be considered, and the type of investigation afforded by the computational constraints. In this talk, we present our recent work in computational optimization that allows for the evolution of feedback controllers for bipedal gait and enables the simulation of stable walking over changing terrain. By introducing feedback control, we can simulate models of increased complexity (and hence realism), and take into account the interaction with the environment in greater detail.

To examine the utility of this computational approach for investigating hominin bipedalism, we optimized simulated bipedal walking using various cost functions (e.g. maximizing velocity, minimizing metabolic cost, maximizing stability). Furthermore, in order to examine the relationship between commonly-proposed selection pressures and morphological change, we studied the effect of morphological variability on the different performance measurements. These simulations revealed a complex relationship between morphology, locomotor control and the environment, and shed light on hypotheses regarding possible evolutionary pressures which shaped the emergence and evolution of hominin bipedalism.

@inproceedings{aaps09,
  author = {Erez, Tom and Smart, William D. and Pontzer, Herman},
  title = {A New Computational Method for Simulation and Optimization of Hominin Gait},
  booktitle = {American Association of Physical Anthropologists Annual Meeting},
  address = {Chicago, IL},
  month = {April},
  year = {2009}
}