The Ancient Origins of Neural Substrates for Land Walking.
Level 5 - mechanism / opinion, no new human data
Bench and animal neurobiology research (non-human comparative biology model)
PubMed 29425489 · doi:10.1016/j.cell.2018.01.013
What was done
Investigated the behavioral and developmental neural substrates of walking-like locomotion in the little skate (*Leucoraja erinacea*), evaluating its pelvic fin gait patterns and the Hox transcription factor-dependent regulatory programs controlling fin muscle innervation compared to tetrapod limb networks.
What was found
The little skate exhibits core tetrapod-like locomotor features, including left-right alternation and reciprocal extension-flexion of its pelvic fins. It uses a conserved Hox transcription factor-dependent network required for selective fin muscle innervation that creates peripheral connectivity modules distinct from axial swimming circuits. The abstract reports no numerical values or sample sizes.
Why it matters
This study shows that the foundational neural circuits and genetic machinery necessary for walking did not originate with the tetrapod transition to land, but were already present in common marine vertebrate ancestors approximately 420 million years ago.
Limits
The abstract provides no sample sizes, effect sizes, or quantitative data. Findings rely entirely on an animal model (*Leucoraja erinacea*) and comparative evolutionary biology, with no direct clinical or human physiological data.
Cited by
- supports The genetic programs expressed in motor neurons controlling trunk musculature are homologous to those in undulating fish, representing conserved ancestral motor circuits upon which limb- and digit-controlling motor neurons evolved.