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The nerve circuits that enable people to walk first appeared more than 400 million years ago in fish whose descendants still walk the seafloor on their fins. This is the finding of a study published online February 8 in the journal Cell.

The new study shows that the fish species little skate (Leucoraja erinacea)—which are related to rays and sharks—use paired muscle groups, genetic regulatory proteins, and spinal cord nerve circuits similar to those used by humans to coordinate “bipedal locomotion.”
 
“Given that that skates use many of the same neural circuits that we do to walk, but with six muscles instead of the hundreds we use, the fish provide a simple model to study how the circuits that enable walking are assembled,” says lead study author , associate professor in the at NYU Langone Health. “Until we understand how spine–limb nerve connections are wired, we can’t expect to reverse spinal cord damage and paralysis,” says Dr. Dasen, a member of the at NYU Langone Health.

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