Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hey
Speaker 1: brain Stuff, I'm Lauren vogel Bomb and this this is
Speaker 1: a classic episode from our archives. We humans tend to
Speaker 1: think of ourselves as being at the top of the
Speaker 1: evolutionary ladder, but the truth is that we exist on
Speaker 1: more of a continuum alongside countless other creatures with features
Speaker 1: worth exploring. One that surprised us is how much fish
Speaker 1: can teach us about walking. Hey, brain Stuff, Lauren vogel Bomb. Here,
Speaker 1: where did you get that walk? Like many people, you
Speaker 1: might guess our vertebrate gate originates with the first backboned
Speaker 1: creatures to scramble out of the sea, but a study
Speaker 1: published in the journal Cell indicates that the first walkers
Speaker 1: did it underwater. The Late Devonian vertebrate land invasion roughly
Speaker 1: three eight two million years ago, was a big deal
Speaker 1: in Earth's history. Previously confined to the ocean, our tetrapod
Speaker 1: forefathers took to the surface swirld and over the course
Speaker 1: of millions of years, traded fins and gills for limbs
Speaker 1: and lungs. A tetrapod, by the way, just means vertebrates
Speaker 1: with two pairs of limbs. The remarkable thing, says the
Speaker 1: team of researchers, is that the neural circuits involved an
Speaker 1: ambulatory limb control were already established millions of years before
Speaker 1: the first tetrapod strutted its stuff. In other words, much
Speaker 1: of the software was in place well before the walk
Speaker 1: about hardware. The researchers studied the neural circuitry of the
Speaker 1: little skate. This cartilaginous fish might not be much to
Speaker 1: look at, but it's considered one of the most primitive
Speaker 1: vertebrates alive today. Travel back roughly four and twenty million
Speaker 1: years and you'll find a common ancestor of both skates
Speaker 1: and tetrapods. The little skate is also interesting because it's
Speaker 1: one of several ambulatory fish that walk across the sea floor.
Speaker 1: The skate uses its large pectoral fins to swim and
Speaker 1: smaller pelvic fins to walk with alternating left right motions,
Speaker 1: much like the gate of a land animal. This similarity
Speaker 1: impressed the researchers, but these similarities would go beyond movement.
Speaker 1: The team employed RNA sequencing to study the expressed genes
Speaker 1: in these skates motor neurons. Many of these genes pop
Speaker 1: up in mammals as well, and that includes neural subtypes
Speaker 1: involved in the muscle control of bending and straightening limbs. This,
Speaker 1: according to the study findings, constitutes a conserved genetic program
Speaker 1: for walking. Study co author Jeremy S. Dayson says that
Speaker 1: neither swimming nor walking accurately described the skates movements, but
Speaker 1: perhaps this isn't too surprising given the human centric nature
Speaker 1: of our language, he said via email. The skate ray
Speaker 1: mode I would call ambulatory swimming, whereas the axial tail
Speaker 1: based is more like spinal swimming. The ambulatory swimming mode
Speaker 1: is really the one which made walking possible in both
Speaker 1: skates and tetrapods. The study sheds light on the underwater
Speaker 1: history of walking, but the researchers hope that it will
Speaker 1: lead to an improved understanding of motor neurons and even
Speaker 1: the treatment of human neurological to orders. Jason stresses that
Speaker 1: while the neural complexity of higher organisms does hinder our
Speaker 1: study of animals such as mice, the little skates archaic
Speaker 1: simplicity makes it a perfect starting point. He said, I
Speaker 1: think one of the advantages of studying neural circuits and
Speaker 1: skates is that they can accomplish this behavior using a
Speaker 1: relatively simple set of connections between neurons and muscle, we
Speaker 1: hope we can exploit the simplicity to understand the basic
Speaker 1: architecture of the circuits controlling walking. The exact wiring of
Speaker 1: these circuits is still not fully understood in humans or
Speaker 1: other tetrapods, but such knowledge could one day aid in
Speaker 1: the treatment and repair of human spinal cord injuries and
Speaker 1: motor neuron diseases such as a myotrophic lateral sclerosis or
Speaker 1: a l S. But as the saying goes, you have
Speaker 1: to crawl before you can walk, or should we say swim.
Speaker 1: Today's episode was originally produced by Tristan McNeil and is
Speaker 1: based on the article ain't fish strutted the sea floor
Speaker 1: before land Animals? On How stuff Works dot Com, written
Speaker 1: by rob Bert Lamb. To hear more from Robert about
Speaker 1: things strutting to see floor, check out his weird fiction
Speaker 1: podcast mini series The second oil Age. You'll hear a
Speaker 1: familiar voice in the first episode. Brain Stuff is production
Speaker 1: of I Heart Radio in partnership with how Stuffworks dot
Speaker 1: Com and is produced by Tyler clang Or more podcasts
Speaker 1: from my heart Radio, visit the iHeart Radio app, Apple podcasts,
Speaker 1: or wherever you listen to your favorite shows.