Speaker 1: Welcome to brain Stuff production of iHeart Radio, Hey brain Stuff,
Speaker 1: Lauren vocal bomb here. Convergent evolution is the idea that
Speaker 1: two organisms that aren't very closely related can independently evolve
Speaker 1: a very similar trait. For instance, the last ancestor that
Speaker 1: we shared in common with an octopus probably looked a
Speaker 1: lot like a worm, even though that animal might have
Speaker 1: been able to detect light and dark. It took something
Speaker 1: like seven dred and fifty million years of both human
Speaker 1: and octopus ancestors working on being able to see properly
Speaker 1: to evolve the incredibly similar eye structures that humans and
Speaker 1: octopuses now share nifty. But this isn't how it always happens. Take,
Speaker 1: for instance, the voice box of a bird. It's called
Speaker 1: a syrinx, and no other organism on Earth has one.
Speaker 1: It's something of an evolutionary mystery. Why not? Actually, After all,
Speaker 1: other animals need to be able to communicate, just like
Speaker 1: both cephalopods and mammals need to be able to see
Speaker 1: what they're doing. In fact, the SEARINGX is arguably much
Speaker 1: weirder than the high acuity camera style I we share
Speaker 1: with the octopus because the SEARINGX came out of nowhere.
Speaker 1: Evolutionarily speaking, it could be argued that the synx is
Speaker 1: a bit redundant in bird anatomy, as they also possess larynxes,
Speaker 1: the voice box structure that they share with we mammals
Speaker 1: and some amphibians and reptiles, though it only functions very
Speaker 1: well in mammals and a few lizards. The larynx is
Speaker 1: what enables cows to move, dogs to bark, and babies
Speaker 1: to cry, and it's situated at the top of the throat. However,
Speaker 1: birds use their synx to make their fluty vocalizations. It's
Speaker 1: similar to the larynx and that it's made of folds
Speaker 1: of vocal membranes supported by cartilage. However, the synx is
Speaker 1: buried deep in a bird's chest, right above where their
Speaker 1: tracheo bronchial tube splits off into their lungs. In twenty sixteen,
Speaker 1: paleontologists from the University of Texas in Austin reported that,
Speaker 1: based on fossil evidence, the structure we know as the
Speaker 1: syrinx is around sixties million years old. Since then, the
Speaker 1: research team has been comparing the larynx and syrinx anatomy,
Speaker 1: genetics and development of birds to those of modern reptiles
Speaker 1: and have discovered the evolution of the syrinx is even
Speaker 1: stranger than previously thought. In a paper published in eighteen
Speaker 1: issue of the Proceedings of the National Academy of Sciences,
Speaker 1: the research team reported the function, form, and development of
Speaker 1: the syrinx and the larynx are actually quite different. For starters,
Speaker 1: the vocal cords of the larynx are manipulated by muscles
Speaker 1: attached to the cartilage that supports them. The seynx, on
Speaker 1: the other hand, partially attaches to muscles that in other
Speaker 1: animals fastened the tongue to the bones connecting the arms
Speaker 1: to the rest of the body. Secondly, while baby birds
Speaker 1: and baby lizards are developing different types of cells form
Speaker 1: their respective voice boxes, larynxes are made of a mixture
Speaker 1: of mesoderm and neural crest cells, which are a temporary
Speaker 1: group of cells that arise from the ectoderm, while the
Speaker 1: syrinx is created exclusively using mesoderm cells. So at some point,
Speaker 1: the ancestors of modern birds just started making a new
Speaker 1: voice box, which eventually took over the job of the larynx.
Speaker 1: As a result, now birds can sound like this. This
Speaker 1: research is exciting because although convergent evolution is a really
Speaker 1: cool thing for scientists to wander over, a true evolutionary
Speaker 1: outlier is arguably cooler. Today's episode was written by Jesselyn
Speaker 1: Shields and produced by Tyler Clang. Brain Stuff is a
Speaker 1: production of I Heart Radio's How Stuff Works. For more
Speaker 1: on this and lots of other convergent topics, visit our
Speaker 1: home planet, how stuff works dot com. And for more
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