How Do Birds Sing?

Birds are the only creature in the world that have the specially evolved organ called the syrinx, and it's what lets them sing. Learn how it works in this episode of BrainStuff.

Learn more about your ad-choices at https://www.iheartpodcastnetwork.com

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff production of iHeart Radio, Hey brain Stuff,
Lauren vocal bomb here. Convergent evolution is the idea that
two organisms that aren't very closely related can independently evolve
a very similar trait. For instance, the last ancestor that
we shared in common with an octopus probably looked a
lot like a worm, even though that animal might have

(00:24):
been able to detect light and dark. It took something
like seven dred and fifty million years of both human
and octopus ancestors working on being able to see properly
to evolve the incredibly similar eye structures that humans and
octopuses now share nifty. But this isn't how it always happens. Take,
for instance, the voice box of a bird. It's called

(00:46):
a syrinx, and no other organism on Earth has one.
It's something of an evolutionary mystery. Why not? Actually, After all,
other animals need to be able to communicate, just like
both cephalopods and mammals need to be able to see
what they're doing. In fact, the SEARINGX is arguably much
weirder than the high acuity camera style I we share
with the octopus because the SEARINGX came out of nowhere.

(01:09):
Evolutionarily speaking, it could be argued that the synx is
a bit redundant in bird anatomy, as they also possess larynxes,
the voice box structure that they share with we mammals
and some amphibians and reptiles, though it only functions very
well in mammals and a few lizards. The larynx is
what enables cows to move, dogs to bark, and babies

(01:29):
to cry, and it's situated at the top of the throat. However,
birds use their synx to make their fluty vocalizations. It's
similar to the larynx and that it's made of folds
of vocal membranes supported by cartilage. However, the synx is
buried deep in a bird's chest, right above where their
tracheo bronchial tube splits off into their lungs. In twenty sixteen,

(01:52):
paleontologists from the University of Texas in Austin reported that,
based on fossil evidence, the structure we know as the
syrinx is around sixties million years old. Since then, the
research team has been comparing the larynx and syrinx anatomy,
genetics and development of birds to those of modern reptiles
and have discovered the evolution of the syrinx is even

(02:12):
stranger than previously thought. In a paper published in eighteen
issue of the Proceedings of the National Academy of Sciences,
the research team reported the function, form, and development of
the syrinx and the larynx are actually quite different. For starters,
the vocal cords of the larynx are manipulated by muscles
attached to the cartilage that supports them. The seynx, on

(02:32):
the other hand, partially attaches to muscles that in other
animals fastened the tongue to the bones connecting the arms
to the rest of the body. Secondly, while baby birds
and baby lizards are developing different types of cells form
their respective voice boxes, larynxes are made of a mixture
of mesoderm and neural crest cells, which are a temporary

(02:53):
group of cells that arise from the ectoderm, while the
syrinx is created exclusively using mesoderm cells. So at some point,
the ancestors of modern birds just started making a new
voice box, which eventually took over the job of the larynx.
As a result, now birds can sound like this. This

(03:15):
research is exciting because although convergent evolution is a really
cool thing for scientists to wander over, a true evolutionary
outlier is arguably cooler. Today's episode was written by Jesselyn
Shields and produced by Tyler Clang. Brain Stuff is a
production of I Heart Radio's How Stuff Works. For more

(03:36):
on this and lots of other convergent topics, visit our
home planet, how stuff works dot com. And for more
podcasts from my heart Radio, visit the iHeart Radio app,
Apple Podcasts, or wherever you listen to your favorite shows.