This episode is supported by Edx. Termites, prairie dogs, and people are all
great builders, each in their own way. And we all share one crucial problem. Put a bunch of us in a closed space, breathing
Oxygen in and CO2 out… and it doesn’t end well. Our tallest skyscrapers and deepest mines
are almost completely cut off from outside air. To keep those inside from suffocating, human
engineers use giant machines to bring in fresh air and pump stale air out. Termite mounds have the same problem. The largest are more than 10 meters high. On a human scale, that’s like a skyscraper
three and a half kilometers tall! Only instead of condos and offices, it holds
one big farm. The termites collect wood, which grows fungus,
that the termites eat. All that fungus and the millions of termites
that tend to it create a ton of CO2, which would suffocate the colony *and* their crops
if it builds up. To keep the air fresh, the whole mound acts
like a big lung. During the day, the sun heats the outer chambers
more rapidly than the core, moving air up the outside and down the middle. During the night, this current reverses as
the outer chambers lose heat to the cool night air. The whole time, CO2 and oxygen are exchanged
through tiny holes in the outer walls. What’s amazing is this is all constructed
without a boss. No central architect designing the structure. Just instinct and cooperation lets termites
build huge ventilation engines powered by nothing but daily temperature cycles. Leafcutter ants farm fungus on massive scales
too. One colony in South America covered nearly
50 square meters and was home to over 8 million ants! But unlike those towering termites, the ant
labyrinth reached 8 meters underground. So how do they ventilate their agricultural
city? Before we answer that, I want you to try something. Take a piece of paper, hold it under your
lips, and let the other end curl down. If you blow only across the top of the paper,
what do you think will happen? The force of the air hitting the paper should
push it down, right? Well watch this. Here’s what’s happening: Air is a fluid. When I force air across the top of the paper,
that stream pulls other air along, due to viscosity, which is like the friction of
fluids. This leaves an area of low pressure behind, and the paper is pulled up to fill
it. This is called the Coandă effect. What does that have to do with ants? Check this out. When a breeze flows over a hill, the air is
deflected over the top. This pulls air along too, just like when I blew over the paper, drawing air out of the ant hill along the
way. The ants build lower entrances nearby, where
air is drawn in to replace it, ventilating the whole colony with a little breeze. Prairie dogs get the same effect from their
mounds. Breezes over taller hills draw air through
the connected tunnel system, keeping the whole town breathing fresh. There’s even a tiny shrimp that uses this
same system to keep fresh water flowing through its burrows. Persian and Egyptian architects have used
similar structures to cool buildings for centuries, but tiny animals beat us to that technology
by millions of years Nature is full of species that build their
environment to suit them, countless expert animal architects. Sometimes, all you need to solve the most
complex engineering problems is the awesome power of evolution, …and that’s a breath of fresh air. Stay curious. Thanks to edX, our non-profit partner for
sponsoring this episode. edX.org is where you can learn for free from
Harvard, MIT and other universities around the globe. If you liked this video, you should go check
out Harvard’s Architectural Imagination course. Led by Professor Michael Hays, this online
course shows you how to look at architecture as an expression of culture as well as technical
achievement. It brings you closer to the work of actual
architects and historians through hands-on exercises and historic examples. edX.org offers university level courses in
everything from artificial intelligence to leadership, data science to robots and cybersecurity. There are even courses from my alma mater,
the University of Texas! edX.org puts a universe of free online learning
at your fingertips. Visit edx.org today and discover the courses
that will keep you learning!
Great video, interesting stuff. Now the real questions exists, why does his shirt say "TACO" but also has an image of a taco.