272 But to Back Up a Bit . . . We’ve been developing the art of building since the dawn of the agricultural revolution 8,000 years ago. That extended worldwide moment was arguably the most disruptive in history—for us and the rest of life on earth. Rather than hunt and forage for our food, we grew it in one spot, and next thing you know we had architecture, political states, wealth and poverty, global tension, and Wi-Fi-enabled drive-thru hamburger stands everywhere. However, for the last few centuries we’ve also been learning through science. We now know an awful lot more about how things work than we ever did before, but we can also dimly see how much we still don’t know. In many ways, the history of architecture follows the development of materials— follows the history of people messing around with things found in the landscape to create bricks, then boards, then toilets, then building-integrated photovoltaic panels. People learned to fire clay to make pottery, and when the kilns were made of limestone they discovered that the intense heat also changed the rocks: lime plaster, concrete, Pantheon. In some places, the potters saw shiny metal oozing out of certain heated rocks: copper, bronze, iron, Golden Gate Bridge. Two hundred years ago engineers in England placed iron bars in the newly invented Portland cement concrete, and architects went wild: the result was every downtown skyline in the world, with lights, plumbing, and comfort hundreds of feet in the air. It seemed like the party would never stop, but the hidden costs are arriving and starting to hurt. Building materials account for 9 to 15 percent of global emissions, so we have to change not just the way we build, but what we build with. For the past century, it has been increasingly easy and cheap to extract, process, assemble, and transport everything we use in building. Every modern industrial society has codified systems, laws, and standards of construction that are based on abundant fossil fuels and having an “away” where we can throw things—and which even “Sound Wall” made of 3-D-printed rubber by Rael-San Fratello Architects.