There are, of course, lots of ways to resist progress. People take up knitting or quilting or calligraphy. They bake their own bread or brew their own beer or sew their own clothes using felt they have fashioned out of wet wool and dish soap. But, both in the scale of its ambition and in the scope of its anachronism, paleo eating takes things to a whole new level. Our Stone Age ancestors left behind no menus or cookbooks. To figure out what they ate, we have to dig up their bones and study the wear patterns on their teeth. Or comb through their refuse and analyze their prehistoric poop. And paleo eating is just the tip of the spear, so to speak. There are passionate advocates for paleo fitness, which starts with tossing out your sneakers. There’s a paleo sleep contingent, which recommends blackout curtains, amber-tinted glasses, and getting rid of your mattress; and there are champions of primal parenting, which may or may not include eating your baby’s placenta. There are even signs of a paleo hygiene movement: coat yourself with bacteria and say goodbye to soap and shampoo.