We say the rarajipari is the game of life, ' Angel said. 'You never know how hard it will be. You never know when it will end. You can't control it. You can only adjust.

Distance running was revered because it was indispensable; it was the way we survived and thrived and spread across the planet. You ran to eat and to avoid being eaten; you ran to find a mate and impress her, and with her you ran off to start a new life together. You had to love running, or you wouldn't live to love anything else. And like everything else we love-everything we sentimentally call our 'passions' and 'desires'-it's really an encoded ancestral necessity. We were born to run; we were born because we run.

Every morning in Africa, a gazelle wakes up, it knows it must outrun the fastest lion or it will be killed. Every morning in Africa, a lion wakes up. It knows it must run faster than the slowest gazelle, or it will starve. It doesn't matter whether you're the lion or a gazelle-when the sun comes up, you'd better be running.

Humans are built for endurance, not speed. We're awful sprinters compared to every other animal. We try to run our races as if they were speed races, but they are not. They're endurance races. Even a marathon, the way it's run now, it's not an endurance contest.

Running is the heart of what it means to be human.

human urine is both nutrient-rich and an effective tooth whitener

Only recently have we come up with the technology to turn lazing around into a way of life. We've taken our sinewy, durable, hunter-gatherer bodies and plunked them into an artificial world of leisure.