Run on tip-toe like your ancestors (Image: Tatiana Morozova/iStock)

HUMANS living millions of years ago were endurance runners, but how did they do it without air-cushioned soles? The secret might have been to land on the balls of their feet.

Daniel Lieberman at Harvard University and colleagues compared the gait of endurance runners in the US and Kenya and found that more than two-thirds of those who grew up running barefoot or had trained themselves to do so as adults ran on their tiptoes, landing on the balls of the feet first (Nature, DOI: 10.1038/nature08723). The trend is unusual: …