Letters

Cartilage risk
I enjoyed Nathan Seppa’s article “Cartilage creation,” (SN: 8/11/12, p. 22) about attempts to generate new cartilage from somatic stem cells. He writes that cartilage evolved “in ancestors who lived shorter lives, carried less body weight and roamed an unpaved world.” Implications: The risk of osteoarthritis increases with age, body weight and impact on concrete, such as a long-term runner might experience.