Medical knowledge and technical savvy are biodegradable. The sort of medicine that was practiced in Boston or New York or Atlanta fifty years ago would be as strange to a medical student or intern today as the ceremonial dance of a !Kung San tribe would seem to a rock festival audience in Hackensack. 620
It is from the progeny of this parent cell that we all take our looks; we still share genes around, and the resemblance of the enzymes of grasses to those of whales is in fact a family resemblance. 603
