Clock genes are a set of genes known to contribute to the regulation of the human body's internal 24-hour cycle, also known ...

Nature 400, 446–449 (1999). Vitousek, P. M. et al. Human alteration of the global nitrogen cycle: sources and consequences. Ecological Applications 7, 737–750 (1997).

The idea that the human body completely regenerates itself every seven years is a widely shared “fact.” But how much truth is there to this claim? While the body is constantly renewing itself, the ...