The molecular clock: constant-rate change as a dating instrument

An undated manuscript can sometimes be dated the same way a fossil can: by counting how much of something has quietly built up since the clock started running. Both radiocarbon decay and the molecular clock used in genetics rest on one shared assumption -- that some underlying process moves forward at a rate steady enough for its accumulated total to stand in for elapsed time. This page gathers conjectures that make the same bet about scribal copying: that errors, script drift, and numeral corruption pile up at something close to a constant rate, so counting the differences between an undated copy and its known ancestor can date the undated one, as long as the rate has first been calibrated against manuscripts that do carry a real date.

The scribal clock and The scribal generation clock both test the clock directly, asking whether accumulated copying error really does tick at a steady enough rate to date an undated manuscript against its family. The dead-language clock applies the same idea to a dying language rather than a copied text, treating vocabulary loss as its own kind of clock. Horoscopes cast with yesterday's sky uses recomputed historical horoscopes as a calibration check: an astrologer working from yesterday's sky, rather than the correct one, leaves a datable error of a very specific size.