GENETICS × TECHNOLOGY

Copying DNA at Will

1983 to 1985 CE

Phanerozoic · Cenozoic · Quaternary · Holocene · Meghalayan

Heat separates the two strands of a DNA molecule, short primers mark out the stretch you want, an enzyme copies it, and cooling lets the cycle start again. Each round doubles what you have, so one molecule becomes a billion in an afternoon. It only became routine once someone borrowed the copying enzyme from a bacterium that lives in hot springs, and so survives the heating step instead of having to be replaced every cycle.

Why it matters

Ancient bones, a crime scene, a virus on a nasal swab: each holds DNA in quantities far too small to read. This is the step that makes them readable, and it is why several of the discoveries further along this timeline were possible at all.

Dating & uncertainty

The idea dates from 1983 and the first published application from 1985. A heat-stable enzyme from a hot-spring bacterium made it routine two years later.

Sources

1. Saiki et al. (1985), Science · Enzymatic amplification of beta-globin genomic sequences and restriction site analysis for diagnosis of sickle cell anemia
2. Mullis (1990), Scientific American · The unusual origin of the polymerase chain reaction
3. Heather & Chain (2016), Genomics · The sequence of sequencers: the history of sequencing DNA

Earth history as one day

23:59:59.9992818 µs before midnight

if Earth’s 4.54 billion years were compressed into a single day