Period· The columns of time
Contemporary
1800 → Today
Two centuries in which the species goes from one billion to eight, and becomes the main agent of change on the surface of its own planet. Measured against everything to their left on the frieze, they are a rounding error.
What the evidence shows
The band opens with industrialisation and has no closing edge, because it has not closed. Within its 226 years the human population multiplies by eight, life expectancy roughly doubles, and the burning of fossil carbon alters the composition of the atmosphere enough to be read, layer by layer, in ice cores. Set beside the Palaeolithic band at the other end of this frieze, it occupies about seven hundredths of one per cent of the history of the species. Both of those statements are true at once, and holding them together is most of what a timeline is for.
Bounds and conventions
The only band with no closing boundary. Its opening date is conventional and moves with the author and the country, from the 1780s to the 1850s, depending on whether one dates the change by machines, by fuel, by politics or by population.
From 1800. A historiographical convention.