Food & agriculture · c. 6,000 BCE

Irrigation

Canals led river water to fields, letting farming thrive where rain alone could not.

Farmers in Mesopotamia and Khuzistan were diverting water by about 6000 BCE, and irrigated Sumerian barley reached yields few later societies matched. Managing shared canals also pushed the growth of administration and early states.

See it in the living tree Wikipedia

Arcs above join it to what it stood on, arcs below to what it led to. The bar places this stretch on the tree's whole timeline.

What it built on 2

What it led to 6

Related measurements

The dashed line marks when it first worked.

World population over a million years Latest: 6.27k million people (2000) Source: DeLong 1998, table 'Total World Population' (Kremer series); Kremer 1993, Population Growth and Technological Change: One Million B.C. to 1990, QJE 108(3)

Share of people living in cities Latest: 57.5 % (2025) Source: Our World in Data

World GDP over a million years Latest: 41k billion 1990 international $ (2000) Source: DeLong 1998, Estimating World GDP, One Million B.C. - Present; Wikipedia: Gross world product (DeLong table, cross-check)