Urban worldsOur World

Cities

Walk through settlements that concentrated culture, trade, and invention.

Origin depth

Official Earth time scaleSelect an eon on the road to reveal its eras.ICS 2026/06 ↗

Cosmic Originsbefore Earth’s geological eons

c. 13.8 billion years agoUniverse

The Big Bang

The universe expands and cools from a hot, dense early state.

Within the first few hundred million yearsEarly Universe

The first stars ignite

Gravity gathers primordial gas and the cosmic dark ages begin to lift.

c. 4.54 billion years agoSolar System

Earth takes shape

Rock and metal gather around the young Sun.

At least 3.5 billion years agoEarth

Microbial life leaves evidence

Ancient rocks preserve traces of a living planet.

c. 2.4 billion years agoAtmosphere & oceans

Oxygen transforms the atmosphere

Microbial photosynthesis changes the chemistry of Earth.

c. 1.8 billion years agoEarth

Complex cells diversify

Cells with internal structures establish a new branch of life.

c. 600 million years agoGlobal oceans

Large multicellular life spreads

Complex bodies become a visible part of the fossil record.

By c. 200 million years agoEarth

Early mammals live alongside dinosaurs

Small mammals and their close relatives are part of Mesozoic ecosystems.

c. 56 million years agoAsia, Europe & North America

Early primates diversify

Small tree-dwelling primates spread through warm forests.

c. 7 million years agoAfrica

The hominin story begins

A lineage of African apes starts following its own evolutionary path.

c. 2.8 million years agoAfrica

Early Homo enters the fossil record

A jaw from Ethiopia preserves evidence attributed to our genus.

c. 300,000 years agoAfrica

Homo sapiens emerge

Our species appears within a diverse human world.

c. 60,000–40,000 years agoGlobal

Humans journey beyond Africa

Later waves of migration expand our species’ global presence.

c. 10,000 BCEGlobal

The agricultural turn

Communities reshape land, food, and settlement.

c. 9,000 BCEMiddle East

Jericho

A settlement endures near a desert spring.

c. 3,500 BCEMiddle East

Uruk

One of the first great cities grows in Mesopotamia.

508–507 BCEEurope

Athens

Political participation is radically reimagined.

762 CEMiddle East

Baghdad

A new capital becomes a center of learning.

15th–16th centuries CEAfrica

Timbuktu

Trade and scholarship meet at the Sahara’s edge.

c. 2007–2008 CEGlobal

An urban planet

Humanity approaches a majority living in urban areas.

Branch road complete

You’ve reached the end of Cities

Return to “The agricultural turn” and continue along The Human Story, or search for another origin below.