Lecture 24: Threshold 7—Agriculture

Threshold 7—Agriculture ................................................................

LECTURE

Humans transformed the environments of entire continents by

systematically ¿ ring the land.

T

hreshold 7 of this course introduces a new type of technology:

agriculture. The appearance of agriculture set human history off in

entirely new directions by increasing human control of food, energy,

and other resources. Rather as gravity pulled together clouds of hydrogen

and helium atoms to form the ¿ rst stars, so agriculture generated denser

and denser human communities until, eventually, entirely new forms of

complexity began to emerge, including cities, states, and entire civilizations.

This lecture describes the appearance of agricultural societies, de¿ nes

agriculture, and discusses agriculture’s impact on human history.

The “early Agrarian era” is the ¿ rst of two subdivisions of the Agrarian era

of human history. It began with the appearance of agriculture, slightly more

than 10,000 years ago, and ended with the appearance of the ¿ rst cities, about

5,000 years ago. That marks the beginning of the second subdivision of the

Agrarian era, which we will call the “later Agrarian era.” The early Agrarian

era was the ¿ rst era of human history in which there were communities that

supported themselves mainly from agriculture.

Seen globally, the early Agrarian era lasted from the appearance of

agriculture, more than 10,000 years ago, until the appearance of the ¿ rst

Agrarian civilizations, just over 5,000 years ago. However, in many parts

of the world agriculture appeared later, and so did Agrarian civilizations, so

dates for the era vary signi¿ cantly in different regions. To understand global

changes during this era, it will help to think of the world as divided into four

major “world zones,” whose histories were so different that they might as

well have taken place on different planets. These were Afro-Eurasia (Eurasia

and Africa), the Americas, Australasia (including Papua New Guinea), and

the Paci¿ c.