How did the development of agriculture lead to the establishment of a complex society?

In 1831, in the United States, Cyrus McCormick invented a horse-drawn mechanical reaper that could harvest grain five times faster than could a man with a handheld scythe. Also about that time, traders began bringing fertilizers into Europe from the Andean coast of South America. The use of machines and fertilizer produced a dramatic increase in farm production.
People was affected because progress in farming made the industrial revolution possible by providing plenty of cheap food for the towns. This revolution occurred first in Britain about 1750-1850. Thousands of families had to move to industrial towns to work in coal mines, iron foundries, shipyards, and textile mills. They had little choice. The small farmers who could not afford the new farming methods received less cash for their produce and so could not pay their rent. They had to leave their farms to live in overcrowded, disease-ridden slums. Instead of families farming together, men now had to work away from home. Even children worked long hours in factories. Other nations soon experienced similar changes.
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