Anthropologist Alan Macfarlane of Cambridge University has an intriguing theory about the origins of the Industrial Revolution. You can hear about it in the course of these lectures on population growth.
But what does that have to do with tea?
Macfarlane notes that one of the big puzzles for modern demographers is why the population of England began to expand rapidly in the second half of the 18th century, well before the agricultural revolution improved the common person’s diet and before the Industrial Revolution made the British wealthier. When the population began to burgeon, antibiotics had not yet been invented, and public health activists had not yet begun to improve the water supply and sewage disposal.
Observers writing in the late 18th century, including Malthus, did note that fewer people were dying of intestinal diseases. The late 18th century was also the beginning of the great English love affair with tea when tea had become affordable and was imported into England in great quantities. And in order to prepare tea, people had to boil their water, a process which killed many bacteria. Moreover, Macfarlane contends that tea contains chemicals which kill microbes, even when the liquid is cold.
Thus a rapidly increasing population which couldn’t find employment in the countryside was pouring into the cities, just in time to staff the early factories of the Industrial Revolution.