As tribes grew into cities, and cities in a globalized world, the need for privacy likewise expanded from keeping secrets from family members to keeping secrets from neighboring strangers and multinational corporations. At each expanding interval, humans were faced with both the capacity for privacy and incentive to reveal information.

We know that the technological capacity for privacy developed along with the mathematical prowess of the Ancient Greeks, who used their sophisticated understanding of geometry to design houses that maximized light exposure, while minimizing public views from the street. After Greece collapsed, the Romans happily borrowed the Greek's philosophy, but not their penchant for privacy. "Think of Ancient Rome as a giant campground,” writes Angela Alberto in A Day in the Life of Ancient Rome. Even the Roman rich, who could afford larger houses, ceded their privacy. It was a cultural expectation that the Roman aristocracy would open up their homes to events. The famed "peristyle" open-architecture of Roman mansions turned their private dwellings into a constant museum tour.

"Great fortune has this characteristic, that it allows nothing to be concealed, nothing hidden; it opens up the homes of princes, and not only that but their bedrooms and intimate retreats, and it opens up and exposes to talk all the arcane secrets," complained Pliny the Younger, a Roman author who was alive in the first century A.D., according to a translation of his letters by Andrew Wallace-Hadrill, an honorary Roman Studies professor at Cambridge.

The lower socioeconomic class of western society didn't really even get the chance at privacy within the home until architects started building houses with internal walls around the 15th century. And, to be sure, it wasn't primarily motivated because medieval Europeans wanted privacy. Internal walls were designed, in part, to keep the nasty smoke from central fire pits from choking the house guests. “There was no classical or medieval latin word equivalent to ‘privacy.’ Privatio meant ‘a taking away,’” wrote Georges Duby, author of the epic five-volume set, A History Of Private Life.

But perhaps what humans want most today is information privacy. The idea of recorded information is relatively new. Mass literacy is only a few hundred years old. And, the technology to transmit ideas to foreign regions is even newer. But we know how America reacts when information technologies are introduced.

By the 18th century, America had grown accustomed to some information privacy. The pony express was delivering mail across the great plains in opaque folds of paper, free from the prying eyes of government spies and nosy neighbors. Then, the postcard was introduced. Cheaper and quicker, they were an instant success. In 1908, the Post Office had sent almost 7.5 postcards for every living American (670 million).