Back in the 1940s, the early IT pioneer Claude Shannon fell in love with a computer called Betty, and no one raised an eyebrow. At the time, “computer” was simply the term for a person who performed routine calculations for technical or scientific purposes. Seventy years later, digital processors do all that work and more, and the only “human computers” are mathematical whizzes who can occasionally match the digital processors’ feats. “We imitate our old imitators,” writes Brian Christian in his absorbing “The Most Human Human.”…