People love lists: the Ten Commandments, the Seven Deadly Sins, and the Four Beatles. But they are fascinated by rankings, which are lists organized according to some measure of value or merit. Who were the most important women in history? The best writers or most influential artists? Our least illustrious presidents? Who’s bigger: John, Paul, George, or Ringo?
This is a book about measuring the “significance” of historical figures. We do not answer these questions as historians might, through a principled assessment of their individual achievements. Instead, we evaluate each person by aggregating the traces of millions of opinions in a rigorous and principled manner. We rank historical figures just as Google ranks web pages, by integrating a diverse set of measurements about their reputation into a single consensus value.
Significance is the result of social and cultural forces acting on the mass of an individual’s achievement.
Significance is related to fame but measures something different. Forgotten U.S. president Chester A. Arthur (1829–1886)  is more historically significant than young pop singer Justin Bieber (1994–) , even though he may have a less devoted following and lower contemporary name recognition. Significance is the result of social and cultural forces acting on the mass of an individual’s achievement. We think you will be impressed by the extent to which our results capture what you think of as “historical significance.” And our computational, data-centric analysis provides new ways to understand and interpret the past.
We will be interested in the concept of people as memes, simple ideas that reproduce when spread from mind to mind. Memes were introduced by Richard Dawkins (1941–)  in his book The Selfish Gene [Dawkins, 1990]. He observed that ideas undergo the same processes of natural selection and modification as that of biological species, and hence can be studied using the same tools of evolutionary theory.
For example, the “teenaged pop star” meme that is Justin Bieber (1994–)  reproduces every time someone reads his Wikipedia page, or he makes news for some performance or gossip-worthy transgression. It weakens whenever a newly grown-up fan removes his poster from the bedroom wall. The Bieber meme will continue to thrive until some future star comes to occupy his particular environmental niche.
Many historical figures reduce to small stories of who they are and why they are known. The meme of Betsy Ross (1752–1836)  as the “woman who first sewed the American flag” is an excellent example. It does not really matter whether she actually did sew the first flag (the evidence isn’t very strong here) but catching this meme is valuable as a cultural reference in American colonial history and the evolution of gender roles.
Thinking about historical figures as memes turns the processes of fame into a legitimate area of study. We can think of people as occupying niches in history, analogous to how species thrive in particular ecological systems. Sometimes cultural niches disappear, along with memories of all those who occupied them. Historical figures are always in danger of being displaced, whenever stronger but analogous memes rise up to replace them.
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