PageRank is a stunningly simple and obvious idea in hindsight, yet it took many years for the concept to spring out of the academic research community and drive the phenomenal popular success of Google. In the research paper, “Stand on the shoulders of giants”, Massimo Franceschet takes a fresh look at predecessors from various other fields, and finds that the historical background of the PageRank algorithm is richer than previously suspected.
The Google founders initially struggled to raise capital and interest from investors. At the time, the prevailing industry attitude towards search came from library and information science, involving semantic text analysis and natural language processing. Needless to say, this didn't work very well, as anyone who used a search engine in the 1990s knows. As Google has proven, the best results come from treating the web as a network and basing the core of the search engine on graph algorithms The natural language processing and text analysis can supplement this, but it’s the structure of links which is essential.
PageRank is patented by Stanford University - yet it is not a wholly unique development. There is a precedent of related research, which dates back much further:
In 1941, Leontief published a paper in which he divides a country’s economy into sectors that both supply and receive resources from each other, although not in equal measure. One important question is: what is the value of each sector when they are so tightly integrated? Leontief’s answer was to develop an iterative method of valuing each sector based on the importance of the sectors that supply it.
This work eventually resulted in a Nobel Prize for Leontief, yet it is not until now that the relationship between his work and PageRank has been fully recognized.
Indeed — as an observer argues in the comments here, long before the modern computer industry, the Brontë sisters elucidated a very similar model, where a aristocrat’s social status was based on the number of their connections to others of high status.