This is intriguing, but not necessarily surprising. People have been rediscovering calculus for ages.
It does bring to mind the question of what /else/ has been lost to the ages, and how far ahead we would be right now without it. Like Ramujan, brilliance is not limited to the wealthy; just that the application of it often is (the wealthy can afford the time/energy to become educated, etc).
The most interesting thing that has been lost to history, would properly be some of the works of Aristotle, as the western worlds understanding of science was bootstrapped from his works during the reformation.
I recall discussing in a class that Archimedes was known to have approximated integrals and may have even known enough about limits to have derived integral calculus.
Article subtitle is "A long-lost text by the ancient Greek mathematician shows that he had begun to discover the principles of calculus." This has been known for several decades, ever since Heiberg transcribed some of the text (I don't know how much), per the article.
I refer you to The History of the Calculus and Its Conceptual Development, a 1949 book by Carl B. Boyer, reprinted by Dover Publications [ISBN 0486605094]. Boyer writes several pages about Archimedes' method of exhaustion, notions of the infinitesimal, and so on. The main footnote reads:
For the works of Archimedes in general, see Heiberg, Archimedes opera omnia and T. L. Heath, The Works of Archimedes. For Archimedes' Method, see T. L. Heath, The Method of Archimedes, Recently Discovered by Heiberg; Heiberg and Zeuthen, "Eine neue Schrift des Archimedes"; and Smith, "A Newly Discovered Treatise of Archimedes."
Boyer is clearly using Heiberg's work on the Archimedes Palimpsest.
It does bring to mind the question of what /else/ has been lost to the ages, and how far ahead we would be right now without it. Like Ramujan, brilliance is not limited to the wealthy; just that the application of it often is (the wealthy can afford the time/energy to become educated, etc).