Cambridge University curators said Tuesday that they believe two long-missing notebooks used by Charles Darwin were stolen.
The two so-called Transmutation Notebooks have been missing since 2001, and were originally thought to have been lost somewhere in the university’s archives, according to NBC News.
However, Jessica Gardner, the university librarian and director of library services, said Cambridge has concluded the notebooks were stolen after conducting the “largest search in the library’s history” to no avail.
The university added that the materials may yet be found within the archives during the continued search, which is ongoing and may take up to five more years. The archive contains more than 130 miles of shelved books.
One of the two notebooks contains the naturalist’s famed “Tree of Life” sketch, an early attempt at illustrating his theory of evolution more