"To smoke or not to smoke" was not the question. Something had been smoked in the pipe bowls and stems unearthed from William Shakespeare' garden in Stratford-upon-Avon; the question was what. Researchers in South Africa now have gas chromatography mass spectrometry to thank for their answer. A piece in the Conversation based on the report published in the South African Journal of Science explains the "technique is very sensitive to residues that can be preserved in pipes even if they had been smoked 400 years ago." Eight of the 24 pipe-fragment samples tested were shown to contain cannabis; another had evidence of nicotine, and two more "evidence for Peruvian cocaine from coca leaves."
Of those, only four of the cannabis samples were from Shakespeare's garden; the others were from the Stratford-upon-Avon area. Study author Francis Thackeray writes that the research establishes that a wide range of plants were smoked in the area during the early 17th century, and he leans on Shakespeare's own words to try to draw connections. Thackeray references Sonnet 76, which refers to "invention in a noted weed"; he interprets weed as cannabis and invention as writing. As for whether we can conclude that Shakespeare got high, Thackeray writes "one can well imagine" it. (In April, Texas researchers reported another Shakespeare find.)