What do lemons and oranges have to do with The Godfather? According to a paper published in the Journal of Economic History last month, a booming citrus industry is to blame for the rise of the Sicilian Mafia during the 19th century.

The demand for lemons and oranges exploded in the 18th century after James Lind, a British Navy surgeon, came to this startling revelation: scurvy could easily be prevented, by eating citrus fruit.

Until this point, lemons had been considered luxury goods, used for decorations and scent but not food. Then, between 1837 and 1850, Sicilian exports of lemon juice rose from 740 barrels to almost 20,707. Land devoted to citrus fruit cultivation in Sicily increased from 7,695 hectares (19,014 acres) in 1853 to 26,840 hectares (66,320 acres) in 1880.

James Lind was the military surgeon who discovered a way to prevent scurvy, a disease that did more harm to the British Navy than the French and Spanish fleets combined. Wikimedia Commons/Hudson, A.E.A

Sicily was one of the few places in Europe with the climatic and geographical sweet spot required to grow lemons, and it proved extremely fruitful (pun intended). “[C]itrus cultivation yielded more than 60 times the average profit per hectare for the rest of the island,” John Dickie, a specialist in Italian history at University College London, explained in his book Cosa Nostra: A History of the Sicilian Mafia.

But lemons were extremely vulnerable to thieves who would sneak into lemon orchards at night to steal the valuable commodity. This is where the mafia (or, rather, the proto-mafia) stepped in. Lemon producers hired men in the "mafie" to protect their precious crops and act as intermediaries between retailers and exporters. From here, they developed into a protection racket and, ultimately, a violent criminal organization we know as the Sicilian Mafia.

Using two different data sets (the Damiani Inquiry (1881-1886) and a report by Cutera, a police officer in Palermo, in 1900), the team revealed a correlation between the intensity of mafia activity and the production of citrus fruit – a parallel matched by no other industry or crop.