In 1966, famed science communicator Carl Sagan and his Soviet colleague Iosif Shklovsky released a book titled Intelligent Life in the Universe. This was an English-language version of an earlier work by Shklovksy (Universe, Life, Intelligence) that was published in 1962 in the USSR. The book remains one of the most highly-influential books on the subject of extraterrestrial intelligence and the search for its existence.
In Chapter Thirty-Three, "Possible Consequences of Direct Contact," they claim that scientists should take the possibility that extraterrestrials have visited Earth in the past seriously. They further suggested that evidence of past contact could be preserved in the folklore and mythological traditions of various cultures.
As an example, Sagan and Shklovsky point to an account of the contact made between the Tlingit people of the Pacific Northwest and the La Perouse French expedition in 1786. This event was recorded a century later by anthropologist G.T. Emmons during one of his many visits to the area.
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