In 1965, John Hajnal discovered it divides Europe into two areas characterized by a different levels of nuptiality.
John Hajnal, FBA (b. 26 November 1924 in Darmstadt, then People's State of Hesse, Weimar Germany – d. 30 November 2008 in London), born John Hajnal-Kónyi, was a Hungarian-British academic in the fields of mathematics and economics (statistics).
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