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Why 1950? Scientists established 1950 as the origin year for the BP scale because it is the year in which calibration curves for carbon-14 or Radiocarbon Dating were established. 1950 also predates atmospheric testing of Nuclear Weapon s, which altered the global balance of Carbon-14 to Carbon-12 . "Before Present" or "Before Physics" This reliable site explains: "An aspect of the introduction of the original NBS National Bureau of Standards standard was that its use implied that A.D. 1950 constitutes 0 B.P. in 14C age computations. The choice of A.D. 1950 was, to a degree, arbitrary; it was adopted to honor the publication of the first 14C dates in December 1949 (Arnold and Libby, 1949). The agreement to use A.D. 1950 as the calendar zero reference year for 14C dating redefined the meaning of B.P. from 'Before Present' to 'Before Physics' (Flint and Devey, 1962)" (Taylor 1987:97–98). Of course, we still say "before present." See also References # AD or BC? Questions at California State University, Los Angeles # 14C-Age Definition # Mook, Willem G and van der Plicht, Johannes (1999). [http://www.radiocarbon.org/Subscribers/Fulltext/v41n3_mook_vdplicht_227.html |