Does radio-carbon dating disprove evolution?

Hi Percy,
One quick correction to your calculation. Isotopic deviations are reported as parts per thousand deviation from a standard. So a deviation of 25 parts per thousand actually corresponds to:
25 = 1000*{(¹⁵N/¹⁴N)_sample - (¹⁵N/¹⁴N)_standard}/(¹⁵N/¹⁴N)_standardwhich, when you calculate through, gives an enrichment of ¹⁵N of 0.01%, to a total abundance of 0.376% ¹⁵N.This is mainly being nitpicky, but illustrates the point you make even moreso than before.¹⁵N levels of 2% have been found in some interstellar grain material, but they're exceedingly rare.