https://www.snopes.com/fact-check/gone-blonde/

Evidently these things or things very like them have been published (here and elsewhere) since at least the time of the Civil War. This quote is said to be from an article dated 1890:

The girl with the golden tresses is doomed, and within six hundred years blondes will be extinct. The fate of the blonde was foretold today by Major C. E. Woodruff in a lecture at the Association for Advancement of Science at Columbia university. The major said the blondes were on the toboggan and were scheduled to disappear in six centuries. The gallant major said her peroxide sister might endure, but the real twenty-two karat blonde would be only known in history in future ages. Major Woodruff said science might discover some method of controlling the color of hair.

19 October 1890   (p. 22).    Flag of Our Union.   “Golden Hair.”

Well…Wikipedia only lists a starting date for that paper and mentions publishers through 1871. Library of Congress has only: The Flag of Our Union (Boston [Mass.]) 1846-1870…hm, how weird did it get?

The oldest reference in the Snopes article is dated 26 August 1865   (p. 536).    The Marion Daily Star.   “Blondes Doomed to Vanish from Earth.” The Marion Daily Star, founded 1877, once owned and published by Warren G. Harding, is presently called The Marion Star and headquartered in Marion, Ohio. Is it me or is there something extremely screwy with these dates?