How progressive greying was proven

FEATHER

THE earliest published record I could find referring to the loss of pigment over time in birds was from 1853, by an Austrian biologist called Frauenfeld. He or for “old age”, and “chromatism” from the Greek for “colour”.) Although Frauenfeld (1853) had already noticed that normally coloured birds can lose the pigment in their plumage later in life, this phenomenon remained undocumented for another century, as it was unappreciated by many later workers.