atavistic (adj.)

1833, in biology, "reversion by influence of heredity to ancestral characteristics, resemblance of a given organism to some remote ancestor, return to an early or original type," from French atavisme, attested by 1820s, said to have been coined by French botanist Antoine-Nicolas Duchesne, from Latin atavus "ancestor, forefather," from at- perhaps here meaning "beyond" + avus "grandfather" (from PIE *awo- "adult male relative other than the father;" see uncle).

adjectival word-forming element, from French -istique or directly from Latin -isticus, from Greek -istikos, a compound of the adjectival suffix -ikos (see -ic) + the noun suffix -istes (see -ist).