According to classicist William Hansen, although satyrs were popular in classical art, they rarely appear in surviving mythological accounts. Different classical sources present conflicting accounts of satyrs' origins. According to a fragment from the Hesiodic "Catalogue of Women", satyrs are sons of the five granddaughters of Phoroneus and therefore siblings of the Oreads and the Kouretes. The satyr Marsyas, however, is described by mythographers as the son of either Olympos or Oiagros. Hansen observes that "there may be more than one way to produce a satyr, as there is to produce a Cyclops or a centaur." The classical Greeks recognized that satyrs obviously could not self-reproduce since there were no female satyrs, but they seem to have been unsure whether satyrs were mortal or immortal.