Laudator Temporis Acti

Concerning the Hyperboreans, Pindar, Pythian Odes 10.41-42 (tr. Anthony Verity) says that "disease has no place among that holy people, nor ruinous old age" (νόσοι δ' οὔτε γῆρας οὐλόμενον κέκραται / ἱερᾷ γενεᾷ). There was no ruinous old age because the Hyperboreans killed everyone at age 60. See Hellanicus (Fragmenta der Griechischen Historiker 4 F 187b Jacoby), preserved in Clement of Alexandria, Stromateis 1.72.2 (tr. John Ferguson):

Hellanicus says that the Hyperboreans live beyond the Rhipaean mountains. They learn justice, and eat no meat but live on berries. They take their sexagenarians outside the gates and eliminate them.

τοὺς δὲ Ὑπερβορέους Ἑλλάνικος ὑπὲρ τὰ Ῥίπαια ὄρη οἰκεῖν ἱστορεῖ, διδάσκεσθαι δὲ αὐτοὺς δικαιοσύνην μὴ κρεοφαγοῦντας, ἀλλ´ ἀκροδρύοις χρωμένους. τοὺς ἑξηκονταετεῖς οὗτοι ἔξω πυλῶν ἄγοντες ἀφανίζουσιν.

Pliny the Elder and Pomponius Mela, on the other hand, say that Hyperboreans on the verge of old age died voluntarily.

Pliny, Natural History 4.12.89 (tr. H. Rackham):

Death comes to them only when, owing to satiety of life, after holding a banquet and anointing their old age with luxury, they leap from a certain rock into the sea: this mode of burial is the most blissful.

mors non nisi satietate vitae epulatis delibutoque senio luxu e quadam rupe in mare salientibus; hoc genus sepulturae beatissimum.

Pomponius Mela 3.5.37 (tr. F.E. Romer):

The Hyperboreans inhabit groves and forests, and when a sense of having been satisfied by life (rather than boredom) has gripped them, they cheerfully wreathe themselves in flowers and actually throw themselves into the sea from a particular cliff. For them that is the finest death ritual.

habitant lucos silvasque, et ubi eos vivendi satietas magis quam taedium cepit, hilares, redimiti sertis semet ipsi in pelagus ex certa rupe praecipites dant. id eis funus eximium est.

Related post: Senicide, Part I.