gerh₂-
“to grow old, to mature”age, ripen, mature
Root for aging, yielding Greek geron (old man), English gerontology, crane (gray bird).
Discussion
The PIE root *gerh₂- (to grow old, to mature, to ripen) produced vocabulary for ageing and its social consequences across the major branches. The base root complements the derived *ǵerH-ont- ("the old one, elder") already treated separately.
Latin grānum (grain — the ripened seed, that which has matured) may connect through the concept of the fully grown/ripened product, though this etymology is debated. More securely, the Greek gérōn (old man) and géras (honour due to elders) descend from this root — see the full treatment at *ǵerH-ont-.
Sanskrit járati ("he grows old") and járas- ("old age") preserve the verbal sense directly. The Vedic concept of old age as both decline and accumulated authority mirrors the Greek géras — aging confers both weakness and privilege.
The root connects to *h₂el- (to grow, to nourish) as part of the PIE vocabulary of biological development. Where *h₂el- covered growth in general (young → adult), *gerh₂- specifically covered the final phase: maturation into old age. The PIE speakers apparently distinguished growing UP from growing OLD — two phases of the same biological process with different social meanings.
Notes
Pokorny 390-391. English crane (gray bird), gerontology.