A growing body of research is pointing to the critical, but unappreciated, role that older animals play in ensuring the survival of wildlife populations. Conservationists say the new findings should lead to policies that protect these elders and the essential knowledge they impart. When drought grips the African savanna, an aging elephant matriarch leads her herd to water she remembers from decades past. In the cold Pacific, an older killer whale guides her pod to elusive salmon, sharing her catch when prey runs thin. And over the open ocean, a seasoned albatross traces vast, invisible routes it has refined over years, returning unerringly to feed its chick.  Across land, sea, and sky, these animals deploy memory, skill, and experience accumulated over long lives. So what happens when such older individuals are selectively removed through hunting, fishing, or other human pressures?…