Orca

Orcas demonstrate the most extreme matrilineal social structure among mammals—both sons and daughters remain with their mothers for life. This 'bisexual philopatry' creates multi-generational matrilines where the oldest female leads through accumulated ecological knowledge. The system resembles spotted hyenas in its female-centered structure but differs in that males remain integrated rather than subordinated.

Post-reproductive females continue leading. Orca females often live 30+ years past reproductive age, maintaining leadership through knowledge rather than reproductive activity. This 'grandmother' leadership is rare in mammals and demonstrates that leaders' value can transcend their direct reproductive contribution.

Sons never leave. Unlike most mammals where males disperse, orca males remain with mothers for their entire lives—sometimes 50+ years. Sons mate with females from other pods but always return home. This creates a unique male experience: lifelong integration without reproduction within the natal group.

Pod identity is cultural. Different orca populations have distinct vocalizations, hunting techniques, and prey preferences—cultural traditions transmitted across generations within matrilines. This cultural differentiation creates 'ecotypes' that function almost like separate species despite genetic compatibility.

For organizations, orcas demonstrate that matrilineal structures can include rather than exclude males. Female leadership doesn't require male subordination—males can remain integrated while females lead through knowledge.