How do llamas and alpacas adapt to life in the Andes?

Llamas and alpacas are South American camelids that evolved in the high Andes, where oxygen is lower and temperatures can swing sharply between day and night. Their bodies are well suited to efficient oxygen use at altitude, and their woolly coats help insulate them from cold mountain weather. They graze on tough highland vegetation and can travel across rough terrain with relatively little water compared with many livestock species. For centuries, Andean people have relied on them for transport, fiber, and meat. Their adaptation to mountain life makes them important animals in both ecology and culture.