Wolves

Gray wolves (Canis lupus) were once the most widely distributed land mammal on Earth, ranging across the Northern Hemisphere from tundra to desert. They hunt in coordinated packs, reading each other's signals with remarkable precision. Wolves domesticated themselves — early wolves that tolerated humans were fed, gradually selecting for tameness — giving rise to domestic dogs approximately 15,000–40,000 years ago. Wolf reintroduction to Yellowstone (1995) triggered a 'trophic cascade' of ecological changes: wolves hunted elk, which moved to different areas, allowing riverside vegetation to recover, which changed river courses and reduced erosion. This demonstrated that apex predators structure entire ecosystems. Wolves were hunted to near-extinction across Europe and North America in the 19th–20th centuries; conservation efforts have partially restored populations.