Elephants, lions, cheetahs and camels could one day roam the western US under a proposal to recreate North American landscapes as they existed more than 13,000 years ago, when humans first encountered them. The plan, proposed in a commentary in Nature and co-authored by 13 ecologists and conservation biologists, would help enrich a North American ecosystem that was left almost devoid of large mammals at the end of the Pleistocene period. It would also help preserve wildlife that faces the threat of extinction in Africa and Asia. Between 50,000 and 10,000 years ago, 97 of 150 genera of large mammals...
