A bison in Yellowstone, descended from a small number of genetically-pure survivors that found refuge in the national park following the annihilation of 30 million in the American West.  What's the value of keeping a species alive beyond economics and ledger sheets?  Photo courtesy Jacob W. Frank/NPS
A bison in Yellowstone, descended from a small number of genetically-pure survivors that found refuge in the national park following the annihilation of 30 million in the American West. What's the value of keeping a species alive beyond economics and ledger sheets? Photo courtesy Jacob W. Frank/NPS