As homo sapiens has emerged as the dominant species on Planet Earth, it has often been at the expense of other species.
Extinction is a natural part of evolution, but as civilisation and industrialisation has gathered pace, so has the extinction rate. And it is not just large, lumbering animals requiring vast tracts of uncultivated land. The passenger pigeon, for instance, used to travel across the US in flocks of billions of animals when Europeans first settled America. But after decades of increasingly mechanised hunting, the last one died in 1919.
Stewart Brand is a natural history futurist who believes mankind is on the brink of helping some of them get a second chance. Here he tells BBC Future how we might do it.