Abstract:
A group of conservation biologists recently proposed to populate western North America
with African and Asian megafauna, including lions, elephants, cheetahs, and camels, to
create a facsimile of a species assemblage that disappeared from the continent some
13,000 years ago. The goals of this program, known as ‘‘Pleistocene re-wilding’’, are to
restore some of the evolutionary and ecological potential that was lost from North America
during the Pleistocene extinctions, and help prevent the extinction of selected African and
Asian mammals. Pleistocene re-wilders justify this conservation strategy on ethical and
aesthetic grounds, arguing that humans have a moral responsibility to make amends for
overexploitation by our ancestors. They believe that the flora of many North American terrestrial
ecosystems has gone basically unchanged since the end of the Pleistocene, so
re-wilding would help restore evolutionary and ecological potential and improve ecosystem
functioning. This paper discusses some of the pros and cons of this proposal, including
the ethical, aesthetic, ecological, and evolutionary issues, assesses its potential economic
and political impacts on other conservation practices, both in North America and elsewhere,
and reviews the realities of large mammal reintroductions. It is concluded that
Pleistocene re-wilding with exotic species will not restore the evolutionary or ecological
potential of native North American species nor extinct Pleistocene megafauna and their
ancient ecosystems, but may instead jeopardize indigenous species and North American
ecosystems. Resources would be better spent on preserving threatened organisms in their
native habitats and reintroducing them to places in their historical ranges from which they
were only recently extirpated.
