Our Expert Voices conversation on de-extinction.

Without ecology, the genetic resurrection of extinct species could be little more than an interesting spectacle. Every organism plays a part in maintaining ecosystems (e.g. seed dispersal, predation), and the loss of species can alter ecosystem function.

Three guidelines to maximize the benefit of de-extinction:

1. Target ecologically unique species: Energy is better spent attempting to bring back species that held unique positions in their ecosystem, rather than species whose roles were similar to other species. Example: the Christmas Island pipistrelle, which was the only insectivorous bat on its island.
2. Focus on recent extinctions: The more recent the better. Ecosystems can change drastically over time, making function difficult to recover. The woolly mammoth, a proposed candidate for de-extinction, likely has been extinct too long to be placed back into current ecosystems.
3. Ensure recovery of meaningful abundance: Without enough individuals in an ecosystem, a species won't have much impact. Barriers to restoring abundance include climate, disease, policy, and human-animal conflict. The conflicts caused by massive passenger pigeon flocks could be a barrier to restoration of this species.

Bottom line: Ultimately, de-extinction should aim to restore lost ecological function by re-creating species' ecology as well as biology.

Other voices in the conversation: Joseph Bennett, biologist, Carleton University: Keep animals from going extinct in the first place Ben J. Novak, biologist, The Great Passenger Pigeon Comeback: De-extinction is like any other conservation program Alejandro Camacho, legal scholar, University of California, Irvine: Wildlife laws aren't ready for the return of extinct species John Hawks, paleoanthropologist, University of Wisconsin-Madison: Bringing back Neanderthals