Since 1999, the Lazarus Project, directed by Mike Archer of the University of New South Wales, has tried to revive the genome of the Australian frog Rheobatrachus silus, which went extinct in 1983. They have at long last succeeded — somewhat. Before they went extinct, R. silus frogs were best known for their unusual pregnancies: females ingested their eggs, brooded their young in their stomachs, and gave birth to them through their mouths. Scientists chose this frog because it was easy to find a related species, the Mixophyes fasciolatus, in which to insert DNA material. The cloning method involved implanting a “dead” cell nucleus from an R. silus into a fresh M. fasciolatus egg whose DNA had been deactivated by UV light. Some of these treated eggs grew to the early embryo stage; the longest that any of the embryos survived was three days — but genetic tests confirmed that the dividing cells contained genetic material from the extinct frog.
Various methods to clone an extinct species are possible — none of them so far wholly successful. The last attempt before R. silus centered on the Pyrenean ibex, extinct since 2000. (The efforts of the Spanish team behind the research resulted in a viable embyro; it died, however, immediately after its birth due to lung malfunction.) Most scientists who have attempted to resurrect extinct species have used a full intact cell from the species. Very often, as in the case of dinosaur fossils so far, the DNA in the preserved cells is broken. If cloning works, it results in an embryo that must be implanted in a closely related species to serve as a surrogate mother.With R. Silus, chunks of the extinct species’ DNA was substituted into the existing DNA of the extinct species’ cells in such a way to allow replication. The new animal would have enough of the extinct species’ DNA to resemble it. Scientists at the University of Stanford also believe they can backbreed. In the cases of some species, enough DNA exists, these scientists believe, that if certain animals are bred while selecting for offspring with more and more of the desired animal’s DNA, the emerging offspring would closely resemble the extinct animal.
Bringing back species summons up ethical and practical concerns that should be balanced against what the “resurrected” animals can tell us about our planet and even our own biology. Scientists like Stewart Brand, environmentalist and founder of the think tank The Long Now Foundation, believe that resurrecting extinct species would increase our knowledge of science, and others, such as the group Revive and Restore (currently attempting to bring back the passenger pigeon) believe that the effort would right past human wrongs. Other scientists, such as paleontologist Michael Archer, believe that resurrecting species will have help us learn to preserve biodiversity, to restore diminished ecosystems, and to prevent future extinctions. Opponents of resurrection argue that our changed environment may not be able to sustain returned species and that government and private funds should be going into protecting endangered species instead. This debate will continue: private research groups will try to resurrect species, and if there is a breakthrough, the government can be counted on to step in and regulate.