In the movie Jurassic Park (1993), ambitious scientists and their patron, John Hammond, populate an island with living dinosaurs as part of a theme park attraction. The scientists accomplish this by extracting dinosaur blood from the preserved bodies of mosquitos and reconstructing dinosaur genomes. While the film takes some liberties (to say the least), there is such a concept as "de-extinction," and there may come a day when de-extinction transcends fiction.
Techniques such as SCNT (somatic cell nuclear transfer) have already allowed scientists to clone extant (living) mammals, the first being Dolly the sheep back in 1996. In 2003, scientists went a step further by cloning a Pyrenean ibex, a subspecies of Spanish ibex that had gone extinct a few years earlier. Sadly, the cloned animal died shortly after birth.
When it comes to de-extinction, scientists are not only asking "how"; they're also asking "why." As Jurassic Park fans know, de-extinction didn't work out so well for Hammond and his scientists, many of whom were motivated by greed. Hammond's dinosaurs became the ultimate invasive species—they were living in a time and place in which they were not native—and this was to the detriment of all.
While scientists admit de-extinction may be possible someday, the biological resurrection of dinosaurs seems to be off the table, at least for now. Because DNA breaks down over time, beginning at an animal's time of death, dinosaur DNA may be too old and fragmented to reconstruct. However, this is less of a hurdle for more recently extinct species, such as the Tasmanian tiger, the passenger pigeon, and even the woolly mammoth.
The gastric-brooding frog, which went extinct in the 1980s, is another potential candidate for de-extinction. As part of the ongoing Lazarus Project, researchers are working toward reviving this unique Australian frog, which brooded young in its stomach and gave birth through its mouth.
Meanwhile, Earth may be entering its sixth mass extinction event, this time brought on by humans. Could de-extinction somehow right the wrongs of our recent ancestors who pushed species like the dodo and the Stellar's sea cow to extinction?
The ethics of de-extinction are still up for debate. On one hand, it could potentially bring animals back that played an important role in their ecosystems. This could, in theory, improve biodiversity. On the other hand, de-extinction might distract from efforts to conserve species that are still living and in need of our help.
If species were brought back from extinction, they would need to be very carefully re-introduced into the environment. In many cases, the environment in which an extinct species lived no longer exists as it once did. Therefore, we'd need to not only figure out how to bring species back, but also avoid placing them in situations that would lead to their re-extinction. (For more on this discussion, read A mammoth undertaking: Can de-extinction be ecologically responsible?)
From cave lions and giant ground sloths to elephant birds and megalodon sharks, some truly incredible species are gone forever. The idea that science could someday recreate what once was—just like in the fictional Jurassic Park—is a tantalizing idea that remains rife with ethical questions. What do you think? Is extinction forever? Maybe, but maybe not.