The way some scientists have been talking over the past few months, humans could one day be hiking around the forest and run into a Neanderthal hunting a woolly mammoth as synthetic biologists have been kicking the tires on reviving long-extinct species.
While much time has been spent discussing how it would be done, what species would make viable candidates for "de-extinction" and whether or not it would be ethical to revive a species, there has been little talk about how species would be reintroduced into the wild.
But environmentalists are increasingly seeing genetic engineering as a possible solution to some of the problems they are seeing. When species conservation efforts fail, some see resurrection as the next best thing.
"Some of my colleagues think it should be called resurrection ecology, but the word conservation itself has no intrinsic meaning that has remained the same throughout the course of its use," says Kent Redford, a conservational biologist who is helping to organize a conference in London next week to discuss the potential benefits and consequences of synthetic biology. "I'm not a traditionalist who believes there's only one thing called conservation."
At a de-extinction event hosted at the National Geographic Museum in Washington, D.C. last month, speakers suggested more than 25 plants and animals that would make good "potentially revivable species," including the dodo, the woolly mammoth, mastodon and saber-toothed cat. Candidates should be judged on whether their original habitat is intact or restorable, whether the extinction was recent and whether the species is "iconic, beloved [or] missed."
Scientists also think species should be considered for de-extinction if "rewilding the species [is] workable for the habitat." That's one of the questions Redford and other conservationists say is most important. If an ecosystem has significantly changed since a species went extinct, a reintroduced species could wreak havoc on existing species, creating "invasive species from the past," Redford says.
Redford suggests that scientists can use "bio domes"—self-contained mini ecosystems—to judge how a resurrected species would interact with existing ones. If species are reintroduced under "extremely controlled conditions," scientists can predict whether or not it's safe to reintroduce the species to the larger environment.
While cloning and de-extinction gets the most attention from the public, synthetic biologists are quick to point out that there are many other uses of DNA engineering that don't involve cloning. They are working on technology that would allow bacteria to create biofuels or synthetic versions of naturally-occurring substances such as palm oil, a substance used in cooking, plastics and cosmetics. Redford says palm farms have been a "major driver of deforestation" in Southeast Asia, where large swaths of forests have been cleared to grow the plants. He says that bacteria farms that create palm oil could take up much less space and allow the forest there to be revitalized.
Redford says the idea of de-extinction raises public awareness of synthetic biology, so they may be more receptive to its other uses.
"The issue of restoring extinct species is a very small part of the conversation that needs to take place. But it serves as a strange attractor because it piques people's imaginations," he says. "It has the ability to give hope to people, to let them know that we are capable of the human ingenuity to make things better."
Some synthetic biologists disagree. Jay Keasling, director of the Synthetic Biology Engineering Research Center at the University of California, Berkeley, says synthetic biologists have to be "measured about what [they] say in the media" and that people will be "up in arms" if scientists start discussing cloning Neanderthals.
"I think as scientists we owe it to the public to be careful about what we talk about," he says. "There's a lot of things we can do now that will really benefit people and solve enormous problems."