What If Extinction Is Not Forever? There Are Ethical, Legal, and Social Ramifi Cations to Be Addressed Jacob S

POLICYFORUM

GENOMICS Although new technologies may make it possible to bring extinct species back to life, What If Extinction Is Not Forever? there are ethical, legal, and social ramifi cations to be addressed Jacob S. Sherkow 1 and Henry T. Greely2

1930s film shows a dog running and jumping inside a fenced enclo- Asure ( 1)—except that the dog has a strange-shaped head, odd stripes, and a rigid tail that can only move side-to-side. The “dog” is actually one of the last thyla- cines, a marsupial predator also called the Tasmanian tiger. The fi lm was taken shortly before humans extinguished the species for- ever. Or did we? Recently, new technolo- gies have made it plausible to try to revive many recently extinct species. Scientists around the world are discussing, and work- ing toward, “de-extinction” (2 ). Currently, three approaches to de-extinc- tion seem most likely to succeed: back- breeding, cloning, and genetic engineer- ing. If the extinct species left closely related descendants, it might be possible to use selective breeding to produce progeny with Tasmanian tiger. By the 1930s, settlers, encouraged by government bounties, had hunted the thylacine to the phenotypes of the extinct species, as the extinction in the wild. Well-preserved specimens could pave a way to bringing it back. auroch project in Europe has been doing since 2008 (3 ). With newly cheap genome the extinct species’ genomic sequence. The high levels of deformity and early death sequencing methods, one might guide back- modifi ed cells could then be used to produce ( 7). The Animal Welfare Act and its institu- breeding with genome sequences from sam- living birds that, genomically, were mainly tional animal care and use committees limit ples of the extinct species. Of course, back- band-tailed pigeon but partially passenger precisely this kind of suffering (8 ). Beyond breeding will only be possible in situations pigeon (5 ). By using targeted replacement physical suffering, some animal advocates where the genetic variations of the extinct of genomic sequence ( 6) across several loci, might oppose de-extinction as they oppose species survive in the descendant species. much of the extinct genome could be recon- zoos—on the grounds that they exploit ani- Cloning provides another possibility. structed within several generations. mals for unimportant human purposes, like Using cryopreserved tissue from the last Neither the back-breeding nor genetic entertainment. known Pyrenean ibex, a Spanish group engineering approaches would yield an ani- Newly de-extinct creatures might prove used somatic cell nuclear transfer (SCNT) mal that had exactly the same genome as excellent vectors for pathogens. An extinct to revive that extinct subspecies. Out of any member of the extinct species for many animal’s genome could also conceivably several hundred efforts, however, only one years, if ever. The cloning approach, in the harbor unrecognized, harmful endogenous fetus survived to term, and it died minutes few cases where viable nuclei are avail- retroviruses. after birth from lung abnormalities (4 ). able, would produce a genomic twin to one If the species either is released or escapes This example highlights two problems with member of the extinct species—but only into the general environment, it might do SCNT: it is neither very safe nor effi cient one. Does one individual (or a set of clones) substantial damage. Even extinct species and will only work if viable cell nuclei are make a “species”? Even if genomic iden- that were not pests in their past environ- available. This will likely be the case in only tity is necessary, is it suffi cient? The revived ments could be today. For example, less than a few very recent extinctions. individuals would not have the same epigen- 200 years ago, billions of passenger pigeons Genetic engineering offers a third etic makeup, microbiome, environment, or migrated each year between the eastern approach. Take an extinct species—say, even “culture” as their extinct predecessors. United States and Canada. Today, those the passenger pigeon—that left suffi cient regions have far more humans, far larger samples to allow high-quality whole- Risks and Objections urban centers, very different agriculture, genome sequencing. DNA in cells from a Objections to bringing back extinct animals and largely transformed ecosystems. The similar living species—perhaps the band- fall into five categories: animal welfare, American chestnut, a main food source for tailed pigeon—could be edited to match health, environment, political, and moral. the passenger pigeon, is now nearly extinct Animals created in the de-extinction in the wild. Even in the same location, the 1Center for Law and the Biosciences, Stanford Law School, process could end up suffering, either as passenger pigeon would today be an alien, Stanford CA 94305, USA. 2Stanford University, Stanford CA a result of the processes used or because and potentially invasive, species—perhaps 94305, USA. of their particular genomic variations. We another starling or even an avian kudzu.

*Corresponding author. [email protected] know, for example, that SCNT can lead to The political risks are considerable, MARKKU MURTO/ART/ALAMY CREDIT:

32 5 APRIL 2013 VOL 340 SCIENCE www.sciencemag.org Published by AAAS POLICYFORUM too. Current protection of endangered and species in whose extinction humans played stantial government expenditure. One might threatened species owes much to the argu- the sole, the leading, or a substantial role? argue that governments fund science proj- ment of irreversibility. If extinctions—par- The last benefi t might be called “wonder,” ects with similarly small practical relevance, ticularly extinctions where tissue samples or, more colloquially “coolness.” This may be but those “cool” projects, like the Mars rov- are readily available—are not forever, pres- the biggest attraction, and possibly the big- ers, present fewer risks and objections. ervation of today’s species may not seem as gest benefi t, of de-extinction. It would surely Second, should de-extinction be cate- important. Also, genetics and, more broadly, be very cool to see a living wooly mammoth. gorically banned? Here the answer seems a modern bioscience, could face a backlash And while this is rarely viewed as a substan- fairly clear “no.” The risks look fairly small if citizens perceive public investments in tial benefit, much of what we do as indi- and probably manageable. If people want to bioscience as being used to revive species viduals—even many aspects of science— devote their own time, money, and efforts to rather than cure human disease. we do because it’s “cool.” the endeavor, the risks to the world do not Finally, some people will complain that, seem to justify complete prohibition. whatever its consequences, de-extinction is Legal Issues Third, should de-extinction be regu- just wrong—it is “playing god,” “reversing We may also need to consider several legal lated? Here, we think the answer is “Yes— natural selection,” or an act of hubris. Oth- issues. First, would a de-extinct species be somewhat.” The animal welfare and envi- ers may argue that we cannot know enough “endangered”? The answer is unclear. In the ronmental concerns are real. They could be about the consequences to re-introduce a United States, the Endangered Species Act mitigated by protective action but only if species. But neither do we know the full provides for listing as “endangered” any the law requires it. Bringing all de-extinc- consequences of its extinction or its con- species “over utilized” for scientifi c pur- tion efforts under something like the Ani- tinuing nonexistence. poses, inadequately protected by current mal Welfare Act and requiring careful envi- regulations, or whose existence is threat- ronmental assessments before any planned Benefi ts ened by other “manmade factors” ( 11)—all releases (as well as approved precautions Like the risks or objections to de-extinc- considerations that would seem to apply to against inadvertent release) do seem appro- tion, we see the benefi ts falling into fi ve cat- a newly revived species. Ironically, inter- priate. Whether other kinds of regulation egories: scientifi c knowledge, technological national organizations typically tie endan- are needed is less clear, although there may advancement, concrete environmental ben- gered status to whether species’ population be some cases, like any attempted revival of efi ts, justice, and “wonder.” These benefi ts has declined—the opposite of the concern extinct hominid species, where special con- are quite similar to the arguments made for about newly revived species ( 12). Uncer- trols, or bans, would be appropriate. preserving currently endangered or threat- tainty about the status of de-extinct species De-extinction is a particularly intrigu- ened species. will affect numerous civil, criminal, and ing application of our increasing control De-extinction could allow scientists the international laws. over life. We think it will happen. The most unique opportunity to study living members Second, could a revived species be pat- interesting and important question is how of previously extinct species (or, at least, ented? This answer also seems unclear. humanity will deal with it. close approximations to those species), pro- The United States and many other coun- viding insights into their functioning and tries allow patents on living organisms (13 ). References and Notes evolution. Some revived species may be Although “products of nature” cannot be 1. Last Tasmanian tiger, thylacine (1933); www.youtube.com/watch?v=6vqCCI1ZF7o. translated into useful products; for exam- patented, is a revived species a “product 2. C. Zimmer, Natl. Geogr. (2013); http://ngm. ple, it is conceivable that new drugs may be of nature” in light of the inevitable differ- nationalgeographic.com/2013/04/species-revival/ derived from extinct plants. ences from its predecessors? Additionally, zimmer-text. De-extinction could lead to techno- the “lost arts doctrine” may allow the pat- 3. The Tauros programme, www.taurosproject.com/. 4. J. Folch et al., Theriogenology 71, 1026 (2009). logical advances. The most likely would enting of previously existing species if they 5. M. Ridley, Wall Street Journal, 2 March 2013, p. C4. be improvements in genetic engineering, have been completely lost to the public ( 14). 6. H. H. Wang et al., Nat. Methods 9, 591 (2012). such as the targeted replacement of large Last, would de-extinction be regulated 7. P. Chavatte-Palmer et al., Placenta 33, (suppl.), S99 (2012). stretches of genomic DNA ( 6). and if so, how? Again, the answer is unclear. 8. 7 U.S.C. § 2131 et seq. Some researchers argue that “re-wild- And even if there were no legal regulation, 9. S. A. Zimov, Science 308, 796 (2005). ing” with existing species, locally extinct in the concerns previously discussed could 10. Pleistocene Park, www.pleistocenepark.ru/en/ particular habitats, can help restore extinct dampen the enthusiasm for de-extinction by background/. 11. 16 U.S.C. § 1533(a)(1)(A). or threatened ecosystems (9 ). The same can some research entities, such as universities. 12. IUCN, IUCN Red List Categories and Criteria (1994); be argued about the restoration of extinct This could drive the efforts toward less con- http://www.iucnredlist.org/technical-documents/ species. The revival of the wooly mammoth trolled, or constrained, enterprises. categories-and-criteria/1994-categories-criteria. as a major grazing animal in the Arctic, for 13. Diamond v. Chakrabarty. 446 U.S. 303 (1980). 14. M. L. Rohrbaugh, AIPLA Q. J. 25, 371 (1997). example, might provide substantial ben- What Should Be Done? efi ts by helping restore an arctic steppe in The answer to the question—What to do Acknowledgments: The authors participated in two work- the place of the less ecologically rich tun- about de-extinction?—depends in part on shops on de-extinction organized by Revive and Restore and dra ( 10). closely defining the question. Consider the National Geographic Society, one in February 2012 (H.G.) and one in October 2012 (H.G. and J.S.). (H.G. was on the Justice is a viscerally attractive argu- three different “bottom-line” questions. planning committee for the second workshop.) We would like ment for de-extinction, at least for species First, should de-extinction be publicly to acknowledge the tremendous contribution the speakers at that humans drove to extinction: We killed funded? This answer seems, to us, “largely those workshops made to our understanding of de-extinction them. We have the power to revive them. We no.” The potential tangible benefits from and the issues it raises. have a duty to do so. But to whom or what de-extinction are too small and the poten- do we owe that duty? Would it apply to all tial objections are too serious to justify sub- 10.1126/science.1236965

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