Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
De-extinction, Authenticity and Wildlife Conservation Doug Campbell Department of Philosophy What is de-extinction? • It is the procedure of recovering extinct genes and pasting them into living organisms. Conservation applications of de-extinction: #1. Restoring genetic health to genetically depauperate species by the recovery and intra-species transfer of extinct genes. Black Footed Ferret Kakapo Conservation applications of de-extinction: #2. Genetic fortification and facilitated evolution of species by inter-species gene transfer (where the donor species might be extinct) American Chestnut (which has been made resistant to Chestnut blight by adding an anti-fungal enzyme from wheat.) Asian elephant, which might be enabled to range up towards the Arctic circle if given few mammoth genes Conservation applications of de-extinction: #3. Restoration of lost ecosystems via the engineering, through inter-species gene transfer, of living proxies for extinct keystone species. Conservation applications of de-extinction: #4. The resurrection of extinct species (i.e., of entire genomes) Passenger Pigeon Pyrenean Ibex Gastric brooding frog Moa Tasmanian tiger Huia Conservation applications of de-extinction: #5. The triaging of endangered species and reversible managed extinction of selected species. Where should we draw the line? Some positions: De-extinction has no legitimate place in conservation at all Increasingly extreme De-extinction of genes is OK The re-engineering of existing species is OK The re-engineering of environments is OK The de-extinction of species is OK No holds barred de-extinction 1. Recovering lost genetic diversity 2. Facilitated adaptation 3. Proxies for keystone species 4. Species deextinction 5. Managed extinction ✗✓ ✗✓ ✗✓ ✗✓ ✗✓ “How to Clone a Mammoth” by Beth Shapiro (2015) • Shapiro is a paleogeneticist at University of California, Santa Cruz. • She defends an intermediate position Shapiro’s position: Increasingly extreme The re-engineering of environments is OK Species de-extinction isn’t. 1. Recovering lost genetic diversity 2. Facilitated adaptation 3. Proxies for keystone species 4. Species deextinction 5. Managed extinction ✓ ✓ ✓ ✗ ✗ My aim: to put pressure on Shapiro’s position, and argue in favor of the conservation-value of species deextinction The de-extinction of species is OK No holds barred de-extinction ? Increasingly extreme The re-engineering of environments is OK Species de-extinction isn’t. 1. Recovering lost genetic diversity 2. Facilitated adaptation 3. Proxies for keystone species 4. Species de✓ extinction 5. Managed ? extinction ✓ ✓ ✓ ✗ ✗ Major Caveats 1. I don’t think we should devote any of our inadequate conservation resources to de-extinction now. – We should just be freezing samples in preparation. 2. I agree that if the idea of species de-extinction were to begin to occupy the thoughts and attention of conservationists, then this would be bad. – It would be a distraction from other far more pressing issues (like present government polices). 3. I don’t think that the techniques of synthetic biology provide any sort of general hi-tech panacea for species extinctions of the past or the future. – De-extinction is only technically plausible for a small subset of extinct species, and even then it will almost always be much more difficult and expensive than preventing a species from going extinct in the first place. Another caveat • If I am right, then there are good reasons to reverse certain historical extinctions. But it remains possible that, although these good reasons exist, they are offset by even stronger reasons not to reverse historical distinctions. 1. Moral hazard. (It will no longer be the case that “extinction is forever”, which will let rapacious developers and industrialists off the hook.) 2. It is a thin edge of a GMO wedge. 3. It might destabilize existing ecosystems. 4. Etc… • Which reasons are strongest—those for making species de-extinct, or those against? • I set this (big!) question aside. Extinct species are gone forever. We will never bring something back that is 100 percent identical—physiologically, genetically, and behaviorally identical—to a species that is no longer alive. (p. 10) It is not important that we cannot bring back a creature that is 100 percent mammoth or 100 percent passanger pigeon. What matters is that—today—we can tweak an elephant cell so that it expresses a mammoth gene. (p. 207) The product of de-extinction won’t be the same thing as the original species… Crucially however, I don’t care that it’s not the same thing as the original... The task ahead is not to make perfect replicas of species that were once alive. First, it is technically not possible to do so and is unlikley ever to be technically possible to do so. Second, there is no compelling reason to make perfect replicas of extinct species. The goal of de-extinction is to restore or revive ecosystems.… We don’t need to create exact replicas of extinct species to achieve this goal. Instead, we can engineer species that are alive today so that they can act as proxies for extinct species. (p. 205) Shapiro’ claims A mammoth will not have to be pure in order to be received as a mammoth. This is a relief, because … while 100 percent mammoth is out of the question, 1 percent mammoth may not be. (p. 130) In my mind, it is ecological resurrection, and not species resurrection, that is the real value of de-extinction. We should think of de-extinction not in terms of which life form we will bring back, but what ecological interactions we would like to see restored. (p. 131) Shapiro’s claims, in my words S1: It is not technically possible, and almost certainly will never become technically possible, to create organisms that are perfect replicas of extinct organisms. S2. In order to resurrect an extinct species, it would be necessary to create organisms that are prefect replicas of extinct organisms. S3. Even if it were possible to resurrect an extinct species (which it isn’t, because of S1 and S2), there would be no compelling conservation-based reason to do so. She is the paleogeneticist, and I am the philosopher: so I defer to her on S1 I will argue for the following claim, which contradicts S1 and S2: C. There are compelling conservation-based reasons to resurrect some species, and these reasons apply even if the resurrected organisms are not perfect replicas of the originals. Plan • First I give two brief arguments that suggest C must be true: C. There are compelling conservation-based reasons to resurrect some species, and these reasons apply even if the resurrected organisms are not perfect replicas of the originals. • Then I attempt to identify the ‘compelling conservation based reasons’ that C mentions. First Argument for C: The clone/extinction thought-experiment Scenario 1 • Stage 1. Goats are produced via cloning, using sheep as the surrogate parents. • Stage 2. All goats except the cloned goats die out. • Stage 3. The only goats now to be found are goats that are the products of cloning. • Are goats now extinct? Surely not. The species lives on, albeit that there maybe telltale signs in the species’ genes that it was cloned. Scenario 2 • Stage 1. Goats go extinct. • Stage 2. New goats are produced via cloning, using sheep as the surrogate parents and stored goat cell samples. • Stage 3. The only goats now to be found are goats that are the products of cloning. • Are goats now extinct? Surely not. This situation differs from scenario 1 only in regards the order in which Stage 1 and Stage 2 occur, and this appears to be irrelevant to whether the species is now extinct. Scenario 1 Scenario 2 Why does the clone/extinction thought experiment suggest that C is true? C. There are compelling conservation-based reasons to resurrect some species, and these reasons apply even if the resurrected organisms are not perfect replicas of the originals. • Answer: – Were we to save goats (or any other species) from extinction in the manner of scenario 1, this would be a major conservation victory. – By the same token, it should be a major conservation victory were we to render goats de-extinct in the manner of scenario 2. » There is apparently no difference between the two scenarios that should make a difference to the conservation value of the outcome. – This is true regardless of whether the cloning process introduces slight changes into the genetics of the goats. Second Argument for C: The facilitated adaptation argument Threatened Asian Elephant “Facilitated adaptation” Asian elephant that is no longer threated A great conservation success!! (According to Shapiro) But Threatened if facilitated Pyrenean evolution can be a Ibex conservation success story, Extinction then so too, by the same Cloningreasoning, can de-extinction (even if the deextinct organisms Slightly aren’t exactly the modified same as their “de-extinct” forebears). Pyrenean Ibex Of no conservation value. (According to Shapiro) The question the rest of the talk will focus on: C. There are compelling conservation-based reasons to resurrect some species, and these reasons apply even if the resurrected organisms are not perfect replicas of the originals. What are these reasons? Case study: the huia The huia appears to be a good candidate for deextinction for several technical reasons 1. Genetic material. There are thousands of museum specimens. 2. Habitat. There are multiple predator free mainland islands and offshore islands to which they could be translocated. 3. Animal husbandry. Huia were easily kept in captivity. 4. Containment. Huia were not capable of sustained flight. 5. Founder group size. They formed life-long pairs, which means only a relatively small founder group is needed. 6. Smallish genome. 7. Technique. The primordial germ cell transfer method can be used instead of cloning with birds. It is much more efficient. A drawer full of huia at Auckland museum: What compelling reasons are there to make the huia de-extinct? 1. We owe it as a debt of restorative justice to the huia themselves. – But we can’t owe a debt of restorative justice to a species, since species are not intentional agents (Sandler 2013) – Nor we can we owe such a debt to individual huia, since there presently are none. 2. We should do it to mitigate human guilt. – But a child isn’t guilty for the crimes of her parents. 3. We should do it to turn back the clock and right our ancestors’ wrongs. – But it is not clear that there is in general anything morally ‘wrong’ in one species causing the extinction of another. 4. We should do it to recover things of value that were lost when the huia went extinct. Possible sources of value that justify the conservation of species Seldom obtains, and • Anthropocentric values when it does it is philosophically uninteresting – Commodity/economic value (directly money related) – Amenity value (improves human lives in a way Controversial that is not directly money related.) – Moral value (e.g., as an aid to our being better Hard to argue for in the case of a species people.) that is already extinct – Option value: the value we should place on a species based on our ignorance of ways in which it might turn out to be directly valuable. • Intrinsic values – The intrinsic value of individual plants/animals Controversial – The intrinsic value of ecosystems Controversial Bryan Norton (2003, p. 470) on why arguments from amenity value are most effective “To those who are uncommitted to environmentalism … appeals to intrinsic values in nature and to the rights of nonhumans appear ‘soft’, ‘subjective’, and ‘speculative’. We can accept this fact of political life without agreeing with it. Whatever the answer to the intellectual question of whether nonhuman species have intrinsic value, ... human oriented reasons carry more weight in current policy debates” Why was the huia of amenity value? 1. It was of enormous aesthetic value to human beings enjoying the NZ bush. 2. It was of enormous cultural value to the Māori. The cultural value of the huia • It was the most tapu of all creatures for the Māori. • Its extinction was a devastating cultural loss for the Ngati Huia. The aesthetic amenity value of the huia • It was a very charismatic animal. – Extreme sexual dimorphism (most extreme of any bird in the world) – Beautiful appearance. – Very attractive song. – Very confiding. – Monogamous breeding pairs that fed cooperatively. The huia is a close relative of the kokako The huia’s demise • The tale of its demise was especially tragic. • Buller: – “While we were looking at and admiring this little picture of bird-life, a pair of Huia, without uttering a sound, appeared in a tree overhead, and as they were caressing each other with their beautiful bills, a charge of No. 6 brought them both to the ground together. The incident was rather touching and I felt almost glad that the shot was not mine, although by no means loth to appropriate 2 fine specimens.” Buller The huia’s demise • The 1902 visit of the Duke of York to Rotorua • A plausible claim: – the extinction of the huia was an act of barbaric environmental vandalism, that—quite apart from the fatal harm it did to the huia themselves—also causes ongoing harm to us and to our decedents. – How has the extinction of the huia harmed us? • By making the New Zealand bush a lot less wonderful than it used to be. • By making our actual experiences less rich and (for those of us who wouldn’t have gone into the bush to see them anyway) by imposing restrictions on what we could choose to experience. • By making the world less diverse, varied and interesting (this goes for extinction generally). • Similarly, we would be harmed were someone to set about making, say, the tui, or the bellbird, or the kokako extinct. An analogy with the destruction of natural, historical and cultural landmarks and artifacts • I will now focus in particular on the aesthetic amenity value of the huia. • My claim will be that there is at least one compelling conservation-based reason to resurrect the huia: namely, to recover the aesthetic amenity value that was lost when it went extinct. Is it possible to recover the huia’s aesthetic amenity value? A Picasso Lots of aesthetic value It is destroyed A replica is made Not much aesthetic value Ancestral huia Lots of aesthetic value Raven Information about superficial appearance Not much aesthetic value Superficial huia DNA Eggs Lots of aesthetic value Huia from old eggs ?? The relationship R • Let us say that the ancestral huia and the new birds stand in relation R to each other iff the aesthetic value possessed by the ancestral huia is also possessed by the new birds. Ancestral huia Lots of aesthetic value Raven Information about superficial appearance not R Not much aesthetic value Superficial huia DNA R ? Eggs Lots of aesthetic value Huia from old eggs ?? What is relation R? • A pretty obvious, biologically unsophisticated hypothesis: – Relation R obtains iff both: 1. The new birds are descended from the ancestral huia; and 2. The new birds share (essentially) the same form, physiology and behaviour as the ancestral huia. • Note that neither condition 1 nor 2 appears to be sufficient by itself. A more biologically sophisticated hypothesis: • Relation R obtains iff both: 1. 2. The genes of the new birds have been inherited in a counterfactual supporting way from the ancestral huia; and The genes of the new birds are being phenotypically expressed as they were in the ancestral huia. • This implies that Relation R can obtain to different degrees depending on how many genes have been inherited and are being expressed correctly. • It also submits to an adaptivist reading: – Relation R obtains to the degree that the traits of the new birds are explained by natural selection operating on the population of ancestral birds. Junk DNA and hybrids • Junk DNA case: the new birds have kokako junk DNA, but all their phenotypically expressed genes are copied from the ancestral huia. • Hybrid case: the new birds have kokako junk DNA, and also have some kokako genes. But most of their genes are huia genes, and the kokako genes do not interfere with the phenotypic expression of the huia genes or vice versa (i.e., the two sets of genes ‘play well’ with each other.) • In both these cases relation R will obtain to a degree, and as a result some but not all of the aesthetic value of the ancestral huia will have been be recovered by creating the new birds. • Presumably a law of diminishing returns will operate. Conclusion • Shapiro’s claims: – S1: It is not technically possible, and almost certainly will never become technically possible, to create organisms that are perfect replicas of extinct organisms. – S2. In order to resurrect an extinct species, it would be necessary to create organisms that are prefect replicas of extinct organisms. – S3. Even if it were possible to resurrect an extinct species (which it isn’t, because of S1 and S2), there would be no compelling conservation-based reason to do so. • My claim (which contradicts S1 and S2): – C: There are compelling conservation-based reasons to resurrect some species, and these reasons apply even if the resurrected organisms are not perfect replicas of the originals. • Evidence: – The cloning/extinction thought experiment. – The facilitated adaptaton argument. • What are the compelling conservation based reasons in question? – The recovery of lost aesthetic amenity values (among others). – These can be recovered provided my hypothesis about relation R is correct. – The burden is on the opponent to show why this hypothesis is inadequate.