Extinction Is Forever?

I was watching yet another presentation about the possibility of reviving extinct life forms (http://www.ted.com/talks/hendrik_poinar_bring_back_the_woolly_mammoth.html). Now that we appear to have the technology, at least in theory, to extract DNA from long dead animals and place it in currently extant species there seem to be more and more articles about how terrific it would be to bring them back from oblivion. This particular talk concerned reviving the woolly mammoth but I have seen similar ones suggesting restoring the thylacine, or Tasmanian tiger, to life.

Technology has been astonishingly uninspiring when it comes to saving the world’s current long list of endangered species. While there have been a few cases of successful artificial insemination or an embryo from an endangered species being reared to term by a surrogate (http://www.scientificamerican.com/article.cfm?id=cloning-endangered-animals), the majority of effective conservation programs have relied on natural breeding to create enough animals to sustain a population, along with addressing the causes why the species became endangered in the first place. There are too many unknowns when it comes to artificially breeding wild animals: how best to harvest the eggs and collect sperm, how to freeze gametes and embryos, synchronising reproductive cycles, carrying a foreign species to term, providing appropriate milk, etc, etc. All these difficulties, and more, apply to the resurrection of extinct species.

If we are able to successfully impregnate a surrogate that takes the pregnancy to term, then what? We have a single individual being reared by an individual of a different species. If this works what do we then do with our mammoth or thylacine? Apparently appropriate mammoth habitat exists in Siberia. But what would our solitary mammoth do in such a place? We would need to produce at least 50 mammoths (probably more like 500: http://www.eoearth.org/article/Minimum_viable_population_size?topic=58074), to create a self-sustaining population. Given the paucity of genetic material available to play with, these mammoths would be virtual clones with very little genetic diversity. All conservation programs seek to maximise genetic diversity to avoid the problems that now occur in inbred populations e.g. Tasmanian devils and their contagious cancer.

What would be the point of bringing back one species? The mammoth will be no more than a curio, devoid of any real value, unless you bring back its entire ecosystem. This ecosystem would need to include not just all the extinct animals but also all the plants it shared its former existence with.

There is more logic in restoring the thylacine as it only became extinct in the 1930s, not 4000 years ago, but even there the Tasmanian ecosystem has changed in the past 70 years. Would it not make more sense to invest all that time, money and expertise into preventing other species from heading down the same extinction path, instead of wasting it on frivolous projects whose only purpose seems to be to let scientists marvel at their own cleverness?

Dr. F. Bunny

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