Two weeks ago I posted about how, theoretically at least, one could go about bringing an extinct species back to life by cloning. Its clear that for long-extinct species like the mammoth, where only degraded remains are available, cloning is still a very long way off and in fact may not ever be possible. But for species that have only recently gone extinct, or are on the verge of extinction, correct preservation of tissues could see clones created (in fact this has already happened in the case of the pyrenean ibex). But should we bother going down this path?
Some people would say that we have a moral imperative to bring back extinct species, once we have the technology to do so, in situations where humans caused the extinction. However in many cases the original extinction was caused by hunting, habitat loss and/or the introduction of predators, and these underlying issues are still present. For instance, mammoth habitat of cold tundra grasslands, which during the ice ages ranged across northern Europe and the Americas, is now restricted to the Arctic, and is increasingly at risk from climate change. Loss of this habitat at the end of the last ice age is thought to be one of the main reasons mammoths went extinct in the first place, and the situation hasn’t improved. Should we really be contemplating bringing back populations of extinct species when we have trouble even saving the species we still have, and we are destroying habitat at an ever-increasing rate? Introductions of long-extinct species could also significantly alter already fragile ecosystems and have disastrous consequences for the organisms already present.
Aside from suitable habitat, for a species to be viable and self-sustaining there needs to be sufficient genetic diversity in the population to guard against the detrimental effects of inbreeding depression, and for the species to be able to adapt to new environmental challenges. Simply producing several clones from one specimen would not create a viable breeding population – for one thing you would at least need one male and one female. Clones of several genetically different individuals would be required to ensure the population’s survival. This may not be too difficult for critically endangered or recently extinct species where several well-preserved tissue specimens are available. However, for the majority of extinct species the genome would have to be artificially “rebuilt” before cloning could take place, so you would need to have genome sequences of several different individuals in order to produce genetically different clones. For many extinct species we simply don’t have enough different well-preserved specimens to achieve this.
There is a danger that cloning will be persued for the sake of it, because wouldn’t it be cool to see a live mammoth/tasmanian tiger/huia once again? However, with this attitude the cloned animal is likely to end up being little more than a curiosity in an amusement park. There may be some merit in bring back an extinct species for what it could tell us about evolution and physiology, but I don’t think this is enough to justify the enormous cost. The millions of dollars it would take to bring back a few specimens of an extinct species would be better spent on preserving large chunks of habitat, eradicting introduced predators, and educating the public about for our critically endangered species, to ensure that in future we don’t have to rely on cloning to save the species we still have.
Footnote: The Neanderthal genome was published in Science last week, and along with it is an interesting news focus article about cloning Neanderthals. Its an interesting read (unfortunately its behind a pay-wall, so for those without full-text access to Science, the brief synopsis is that the ethical and technical issues around cloning Neanderthals are so great is unlikely they’ll ever be overcome).