Bringing back the dead
On Friday, March 15 2013, National Geographic hosted the first-ever public exploration of the subject of reviving extinct species at TEDxDeExtinction, a daylong event at Grosvenor Auditorium in Washington, DC. The purpose of this event was to showcase the prospects of bringing extinct species back to life, along with a discussion of ethical issues.
I recently posted on attempts to back-breed the extinct Tarpan sub-species of horse. While the capacity of back-breeding to recreate an extinct species is questionable, some other de-extinction methods are now just starting to have some (arguable) success.
The Pyrenean Ibex or bucardo went extinct in 2000 when the last known living animal, a 13-year-old female named Celia, was found dead lying next to a fallen tree. In 2009 the journal Theriogenology described the use of frozen skin cells from Celia to create clone embryos. Scientists made the embryos by inserting the bucardo’s DNA into domestic goat eggs emptied of their original genetic material. One live birth was reported, with the kid dying of lung abnormalities only a few minutes after birth. Sadly, this is the fate of many cloned animals, due to the damage caused when transferring the DNA.
Cloning has been more successful in endangered species, where living (or recently deceased) animals are still available. The European mouflon, a rare breed of wild sheep found on Sardinia, Corsica and Cyprus, was the first clone of an endangered mammal species to survive. The lamb, named Ombretta, was created from cells from a ewe found recently dead at a wildlife rescue center on the island of Sardinia.
Jurassic Park will probably never happen. DNA degrades over time. Based on a recent study of moa bones, it looks like DNA has a half-life of around 521 years. So no dinosaurs, woolly mammoths or Neanderthals – so much for all four of the Ice Age movies and some classic science fiction stories.
Many more recently extinct species, such as the passenger pigeon, quagga, moa, thylacine, great auk, dodo and the huia, may be recoverable from museum specimens. The Revive & Restore project (convenors of the above-mentioned TEDx), seeks to do just that, starting with the passenger pigeon.
The challenge in cloning these species (apart from the viability of the DNA) will be the availability of closely-related species that can provide eggs and host the cloned embryos.
Putting aside the practical challenges and the ethics of cloning (a big subject in itself), let’s assume that it is scientifically feasible by some means to bring back extinct species. Is it a good idea?
Let’s start by understanding why these species went extinct in the first place. With the possible exception of the Falklands Wolf, these species disappeared for anthropogenic reasons – as a combination of human competition for territory, hunting, introduction of new predators and destruction of habitat. A quick search of the IUCN Red List will reveal the same common factors in critically endangered species such as the kakapo.
So given what a challenge it seems to be to simply preserve many fragile species that are still alive and have a chance to stay so, is it wise to divert resources into bringing back additional extinct species? Shouldn’t we address the fundamental causes?
Can we realistically re-introduce these species to their original habitats? How about the great auk, for example?
According to the Natural History Museum, “The great auk, Pinguinus impennis, is one of the most powerful symbols of the damage humans can cause. The species was driven extinct as a result of centuries of intense human exploitation. “. The fact that they congregated on remote islands and weren’t in fact competing for territory with humans might give them a chance.
The thylacine on the other hand, would be facing a very different Tasmania to the one it once roamed.
In 1863, John Gould predicted that the thylacine was doomed to extinction:
When the comparatively small island of Tasmania becomes more densely populated, and its primitive forests are intersected with roads from the eastern to the western coast, the numbers of this singular animal will speedily diminish, extermination will have its full sway, and it will then, like the Wolf in England and Scotland, be recorded as an animal of the past.
The last known thylacine died in 1936.
Tasmania now is significantly different to the thylacine’s Tasmania. According to the Tasmanian Parks and Wildlife Service, the thylacine’s preferred habitat was a mosaic of dry eucalypt forest, wetlands and grasslands. They emerged to hunt on grassy plains and open woodlands during the evening, night and early morning. Unfortunately Tasmania’s once-extensive grasslands and grassy woodlands are now considered one of the State’s rarest and most endangered vegetation types. It is estimated that around 4,000 square km of grassland existed at the time of European settlement, of which only 12% remains and continues to degrade.
Where is a de-extinct tiger to go? Could it ever be rewilded, or would it always remain a caged curiosity?