‘De-extinction’ about as sensible as ‘de-death

A conference held in Washington DC on 15 March, and organised by National Geographic and TEDx, focused on the science and ethics of ‘species-revival’. American, British and Australian scientists, along with ethicists and others, debated whether biologists should attempt to bring extinct animals back to life – a concept some call ‘de-extinction’.

The conference heard that Australian scientists involved in a scheme called Project Lazarus had successfully reactivated the DNA of an extinct amphibian, the gastric-brooding frog Rheobatrachus silus, and that other long-gone animals could be next.

The frog was native to Australia and uniquely swallowed its eggs, bred them in its stomach and gave birth through its mouth. It is believed to have become extinct in 1983 but in the 1970s an Adelaide researcher had put samples of the frog in a freezer.

Project Lazarus leader Professor Mike Archer, from the University of New South Wales, told the Washington conference that the team wanted to bring the frog back to life. They had taken the first step by inserting the extinct frog's DNA, obtained from the frozen samples, into donor eggs from a distant cousin – the Great Barred Frog.

“We are watching Lazarus arise from the dead, step by exciting step," Archer said. "We've reactivated dead cells into living ones and revived the extinct frog's genome in the process. Now we have fresh cryo-preserved cells of the extinct frog to use in future cloning experiments."

Andrew French, a reproductive biologist who led the technical work with fellow scientist Jitong Guo, said breakthroughs in genome sequencing meant scientists could do much more with partially damaged DNA samples than previously. That meant there was a serious possibility the long-extinct Tasmanian Tiger or thylacine could make a comeback.

But Professor Corey Bradshaw, director of ecological modelling at the University of Adelaide, said that as a conservation scientist he was disappointed that “this tired fantasy” of bringing extinct animals back to life still managed to generate serious interest.

Writing in the Australian academic newsletter, The Conversation, Bradshaw dismissed Archer’s claims and said that such efforts ignored the real problem of why extinctions occurred.

“Leaving aside for the moment the astounding inefficiency, the lack of success to date and the welfare issues of bringing something into existence only to suffer a short and likely painful life, the principal reason is that it does not address the real problem – namely, the reason for extinction in the first place,” Bradshaw said.

“Even if we could solve all the other problems, if there is no place to put these new individuals the effort and money expended is a complete waste.

“Habitat loss is the principal driver of species extinction and endangerment. If we don’t stop and reverse this now, all other avenues are effectively closed. Cloning will not create new forests or coral reefs, for example.”

He said the flaws did not end with a lack of space in a natural world shrinking as a result of more than 26 million new humans each year. The loss of genetic diversity leading to inbreeding depression was a major issue that cloning did not even begin to address.

“Without sufficient genetic variability, a population is almost certainly more susceptible to disease, reductions in fitness, weather extremes and over-exploitation. Studies show convincingly that genetic diversity is lower in threatened than in comparable non-threatened species, and there is growing evidence on how serious inbreeding effects are in determining extinction risk.”

As ecologists have begun to realise, animal populations have to number in the hundreds or even thousands of genetically distinct individuals to have any chance of surviving. Bradshaw said that to suggest cloning could artificially recreate the genetic diversity essential for population persistence was therefore “arrogant and irresponsible”.

“Cloning is also an expensive business – it can cost upwards of tens of thousands to several millions of dollars to clone a single animal. Like the costs associated with most captive breeding programmes, this is a nonsensical waste of finite funds.

“Think of what we could do with that money for real conservation and restoration efforts, such as buying conservation easements, conservation land acquisition and restoring ecosystems. Even if the costs come down over time, cloning will always be more expensive than the equivalent investment in habitat restoration and protection.”

Bradshaw said ‘de-extinction’ was about as realistic as ‘de-death’ and that “I for one am not in favour of sharing the neighbourhood with re-animated zombies”.