Could long-gone beasts rise from the dead?

Published on Wednesday 7 January 2009 20:57

EXTINCT species from Neanderthals to the dodo could one day once again roam across the earth, it has been claimed.

A list of the top ten beasts most likely to be brought back from the dead has been drawn up by experts looking at the availability of DNA.

Sabre-toothed tigers, giant sloths and the enormous woolly mammoth, as well as Neanderthals, are among the species New Scientist magazine predicts most likely to be successfully resurrected.

The predictions were based on the possibility of extracting DNA from well-preserved specimens which could be used to provide a genome – or genetic blueprint – of the extinct creatures.

Scientists also took into account the existence of suitable living surrogate species to provide an egg in which to implant the genome so an embryo could grow.

Another factor was the potential excitement that would be caused by bringing each of the species back from the dead.

Such an ambitious goal of bringing back an extinct species remains out of reach given today's technology, but some experts believe it is only a matter of time before creatures from the past are resurrected.

DNA less than 100,000 years old can be preserved more or less intact in certain circumstances, such as when an animal is frozen in permafrost or dies in a dark cave or somewhere extremely dry.

Last year scientists published the near-complete DNA blueprint of the woolly mammoth, which led to speculation that the huge creature could be brought back from the dead 10,000 years after it became extinct.

However, Professor Svante Paabo, from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, said such projects remain a long way off.

"It's hard to say that something will never be possible, but it would require technologies so far removed from what we currently have that I cannot imagine how it would be done," he said.

The genome of the Neanderthal, a species closely related to modern humans, is also being mapped. However, the idea of resurrecting the species is so controversial it is unlikely any scientist would try it.

"I find the idea of resurrecting the Neanderthal so ridiculous that any speculation on surrogate mothers is superfluous," said Prof Paabo.

The first species to be brought back from extinction in the future could well be one currently alive but under serious threat, such as the gorilla.

Conservationists are freezing tissue samples from some threatened species, so clones could be created with the help of a closely related surrogate species if a suitable habitat became available.

For gorillas, the most suitable surrogate in which to implant the embryo would be the chimpanzee.

Resurrecting dinosaurs, as depicted in the film Jurassic Park, is considered impossible because of a lack of suitable DNA.

No genetic information is likely to survive more than a million years.

Evolution expert Dr Henry Nicholls, writing in New Scientist, acknowledged there were huge complications in bringing back any animal.

"Bringing extinct creatures back to life raises a host of practical problems, such as where they will live, but let's not spoil the fun," he said.

Candidates for revival range from small to scary

SABRE-TOOTHED TIGER: Became extinct 10,000 years ago. There are well-preserved specimens from the La Brea tar pits in Los Angeles. The African lion could be a good surrogate mother.

IRISH ELK: Giant deer that died out 7,700 years ago. Its closest living relative is the much smaller fallow deer. The differences between the species mean the fallow deer would be unlikely to perform well as a surrogate.

DODO: Extinct since 1690. In 2002, Oxford University geneticists cut into a bone at the Natural History Museum, but it yielded only fragments of DNA. There is still hope more will be found to produce a genome sequence. Pigeon egg could be a surrogate.

WOOLLY RHINOCEROS: Extinct for 10,000 years but plenty of specimens are preserved in permafrost. It is likely geneticists will publish the complete genome before long. It has close living relatives that might make suitable surrogates, but they are all on brink of extinction.

GIANT GROUND SLOTH: Before it died out 6,000 years ago, this animal stood about six metres tall and weighed about four tonnes. Several specimens have been found with hair, an excellent source of DNA.

MOA: Giant bird has been extinct for only about 1,500 years, so there are plenty of well-preserved bones and eggs in caves in New Zealand. It could be possible to grow an embryo in an ostrich egg.

NEANDERTHAL: Closely related to modern-day Homo sapiens, Neanderthals roamed the earth 25,000 years ago. A draft sequence of the Neanderthal genome should be published sometime this year. Humans would make ideal egg donors and surrogate mothers.