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Neanderthal

(Homo neanderthalensis)

A draft sequence of the Neanderthal

genome should be published sometime this year. ^“To have a reasonable-quality genome, say comparable to the chimpanzee, will then be another two years of work or so,^” says

Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. While he and his colleagues hope the genome will offer unique insights into the differences between us humans and our mysterious cousins, there is speculation it could also be used to resurrect the Neanderthal. Because of our very close shared ancestry, humans would make ideal egg donors and surrogate mothers.

However, while Soviet scientists might once have tried to create a human-ape hybrid, today it is hard to imagine even the most crazed of mad scientists entering such taboo territory. ^“I find the idea of resurrecting the Neanderthal so ridiculous that any speculation on surrogate mothers is superfluous,^” says Pääbo. At most, researchers might replace some human genes with the Neanderthal versions in cells growing in a dish to see what the effect is, he says.

Short-faced bear

(Arctodus simus)

This towering beast would dwarf the world ^’s largest living land carnivore , the polar bear. The short-faced bear may have been a third taller than the polar bear when standing upright, and it weighed up to a tonne. Recovering its DNA should be possible as there are specimens encased in permafrost. The short-faced ^’s closest living relative is the spectacled bear of South America. The two species parted evolutionary company only around 5 million years ago, but unfortunately, at just a tenth the body mass of the short-faced bear, the spectacled bear is unlikely to be a particularly good surrogate.

Revival recipe

YOU WILL NEED:

~ Well-preserved DNA

~ Several billion DNA building blocks ~ A suitable surrogate species

~ Some seriously advanced technology

HERE’S WHAT TO DO…

1. Extract the DNA from your extinct species, sequence the fragments and assemble to obtain a complete genome. REALITY CHECK: genome sequences from extinct animals are likely to be riddled with lethal errors.

2. Now take your DNA building blocks and recreate the DNA of your extinct beast, in the correct number of chromosomes.

REALITY CHECK: it is not yet possible to make such long DNA molecules from scratch, but we should be able to one day.

3. Package the chromosomes up into an artificial nucleus and pop it in an egg collected from your suitable surrogate species. This should then develop into an embryo, which will be a clone of a long-dead animal.

REALITY CHECK: finding compatible species, let alone extracting eggs from them, could be a huge problem. Plus, no one has yet managed to clone birds or reptiles.

4. Grow a baby animal from the embryo. For mammals, implant the embryo in the womb of a compatible surrogate mother. For a reptile or bird, incubate embryo using yet-to-be-developed techniques. For an amphibian or fish where fertilisation takes place outside the body, just sit back and watch.

REALITY CHECK: compatible surrogate mothers may not exist for many extinct mammals.

HOW TO CHEAT:

Rather than synthesising the entire genome from scratch, you could take

the DNA of a closely related living species and modify it to be more like that of the extinct species you are aiming for. REALITY CHECK: some living species have already been made superficially more like extinct ones, but with today’s knowledge and technology they remain far from the real thing.

Tasmanian tiger

(Thylacinus cynocephalus)

The last Tasmanian tiger or thylacine – an individual known as Benjamin – died in Hobart Zoo in 1936. The existence of various preserved tissues less than a century old means geneticists should be able to get good-quality DNA and produce a complete sequence of the thylacine genome before too long. When it comes to resurrection, marsupials like the thylacine might be easier than most other mammals. Pregnancy in marsupials typically lasts just weeks, and a simple placenta forms only briefly, meaning there might be less risk of incompatibility between an embryo and a surrogate mother of another species. For the thylacine, the surrogate would be the Tasmanian devil. After birth, the fetus could be raised on milk in an artificial pouch.

DODO(Raphus cucullatus)

In 2002, geneticists at the University of Oxford got permission to cut into the world’s best-preserved dodo specimen, a foot bone – complete with skin and feathers – held under lock and key at the university’s Museum of Natural History. “It was one of the scariest things I’ve had to do,” recalls Beth Shapiro, an ancient DNA specialist now at Pennsylvania State University. This yielded minute fragments of dodo mitochondrial DNA but nothing more. Since then, no other specimen has yielded even a whiff of dodo DNA, but there is still hope that some will one day be found. “We’re still looking,” says Shapiro. If one turns up and a genome sequence could be produced from it, it would then be down to pigeons to help bring their famous cousin back from the dead.

Woolly rhinoceros

(Coelodonta antiquitatis)

Resurrecting the woolly rhino has lots going for it.

As with the mammoth, there are plenty of specimens preserved in permafrost, and the availability of hair, horns and hooves is a big plus. These tissues can be cleaned up with shampoo and bleach to remove contaminant DNA from microbes and fungi before using enzymes to release an abundance of near-pure rhino DNA. This makes it likely that geneticists will publish the complete genome of this hirsute beast before long.

However, although the woolly rhino has close living relatives that might make suitable surrogates, all contemporary rhino species are themselves on the brink of extinction. As long as this remains the case, resurrecting a woolly rhino is unlikely to be a top priority.

Moa

(Dinornis robustus)

There is plenty of moa DNA to be found in well-preserved bones and even eggs in caves across New Zealand, so obtaining a moa genome should be doable. But which one?

It would be tempting to go for the massive Dinornis robustus, which stood more than 3 metres tall, but starting with the more modestly sized Megalapteryx didinus might make more sense. Although only distantly related to ostriches, it might be possible to boot up the moa genome in an ostrich egg.

As no bird has yet been cloned, however, perhaps the most feasible approach would be to engineer an ostrich embryo to be moa-like.

I rish el k

(Megaloceros giganteus)

Deer-hunting enthusiasts would give almost anything for a chance to stalk this Pleistocene giant, once found across Europe. A typical male Megaloceros stood more than 2 metres tall at the shoulder and sported antlers 4 metres wide. It is actually a deer rather than an elk, and its closest living relative is the much smaller fallow deer, the two species having parted evolutionary company around 10 million years ago. The gulf between the two species means it is hard to see how a complete genome could be converted into a living, breathing animal.

Gorilla

(Gorila gorila)

The first species to be brought back from extinction will most likely be one that is alive today. 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 becomes available. For gorillas, the surrogate would be the chimpanzee. ~

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