UNDERSTAND

DE-EXTINCTION

Harvard’s Prof George

Church is working on resurrecting the mammoth

2 zebras. So scientists are choosing the zebras that look most like quaggas and letting them breed. The aim, over successive generations, is to create animals that look like quaggas. Other projects, however, involve assisted reproduction and some rather elegant genetics. Some are using cloning; others, stem cell science. For example, Prof George Church at Harvard Medical School aims to create a mammoth by ‘editing’ mammoth genes into elephant cells.

Will these animals be the same as the originals? No, they can never be exactly the same. When he is done, Church will have created not a true mammoth, but an elephant with a sprinkling of judiciously placed mammoth DNA. It will have long, shaggy fur, thick rolls of insulating body fat, and haemoglobin that can ferry oxygen around the body at sub-zero temperatures. This will be an animal that looks like a mammoth, but is really an elephant whose DNA has been altered so it can live in the cold. You could call it a ‘mammophant’ if you like, or an ‘elemoth’.

Added to that, we now realise that all animals are a product of their DNA and of the environment in which they live, along with the interaction between the two. Created in a lab, nurtured in the womb of a modern elephant, and raised in a world that has changed radically since mammoths went extinct thousands of years ago, the experiences of this newage pachyderm will be different to those of its Ice Age doppelgänger… all of which will conspire to make it less similar to the original woolly mammoth. But does this matter? Many will argue that, if the de-extinct animal looks and acts like its predecessor, then that’s good enough.

Could we resurrect dinosaurs? Sadly, a real-life Jurassic Park is out of the question. There are limitations on which species can undergo de-extinction. First up, scientists need to have a source of the animal’s DNA. Sometimes this comes from preserved museum specimens or from cells that have been collected from live animals and frozen away. Sometimes it can come from fossils. But DNA disintegrates over time, meaning that after a couple of million years there is simply no DNA left. Dinosaurs famously went extinct 65 million years ago, so their DNA is lost forever. No DNA, no dinosaurs.

And if you’re hoping to meet a dodo, that icon of extinction, then don’t hold your breath either. Although it died out comparatively recently – a few hundred years ago – its final resting place, Mauritius, was simply too hot to preserve its DNA. 2

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Although the dodo only died out in the 16th Century, we don’t have any DNA samples to clone it

JARGON BUSTER

CLONING

This is one of the principle methods used to bring back certain animals. DNA from an adult cell is coaxed into a more youthful state, which is then used to create an animal that’s almost genetically identical to the donor.

ECOSYSTEM

This is a biological community of interacting life forms and the space they live in. Healthy ecosystems are essential to the survival of life on Earth: they provide services including purifying the air, pollinating our crops and sequestering carbon.

GENE EDITING

The ability of scientists to alter the DNA of living things with pinpoint accuracy. The core components of DNA can now be removed, replaced or added to at will using a process called CRISPR-Cas9.

RESURRECTION BIOLOGY

Another term for de-extinction. This blend of high-tech methods is enabling scientists to bring back species from the brink of extinction and beyond.

STEM CELL

These versatile ‘shapeshi ing’ cells can turn into other cell types. Scientists have made northern white rhino stem cells, and next plan to use them to produce eggs and sperm for rhino IVF.

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P H O T O S