ECOS 38 (6): Book Reviews: Rise of the Necrofauna


The Science, Ethics, and Risks of De-Extinction

Britt Wray

Greystone Books
288 pages
ISBN: 10 1771641649
Hardback RRP: £19.99

Review by Simon Ayres

Dabbling in de-extinction – reckless, bold, or both?

You must have heard of the idea to bring woolly mammoths back from extinction using genetic material dug up from the Siberian permafrost. Well, there really are people working on this, as well as on other extinct animals. This book delves into the science, ethics, politics and philosophical questions around de-extinction, providing a clear overview of a complex subject.

Along with the woolly mammoth, the host of extinct species mentioned in the book include passenger pigeon, Yangtze River dolphin, dodo, gastric-brooding frog, Pyrenean ibex, great auk, heath hen, quagga, thylacine, and the aurochs. The detailed case studies concentrate on woolly mammoth and passenger pigeon.

The book is well structured with each chapter discussing a particular topic around de-extinction. The science is fairly complex, but explained well for the non-specialist. Three methods for de-extinction are presented. A notable point common to the two main methods is that the exact genetic configuration of an extinct animal is not likely to be recovered. Although it is theoretically possible, the practicalities render it an unrealistic proposition. It is more a case of inserting characteristics (by breeding or genetic modification) into a similar species until you get something that looks like and behaves like the extinct animal.

Selective breeding is the most straightforward method, and is a familiar practice from breeding domestic animals. The book cites the example of aurochs and the work being done by True Nature Foundation, the project partners for a scheme I oversee called Cambrian Wildwood. The complete genome of a British aurochs was recently sequenced and compared with domestic cattle, and showed that Highland cattle, Welsh black and Kerry cattle are very close to aurochs. Aurochs colouration is present in Highlands, and seasonal rather than permanent long coats have been bred into Highlands. Size is the most obvious differential, and this has a high level of heritability so is easy to breed for. The ‘species’ suited to de-extinction by this method are limited to sub-species of living species, and include aurochs, tarpan and quagga, whose characteristics have been successfully bred into the plains zebra.

Cloning is another method of de-extinction, but of limited potential because cells from living tissue must be used. In other words, the sample must be collected from the last individual of a species before it dies. Where it has more potential is with surviving but critically endangered species. It is technically difficult but proven to be possible by the successful cloning of Dolly the sheep.

Genetic engineering has been evolving very rapidly over recent years with wide ranging applications, in particular agriculture and medicine, with de-extinction being a fringe activity in this field. Scientists are working on passenger pigeons and woolly mammoths. The basic idea is to use DNA recovered from dead animals in order to sequence the genome of the extinct animal. Then the DNA of a close living relative is modified by editing the contrasting genes into the genetic code of the extinct animal.

A major problem is that as soon as an animal dies, its DNA starts to decay, or fragment. So recovering the preserved tissue of a mammoth gives you a bunch of DNA fragments. These can be pieced together in the right order like a complicated puzzle by comparing different samples, and in fact the genome sequencing of woolly mammoth has been achieved. There are 1.4 million genetic differences between mammoth and its closest living relative the Asian elephant, too many to individually edit. However, a selection of genes can be edited to create a chosen set of characteristics. So far, 45 genes have been modified from elephant to mammoth traits.

Besides the considerable technical hurdles, there are other biological problems. For example, where are the re-created animals going to live? How will a social species like mammoth, born to a surrogate elephant mother, learn how to be an actual mammoth. How do you accommodate a hot climate animal and her cold climate offspring?

Complex legal issues arise, for example regulations concerning both genetically modified organisms and endangered species would apply to un-extinct animals, with potential for these being at odds.

Philosophical questions abound, for example what is the point of de-extincting a species? Is it purely for our aesthetic enjoyment or entertainment? Is that enough justification? Is it to fulfil an ecological role? If so, can that role be satisfied by a living species? Things could go wrong, for example a re-created species breeding in the wild with a related, possibly endangered species.

These and many more questions are explored in this fascinating book written in plain language. My only complaint about this non-fiction text is that the text sometimes borrows stylistic attributes from fiction writing. For example, describing the physical appearance and mannerisms of scientists that the author met during her research. Or telling us about how she was making a cup of tea when a certain email arrived. Some of the explanations are laborious, for example half a page on explaining what a population bottle neck means by referring to what happens if you try to empty marbles out of a bottle with a narrow neck. I suspect there was some padding out of the word count, but the book would be better if it remained purely factual.

A nice touch is referencing de-extinction to the lessons illustrated in Shelley’s Frankenstein. In this story, the created being is not initially monstrous, but becomes a monster due to being neglected by its creator. If we are to exercise god-like powers of creation we need to also exercise god-like wisdom.


Ayres, Simon “ECOS 38 (6): Book Reviews: Rise of the Necrofauna” ECOS vol. 38(6) 2017, British Association of Nature Conservationists,

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