Our home for bold arguments and big thinkers.

frozen woolly mammoth exhibit
AP Photo/Wally Santana
We’re getting close to resurrecting animals like the woolly mammoth—but should we?

Seven reasons we shouldn’t bring extinct animals back to life

Dr. Lynn J. Rothschild
By Dr. Lynn J. Rothschild

Astrobiologist at NASA's Ames Research Center

Extinction is forever—or so we thought.

What if we could have a redo? What if we could undo hitting that delete button and bring back extinct creatures? This technological process—so-called “de-extinction”—is nearly there, and discussions are therefore shifting from “can we?” to “should we?”

It’s easy to argue for de-extincting plants. Imagine if Camellia sinensis (tea), Coffea arabica (which accounts for 60–80% of the world’s coffee production), or—heaven forbid!—Theobroma cocoa (chocolate) went extinct. An international crisis would be called, and it would become a global priority to de-extinct them. What about other species critical to human civilization, such as rice or honeybees? And what about warm fuzzy creatures, the sorts of animals that may have met their demise because of human handiwork, such as passenger pigeons, mammoths, and other extinct mammals, turtles, and birds, which were so fantastically diverse until relatively recently?

De-extincting plants and mammoths are entirely different propositions, and to the latter, I say no.

As an evolutionary biologist, I think it would be amazing to bring back extinct creatures. You could poke, prod, and study them with today’s arsenal of scientific techniques. But, with the exception of viruses which have been resurrected, that’s not really what de-extinction is about. Instead, de-extinction is the process of taking extinct species’ DNA and inserting it into a similar species to create a hybrid new creature. The much-spoken-about woolly mammoth project is using Asian elephants as the host; the result is actually only about 2% wooly mammoth. Likewise, people from European ancestry are roughly 1-2% Neanderthal, but they don’t walk around claiming to be de-extincted Neanderthal.

And besides, if we can’t save what we have today, why do we imagine we will do better with some de-extincted laboratory genetic mosaics, made to look like the departed species?

There are seven categories of reasons why we should not de-extinct animals, from biological to philosophical. I like to think of them as the seven “E”s.

1. Extinction

These animals went extinct in the first place for a reason: humans thought they were useful for dinner or couture, too much of a pest, eradicated their natural habitat, or suffered some other catastrophe. Have the reasons for the original extinction disappeared? If not, who’s to say that it wouldn’t just happen again? When I go on field trips, whether to the Masai Mara or the Andes, there are two kinds of animals: fit and healthy, or dead.

2. Evolution

Even if we beat evolution on the front end by bringing back the extinct, what will happen when evolution takes over with the resurrected species? We may not be happy with the results. But even if these animals were brought back, there would be a small population at best with an extremely limited genetic diversity. We even see this with humans as six centuries of inbreeding in the House of Habsburg ended with Charles II of Spain not being able to properly chew his food, in addition to a large number of physical, sexual, intellectual, and emotional problems. (The modern English bulldog is another cautionary tale of the dangers of inbreeding.) Unless you can create genetic diversity with over 100 genetically different individuals, the small populations of de-extincted animals will lead to unhealthy, quite possibly sterile descendants, resulting in Extinction 2.0 anyway.

3. Ecology

“No man is an island”—and neither are creatures. All living things need an ecosystem in order to thrive. When we have re-introduced endangered species back into the wild in the past, there have been all sorts of ripple effects and unintended consequences. The most famous example was the reintroduction of the gray wolf to Yellowstone: elk and deer were hunted by the wolves, and with the reduced populations, the aspens thrived, helping the beavers. It’s impossible to know how a local ecology would change with a species brought back from the dead—we might bring the wooly mammoth back, yes, but would that mean? Have we considered their effects on the current ecosystem?  Animals also host ecosystems of microbes, on their skins, in their guts, in their ears, on their genitals. This so-called microbiome affects diet, the immune system, even mood and behavior. The native host microbiome would be impossible to reconstruct.  The new, artificial one will have unknown effects.

4. Ethology

Animals like birds and mammals learn behavior by watching other members of their species. What happens if you’re the first one to jump back out of the time capsule? The captive condor breeding program was a good example of the dangers of not having parents of the same species. Even though the human “parents” used puppets to prevent the young birds from imprinting on humans, captive-born birds released into the wild showed an unhealthy curiosity about humans, and were less social with other condors. Will the mammoths simply be considered the embarrassment of the elephant litter, and not learn proper behaviors? With no parents to teach the offspring, they will absorb the whims of other like species—or humans—instead.

5. Economics

According to the Performing Animal Welfare Society, a healthy elephant costs about $70,000 per year to care for, and an elderly one costs even more. Spending money to bring back the first mammoth will surely generate excitement and keen interest. But when the thrill subsides, who will pay the bills… in perpetuity? Are we really considering bringing back creatures only to euthanize them when the funding runs dry?

6. Emotion

When something dies, we experience a sense of loss, sometimes tangible and sometimes abstract. Who would not feel a terrible sense of loss if elephants were to go extinct even if one seldom if ever sees one? But this feeling of loss is not worth the financial, biological, and ethical costs of de-extinction.

7. Ethics

Why do we want to bring these creatures back? Do we feel guilty for our role in making them die off in the first place? Do we feel the need to repay our ancestors’ debt to these species with restorative justice? But who is the justice for? Certainly not for the de-extincted individuals, who will likely go through a period of being malformed, malnourished, and maladjusted when we run out of interest, ending in a likely second extinction. Is it ethical to “atone” for the actions of our ancestors when it may cause a different type of suffering?

In the end, it comes down to our idea of what “natural” is. Is it natural to have a woolly mammoth on the Siberian steppe, just like they once were? By that reasoning, it should be just as natural to have a sky filled with pterodactyls. Or maybe a sea filled with trilobites. Or maybe an anaerobic earth, which is what our planet was like through much of evolution. Or maybe face the fact that the pristine Earth did not have life here at all. You can’t just pick and choose, and then hide behind the mantle of “natural.”

Jurassic Park was an awful idea, and Pleistocene Park is no better. So, instead of de-extinction, let’s focus on saving the ecologically important, interesting, and yes—charismatic—creatures we have today. De-extinction is not Plan B.

This article has been adapted from Rothschild’s statements at an Intelligence Squared debate, “Don’t bring extinct creatures back to life.

This piece was adapted from Rothschild’s opening statement at an Intelligence Squared US debate, Don’t bring extinct creatures back to life, in January. You can watch the entire debate—also featuring Stewart Brand, George Church, and Ross MacPhee—here