back to the Mesozoic period, from around 250 million years ago to sixty-five million years ago. By comparison, the Pleistocene is relatively modern history, ending a mere eleven and a half thousand years ago. And the vision behind Pleistocene Park is not thrills, spills, and profit, but the serious use of science and technology to stabilize an increasingly unstable environment. Yet there is one thread that ties them together, and that’s using genetic engineering to reintroduce extinct species. In this case, the species in question is warm-blooded and furry: the woolly mammoth.
The idea of de-extinction, or bringing back species from extinction (it’s even called “resurrection biology” in some circles), has been around for a while. It’s a controversial idea, and it raises a lot of tough ethical questions. But proponents of de-extinction argue that we’re losing species and ecosystems at such a rate that we can’t afford not to explore technological interventions to help stem the flow.
Early approaches to bringing species back from the dead have involved selective breeding. The idea was simple—if you have modern ancestors of a recently extinct species, selectively breeding specimens that have a higher genetic similarity to their forebears can potentially help reconstruct their genome in living animals. This approach is being used in attempts to bring back the aurochs, an ancestor of modern cattle.10 But it’s slow, and it depends on the fragmented genome of the extinct species still surviving in its modern-day equivalents.
An alternative to selective breeding is cloning. This involves finding a viable cell, or cell nucleus, in an extinct but well-preserved animal and growing a new living clone from it. It’s definitely a more appealing route for impatient resurrection biologists, but it does mean getting your hands on intact cells from long-dead animals and devising ways to “resurrect” these, which is no mean feat. Cloning has potential when it comes to recently extinct species whose cells have been well preserved—for instance, where the whole animal has become frozen in ice. But it’s still a slow and extremely limited option.
Which is where advances in genetic engineering come in.
The technological premise of Jurassic Park is that scientists can reconstruct the genome of long-dead animals from preserved DNA fragments. It’s a compelling idea, if you think of DNA as a massively long and complex instruction set that tells a group of biological molecules how to build an animal. In principle, if we could reconstruct the genome of an extinct species, we would have the basic instruction set—the biological software—to reconstruct individual members of it.
The bad news is that DNA-reconstruction-based de-extinction is far more complex than this. First you need intact fragments of DNA, which is not easy, as DNA degrades easily (and is pretty much impossible to obtain, as far as we know, for dinosaurs). Then you need to be able to stitch all of your fragments together, which is akin to completing a billion-piece jigsaw puzzle without knowing what the final picture looks like. This is a Herculean task, although with breakthroughs in data manipulation and machine learning, scientists are getting better at it. But even when you have your reconstructed genome, you need the biological “wetware”—all the stuff that’s needed to create, incubate, and nurture a new living thing, like eggs, nutrients, a safe space to grow and mature, and so on. Within all this complexity, it turns out that getting your DNA sequence right is just the beginning of translating that genetic code into a living, breathing entity. But in some cases, it might be possible.
In 2013, Sergey Zimov was introduced to the geneticist George Church at a conference on de-extinction. Church is an accomplished scientist in the field of DNA analysis and reconstruction, and a thought leader in the field of synthetic biology (which we’ll come back to in chapter nine). It was a match made in resurrection biology heaven. Zimov wanted to populate his Pleistocene Park with mammoths, and Church thought he could see a way of achieving this.
What resulted was an ambitious project to de-extinct the woolly mammoth. Church and others who are working on this have faced plenty of hurdles. But the technology has been advancing so fast that, as of 2017, scientists were predicting they would be able to reproduce the woolly mammoth within the next two years.
One of those hurdles was the lack of solid DNA sequences to work from. Frustratingly, although there are many instances of well-preserved woolly mammoths, their DNA rarely survives being frozen for tens of thousands of years. To overcome this, Church and others have taken a different tack: Take a modern, living relative of the mammoth, and engineer into it traits that would allow it to live on the Siberian tundra, just like its woolly ancestors.
Church’s team’s starting point has been the Asian elephant. This is their source of base DNA for their “woolly mammoth 2.0”—their starting source code, if you like. So far, they’ve identified fifty-plus gene sequences they think they can play with to give their modern-day woolly mammoth the traits it would need to thrive in Pleistocene Park, including a coat of hair, smaller ears, and a constitution adapted to cold.
The next hurdle they face is how to translate the code embedded in their new woolly mammoth genome into a living, breathing animal. The most obvious route would be to impregnate a female Asian elephant with a fertilized egg containing the new code. But Asian elephants are endangered, and no one’s likely to allow such cutting-edge experimentation on the precious few that are still around, so scientists are working on an artificial womb for their reinvented woolly mammoth. They’re making progress with mice and hope to crack the motherless mammoth challenge relatively soon.
It’s perhaps a stretch to call this creative approach to recreating a species (or “reanimation” as Church refers to it) “de-extinction,” as what is being formed is a new species. Just as the dinosaurs in Jurassic Park weren’t quite the same as their ancestors, Church’s woolly mammoths wouldn’t be the same as their forebears. But they would be designed to function within a specific ecological niche, albeit one that’s the result of human-influenced climate change. And this raises an interesting question around de-extinction: If the genetic tools we are now developing give us the ability to improve on nature, why recreate the past, when we could reimagine the future? Why stick to the DNA code that led to animals being weeded out because they couldn’t survive in a changing environment, when we could make them better, stronger, and more likely to survive and thrive in the modern world?
This idea doesn’t sit so well with some people, who argue that we should be dialing down human interference in the environment and turning the clock back on human destruction. And they have a point, especially when we consider the genetic diversity we are hemorrhaging away with the current rate of biodiversity loss. Yet we cannot ignore the possibilities that modern genetic engineering is opening up. These include the ability to rapidly and cheaply read genetic sequences and translate them to digital code, to virtually manipulate them and recode them, and then to download them back into the real world. These are heady capabilities, and for some there is an almost irresistible pull toward using them, so much so that some would argue that not to use them would be verging on the irresponsible.
These tools take us far beyond de-extinction. The reimagining of species like the woolly mammoth is just the tip of the iceberg when it comes to genetic design and engineering. Why stop at recreating old species when you could redesign current ones? Why just redesign existing species when you could create brand-new ones? And why stick to the genetic language of all earth-bound living creatures, when you could invent a new language—a new DNA? In fact, why not go all the way, and create alien life here on earth?
These are all conversations that scientists are having now, spurred on by breakthroughs in DNA sequencing, analysis, and synthesis. Scientists are already developing artificial forms of DNA that contain more than the four DNA building blocks found in nature.11 And some are working on creating completely novel artificial cells that not only are constructed from off-the-shelf chemicals, but also have a genetic heritage that traces back to computer programs, not evolutionary life. In 2016, for instance, scientist and entrepreneur Craig Venter announced that his team had produced a completely artificial living cell.12 Venter’s
