Carnivorous Nights (6 page)

It was mind-boggling, thrilling, and slightly disturbing. And given the pace of biotechnology—the mapping of the human genome, gene ther-apy—it seemed well within the realm of possibility. “So, within twenty years or so, will cloning extinct species be routine?” we asked. We imagined a zoo of once extinct animals: dodos, passenger pigeons, woolly mammoths.

Don looked at us as if we were the mad scientists. “We have to mitigate the enthusiasm with the reality of what we're doing,” he said gently.

DNA is not life, he reminded us. It's a blueprint for life, meaning that it tells a life, an organism, what species it will be, what it will look like, how it will grow. Sometimes it tells an organism how to behave or what its disposition will be. Because DNA is itself inanimate and made up of chemicals, an organism's DNA can survive well after death, sometimes for thousands of years.

Retrieving thylacine DNA was the cloning team's first task. Because the tiger pup was so old, dating from the mid-nineteenth century, it was preserved in ethyl alcohol (ethanol) rather than formalin as more recent specimens would be. (Formalin, a preservative that came into vogue around the same time the pup was pickled, destroys DNA; ethanol doesn't.) The scientists took samples from the tiger pup—from its organs, muscle, and bone marrow—and then extracted hundreds of thousands of DNA strands. In the media, the extraction was hailed as a triumph. Later, upon analysis, however, the DNA was found to be contaminated. It was a bit awkward. The pickled tiger pup had figured prominently in the press as the key to bringing the thylacine back to life—and the museum had already announced that the extraction had been successful. But what could
they do? They were scientists, not sideshow barkers. They began to look at other tiger specimens in the collection. The museum owned thylacine pelts, organs, bones. Ultimately, the cloning team extracted DNA from a thylacine femur and molar. It was good—in thousands of fragments—but they could work with it.

The next step was making sure they had all the correct bits and pieces of the tiger's DNA. They still needed to figure out how many chromosomes the tiger had and what was in them. Later, they would reassemble the DNA, like the pieces of a jigsaw puzzle. Karen led us over to her computer terminal. It was awash with graphs and symbols, documenting the tiger's life code.

When
—if—
they were able to re-create the tiger's entire genome (which in itself would be an incredible scientific achievement, Don pointed out), they would be ready for the ultimate stage of the project: cloning a tiger.

“Of course, having just one wouldn't do any good,” Karen said. “We'd have to make at least two hundred tigers.” Then she and Don began to laugh. Even in the heart of the cloning project it seemed like science fiction.

“There's really a lot of pressure,” said Don, still laughing and wiping tears from his eyes. The chances of success—of creating just one thylacine— were 5 to 8 percent in twenty years.

But, he added, the odds could get better. Technology was improving all the time. Since the discovery of the structure of DNA in 1953, scientists have learned to dissect, copy, map, manipulate, and even change the code of life. Through genetic modification, they've created insectresistant breeds of corn. Tomatoes that have extended shelf lives. They have bioengineered cows to produce “farmaceuticals,” including potential treatments for blood clots, anemia, hemophilia, and emphysema. They have put bioluminescent jellyfish DNA into white rabbits to make them glow under ultraviolet light—and they have even introduced spider DNA into goats, causing them to produce copious amounts of superstrong silk webbing in their milk.

Cloning, or bringing to life the twin of an individual, has also become a reality. The first mammal clone, Dolly the Sheep, was created in 1996 from a single cell nucleus taken from the udder of an adult sheep. Recently,
clones of the first endangered species were created by implanting their DNA into the eggs of related animals.

The first such trans-species birth was in 2001 when a cloned guar— an extremely rare species of wild ox that lives in Southeast Asia— was brought to term inside a cow named Bessie. This experiment was followed up in 2003 when a cloned Javanese banteng, a rare species of wild cattle, was born on an Iowa farm. The banteng's “mother” was a beef cow. In China, scientists are currently working to produce embryonic clones of giant pandas that could be “mothered” by black bears.

This is how the tiger clone would be created. If cloning scientists are able to reconstitute the thylacine's genome, they will need to pick a species to be the tiger's surrogate mother, an Eve for a new race of thylacines. This animal will have to be as closely related to the tiger as possi-ble—which presents a bit of a problem.

“The thylacine was the sole remaining representative of its family,” Don said. As a species, the Tasmanian tiger diverged from its closest cousin 25 million years ago. Of the sixty or so species of living marsupial carnivores—all of which are potential candidates—none look very much like the tiger. These species include such creatures as the dusky antechinus, a mouse-sized marsupial with a giant-sized sex life (its copulation is described as “violent” and the males all die of stressrelated disease within three weeks of mating); the spotted-tailed quoll, a forest predator that looks like a cross between a cat and a weasel; and the Tasmanian devil, a black-furred scavenger with powerful, bonecrunching jaws.

“I think it would come down to the devil really,” said Karen. “The devil is the largest of the carnivorous marsupials.”

Although only one third the size of the thylacine, the Tasmanian devil is a fierce beast. And like the thylacine and all marsupials, the devil gives birth to tiny incompletely developed young, which it suckles in a protective pouch.

To create this devil of a tiger, the cloning scientists would take an unfertilized egg from a female Tasmanian devil, remove all the devil DNA from inside, and then micro-inject the tiger's DNA into the egg. Then they would zap the egg with an electrical pulse. The egg and DNA would
fuse, and cell division would begin. Shortly thereafter, they would implant the resulting microscopic embryo into the devil's womb and a few weeks later a tiny tiger would be born.

Alexis, who had been quiet up to this point, suddenly perked up. “So are you saying the tiger would be part devil?” he asked. His eyes gleamed as if he were picturing what a thyla-devil would look like.

Don laughed, three short barks.

In fact, he said, they would have to drive the devil out. A tiny portion of the devil's genome would get into the tiger clone. “It would be less than a millionth devil,” Don said. “We would have to disable the mitochondria if we wanted it to be entirely thylacine.”

Karen was less concerned about the bedeviled eggs. “It might just be that they can survive with devil mitochondria,” she said.

When it came to the question of what would happen to the tiger after its birth, they were stumped. Hand it off to the vet? Marsupials aren't like placentals. The birth occurs when the young are blind, hairless, and in a state of very early development. These underdeveloped infants have to crawl on their own power to the safety of their mother's pouch, where they develop further over many months. How would a cloned tiger make it to the devil's pouch? Could it drink devil milk? Would pet food companies have to develop a baby tiger formula?

“I don't know. Perhaps it might be safer if they were attached and suckling,” Karen said hesitantly. Then again, there was the possibility that the devil stepmom might eat it. Some carnivorous marsupials, she pointed out, can give birth to supernumerary young. “They give birth to many more than they can actually carry. But I don't know of a documented case where carnivorous marsupials have cannibalized their own pouch young.”

“I think it would be fed with droppers,” Don added.

Then there was the problem of the young tiger's health. Clones were difficult to bring to term and not always healthy. Dolly (one of twentyseven implantations that survived) had actually been rather sickly. It was suggested she suffered from premature aging. The cloned guar had died two days after its birth from dysentery. And the second cloned banteng suffered from large-offspring syndrome, weighing eighty pounds at birth (twice the normal size), and was euthanized. Don thought some of the
kinks from these early cloning attempts would be worked out by the time the thylacine was cloned. “That was the first experiment,” he said of Dolly. “Fifteen years down the track, I imagine there will be a success rate of at least one in two. It will become much more routine.” Still, it was possible things wouldn't work right immediately. What they were doing was much more difficult than borrowing DNA from a living animal like a sheep. They were making the tiger's DNA, reconstructing it from tiny fragments in their lab.

Ultimately, their goal was to create a living animal that was genetically close enough to have interbred with a thylacine from the nineteenth or early twentieth century. But their creation would be synthetic, its DNA a best-guess reconstruction. Like a cubic zirconia, the thylacine clone would not be quite the real thing. For example, it might be born missing its stripes. If they chose to or needed to, however, they could manipulate the DNA, tweak it, make little changes to fix any problems.

That was a sobering thought—and one that went way beyond natural selection. It began to remind us of some of Alexis's paintings. In one piece called
The Farm
, which imagined the future of biotechnology, he had painted brick-shaped watermelon, a cow with a rectangular body and eight udders, and a chicken with six wings. Would a future thylacine ever be “fixed” along those lines? It had already been suggested that the tiger clones be made bigger and fiercer so that they could be released on the Australian mainland and compete with dingoes. Would cloning scientists create a super-thylacine, immune to disease and with bulletproof skin? What about making them smaller and more docile? Then they could be sold in a late-twenty-first-century pet shop. They could probably even be made to glow in the dark.

We suspected Don would have been horrified if he could have heard our stream-of-consciousness, horror-movie-driven thoughts. His goals were conservation, preservation, and of course knowledge. Still, he recognized the cloning project had a metaphysical dimension.

Even if his team got the DNA perfectly right (no tweaking, no manipulation, a perfect twin), the question remained: Is DNA what truly makes a species or an individual animal?

“It depends on what a thylacine is, doesn't it?” Don said. “Is the
essence of that animal its genetic component, or does it include its behavior and so forth?” Maybe thylacines were passing down information from generation to generation, along with their genes, over tens of thousands of years. Maybe hunting techniques and vocalizations were learned, not innate. Assuming the thylacine clone had a place to live, how would it know what to do?

And what about a place to live? The obvious choice would be to release the tiger clones into protected habitat in Tasmania. David Brower, the longtime director of the Sierra Club, once said, “Wild species are 2 percent flesh and bone and 98 percent place.” Outside its true habitat, the thylacine clone would be nothing but a glorified lab rat. Don agreed. “We want to use this project to reinforce the importance of conserving habitat in Australia. Whatever we'll spend in the lab, we'll need to spend ten times that on habitat protection. We've spoken to the parks and wildlife people in Tasmania, who inform us that there
is
a lot of suitable habitat down there.”

There was just one small problem with that idea. At present, Tasmania does not permit the use of genetically modified crops, let alone the release of genetically modified animals.

Don was undaunted. “There's also habitat that would be suitable in other areas of the country,” he said. In other words, reintroducing the thylacine onto the Australian mainland was a possibility.

“Near Sydney?”

“Well, the Blue Mountains would be fine.”

“Maybe they could move in with the flying foxes in the botanical gardens,” Alexis chimed in. Alexis was more comfortable with blurring boundaries than most people. In one of his paintings,
Rat Evolution
, an everyday rat was transformed over a series of three mutations into a freakish species of the future, a furless, kangaroo-like beast with armor-plated hindquarters and six-inch-long incisors. Perhaps the Evolutionary Biology Unit would want to look into making those superpowered dingofighting tigers after all.

We only had one more question: “Do you think there's any possibility that the tiger isn't extinct?”

Karen laughed. “Some people still swear they see them.”

Don took it more seriously.

“I'm presuming it's extinct,” he said carefully.

“What about the people who believe the tiger's still out there?”

He paused. “Let's hope it is.”

We knew he didn't believe it for a second. But it was a happy thought. If nothing else, it would make his job a whole lot easier.