Dreaming at the frontiers of animal husbandry
Harpers, February 2005
Reprinted from NATURAL ACTS: A Sidelong View of Science and Nature (2008) by permission of W. W. Norton
ONE MORNING EARLY LAST WINTER a small item appeared in my local newspaper announcing the birth of an extraordinary animal. A team of researchers at Texas A&M University had succeeded in cloning a whitetail deer. Never before done. The fawn, known as Dewey, was developing normally and seemed to be healthy. He had no mother, just a surrogate who had carried his fetus to term. He had no father, just a "donor" of al his chromosomes. He was the genetic duplicate of a
certain trophy buck out of south Texas whose skin cells had been cultured in a laboratory. One of those cells furnished a nucleus that, transplanted and rejiggered, became the DNA core of an egg cell, which became an embryo, which in time became Dewey. So he was wildlife, in a sense, and in another sense elaborately synthetic. This is the sort of news, quirky but epochal, that can cause a person with a mouthful of toast to pause and marvel. What a dumb idea, I marveled.
North American contains about 20 million deer. The estimate is a rough one (give or take, say, 5 million), since no one could ever count them. Some biologists suspect that the number is highest now than it was five hundred years ago, reflecting the impacts of European settlement on the American landscape. Predators eradicated, old forests cut or thinned, more second growth, more edges and meadows--these changes are happy ones for deer. By any measure we've got plenty, and they're breeding like gerbils, poaching lettuce from suburban gardens, overflowing onto highways to become roadkill. Of the two species, mule deer and whitetail, the whitetail (Odocoileus virginianus) is more widely distributed and abundant--more abundant, in fact, than any other large wild mammal on the continent. Given such circumstances, it struck me as odd that someone would use postmodern laboratory wizardry to increase the total. Odder still to increase it, at some considerable cost, by just one. Cloning is expensive. Deer, I imagined, in my ignorance, are cheap.
The news item, drawn from wire services, was only a column filler that didn't offer much detail. It barely alluded to the central question: Why clone a deer? It mentioned that Dewey had been born back in May, seven months earlier, his existence kept quiet pending DNA tests to confirm his identity as an exact genetic copy. That settled, he could now be presented to the world. Dr. Mark Westhusin, of the College of Veterinary Medicine at Texas A&M, spoke for the team that created the fawn, explaining fondly that Dewey had been "bottle-fed and spoil3d rotten his whole life." The item noted that A&M, evidently a leading institution in the field, had now cloned five species, including cattle, goats, pigs, and a cat.
One other claim in this little report (which had the flavor of a reprocessed press release) went unexamined and unexplained: "Researchers say the breakthrough could help conserve endangered deer species." Seeing that, I began planning a trip to Texas.
The notion that cloning might help conserve endangered species has been bandied around for years. Very little such bandying, though, is done by professional conservationists or conservation biologists. One lion biologist gave me a pointed response to the idea: "Bunkum." He and many others who study imperiled species and beleaguered ecosystems view cloning as irrelevant to their main concerns. Worse, it might be a costly distraction--diverting money, diverting energy, allowing the public to feel some bogus reassurance that all mistakes and choices are reversible and that any lost species can be re-created using biological engineering. The reality is that when a species becomes endangered its troubles are generally twofold: not enough habitat and, as the population drops, not enough diversity left in its shrunken gene pool. What can cloning contribute toward easing those troubles? As for habitat, nothing. As for genetic diversity, little or nothing--except under very particular circumstances. Cloning is copying, and you don't increase diversity by making copies.
Or do you? This assumption, like the tone about cheap deer, turns out to merit closer scrutiny.
The people most bullish on cloning are the cloners themselves, a correlation that's neither surprising nor insidious. They don't call themselves "cloners," by the way. Their resumes speak of expertise in reproductive physiology and "assisted reproductive technologies," a realm that stretches from human fertility medicine to livestock improvement, and includes such tasks as in vitro fertilization (IVF, as it's known in the trade), artificial insemination (AI, not to be confused with artificial intelligence), sperm freezing, embryo freezing, embryo transfer, and nuclear transfer (which refers to the information-bearing nucleus of a cell, where the chromosomes reside, not the energy-bearing nucleus of an atom). There's also a process called ICSI (pronounced "icksy"), meaning intra-cytoplasmic sperm injection, helpful to elderly gentlemen whose sperm cells can no longer dart an egg with the old vigor. The collective acronym for all such assisted reproductive technologies is ART. To its practitioners, cloning is just another tool in the ART toolbox.
These ARTists are smart, committed people. Like others who feel a vocational zeal, they do what they believe in and believe in what they do. Blessed is the person so situated. But in their enthusiasm for cloning research, in their need to justify their time and expenditures to boards of directors, university deans, or the public, they send their imaginations to the distant horizon for possible uses and rationales. See what cloning could do for you, for society, for the planet? Some of the applications they propose are ingenious and compelling. Some are tenuous and wacky. Three of the more richly peculiar ones, each fraught with complexities and provocations, are cloning endangered species, cloning extinct species, and cloning pets. College Station, Texas, home of Dewey the duplicate deer, is where I picked up the sinuous trail that interconnects them.
"So this guy brought these testicles to me," says Mark Westhusin, as we sit in his office at Texas A&M's Reproductive Sciences Laboratory on the edge of campus. The testicles in question, he explains, came from a big whitetail buck killed on a ranch in south Texas. The fellow had got hold of them from a friend and, intending to set himself up as a "scientific breeder," hoped that Westhusin could extract some live semen for artificial insemination of his does.
Westhusin, an associate professor in his mid-forties, is an amiable man with a full face and a fashionably spiky haircut. He has already explained to me about "scientific breeders," the term applied to anyone licensed by Texas for the husbandry of trophy-quality deer. Deer breeding is a serious business in Texas, where the whitetail industry accounts for $2.2 billion annually, and where open hunting on public land is almost nonexistent, because public land itself is almost nonexistent. Most deer hunts here occur on private ranches behind high fences, allowing landowners to maintain--and to improve, if they wish--their deer populations as proprietary assets. Texas contains about 3.5 million whitetails, some far more valuable than others. An affluent hunter, or maybe just a passionate one, might pay $20,000 for the privilege of shooting a fine buck. A superlative buck, a giant-antlered prince of the species, can be worth $100,000 as a full-time professional sire. And the market doesn't stop at the Texas border. Westhusin has heard of a man who had a buck--it was up in Pennsylvania or someplace--for which he'd been offered a quarter million dollars. He didn't take it, because he was selling $300,000 worth of that buck's semen every year. Such an animal would be considered in Westhusin's lingo, "clone worthy."
Now imagine, Westhusin tells me, that they're collecting semen from that deer one day, and the deer gets stressed, and it dies. Damn. So what do you do? Well, one answer is that you take cells from the dead buck and then clone yourself another animal with the same exact genotype. While you're at it, you might clone four or five.
"You're certainly not going to go out and clone any old deer just for the sake of cloning it," he says. Then again, when you're practicing--when you're developing your methods on a trial basis--you won't wait for the Secretariat of whitetails. The buck from south Texas, the one whose testicles landed in Westhusin's lab, wasn't superlative but it was good, and the experiment evolved haphazardly.
Working with his students to extract the semen, Westhusin suggested also taking a skin sample from the buck's scrotum, on the chance they might find a use for it. We'll grow some cells," he said, "and maybe, later on, if we have the time and the money, we'll do a little deer-cloning project." Eventually the effort produced a few dozen tiny embryos, which were transferred into surrogate does, resulting in three pregnancies, one of which yielded a live birth. That was Dewey, born May 23, 2003, to a surrogate mother known as Sweet Pea. The donor buck remained nameless.
The fellow who brought in the testicles remains nameless, too, at least as the story is told by Mark Westhusin. "People don't want it to get out that they've got these huge, huge deer on their ranch. Because then the poaching gets so bad," Westhusin says. Down in south Texas, people circle their land with high fences not just to keep the deer in but to keep the poachers out.
Dr. Duane C. Kraemer, a senior scientist and professor at the Texas A&M veterinary college, is also sometimes called Dewey, though not by visiting journalists or staffers reluctant to presume. He's a gentle, grandfatherly man with pale eyes and thinning hair, whose casually dignified style runs to a brown suit and a white pickup truck. His ART specialty is embryo transfer, and that's the step he oversaw on the deer-cloning project.
Kraemer was the mentor of Mark Westhusin, who did his doctorate at A&M and then worked for several years in the private sector before returning as faculty. The relationship between academic reproductive physiologists and the livestock business tends to be close, even overlapping, because this is a practical science. There's money in assisting the reproduction of elite bulls, cows, and horses, and that money helps fund research. Kraemer himself, raised on a dairy farm in Wisconsin, has been at A&M for much of the last fifty years, during which time he took four degrees, including a Ph.D. in reproductive physiology and a D.V.M., and performed the first commercial embryo transfer in cattle.
Working on yellow baboons, a more speculative project with implications for human medicine, he did the first successful embryo transfer in a primate. He also did the first embryo transfer in a dog and the first in a cat. Embryo transfer isn't synonymous with cloning--the embryo being transferred needn't be a clone--but it's a necessary stage of the overall cloning process. Within that specialty, and beyond it, Kraemer has been a pioneer. In the late 1970s, he and colleagues engineered the birth of an addax, a rare African antelope, using artificial insemination with sperm that had been frozen. People at the time asked, Why work with addax? The species, Addax nasomaculatus, didn't seem endangered. Now it's extinct everywhere except for a few 0patches of desert in the southern Sahara. After five decades of quietly working the boundary zone between veterinary medicine and reproductive science, Kraemer is one of the patriarchs in the ART field. Dewey the deer was named in his honor.
For Kraemer, the impetus to work with wildlife came partly from his students, some of whom asked him to teach them skills that might be applied to endangered species. Semen freezing and artificial insemination were proven techniques twenty-five years ago. Embryo transfer and in vitro fertilization showed great promise. Cloning--that was a dream. Kraemer had some small grants to support the student training, but after graduation his young people faced poor odds of landing a job in wildlife or zoo work. "We had told them right up front," he says. "You better have another way of making a living, and you may have to do this on the side." Mark Westhusin, for one, took a job doing research for Granada Bio-Sciences, part of a large cattle company.
Kraemer meanwhile established an effort he called Project Noah's Ark, aimed at putting students and faculty into the field with a mobile laboratory. The lab, in a twenty-eight-foot trailer, was equipped for collecting ova, semen, and tissue samples from threatened populations of wild animals in remote settings, such as the desert bighorn sheep in west Texas. The project's three purposes were to train students, to research techniques, and to preserve frozen tissue samples for possible cloning. Presently the trailer contains a surgical cradle capable of holding an anesthetized bighorn, a portable autoclave (for sterilizing instruments), a laparoscope with fiber optics (for extracting ova from ovaries), three 50-amp generators, and an earnest sign: "Ask not only what Nature can do for you, but also what you can do for Nature.--D. C. Kraemer." Asking what he cold do for Nature by way of assisted reproductive technologies didn't bring Kraemer much financial support. The training ahs gone forward, but the ark itself is in dry dock.
Animal cloning began, back in 1951, with frogs. Robert Briggs and Thomas J. King were embryologists, based at a cancer-research institute in Philadelphia, with a medical interest in understanding how genes are turned on and off during embryo development. Briggs, the senior man, figured that a cloning experiment might bring some insight. What he envisioned was transferring the nucleus of a frog cell, taken from an embryo, into an enucleated frog egg--that is, one from which the original nucleus had been scooped out like the pit from an olive. King, hired for his technical skills, would do the micromanipulation, using delicate scissors and tiny glass needles and pipettes. The transferred nucleus would contain a complete set of chromosomes, carrying all the nuclear DNA required for guiding the development of an individual frog. If things went as hoped, the reconfigured egg would divide into two new cells, divide again, and continue dividing through the full course of embryonic growth to yield a living tadpole. From 197 nuclear-transfer attempts, Briggs and King got 35 promising embryos, of which 27 survived to the tadpole stage. Although the success rate was low, barely one in eight, their experiment represented a huge triumph. They had proved the principle that an animal could be cloned from a single cell.
Two questions followed. First, could it be done with mammals? Second, could it be done not just from an embryo cell, as DNA donor, but from a mature cells snipped off an adult? The second question is weighty because cloning from embryo cells is, except under special conditions, cloning blind. If you don't know the adult character of an individual animal--is it healthy, is it beautiful, is it swift, is it meaty, does it have a huge rack of antlers?--why take pains to duplicate it?
For decades, both questions remained in doubt. Nobody succeeded in producing a documented, credible instance of mammal cloning. One researcher claimed to have cloned mice, but his work fell under suspicion, and it could never be verified or repeated. In 1984 two developmental biologists went so far as to state, in the journal Science, that their own unsuccessful efforts with mice, as well as other evidence, "suggest that the cloning of mammals by simple nuclear transfer is biologically impossible."
Well, no, it wasn't--as proved, that very year, by a brilliant Danish veterinarian named Steen Willadsen. Unlike the developmental biologists who experimented with frogs or laboratory mice, but like Kraemer and Westhusin, Willadsen focused on farm animals. Working for the British Agricultural Research Council at a laboratory in Cambridge, he achieved the first verified cloning of a mammal. He did it--a dozen years before the famously cloned bovid, Dolly--with sheep. He took his donor cells from early sheep embryos, which had not yet begun to differentiate into the variously specialized cells (known as somatic cells) that would eventually form body parts. Such undifferentiated cells, it seemed, were crucial. Transferring one nucleus at a time to one enucleated ovum, fusing each pair by means of a gentle electric shock, following that with a few other crafty moves, Willadsen got enough viable embryos to generate three pregnancies, one of which yielded a living lamb. The following year, afloat on his reputation as a cloner, he left Cambridge for Texas, hired away by the same cattle company, Granada, that soon afterward would also hire Mark Westhusin.
"And so," Duane Kraemer says, "Dr. Willadsen then came and taught us how to do cloning."
But Willadsen couldn't teach them to clone an animal from a skin sample sliced off a buck's scrotum, because he hadn't solved the special problems of cloning from somatic cells. Between early embryo cells (which all look alike) and somatic cells (specialized as skin, bone, muscle, nerve, or any sort of internal organ) lurks a deep mystery: the mystery of development and differentiation from a single endowment of DNA. Each cell in a given animal carries a complete copy of the same chromosomal DNA, the same genetic instructions; yet cells respond differently during development, fulfilling different portions of the overall construction plan, assuming different shapes and roles within the body. How does that happen? Why? What tells this cell to become skin, that cell to become bone, another to become liver tissue? What signals them to implement part of the genetic instructions they carry, and to ignore all the rest? Big questions. Cloning researchers, if they were ever to produce an animal cloned from an adult, didn't necessarily need to answer those questions, but they needed to circumvent them. They needed to erase somehow the differentiation of the donor DNA, and to conjure it into operating as though its role within a living creature had just begun anew.
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That's what Ian Wilmut, Keith Campbell, and their colleagues in Scotland managed in 1996, using some further touches of biochemical trickery. The result was Dolly, her existence revealed in Nature the following year. Dolly's donor cell came from the udder of a six-year-old Finn-Dorset ewe. Her birth was significant, because it meant that cloner could now shop before they bought.
Lou Hawthorne, a cagey businessman with a trim beard, a weakness for droll language, and a soft heart for animals, tells me now the notion of dog cloning arrived at Texas A&M. Hawthorne is the CEO of a California-based company called Genetic Savings & Clone, which offers the services of "gene banking and cloning of exceptional pets." Another man, Hawthorne's chief financial backer, who prefers to avoid media attention, set the enterprise in motion with a personal whim. "It was just one morning, he was reading the paper," says Hawthorne. "Dolly had been cloned. There was an article about it, and he said, 'I think I'd like to clone Missy. I can afford it.'"
The "he" refers to John Sperling, founder of the Apollo Group, a $2 billion empire that encompasses, among other things, the University of Phoenix, a lucrative enterprise in higher education for working adults. Missy was ten years old at the time of Sperling's brainstorm, a dog of unknown lineage but winning charms, adopted from a pound. Asked by Sperling to make inquiries, Lou Hawthorne solicited proposals from a dozen laboratories, the best came from Texas A&M.
Westhusin remembers telling Hawthorne that they could give it a try but that trying might cost a million dollars a year, take five years, and still be uncertain of success. Okay, said Hawthorne. John Sperling, as he'd declared, could afford it. So the R&D effort toward producing a duplicate Missy--or maybe a multiplicity of copies--began at College Station in 1998. Hawthorne, a word man among scientists, named it the Missyplicity Project.
At the start, it was a joint venture between Texas A&M and an earlier company led by Hawthorne, the Bio-Arts and Research Corporation. Missy contributed a patch of skin cells, which were multiplied by culturing in vitro and then frozen for future use. Westhusin's team gathered a pool of female dogs to serve as egg donors. The eggs, harvested surgically from the oviducts whenever a dog showed signs of ovulation, where emptied of their nuclei using micromanipulation tools (tiny pipettes guided by low-gear control arms within the field of a binocular scope) and then refitted with Missy's DNA by nuclear transfer. These refitted cells were nurtured in the laboratory until some of them showed good embryonic development. Promising embryos were then implanted surgically in ready (that is, estrous) surrogate mothers. Among the factors that make dog cloning difficult is that female canines come into estrus irregularly. Unless you're keeping a riotous kennel, you may not have a bitch in heat when you need her. Westhusin and his Missyplicity partners struggled against that limitation and others for almost five years.
Missy herself died in 2002, still unitary, uncloned. But of course it isn't too late. Her genome is on ice.
Meanwhile, two interesting new entities were born in College Station. One was a cloned cat, the world's first, a little domestic shorthair kitten given the name CC, standing for "copycat." The other was Hawthorne's present company, Genetic Savings & Clone, a for-profit enterprise devoted to the gene-banking of pets (in the form of frozen cells) toward the possibility of their eventual cloning. CC, created with nuclear DNA from a calico donor named Rainbow, was delivered by cesarean section just before Christmas of 2001. GSC came into being in response to popular demand.
Alerted to the Missyplicity Project by press reports, dog and cat owners had begun contacting the A&M lab. Some were grieving over recently deceased pets; some were concerned in advance over old animals or sick ones. "We're supposed to be focusing on research here," Westhusin recalls thinking, "and we don't have time to take fifteen phone calls a day and talk to these people about their pets." The callers tended to be emotional, poorly informed, and hopeful. "I buried him three days ago. Do you think there's any chance if I go dig him up that you could get cells off him?" Um, I doubt it, Westhusin would say. "Well, the temperature up here is cold. It's Minnesota..." Westhusin laughs pityingly and so do I. "You want to be nice," he says, "So you sometimes will spend thirty minutes talking on the phone." With the founding of Genetic Savings & Clone, all that grief counseling could be outsourced. Dr. Charles R. Long, another reproductive physiologist and an old friend of Westhusin's was hired to get the company launched. As general manager, he recruited technical staff and established a research lab to work in partnership with the A&M people. Occasionally he found himself playing psychologist to prospective customers, as Westhusin had done. "The people, the overly emotional ones, many times I would quite frankly try to convince them not to make this decision," Long says. Why? Because they were doing it for the wrong reason. "They were doing it to try to get their special animal back, and you can't get your special animal back. There's no such thing as resurrection. At least not in pets." What you get is just a genetic copy, a new animal with the old DNA, "and it's really important for people to understand that." Chuck Long is a bright, unpretentious man with a small neat mustache, the neck of a linebacker, and huge hands. He once loved a golden retriever named Tex, but he wouldn't have cloned the animal. A loving relationship is about discovery. He'd rather discover a new friend than try to relive life with Tex Two.
Where do people get their misguided ideas about cloning? I ask.
"Hollywood," says Long.
Half ignoring his answer, I press: Do they get them from scientists who oversell the technique or from the media?
"From Hollywood, I think," he repeats. "You know, crazy movies like Arnold Schwarzennegger's The 6th Day."
"Was he a clone in that?"
"Yeah, they cloned him."
"I haven't seen that one."
"You've got to see The 6th Day. It really stinks."
After a couple of years at Genetic Savings & Clone, Chuck Long parted ways with Lou Hawthorne, and he now works more comfortably for a Texas company, Global Genetics and Biologicals, involved in the production and international export of elite livestock. GSC itself has severed its partnership with Texas A&M and relocated its headquarters to Sausalito, California, with offices overlooking a kayak beach.
Genetic Savings & Clone isn't the only company that sells a gene-banking service for pets; you also might turn to Lazaron BioTechnologies or PerPETuate, Inc. But GSC alone offers the full deal: delivery of clonal duplicates in the near future. The initial costs of putting your pet's genes into a gene bank is $895. Annual storage runs $100. Dogs, with their unique physiological complications (such as opacity of the eggs, making them harder to enucleate), are still problematic. But commercial cat cloning got under way in 2004, with five clients committed, and if all goes well, their cats will be delivered very soon. "In pet cloning," says Hawthorne, "People have an animal that they perceive is extraordinary. IN some cases, it's just a perception." IN other cases, the extraordinariness is more objective. "You can have an extraordinary mutt," he says. "You can have an animal that has extraordinary intelligence. Extraordinary good looks." Insofar as those traits are genetic, they can be reproduced by cloning, maybe. The delivery price of a healthy young feline, custom created from DNA of proven appeal, guaranteed to resemble closely your old feline, is $50,000. If you think this might met your emotional expectations, act now.
On the other hand, $50,000 buys a lot of pretty good cats.
Cloning endangered species is a different matter. For starters, who pays? Why does anyone finance this technical approach, seemingly so marginal, rather than putting the money toward basic necessities such as habitat protection? And how can cloning possibly freshen a gene pool that's been reduced to a stagnant puddle? I carry these questions to Dr. Betsy Dresser, director of the Audubon Center for Research of Endangered Species, near New Orleans. ACRES is part of the Audubon Nature Institute, a non-profit group of museums, parks, and other facilities (with no connection to the National Audubon Society). Dresser, who ran a similar research center at the Cincinnati Zoo before to New Orleans, has long been a leader in applying captive-breeding efforts and assisted reproductive technologies to endangered species.
She's a brisk, congenial woman, but not easy to get to. ACRES is tucked away in a sunny new building surrounded by bottomland forest at the end of a country road outside the city, on the west bank of the Mississippi River, beneath a towering levee. The land, 12,00 acres of what once was sugar plantation, is protected by a fence and a guardhouse with an electric gate. A sign says "Freeport McMoRan Audubon Species Survival Center," recognizing the patronship of a mining company in establishing this compound. ACRES itself was created with a $15 million appropriations from the U.S. Fish and Wildlife Service. It resembles the visitor's center of a well-funded state park, but more private. On a morning in April, the air is redolent of honeysuckle. I arrive in time to watch surgery on a domestic cat.
Dr. C. Earle Pope, in a blue smock and mask, is harvesting ova. Several other figures, also in blue, assist him around the operating table. The cat has already been anesthetized and opened, its ovaries exposed. Pope wields a fine forceps in one hand, a hollow steel needle in the other, his head raised to view the target area, which is magnified on a video monitor. He works with easy skill derived from years of experience. The hollow needle is backed by a suction device that feeds into a glass vial on a table nearby. With the forceps, Pope gingerly lifts one ovary so that its follicles (the small, bulbous ovarian sacs) protrude like grapes on a bunch. With the needle, he punctures a follicle and sucks out the egg, then moves to another. The ovary bleeds slightly. Poke, suck, poke, suck,, the eggs are whisked away. They accumulate in the vial. When Pope has emptied the follicles of both ovaries, an assistant collects two orange-capped vials and passes them through a window from the operating room to an adjacent lab.
In the lab, which is darkened and barely larger than a closet, a technician moves the eggs from a rinsing solution onto a petri dish. She lifts them, one by one, using an aspirator pipette--that is, with suction applied by her own gentle breath. Her eyes are pressed to a scope. The eggs, surrounded by cloudy globs of ovarian material (called cumulus cells) and air bubbles, are tiny, but they are conspicuous enough to her. You can tell the maturity of ova, she says, by the layers of cumulus cells attached. "These are very good looking." the yield today is twenty-four eggs, about average from a domestic cat. down the hall, she places the petri dish in an incubator. T his afternoon one of Pope's colleagues, Dr. Martha C. Gomez, will enucleate these eggs and endow each with nuclear NDA transferred from an African wildcat.
It won't be the first time such a mix is performed. The African wildcat, Felis silvestris lybica, is a tawny little felid native to Africa and the Middle East, closely enough related to the domestic cat, Felis silvestris catus, to have figured in earlier experiments involving the two subspecies. Using domestic cat eggs, Gomez, Pope, and their team produced three African wildcat clones in 2003, the eldest born on August 6 and named Ditteaux. (That's ditto with Cajun spicing.) The animal from which he and his---his what? not siblings, not twins--two extremely close relatives were cloned, known as Jazz, was itself a product of combined ARTs: the world's first frozen-embryo, thawed-embryo, embryo-transferred wildcat born to a domestic cat. Gomez, Dresser, Pope, and several colleagues co-authored a journal paper on this work, in which they noted that the African wildcat "is one of the smallest wild cats, whose future is threatened by hybridization with domestic cats." A person might ask: If hybridization of a wild subspecies is the threat, in what sense is mixing nuclei from one subspecies with eggs from the other subspecies a solution?
Another skeptical question, which I put to Betsy Dresser, is whether this fancy stuff can somehow mitigate the problem of low genetic diversity in sorely endangered species. If it can't, what's the point? "Well, indeed it can," she says. "What we're trying to do is use cloning to bring in the genetic material from animals that are not reproducing." Among any population, she notes, there are always infertile individuals, marginalized individuals, elderly or unlucky individuals, who fail to breed and so contribute no genes to the next generation. In a large population (though Dresser doesn't mention this point), their exclusion represents Darwinian selection, which drives evolution. But in a very small population (she notes rightly), their participation could be crucial. "If you can use the genetic material from those individuals, it helps widen the genetic pool a bit."
Imagine you've got a captive population of just five black-footed ferrets, with no others surviving on the planet. Four of your ferrets are males, and the fifth is a post-reproductive female. One young male chokes to death while eating a prairie dog with reckless gusto. What do you do? Of course you grab the old female and the dead male, take tissue samples, and clone them. But wait--in this scenario of five, there are no viable black-footed ferret ova to receive the clonal DNA. So you use the next best thing: enucleated eggs from a mink. Then you breed your cloned female with one of the males, breed any daughters she produces with other males, get the cloned male's genes into the reproductive jumble too, and thereby postpone (maybe indefinitely) the doom of your miserable little population. Whether your ferrets ever go back into the wild is another question. Do you dare send them? Do you keep breeding and cloning until you've got a few dozen, a few hundred? All this would be expensive at best and, if you hadn't meanwhile solved the root causes of endangerment (such as insufficient habitat, poaching, or exotic species inflicting too much predation or competition), ultimately futile. No clones of an endangered species, and no descendants of clones, have yet been released to the wild.*
What about the money issue? I ask Dresser. Are resources being diverted that might otherwise pay for habitat preservation? Her answer is candid: "The money that comes to this kid of research is primarily from people that are not going to support habitat." She's a skilled fund-raiser as well as a respected scientist; she has been through this in Cincinnati, now New Orleans, and she knows her constituency. Supporting the research arm of a fine metropolitan zoo is a bit like supporting the symphony, the conservatory, the opera. These people "don't' want to give their money to Africa, or to Asia, or somewhere. They don't want their money in political environments where they're never going to see their name on a plaque." At the various branches of the Audubon Nature Institute, including ACRES, there are more than few grateful plaques.
Back on the city side of the river, I visit the Audubon Zoo on Magazine Street for a glimpse of Ditteaux the cloned wildcat, temporarily on display there. For this interlude of public exposure, he lives in a glass-fronted cage furnished with small boulders, trees, and a six-foot square of scenery meant to approximate northern Africa. He's a handsome animal, lanky and lithe, nervous, his brownish-gray fur marked with pale stripes. As I watch, his pale green eyes come alert to something--the sight of a squirrel outside the building, visible through an opposite window.
Groups of schoolchildren pass Ditteaux's cage. A well-fed boy in an orange T-shirt reads the sign and then asks, "It's a clone?" Yes. With some vehemence, he says, "Okay, that's freaky."
Whatever the downside of investing money and time in such an approach to endangered species, at least one private firm has also done it: Advanced Cell Technology, of Worcester, Massachusetts. Founded originally as a subsidiary of a poultry genetics business, ACT now concentrates mainly on human medical issues. The company's work with wildlife is an adventuresome sideline, bearing no such commercial promise as cloning whitetail deer for the trophy market but offering the possibility of a public good, roughly equivalent to pro bono work by a law firm. It also offers, when successful, good publicity.
In early 2001, ACT announced that "the first cloned endangered animal," an eighty-pound male gaur, had been born to a surrogate mother. The gaur is a species of wild cattle, Bos gaurus, native to southeastern Asia from Thailand to Nepal. Calling it an "endangered animal" was mildly misleading; the international body that keeps track of such things classifies the gaur as "Vulnerable," not actually "Endangered," with somewhere between 13,000 and 30,000 individuals in the wild. But the population is declining, and the trend isn't likely to reverse. Vulnerable or endangered, the species deserves attention.
Two technical points made ACT's gaur work especially notable. First, the nuclear DNA came from gaur cells, derived from a tissue sample, that had sat frozen for eight years in a gene bank at the San Diego Zoo. Second, the enucleated egg cell into which the gaur DNA had been transferred came from a domestic cow. So this too was a case of cross-species cloning--in fact, it was the first recorded case, a precursor to the African wildcat project in New Orleans. Arguably, the technique could be valuable in situations when egg cells of an endangered species are unavailable--when there are no surviving females, say, or so few that you wouldn't dare cut one open to harvest her eggs.
What made the case less encouraging was that the baby gaur, named Noah, did of dysentery within two days. Its death fell hard on Robert P. Lanza, a vice president of ACT, who had led the cloning effort.
At that time, Lanza had nearly sealed an agreement with Spanish officials toward cloning an extinct Spanish subspecies of mountain goat, the bucardo. The bucardo (Capra pyrenaica pyrenaica) had languished at desperately low population level throughout the twentieth century, probably because of competition with livestock, diseases caught from livestock, poaching, and other travails. The last one died in 2000, clunked by a falling tree, but provident biologists had arranged to freeze some of its tissue for posterity. Lanza hoped to clone the bucardo back into existence, using the frozen sample for nuclear DNA, a domestic nanny goat as egg donor, and a nanny again for as surrogate to carry the fetus. That plan collapsed with the death of Noah the gaur. Two years later ACT's cloning team tried again, this time achieving the birth of two cloned calves from another species of wild Asian cattle, the banteng, Bos javanicus. The banteng is unambiguously endangered, with no more than 8,000 individuals in the wild. The nuclear DNA came from another frozen sample that had been stored, for twenty-five years, at the San Diego Zoo.
The gene bank in San Diego, loosely known as the Frozen Zoo, was established three decades ago by a pathologist named Kirk Benirschke, who was soon joined by a young geneticist, Oliver A. Ryder. Benirschke and Ryder foresaw that these cell samples might be useful in genetic studies of relatedness among wild species. They didn't foresee that the frozen cells might be cloned back to life. The collection now represents about 7,000 individual animals of 450 different species; about half of those samples came from animals at other zoos and captive facilities, or from the wild. Ryder is still there, the man to see if you want a morsel of rare or endangered DNA fro some legitimate purpose. Cloners across the country, from College Station to Worcester and beyond, point to San Diego's Frozen Zoo as a prescient enterprise that should be emulated widely, preserving as much genetic diversity as possible from endangered species before their populations decline too far. Ryder, for his part, supports the idea of cloning when it might return a valuable genotype to a breeding population. The original banteng whose frozen cells went to ACT, for instance, died in 1980 without offspring, having made no genetic contribution to the captive banteng population. One of the two clones produced form those cells was healthy, and that animal has since been returned to San Diego; its lost genes may eventually be bred back into the zoo population of banteng, possibly adding some much needed diversity.
But gene banking is no panacea. Ryder himself says, "I think it's gonna be a somber day when we realize that the only thing left of a species is something we've got in the Frozen Zoo."
Among extinct species and subspecies, the bucardo goat represents a good prospect for cloning, because the extinction is so recent and the cell sample was properly preserved. Less propitious circumstances, though, don't prevent people from trying to resurrect a lost beast.
Scientists at Kinki University in Japan have begun work toward cloning a woolly mammoth, using tissue samples from a 20,000-year-old carcass recently excavated from frozen Siberian tundra. Elephants, the mammoth's closest living relatives, will serve as egg donors and surrogate mothers, if the project ever gets that far. Cloning researchers at the Australian Museum in Sydney hope to re-crate the thylacine, a carnivorous marsupial loosely known as the Tasmanian tiger, last seen alive in 1936. For that effort, the starting point is a thylacine pup stored in alcohol since 1866. Alcohol is a gentler preservative than formaldehyde, and the Australians have managed to extract Some DNA fragments in fairly good condition--but no complete DNA strands, let alone any viable thylacine cells with nuclei that could be transferred intact. The optimistic Aussies aim to reassemble their squibs and scraps into a full set of thylacine DNA, perhaps patching the gaps with genetic material from other marsupials. Plausible? Not very, according to Ryder. "What's the chance that you could shred the phone book," he asks, "and then drop it out of a window and have it come back together?" Once they have reassembled their phone boo, if they do, the Australians will create artificial chromosomes for insertion into an egg from some related species, such as the Tasmanian devil. Meanwhile in Hyderabad, India, a team led by Dr. Lalji Singh proposes to clone an Asiatic cheetah, a subspecies extinct in India for the past fifty years. They want to use nuclear DNA from a cheetah loaned by Iran, thought Iran itself has only a few dozen cheetahs in the wild, and none of those has been promised so far. If the Indians do get their chance to proceed, the eggs and the surrogate wombs will be furnished by leopards.
Each of these projects, variously dreamy or doable, represents an effort at cross-species cloning, like the banteng-and-cow work by ACT. This sort of trick raises further issues. What are the physiological consequences of mixing nuclear DNA from a cheetah with mitochondrial DNA (which comes along with the enucleated egg and helps regulate the cell's biochemistry) from a leopard? What are the ecological implications of mixing mammoths with elephants in a world where the mammoths' ecosystem no longer exists? What's the merit or demerit of blurring lines between species (cheetah and leopard, thylacine and devil) by means of laboratory gimmickry, in order to "preserve" a vanishing subspecies or "restore" an extinct species in the wild?
Lines, their integrity or transgression, are exactly what's at issue: the line between one species and another that defines biological diversity, the line between one animal and another that constitutes individuality, the line between living and dead that gives meaning--as well as poignant temporal limit--to life. And yet those lines aren't always easy to draw, let alone to enforce or respect. Even species, even in the wild, sometimes blur into one another: wolves breeding with coyotes, blue-winged warblers with gold-winged warblers, barn swallows with house martins, mule deer with whitetails. True, these natural mongrelizations represent exceptions to the rule of how species are generally demarcated. But they complicate any effort to think clearly about drawing other lines, such as the line between Felis silvestris lybica and Felis silvestris catus, the line between embryo transfer and nuclear transfer, the line between genetically modified organisms and heirloom tomatoes (which have themselves been genetically modified by generations of careful horticulture), the line between extinct and merely frozen, the line between what we can do and what we should do, the line between nature and ART.
Recognizing such complications is not necessarily the same as surrendering to a paralyzing relativism. Lines that suggest boundaries of ethical behavior, of judicious balance between opposing concerns, and of precious entities deserving preservation are important even when they reveal themselves, at close inspection, to be smeary zones of gradated gray. The mapping of such boundaries can't be done by science, which is capable of measuring shades of gray but not choosing among them. That leaves religion, philosophy, social consensus, and common sense. Which of those do we rely on for decisions about assisted reproductive technologies, such as cloning, when the species being assisted is not the banteng or the whitetail deer but Homo sapiens?
Consider the prospect of germline genetic engineering--that is, fiddling with genes in human embryo cells before those cells are grown into human fetuses. Germline engineering is not yet available as a consumer option, for medical purposes or any others, but soon it may be. Select genes would be added to, subtracted from, or modified in an embryo cell, after which the cell would be cloned into a customized human child. This process would permit the correction of genetic weaknesses--bad eyesight, for instance, or sickle-cell anemia--in advance of birth. When that starts happening, as Bill McKibben has warned in his book Enough: Staying Human in an Engineered Age, "the line between fixing problems and 'enhancing' offspring" will disappear, at least for any parents who want their kids to be as bright, robust, good-looking, and competitive as humanly (that is, technologically) possible. FI you can repair your future child's myopia with preemptive genetic tinkering, you might also want to increase her I.Q. by a few dozen points. Will it lead to a world as utopian as Lake Wobegon, where all the children are above average? Of course not. It will just add genetic manipulation of embryos and child cloning to the means by which affluent, fussy people try to distance themselves from bad luck, disappointment, menial work, death, and poor people.
McKibben, his ardent humaneness informed by a lot of careful research and thinking, proposes that we should recoil from such possibilities and declare "Enough!" He suggests that somewhere amid the dizzying possibilities of ART as applied to humans, beyond fertility medicine but short of germline genetic engineering, we might locate "the enough line"--that is, the threshold of ugly and corruptive weirdness across which a wholesome person and a wise society do not go.
As much as I want to agree with him, my own survey of animal cloning forces me to conclude that his "enough" line, like any I might try to draw myself, is a subjective as it is sensible. There is, in fact, no line. There is only a spectrum: a set of choices among shades of gray. Of course, that's not to say some choices aren't nuttier than others.
Cloning adult humans, for instance. Any thorough discussion of assisted reproductive technologies comes eventually to this topic, which the animal-cloning scientists detest and dismiss but which other people consider central. The animal guys are right--it's not central--but, like a parrot in a cage of canaries, it's too big and noisy to ignore. What if John Sperling or some other loopy billionaire decides one morning to commission not the cloning of his lovable mutt but the cloning of himself? If that decision hasn't already been made, quietly in a penthouse somewhere, it probably soon will be; and whatever unique technical difficulties or scientific scruples have so far prevented the consummation of such a desire will soon be overcome. Some people view the prospect of human cloning with great alarm. Bill Clinton labeled it "morally reprehensible." His presidential ethics commission recommended federal laws to prohibit human cloning. Finding myself less certain than Clinton or those advisors about moral or legal verities against which human cloning should be measured, I'd simply call it perniciously stupid. Then again, many things people do nowadays are, in my opinion, perniciously stupid. Not all of them are illegal, and so, I suppose, human cloning needn't be either.
Down in College Station, I'm reminded of all this during my chat with Duane Kraemer, when we bounce from the subject of endangered species back to companion animals. Isn't there something misguided, I ask Kraemer, about cloning your pet? Doesn't it reflect an inclination to deny mortality?
Deny mortality? "We do that every day!" he says brightly. "We get up and brush our teeth. Why do we do that? Because we want to live as long as we can. So denial of mortality is, yeah, it's in our being. And it's not only natural. It's necessary."
Two other voices of wisdom echo through my head, addressing aspects of the question why. One of these voices belonged to J. Robert Oppenheimer, the physicist and founding director of the Los Alamos nuclear-weapons laboratory. Trust me on this seeming digression. Having helped build the first atomic bomb, Oppenheimer resisted the notion that America should rush ahead to build a thermonuclear superbomb. It was fission versus fusion, uranium versus hydrogen, kilotons versus megatons, and the global political context of 1943 versus the context of 1951. His resistance was swept aside by a clever design principle concocted by two other physicists, one of whom was Edward Teller. Asked later by an inquisitorial panel about how the H-bomb decision was made, Oppenheimer declined to speak about technical details. "However," he said mordantly, "it is my judgment in these things that when you see something that is technically sweet, you go ahead and do it and you argue about what to do about it only after you have had your technical success." This scary truth, which might be thought of as Oppenheimer's Axiom, explains many controversial gambits in whizbang scientific engineering. Why do some scientists crave to clone animals? Not just because they can but because they can do so--with an elegant medley of ingenious laboratory moves--in a way that is technically sweet. And therefore irresistible.
The other voice comes from Louis Armstrong, as recorded in 1931:
Oh, when skies are cloudy and gray,
They're only gray for a day,
Bay-bay-bay-bee …
So wrap your troubles in dreams,
And dream your troubles away.
Duane Kraemer is right in noting that this methodology isn't unique to assisted reproductive technologies.
On the morning after our conversation, Dr. Kraemer welcomes me to his home, in a neighborhood just north of the A&M campus, to meet the famous cloned house cat, CC. As we enter, she crosses a living room of draped-over furniture and leaps onto a carpeted cat perch, presenting herself for Kraemer's gentle petting. She's no longer a kitten, She arches her back to my touch, then carefully sniffs my hand. Her fur is soft and clean. She looks like any normal cat. The most striking aspect of her appearance, which I wouldn't notice if I hadn't read some background, is that she's a tiger-tabby shorthair, mottled black-and-gray with a white breast and legs. It's striking because she was cloned from a calico.
CC's color pattern is utterly different from that of Rainbow, her DNA donor. T he cause of this difference is complicated (involving random inactivation of one of her two X chromosomes, which in a female such as CC are redundantly paired, though each may carry a distinct gene for color), but it can be simplified in a single word: random. Cloning isn't resurrection, as the man said. It's not even, quite, duplication.
On CC's right check, otherwise white, I notice a small patch of tan fur, like a birthmark. Yes, says Kraemer, that wasn't present in Rainbow either. The genotype may be identical in a clone, but it gets expressed differently. Maybe one day when she was a fetus, inside the surrogate mother, CC rubbed her little face against the wall of the womb. A smudge. Things happen.