In late November a humble Iowa cow is slated togive birth to the world’s first cloned endangeredspecies, a baby bull to be named Noah. Noah is agaur: a member of a species of large oxlike animalsthat are now rare in their homelands of India, In-dochina and southeast Asia. These one-ton bovines havebeen hunted for sport for generations. More recently thegaur’s habitats of forests, bamboo jungles and grasslandshave dwindled to the point that only roughly 36,000 arethought to remain in the wild. The World ConservationUnion–IUCN Red Data Book lists the gaur as endangered,and trade in live gaur or gaur products—whether horns,hides or hooves—is banned by the Convention on Interna-tional Trade in Endangered Species (CITES).But if all goes as predicted, in a few weeks a spindly-legged little Noah willtrot in a new day in the conservation of his kind as well as in the preservationof many other endangered species. Perhaps most important, he will be living,mooing proof that one animal can carry and give birth to the exact genetic du-plicate, or clone, of an animal of a different species. And Noah will be just thefirst creature up the ramp of the ark of endangered species that we and otherscientists are currently attempting to clone: plans are under way to clone theAfrican bongo antelope, the Sumatran tiger and that favorite of zoo lovers, thereluctant-to-reproduce giant panda. Cloning could also reincarnate some spe-cies that are already extinct—most immediately, perhaps, the bucardo mountaingoat of Spain. The last bucardo—a female—died of a smashed skull when a treefell on it early this year, but Spanish scientists have preserved some of its cells.Advances in cloning offer a way to preserve and propagate endangeredspecies that reproduce poorly in zoos until their habitats can be restored andthey can be reintroduced to the wild. Cloning’s main power, however, is that itallows researchers to introduce new genes back into the gene pool of a speciesthat has few remaining animals. Most zoos are not equipped to collect and cryo-preserve semen; similarly, eggs are difficult to obtain and are damaged by freez-ing. But by cloning animals whose body cells have been preserved, scientists cankeep the genes of that individual alive, maintaining (and in some instances in-creasing) the overall genetic diversity of endangered populations of that species.Nevertheless, some conservation biologists have been slow to recognizethe benefits of basic assisted reproduction strategies, such as in vitro fertiliza-tion, and have been hesitant to consider cloning. Although we agree that everyeffort should be made to preserve wild spaces for the incredible diversity of lifethat inhabits this planet, in some cases either the battle has already been lost orits outcome looks dire. Cloning technology is not a panacea, but it offers theopportunity to save some of the species that contribute to that diversity.A clone still requires a mother, however, and very few conservationistsSLIM FILMS (illustration); LYNDA RICHARDSON Corbis (orangutan); MARTIN WENDLER Peter Arnold, Inc.(ocelot);GERRY ELLIS Minden Pictures (panda); KENNETH W. FINK Photo Researchers, Inc. (bongo); FRANS LANTING Minden Pictures (cheetah); ROLAND SEITRE Peter Arnold, Inc. (gaur); JOHN CANCALOSI Peter Arnold,Inc. (goat) Copyright 2000 Scientific American, Inc.Cloning Noah’s ArkBiotechnology might offer the best way to keep some endangered species from disappearing from the planetby Robert P. Lanza, Betsy L. Dresser and Philip DamianiCloning Noah’s ArkCopyright 2000 Scientific American, Inc.would advocate rounding up wild fe-male endangered animals for that pur-pose or subjecting a precious zoo resi-dent of the same species to the rigors ofassisted reproduction and surrogatemotherhood. That means that to clonean endangered species, researchers suchas ourselves must solve the problem ofhow to get cells from two differentspecies to yield the clone of one.A Gaur Is BornIt is a deceptively simple-looking pro-cess. A needle jabs through the protec-tive layer, or zona pellucida, surroundingan egg that hours ago resided in a livingovary. In one deft movement, a researchassistant uses it to suck out the egg’s nu-cleus—which contains the majority of acell’s genetic material—leaving behindonly a sac of gel called cytoplasm. Nexthe uses a second needle to inject anoth-er, whole cell under the egg’s outer layer.With the flip of an electric switch, thecloning is complete: the electrical pulsefuses the introduced cell to the egg, andthe early embryo begins to divide. In afew days, it will become a mass of cellslarge enough to implant into the uterusof a surrogate-mother animal previous-ly treated with hormones. In a matter ofmonths, that surrogate mother will givebirth to a clone.In practice, though, this technique—which scientists call nuclear transfer—is not so easy. To create Noah, we atAdvanced Cell Technology (ACT) inWorcester, Mass., had to fuse skin cellstaken from a male gaur with 692 enu-cleated cow eggs. As we report in thecurrent issue of the journal Cloning, ofthose 692 cloned early embryos, only81 grew in the laboratory into blasto-cysts, balls of 100 or so cells that aresufficiently developed to implant forgestation. We ended up inserting 42blastocysts into 32 cows, but only eightbecame pregnant. We removed the fe-tuses from two of the pregnant cows forscientific analysis; four other animalsexperienced spontaneous abortions inthe second or third month of the usualnine-month pregnancy; and the seventhcow had a very unexpected late-termspontaneous abortion in August. The statistics of the efficiency of clon-ing reflect the fact that the technology isstill as much an art as it is a science—particularly when it involves transplant-ing an embryo into another species. Sci-entists, including those of us at ACT,have had the highest success rates clon-ing domestic cattle implanted into cowsof the same species. But even in this in-stance we have had to work hard toproduce just a few animals. For every100 cow eggs we fuse with adult cattlecells, we can expect only between 15 and20 to produce blastocysts. And onlyroughly 10 percent of those—one ortwo—yield live births.The numbers reflect difficulties withthe nuclear transfer process itself, whichwe are now working to understand.They are also a function of the vagariesof assisted reproduction technology.Accordingly, we expect that the firstfew endangered species to be