China Turns to Genetics in Bid to Save Its Pandas

The babies were weeks overdue, and until hours before their birth, nobody even knew for sure if the mother was pregnant. But after days of nail-biting and pacing--by both Cheng Cheng the panda and her keepers--the gentle-looking bear gave birth Thursday morning to twins.

Pandas, one of the world’s fastest-fading species, are also among the most mysterious. The black-and-white creatures are called “living fossils” because of the way their breeding patterns have failed to evolve. Their reproductive habits, including a unique “free-floating” egg that keeps scientists guessing, still perplex experts armed with the most modern technology.

Only about 1,000 pandas are left in the world--Cheng Cheng’s offspring increased the global panda population by 0.2%--and as their natural habitat in China’s high-altitude bamboo forests shrinks, so do their chances of perpetuating the species.

“Left to their own devices, extinction of the panda is inevitable,” says scientist Wang Pengyan, the deputy director of the Wolong panda reserve in central China. “Our job is to extend the time that pandas will be in the world.”

This means everything from artificial insemination and test-tube babies created from the eggs of a dead panda to a new, ambitious attempt to clone pandas. Such efforts are exacerbating conflicts between environmentalists and scientists--and have launched a race between cloning specialists East and West.

Critics say that genetic manipulation should be a last resort. But in the meantime, pandas need to work on their chemistry. Not only is the female extremely picky about her mate, she goes into heat only once a year, and then only for about 72 hours. To make matters worse, males, especially the ones in captivity, are not known for their sexual prowess. Not only are their sexual organs diminutive--about thumb-size--but they are not always sure how to use them.

“He may think he knows what he’s doing, but he can’t really tell,” says Zhang Guiquan, the assistant director of the Wolong panda reserve in Sichuan province. “He may try her ear, or wherever, until he finally figures it out or she gets irritated and walks away.”

Genetic Replication an Inspiration

Faced with the pandas’ lack of ardor, Chen Dayuan, a professor at the Institute of Zoology of the Chinese Academy of Sciences, is taking their survival into his own hands. Inspired by Dolly, the sheep cloned in 1996 at the Roslin Institute near Edinburgh, Scotland, and the recent successful cloning of a cow in New Zealand and mice in Hawaii, the embryologist hopes to use the method to save the endangered species.

A patch of skin taken from the belly of a panda during an unrelated operation will provide the cells for cloning. But because of objections to using the rare pandas as experimental animals, Chen is attempting a trans-species cloning: implanting a panda embryo into a surrogate mother of another species, such as a black bear. Dolly the sheep and the other successful clones were implanted in the same species.

“Trans-species cloning has never been done before,” Chen says from his laboratory in Beijing. “It’s very difficult to say whether it will work.”

Researchers around the world are watching the groundbreaking experiments closely, and several U.S. scientists have said they would like to try cloning pandas too--turning the experiments’ success into a matter of national pride.

“Scientists in our country must race with foreign scientists” to be the first to clone China’s national treasure, the official China Youth Daily newspaper wrote. “But unequal funding and research facilities mean we are not beginning at the same starting line.”

But even if the Beijing scientists succeed, the results could do more harm than good, critics warn. Making replicas of existing animals may expand the number of pandas but will limit the gene pool and disrupt natural selection, says Li Guanghan, the director of a panda breeding center in Chengdu who cautiously supports cloning. Chen, the Beijing professor, argues that the scientists will clone an assortment of pandas to breed with wild ones, which will give more of them a chance to mate.

The Chinese Academy of Sciences, which has banned human gene cloning and warned of the environmental dangers of cloning animals and plants, has dropped its ethical objections when it comes to pandas. While the experiments haven’t sparked a philosophical discussion about humans taking over the role of natural creation, it has generated a debate between naturalists and scientists.

“Cloning pandas is just a publicity stunt,” says wildlife biologist William Bleisch, who advised the Sichuan Forest Ministry on how to conserve the pandas’ natural habitat. “It distracts from the real work to be done, which is preserving their environment.”

Success in Breeding Species in Captivity

At the Chengdu Research Base for Giant Panda Breeding--about four hours by car from the panda reserve--where Cheng Cheng gave birth to her twins (Shi Shi and Dian Dian), scientists are doing what they can to help perpetuate the species. Together with the Wolong reserve, they have had the most success in breeding pandas in captivity but have yet to release any into the wild because the bamboo forests are quickly disappearing.

Sichuan’s forests have shrunk by a third, and the lack of trees to absorb rainfall and reduce erosion has turned yearly floods into annual catastrophes. But the disastrous effects of flooding on the Yangtze River this summer brought good news for pandas: a ban on logging in Sichuan province, where the pandas live. “This, more than anything, more than cloning, will help the survival of the pandas,” says panda center director Li.

But until the forest regrows and pandas can once again thrive in the wild, scientists are hedging their bets. A team at the Chengdu center recently plucked eggs from the ovaries of a newly dead female and artificially fertilized them.

“This means we have another source of eggs,” says the lead scientist, Zhang Meijia. “Even though the female was not breeding age, not in season, and, uh, not alive, the eggs were still viable.”

Difficulty Discerning if the Animal Is Pregnant

Despite all the technological advances, scientists are still in the dark once the pandas mate or a female is inseminated. “It’s nearly impossible to tell if they’re actually pregnant,” says San Diego Zoo public relations officer Barbara Ayers, who was on a research exchange at Wolong. San Diego is conducting a similar birth watch with a female panda who is at least several weeks, maybe months, overdue. “Even with ultrasound, the fetus is so small it’s like looking for a needle in a haystack.”

One of the reasons it’s so difficult to tell is because of the free-floating egg. After the egg is fertilized, whether naturally or artificially, it can float around the uterus for up to three months before embedding in the lining and starting to grow. That makes estimating a due date difficult; unlike with humans and other animals, even detectable hormonal levels don’t offer a clue.

The ambiguity bothers the scientists more than the pandas, of course. But because newborn pandas are so tiny--about the size of the palm of a hand--the doctors want to witness the birth to keep the babies from being accidentally squashed by their lumbering mothers.

Twins are common--more than half of births--but the survival of both cubs is not.

Mother pandas must clutch the tiny babies to their nipples to nurse, and many find it too difficult to hold both cubs and feed themselves as well. Minutes after a recent birth in the Wolong reserve, keepers scooped a mewling twin out of the way with a long-handled net just before the mother would have stepped on it.

In the Wild, Few Choices of Mate

Pandas in the wild do a little better. But the intrusion of loggers into their natural habitat in Sichuan and Gansu provinces has isolated panda communities from each other and diminished the number of available mates. Instead of selecting the male with the best genes, the female must settle for whoever is available; scientists warn that it could weaken the species’ ultimate survival.

Chen, the head of the cloning team, knows that he doesn’t have the easiest solution, but it may be the only one. “Scientists in different fields have different opinions,” he says. “But I think if left to breed naturally, the pandas’ future is not too promising.”