One recent morning, inside a renovated camel barn, across town from the White House, and just past a refrigerator on which a form was posted, listing portions of bamboo and something called “Leaf Eater Food, Gorilla,” four adult humans sat with their gazes fixed on a bank of video screens on which absolutely nothing was happening. Everyone in the room was delighted. The images being transmitted were of two creatures in an enclosure in an adjoining room. One of them looked like a large, fuzzy soccer ball—its shape, proportions, and black and white markings were reminiscent of a MacGregor Classic Size 5. The other was the considerable bulk of a middle-aged female Ailuropoda melanoleuca, a giant panda, named Mei Xiang. Mei and the cub, which was born in late summer and is named Bao Bao, were both sound asleep. Except for the slightest flutter of fur rising and falling with their breath, they were absolutely motionless. The audio feed from the enclosure was more nothingness, just a low rushing whoosh made by air passing over a microphone. The observers were nevertheless transfixed as the pandas continued their deep, still sleep. Minutes ticked by. On the screen, one paw flicked, and then the animals resumed their pure repose. The hypnotic appeal kept everyone in the room almost as still and silent as the bears, all eyes on the screens. “Great morning,” one of the observers finally murmured. “Everything is just perfect.”

Whatever strange twists and bends evolution took to create the giant panda worked devilishly well to create an animal that is irresistible. Even inert, they have charisma. That morning, as I sat in the control room of the National Zoo’s Panda House, Mei and the cub offered little more than that one slight flick of a paw and a few minutes later, one small adjustment of their sleeping positions, and yet I had to be dragged away from the screens when it was time to go. The number of people who have volunteered to monitor the cameras and log each minute of the baby panda’s life—a job that could define the word “tedium”— far exceeds the number needed. It is easy to enumerate the elements that contribute to the panda’s allure. Take one part overly large, childlike head; add big eyes (made to appear bigger by black eye patches), rounded ears, chunky build and snazzy fur. Add the fact that pandas rarely kill anything, and their usual posture—sitting upright, bamboo stalk in hand, expression Zen-like, or bumbling along pigeon-toed, wagging their short, flat tails—and you have built the perfect beast. As Brandie Smith, a curator of mammals at the National Zoo, said recently, pandas are the umami of animals; they are simply delicious. It seems that we have the equivalent of panda taste receptors that leave us besotted at the mere sight of one, even when it is sound asleep, curled up in a ball, doing nothing other than being a panda.

If they were simple, they might not be as marvelous. Instead, pandas are peculiar: They are a one-off, limited-edition animal model that has guarded many of its secrets, in spite of the fact that it has been scrutinized by zoologists for decades. Even the basic question of what they are—whether they are more bear or more raccoon or something else altogether—is still tossed around. A study in 1985 by Stephen O’Brien of the National Cancer Institute used molecular analysis to definitively classify pandas as members of the bear family, but they are definitely weird bears. Unlike other bears, for instance, they are not hunters. (Instances of a panda eating another animal are so unusual as to be newsworthy; last year, when a panda in China scavenged the carcass of a goatlike animal, it made headlines for days.) Unlike other bears, pandas do not hibernate. They do not roar in a bear-like fashion. In fact, Smith showed me a video of Bao Bao being examined by zoo veterinarians, and the sound she made sounded exactly like a teenage girl whining, “Owwww! Owwww!” As an adult, Bao Bao will bleat like a sheep. In the meantime, she will grow one of the few functionally opposable thumbs in the animal kingdom. She will use her thumb to strip leaves off her beloved bamboo. When she is mature, she will have a once-a-year estrus of one to three days, during which she will show the only flicker of interest in other pandas she will ever demonstrate; the fact is that the pandas we adore so much simply don’t adore each other. (They hardly tolerate each other’s company.) After her brief coupling up, the panda will have a hormonal surge that will seem to indicate that she’s pregnant, but the surge occurs whether she is pregnant or not. This makes it nearly impossible to tell the difference between a real panda pregnancy and a “pseudo-pregnancy” until the day a cub is born (or not) approximately four months later, which is why there always seems to be such breathless anticipation when a captive panda reaches the end of what might be a real gestation. It’s a lot like a royal baby watch, but with one major difference. When the Duchess of Cambridge is pregnant, there’s no question that she’s pregnant; a panda, on the other hand, keeps you guessing. In short, the panda is the classic mystery wrapped in an enigma, delivered in the most endearing package in the world.

These days, captive pandas are made, not found. Mei’s cub, for instance, is the happy result of artificial insemination. Even though Mei Xiang and the zoo’s male panda, Tian Tian, mate, they aren’t very good at it, so the zoo veterinarians inseminate Mei for insurance each time she is in estrus. In a small, crowded room across the zoo property from the panda enclosure, the reproductive physiologist who did the actual insemination, Pierre Comizzoli, showed me several small metal tanks that contain frozen sperm from many species at the zoo, including samples from Tian Tian, Bao Bao’s father. In another of the panda’s many oddities, it has very hardy sperm. Unlike, say, bull semen, panda semen does well when it’s cryopreserved at minus-200 degrees Celsius. Strangely enough, that hardy sperm produces one of the tiniest babies in the animal world, proportionately speaking: A 250-pound panda delivers a cub that is about the size of a stick of butter, and as fragile and helpless as a china doll.

Are pandas some sort of evolutionary mistake? Their scarcity sometimes makes it seem that way, and so does their eccentricity—the finicky diet, the fleeting day of fertility, the tiny cubs. But that’s not quite so. Their diet is one note, but that one note happens to be among the most abundant forms of vegetation on the planet. Still, bamboo is an odd choice, and scientists have determined that it actually wasn’t the panda’s first choice of meals: Panda ancestors were carnivorous distant cousins of hyenas, saber-toothed cats and badgers. Pandas’ digestive tracts are designed for meat, and they don’t have the long, redundant stomach system of grass-eaters like cows—in other words, they eat a lot of bamboo, but they don’t digest it very well. So why not stick with meat? Apparently, in the course of evolving, pandas lost the taste receptor for high-protein foods. They simply weren’t attracted to meat anymore. Scientists aren’t sure why this happened. Whatever the reason, the result was an appetite for leafy greens, and fortunately, the pandas’ range was covered with bamboo forests that kept them nourished, even though an adult has to eat bamboo almost constantly to maintain its body weight.

The panda’s brief window of breeding might be vexing to zoo staff trying to get their pandas pregnant, but in the wild, pandas have had no trouble reproducing. They are a species way off in the margins, but these were comfortable margins until development began its squeeze on their habitat. In fact, the newest surveys of China’s wild panda population are rumored to contain good news: The number of animals in the large preserves appears to be growing. This suggests that pandas are not a misfit species, dwindling because of their own bad engineering, but instead, a special animal so finely in tune with its environment that any change puts the species in jeopardy.

We are so smitten with the pandas we are able to see in captivity that it’s easy to forget the ones we don’t see, the wild ones that carry on in their solitary, bamboo-crunching way, almost entirely hidden from view in the snowy folds of China’s mountains. At the Smithsonian Conservation Biology Institute in Front Royal, Virginia, I met with a few of the dozen or so researchers who spend their time worrying about those pandas. According to David Wildt, the head of the species survival team, it is sometimes a thankless and often unglamorous task; much of the time, after trekking through hard terrain in lousy weather, researchers end up seeing lots and lots of panda feces but no pandas. There is much to learn even from that, but it couldn’t compare with the pleasure of encountering one of these almost magical animals, especially in its own domain. The strange equation of evolution has created an unusual animal like the panda, as well as having induced in humans a powerful desire to look at pandas, however we can.

Sometimes, of course, the scientists in the field do get lucky. One of the researchers I met at Front Royal, Wang Dajun, a research scientist at Peking University who trained with the Smithsonian and collaborates with the species survival team, spends most of his time tracking pandas on the preserves in western China. He was explaining to me that wild pandas’ elusiveness is more a matter of their hard-to-navigate habitat and their solitary behavior, rather than any fear of humans; they don’t actually seem to mind humans very much. He began to grin, and then explained that one female panda that was tracked beginning in 1989 had become particularly relaxed in his presence. She was so relaxed, in fact, that one spring morning, as she was walking with her cub, she turned to Wang and indicated that she wanted him to babysit so she could head off to feed. Another scientist filmed this episode of Wang providing panda child care. In the video, now posted on YouTube, you will be struck not only by the amazing sight of a panda cub tumbling and frolicking with Wang, but also by the look of utter joy on Wang’s face as he scratches the cub’s belly, extracts the sleeve of his jacket from the cub’s inquisitive grip, and, then, at one point, hoists the cub up in the air and dances with him. “That,” Wang writes on the YouTube page, “was best time in my life.”