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Why Is it so Hard for Pandas to Get Pregnant?

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In the wild, giant panda mating occurs just as nature specials would have you believe. There’s intense competition for each female, and the dominant male will mate with her several times to ensure success. And that strategy works: Wild female pandas generally give birth every two years. But that low birth rate means that captive breeding programs are essential to sustaining the endangered species. And in captivity, mating and successful pregnancies are tricky affairs—which is why it’s always a big deal when a cub is born, and devastating when one dies, as the 6-day-old cub at the National Zoo did last week.

Breeding pandas in captivity requires cooperation from zoos across the world, and is difficult for a number of reasons. Early on, scientists realized that the bears either lost interest in mating naturally or seemed like they didn’t know how. Take, for example, Ling-Ling and Hsing-Hsing, which were given to the National Zoo to commemorate Nixon’s 1972 visit to China. They tried to mate, unsuccessfully, for a decade; once they figured out what they were doing, they had five cubs, but none reached adulthood.

Scientists speculate that the awkward fumbling that sometimes occurs between captive pandas might be because the cubs were taken from their mothers too early and have never seen the deed done; lack of interest in mating might be attributed to lack of competition for the female.

Even if pandas are in the mood, time is working against them. A female is in heat only once a year, in the spring, for 12 to 25 days—but she’s only receptive to mating for two to seven of those days, and she’s only actually fertile for 24 to 36 hours. After that time passes, any more attempts at mating have to wait until the next year. So when scientists aren’t experimenting with other methods to get pandas to go at it—like dosing one male with Viagra or showing a matched pair panda porn—they often rely on artificial insemination to get the job done.

After Mating: The Waiting Game

Neither artificial insemination nor old-fashioned mating will guarantee a pregnancy, and zoologists must bide their time before they know for sure that a panda is expecting. This, too, is complicated. Like many other species, pandas experience embryonic diapause, in which the embryo is fertilized, but not yet implanted in the uterine wall. The offspring can’t continue to grow until it has implanted, so while the gestation period is around 50 days, some panda pregnancies can stretch out to more than 160 days because of diapause.

And as if that all wasn’t difficult enough for zookeepers to figure out, female pandas can experience pseudopregnancy—they aren’t actually pregnant, but exhibit the same behaviors as pregnant pandas (decreased appetite, sluggishness, and even similar changes in hormones). It's almost impossible to distinguish between the two, because recently implanted fetuses are often too tiny to be spotted on an ultrasound. But there are some developments that might help scientists determine whether or not a panda is actually pregnant: Scientists in the reproductive physiology department at the San Diego Zoo used thermal imaging cameras to help determine if their panda, Bai Yun, was pregnant (she was—watch her cuddling with the little guy on the zoo's Panda Cam); the idea is that right before a fetus attaches to the uterus, there is increased blood flow to that area, which will show up as bright red on the camera.

Still, even if a panda is pregnant, and her cub is born, the tiny, blind and toothless young, which is about the size of a stick of butter at birth (or 1/900th the size of its mother), might not survive.

It all adds up to grim odds for pandas: In 2004, there were approximately 1600 left in the wild, and zoos around the world currently hold around 300 of the animals. But despite the rocky start that captive breeding programs had and the ongoing challenges zoos still face, the program has had its successes, especially in the last few years. And as scientists learn more about how these bears mate and raise their young, more pandas will have cubs that live to adulthood.

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Big Questions
Why Does Santa Claus Give Coal to Bad Kids?
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The tradition of giving misbehaving children lumps of fossil fuel predates the Santa we know, and is also associated with St. Nicholas, Sinterklaas, and Italy’s La Befana. Though there doesn't seem to be one specific legend or history about any of these figures that gives a concrete reason for doling out coal specifically, the common thread between all of them seems to be convenience.

Santa and La Befana both get into people’s homes via the fireplace chimney and leave gifts in stockings hung from the mantel. Sinterklaas’s controversial assistant, Black Pete, also comes down the chimney and places gifts in shoes left out near the fireplace. St. Nick used to come in the window, and then switched to the chimney when they became common in Europe. Like Sinterklaas, his presents are traditionally slipped into shoes sitting by the fire.

So, let’s step into the speculation zone: All of these characters are tied to the fireplace. When filling the stockings or the shoes, the holiday gift givers sometimes run into a kid who doesn’t deserve a present. So to send a message and encourage better behavior next year, they leave something less desirable than the usual toys, money, or candy—and the fireplace would seem to make an easy and obvious source of non-presents. All the individual would need to do is reach down into the fireplace and grab a lump of coal. (While many people think of fireplaces burning wood logs, coal-fired ones were very common during the 19th and early 20th centuries, which is when the American Santa mythos was being established.)

That said, with the exception of Santa, none of these characters limits himself to coal when it comes to bad kids. They’ve also been said to leave bundles of twigs, bags of salt, garlic, and onions, which suggests that they’re less reluctant than Santa to haul their bad kid gifts around all night in addition to the good presents.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Big Questions
Who Was Heisman and Why Does He Have a Trophy?
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Brett Deering/Getty Images

On Saturday night, one of three finalists will be named this year's Heisman Trophy winner. But before anyone brings home the hardware, let’s answer a few questions about John Heisman and his famous award.

Who Exactly Was John Heisman?

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His name is mostly associated with the trophy now, but Heisman (right) was a player, coach, and hugely successful innovator in the early days of football. After playing for Brown and then Penn as a collegian from 1887 to 1891, Heisman became a coach at a series of schools that included Oberlin, Buchtel, Auburn, Clemson, Penn, Washington & Jefferson, Rice, and, most notably, Georgia Tech.

For What Football Innovations Does Heisman Get Credit?

Just some little trivial stuff like snapping the ball. Centers originally placed the ball on the ground and rolled it back to their quarterbacks, who would scoop it up and make plays. When Heisman was coaching at Buchtel (which later became the University of Akron), though, he had a 6’4” QB named Harry Clark. Clark was so tall that picking the ball up off the ground was wildly inefficient, so Heisman invented the center snap as an easy way to get the ball in Clark’s hands. Heisman also innovated the use of pulling guards for running plays and the infamous hidden-ball trick.

Any Other Shenanigans on Heisman’s Resume?

You bet. When Heisman found a way to gain an edge, he jumped on it no matter how ridiculous it seemed. When Heisman was coaching at Clemson in 1902, his team traveled to Atlanta for a game against Georgia Tech. Although Heisman was known for being a rather gruff disciplinarian, the Clemson team immediately started partying upon their arrival.

When Georgia Tech’s players and fans heard that the entire Clemson squad had spent the night before the game carousing, they prepared to coast to an easy win. When the game started, though, Clemson roared out of the gate en route to a 44-5 stomping.

How did Clemson crush Tech when by all rights they should have been ridiculously hungover? The “team” that everyone had seen partying the night before wasn’t really Heisman’s Clemson squad at all. He had sent his junior varsity players to Atlanta the night before to serve as drunken decoys, then quietly slipped his varsity team in on a morning train right before the game.

What Kind of Coach Was He?

Heisman worked as an actor in community stock theater during the summer – he consistently received rotten reviews – and allegedly spoke in a brusque, yet bizarrely ostentatious manner. Georgia Tech’s website relates a story of one of Heisman’s speeches he would break out on the first day of practice while describing a football: "What is this? It is a prolate spheroid, an elongated sphere - in which the outer leather casing is drawn tightly over a somewhat smaller rubber tubing. Better to have died as a small boy than to fumble this football."

How Did His Name Get on the Trophy?

After leaving his head-coaching job at Rice in 1927, Heisman became the athletic director at New York’s Downtown Athletic Club. In 1935 the club began awarding the Downtown Athletic Club Trophy to the nation’s top college football star. (Chicago’s Jay Berwanger won the first trophy.) Heisman died of pneumonia the following fall before the second trophy could be awarded, and the club voted to rename the prize the Heisman Memorial Trophy Award.

Did He Ever Really Throw that Iconic Stiff Arm?

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Possibly, but Heisman didn’t have the ball in his hands all that much. Even though he was a fairly small guy at just 5’8” and 158 pounds, he played as a lineman throughout his college career.

The famous “Heisman pose” is actually based on Ed Smith, a former NYU running back who modeled for the trophy’s sculptor in 1934. Interestingly, Smith went years without knowing that he’d modeled for the famous trophy. His sculptor buddy Frank Eliscu had just needed a football player to model for a project, and Smith volunteered.

Smith figured Eliscu was just doing some little personal sculpture and remained totally oblivious to his spot in football history for the next 48 years until a documentary filmmaker called Smith to interview him about the Heisman in 1982. Smith initially had no idea what the guy was talking about, but he eventually remembered his modeling days. In 1985, the Downtown Athletic Club gave Smith his own copy of the Heisman, and in 1986 he even received recognition on the televised ceremony. He looked at the four finalists – Vinny Testaverde won that year – and quipped, "Whoever wins the award, I feel sorry for you, because you're going to be looking at my ugly face for a long time." [Pictured Above: Auburn's Bo Jackson in 1985.]

What’s a Heisman Trophy Worth on the Open Market?

Quite a bit. A number of Heisman winners have eventually sold their hardware, and the trophies fetch quite a bit of loot. O.J. Simpson got $230,000 for his, and several others have gone for six-figure prices. The most expensive trophy that’s changed hands was Minnesota back Bruce Smith’s 1941 award; it fetched $395,240.

How Did Steve Spurrier Change the Process?

SEC fans are going to be floored by this one, but the Ol’ Ball Coach did something really classy when he won the Heisman in 1966. Instead of taking the trophy for himself, Spurrier gave it to the University of Florida so the school could display it and let the student body enjoy it. Florida’s student government thought Spurrier’s generosity was so classy that they paid for a replica for Spurrier so he’d get to have his own trophy, too. Since then both the school and the player have received copies of the trophy.

So Heisman Must Have Been the World’s Greatest Sportsman, Right?

Well, not really. Heisman was on the victorious side of possibly the most gratuitously run-up score in sports history. In 1916 tiny Cumberland College canceled its football program and disbanded its squad, but it had previously signed a contract to travel to Atlanta to play Heisman’s Georgia Tech team. If Cumberland didn’t show up, they had to pay Georgia Tech a $3,000 penalty, which was quite a bit of cash in 1916.

Rather than forfeiting the money, Cumberland scraped together a team of 16 scrubs and went to take their walloping from Heisman’s boys. For reasons that still aren’t totally clear – some say it was to avenge an earlier baseball loss to Cumberland, while others claim Heisman wanted to make a statement about the absurdity of the old system of using total points scored to determine the national champion – the legendary coach showed Cumberland’s ragtag band no mercy. Tech went up 63-0 in the first quarter, but Heisman kept attacking until the final score was 222-0. There are tons of hilarious stats from the game, but the funniest is Georgia Tech rushing for 1,620 yards while Cumberland only squeaked out negative-96 yards on 27 carries.

This article originally appeared in 2010.

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