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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
Who Was Chuck Taylor?
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From Betty Crocker to Tommy Bahama, plenty of popular labels are "named" after fake people. But one product with a bona fide backstory to its moniker is Converse's Chuck Taylor All-Star sneakers. The durable gym shoes are beloved by everyone from jocks to hipsters. But who's the man behind the cursive signature on the trademark circular ankle patch?

As journalist Abraham Aamidor recounted in his 2006 book Chuck Taylor, All Star: The True Story of the Man behind the Most Famous Athletic Shoe in History, Chuck Taylor was a former pro basketball player-turned-Converse salesman whose personal brand and tireless salesmanship were instrumental to the shoes' success.

Charles Hollis Taylor was born on July 24, 1901, and raised in southern Indiana. Basketball—the brand-new sport invented by James Naismith in 1891—was beginning to take the Hoosier State by storm. Taylor joined his high school team, the Columbus High School Bull Dogs, and was named captain.

After graduation, instead of heading off to college, Taylor launched his semi-pro career playing basketball with the Columbus Commercials. He’d go on to play for a handful of other teams across the Midwest, including the the Akron Firestone Non-Skids in Ohio, before finally moving to Chicago in 1922 to work as a sales representative for the Converse Rubber Shoe Co. (The company's name was eventually shortened to Converse, Inc.)

Founded in Malden, Massachusetts, in 1908 as a rubber shoe manufacturer, Converse first began producing canvas shoes in 1915, since there wasn't a year-round market for galoshes. They introduced their All-Star canvas sports shoes two years later, in 1917. It’s unclear whether Chuck was initially recruited to also play ball for Converse (by 1926, the brand was sponsoring a traveling team) or if he was simply employed to work in sales. However, we do know that he quickly proved himself to be indispensable to the company.

Taylor listened carefully to customer feedback, and passed on suggestions for shoe improvements—including more padding under the ball of the foot, a different rubber compound in the sole to avoid scuffs, and a patch to protect the ankle—to his regional office. He also relied on his basketball skills to impress prospective clients, hosting free Chuck Taylor basketball clinics around the country to teach high school and college players his signature moves on the court.

In addition to his myriad other job duties, Taylor played for and managed the All-Stars, a traveling team sponsored by Converse to promote their new All Star shoes, and launched and helped publish the Converse Basketball Yearbook, which covered the game of basketball on an annual basis.

After leaving the All-Stars, Taylor continued to publicize his shoe—and own personal brand—by hobnobbing with customers at small-town sporting goods stores and making “special appearances” at local basketball games. There, he’d be included in the starting lineup of a local team during a pivotal game.

Taylor’s star grew so bright that in 1932, Converse added his signature to the ankle patch of the All Star shoes. From that point on, they were known as Chuck Taylor All-Stars. Still, Taylor—who reportedly took shameless advantage of his expense account and earned a good salary—is believed to have never received royalties for the use of his name.

In 1969, Taylor was inducted into the Basketball Hall of Fame. The same year, he died from a heart attack on June 23, at the age of 67. Around this time, athletic shoes manufactured by companies like Adidas and Nike began replacing Converse on the court, and soon both Taylor and his namesake kicks were beloved by a different sort of customer.

Still, even though Taylor's star has faded over the decades, fans of his shoe continue to carry on his legacy: Today, Converse sells more than 270,000 pairs of Chuck Taylors a day, 365 days a year, to retro-loving customers who can't get enough of the athlete's looping cursive signature.

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Big Questions
What Is the Difference Between Generic and Name Brand Ibuprofen?
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What is the difference between generic ibuprofen vs. name brands?

Yali Friedman:

I just published a paper that answers this question: Are Generic Drugs Less Safe than their Branded Equivalents?

Here’s the tl;dr version:

Generic drugs are versions of drugs made by companies other than the company which originally developed the drug.

To gain FDA approval, a generic drug must:

  • Contain the same active ingredients as the innovator drug (inactive ingredients may vary)
  • Be identical in strength, dosage form, and route of administration
  • Have the same use indications
  • Be bioequivalent
  • Meet the same batch requirements for identity, strength, purity, and quality
  • Be manufactured under the same strict standards of FDA's good manufacturing practice regulations required for innovator products

I hope you found this answer useful. Feel free to reach out at For more on generic drugs, you can see our resources and whitepapers at Pharmaceutical strategic guidance and whitepapers

This post originally appeared on Quora. Click here to view.


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