Learn about how a fever helps you get better; why the first reliable and widely available pregnancy test was the African clawed frog; and a potential breakthrough in the shockingly complicated traveling salesperson problem.
Learn about how a fever helps you get better; why the first reliable and widely available pregnancy test was the African clawed frog; and a potential breakthrough in the shockingly complicated traveling salesperson problem.
How Exactly Does Fever Help You Get Better? by Ashley Hamer
The first reliable and widely available pregnancy test was... a frog? by Cameron Duke
Traveling salesperson update by Cody Gough
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Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/how-does-fever-help-you-get-better
CODY: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from curiosity-dot-com. I’m Cody Gough.
ASHLEY: And I’m Ashley Hamer. Today, you’ll learn about how a fever helps you get better; what frogs have to do with the history of pregnancy tests; and a potential breakthrough in the shockingly complicated traveling salesperson problem.
CODY: Let’s satisfy some curiosity.
You probably know that getting a fever is your body’s way of fighting off illness. But here’s something surprising: it wasn’t until recently that scientists understood how fevers actually help you get better. Here’s the story of how that happened.
The part that was best understood was how fevers start. When a virus or bacterium invades your cells, immune cells called macrophages gobble up the invaders and send out proteins called cytokines to alert the rest of your body that you’re under attack.
One place that alert goes to is the hypothalamus. That’s a part of your brain that controls body temperature, among other things. The hypothalamus is the one that stokes the fires of fever. But why? For a long time, people assumed that higher temperature made it harder for bacteria and viruses to survive. But that turns out to be a small part of fever's power.
Another soldier in the fight against infection is the lymphocyte, or white blood cell. Versions of this cell called T-lymphocytes receive pieces of the invader proteins from the macrophages and use them to target and destroy the infection. They move to where they’re needed with the help of molecules called integrins [IN-tuh-GRIN], which help them stick to blood vessels they use to travel to the infection.
It turns out that both infection-fighting T-lymphocytes and the integrins that help them get where they’re going do much better in toasty temperatures. A 2011 study found that virus-infected mice that had their body temperature raised produced more of a certain type of T-lymphocyte than infected mice that stayed at a normal temperature. And a 2019 study found that fever boosts a protein that helps more integrins cluster on the surface of the lymphocyte, which helps it move more efficiently. Interestingly, this protein only kicked in at a temperature of 101.3 degrees Fahrenheit, or 38.5 degrees Celsius — the kind of temp that would probably leave you bedridden for the day.
Just goes to show how helpful a fever really is. Now, if your fever is high, you should consult a doctor, who may tell you to take something to reduce it. But if not, maybe ride it out. Just know there’s a war going on inside you, and do what you can to help the good guys win.
Today, pregnancy tests are simple and reliable devices you can buy from your local drugstore. But it hasn’t always been this way. Modern pregnancy tests only became widely available in the 1960s. But they were definitely an upgrade from the frogs we used before. Oh yes, you heard me. The first widely available pregnancy test was a frog.
In 1930, A British scientist was performing the scientific equivalent of throwing things against the wall to see what sticks: in his case, messing with a frog’s various glands and hormones to learn what he could about human hormones. The scientist’s name was Lancelot Hogben, which is a name I am definitely going to steal for my next D&D campaign. Hogben was a zoologist who had just returned from South Africa, which explains why this particular study amphibian was Xenopus [ZEEN-uh-puss], aka the African Clawed Frog. Back in the U. K., he was able to continue his work with his favorite study species.
Anyway, our story really begins the day he decided to inject hormones from an ox’s pituitary gland into one of his frogs. When he did this, something strange happened. The frog laid eggs. In fact, this happened every time he did it.
Hogben knew that the pituitary gland is involved in regulating pregnancy. In humans, that’s thanks to a hormone it produces called human chorionic gonadotropin, or HCG. He wondered if this pregnancy hormone was what made the frog lay eggs. So he injected the frog with urine from a pregnant woman and sure enough: the frog laid eggs!
That changed everything. From the 1930s until the invention of the modern pregnancy test, a woman who suspected that she might be pregnant would go to a doctor and provide a urine sample. That urine would be injected into the skin of an African Clawed Frog and reliable results would arrive that day.
These so-called “frog tests” became an industry standard worldwide. The test seems barbaric by today’s standards, but as far as animal-based pregnancy testing goes, it was pretty safe. Other pregnancy tests that used animals always required killing them, so the fact that the frogs could be injected many times without causing any obvious harm was a huge step up.
Eventually, simpler, animal-free tests for HCG in urine became standard, and in the 1970s, the first home pregnancy tests hit drugstore shelves. By then, the frog test had croaked. [continue pun overload]
This test continued (as modern pregnancy tests do) the long-standing tradition of women peeing on things to determine whether they are pregnant. The earliest documented “folk pregnancy test” came from the ancient Egyptians and involved urinating on barley and seeing if it sprouts. This might sound more like superstition than science, but an experiment in 1941 found that it worked 70% of the time. This is because Human Chorionic Gonadotropin, the hormone that modern pregnancy tests are looking for as well as the hormone that makes frogs lay eggs, has a tendency to prevent barley from germinating.
ASHLEY: Computer scientists may have made a breakthrough in a math problem that’s been unsolved for nearly 200 years. I’m talking about the traveling salesman problem, and it’s a lot more complex than you might think. We explained the problem on an episode of Curiosity Daily in 2019, so here’s a quick refresher in case you missed it.
[CLIP 1:18]
Okay, so the leading computer algorithm to solve this problem was developed in 1976, by mathematician Nicos Christofides. His algorithm won’t necessarily find the best trip, but it can find round trips that are at MOST 50 percent longer than the best round trip. A lot of computer scientists agreed that nobody would ever be able to find a better algorithm, and that was true for 44 years. But just last year, a graduate student and two advisors at the University of Washington proposed an algorithm that they say can do a little bit better. And I mean a LITTLE bit: their proposed solution beats Christofides’ 50 percent factor by 0.2 billionth of a trillionth of a trillionth of a percent. That might seem insignificant, especially since it took them 2 years to finalize the 80-page paper that explains their findings. But experts say this is still a huge deal, because it tests the limits of efficient computation. We don’t have time to dig deep into the actual math involved, but you can find a link in today’s show notes to a great write-up in Quanta Magazine with all the details. We should note that Quanta reports the paper itself is yet to be peer-reviewed, but that, quote “experts are confident that it’s correct” [unquote]. Really, the big takeaway is that sometimes, research moves forward in baby steps — but even the tiniest finding can make a world of difference.
Let’s recap today’s takeaways
This test continued (as modern pregnancy tests do) the long-standing tradition of women peeing on things to determine whether they are pregnant. The earliest documented “folk pregnancy test” came from the ancient Egyptians and involved urinating on barley and seeing if it sprouts. This might sound more like superstition than science, but an experiment in 1941 found that it worked 70% of the time. This is because Human Chorionic Gonadotropin, the hormone that modern pregnancy tests are looking for as well as the hormone that makes frogs lay eggs, has a tendency to prevent barley from germinating.
[ad lib optional]
CODY: Today’s stories were written by Ashley Hamer, Cameron Duke, and Cody Gough (that’s me), and edited by Ashley Hamer, who’s the managing editor for Curiosity Daily.
ASHLEY: Scriptwriting was by Cody Gough and Sonja Hodgen. Today’s episode was produced and edited by Cody Gough.
CODY: Join us again tomorrow to learn something new in just a few minutes.
ASHLEY: And until then, stay curious!