A Stroke of Genius: New Research Shows That Sperm Don’t Slither—They Corkscrew

Sperm have been duping us for nearly 350 years.
Sperm have been duping us for nearly 350 years.
Rost-9D/iStock via Getty Images

By 1677, Antonie van Leeuwenhoek had already begun to shape his legacy as the “father of microbiology.” In addition to constructing his own microscopes, the mostly self-taught scientist was the first to study microorganisms in pond water, calling them animalcules. So when a medical student named Johan Ham observed something that appeared to be alive in a human semen specimen, he brought it to van Leeuwenhoek.

Through the microscope lens, van Leeuwenhoek saw it, too: a “small earth-nut with a long tail” that we now know as sperm. After examining some of his own specimens, van Leeuwenhoek asserted that sperm propel themselves forward with “the motion of their tails like that of a snake or an eel swimming in water.”

For nearly 350 years, scientists have supported van Leeuwenhoek’s claim that human sperm move through liquid by lashing their tails from side to side. But a new study published in Science Advances shows that these cheeky little earth-nuts don’t slither like eels at all. Instead, they corkscrew like otters.

A group of researchers from the UK and Mexico used a high-speed camera and other microscopy devices to capture a sperm’s movement in 3D, which revealed that its tail actually only lashes to one side—and if you’ve ever tried to row a boat with one oar, you probably know that sticking to one side will send you spinning in circles. The sperm, however, have figured out a clever fix. They rotate their bodies every time their tails strike sideways, which pushes them forward in a corkscrew motion.

The reason van Leeuwenhoek’s original observation went undisputed for so long is mainly because scientists have continued to view sperm with 2D technology. Without depth, you can’t tell that the sperm’s body is spinning, and the tail looks like it’s simply moving to each side, rather than completing a rotation. And as Hermes Gadêlha, University of Bristol lecturer and co-author of this study, explained in his article for The Conversation, sperm’s size and speed make them hard to observe closely. In less than one second, they can complete about 20 propulsions.

While this study is significant for the mere shock factor of realizing we’ve been wrong for centuries, it could also impact future research on the causes of male infertility. In other words, having a better understanding of how sperm travel to eggs may help us understand why some make it there more easily than others.

[h/t The Conversation]

10 of the Best Indoor and Outdoor Heaters on Amazon

Mr. Heater/Amazon
Mr. Heater/Amazon

With the colder months just around the corner, you might want to start thinking about investing in an indoor or outdoor heater. Indoor heaters not only provide a boost of heat for drafty spaces, but they can also be a money-saver, allowing you to actively control the heat based on the rooms you’re using. Outdoor heaters, meanwhile, can help you take advantage of cold-weather activities like camping or tailgating without having to call it quits because your extremities have gone numb. Check out this list of some of Amazon’s highest-rated indoor and outdoor heaters so you can spend less time shivering this winter and more time enjoying what the season has to offer.

Indoor Heaters

1. Lasko Ceramic Portable Heater; $20

Lasko/Amazon

This 1500-watt heater from Lasko may only be nine inches tall, but it can heat up to 300 square feet of space. With 11 temperature settings and three quiet settings—for high heat, low heat, and fan only—it’s a dynamic powerhouse that’ll keep you toasty all season long.

Buy it: Amazon

2. Alrocket Oscillating Space Heater; $25

Alrocket/Amazon

Alrocket’s oscillating space heater is an excellent addition to any desk or nightstand. Using energy-saving ceramic technology, this heater is made of fire-resistant material, and its special “tip-over” safety feature forces it to turn off if it falls over (making it a reliable choice for homes with kids or pets). It’s extremely quiet, too—at only 45 dB, it’s just a touch louder than a whisper. According to one reviewer, this an ideal option for a “very quiet but powerful” heater.

Buy it: Amazon

3. De’Longhi Oil-Filled Radiator Space Heather; $79

De’Longhi/Amazon

If you prefer a space heater with a more old-fashioned vibe, this radiator heater from De’Longhi gives you 2020 technology with a vintage feel. De’Longhi’s heater automatically turns itself on when the temperatures drops below 44°F, and it will also automatically turn itself off if it starts to overheat. Another smart safety feature? The oil system is permanently sealed, so you won’t have to worry about accidental spills.

Buy it: Amazon

4. Aikoper Ceramic Tower Heater; $70

Aikoper/Amazon

Whether your room needs a little extra warmth or its own heat source, Aikoper’s incredibly precise space heater has got you covered. With a range of 40-95°F, it adjusts by one-degree intervals, giving you the specific level of heat you want. It also has an option for running on an eight-hour timer, ensuring that it will only run when you need it.

Buy it: Amazon

5. Isiler Space Heater; $37

Isiler/Amazon

For a space heater that adds a fun pop of color to any room, check out this yellow unit from Isiler. Made from fire-resistant ceramic, Isiler’s heater can start warming up a space within seconds. It’s positioned on a triangular stand that creates an optimal angle for hot air to start circulating, rendering it so effective that, as one reviewer put it, “This heater needs to say ‘mighty’ in its description.”

Buy it: Amazon

Outdoor Heaters

6. Mr. Heater Portable Buddy; $104

Mr. Heater/Amazon

Make outdoor activities like camping and grilling last longer with Mr. Heater’s indoor/outdoor portable heater. This heater can connect to a propane tank or to a disposable cylinder, allowing you to keep it in one place or take it on the go. With such a versatile range of uses, this heater will—true to its name—become your best buddy when the temperature starts to drop.

Buy it: Amazon

7. Hiland Pyramid Patio Propane Heater; Various

Hiland/Amazon

The cold’s got nothing on this powerful outdoor heater. Hiland’s patio heater has a whopping 40,000 BTU output, which runs for eight to 10 hours on high heat. Simply open the heater’s bottom door to insert a propane tank, power it on, and sit back to let it warm up your backyard. The bright, contained flame from the propane doubles as an outdoor light.

Buy it: Amazon

8. Solo Stove Bonfire Pit; $345

Solo Stove/Amazon

This one is a slight cheat since it’s a bonfire pit and not a traditional outdoor heater, but the Solo Stove has a 4.7-star rating on Amazon for a reason. Everything about this portable fire pit is meticulously crafted to maximize airflow while it's lit, from its double-wall construction to its bottom air vents. These features all work together to help the logs burn more completely while emitting far less smoke than other pits. It’s the best choice for anyone who wants both warmth and ambiance on their patio.

Buy it: Amazon

9. Dr. Infrared Garage Shop Heater; $119

Dr. Infrared/Amazon

You’ll be able to use your garage or basement workshop all season long with this durable heater from Dr. Infrared. It’s unique in that it includes a built-in fan to keep warm air flowing—something that’s especially handy if you need to work without wearing gloves. The fan is overlaid with heat and finger-protectant grills, keeping you safe while it’s powered on.

Buy it: Amazon

10. Mr. Heater 540 Degree Tank Top; $86

Mr. Heater/Amazon

Mr. Heater’s clever propane tank top automatically connects to its fuel source, saving you from having to bring any extra attachments with you on the road. With three heat settings that can get up to 45,000 BTU, the top can rotate 360 degrees to give you the perfect angle of heat you need to stay cozy. According to a reviewer, for a no-fuss outdoor heater, “This baby is super easy to light, comes fully assembled … and man, does it put out the heat.”

Buy it: Amazon

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100 Fascinating Facts About Earth

The best Spaceball.
The best Spaceball.
NASA

Did you know that there’s a place in the South Pacific Ocean called Point Nemo that’s farther from land than any other point on Earth? So far, in fact, that the closest humans are usually astronauts aboard the International Space Station. (And by the way: The map you’re about to look for Point Nemo on might not be entirely accurate; a certain amount of distortion occurs when trying to depict a 3D planet on a 2D surface.)

In this all-new episode of The List Show, Mental Floss editor-in-chief Erin McCarthy is journeying to the center of the Earth, and visiting its oceans, its atmosphere, and even space, in search of 100 facts about our endlessly fascinating planet.

The subjects that fall under the umbrella of “facts about Earth” are nearly as expansive as Earth itself. Geology, biology, astronomy, and cartography, are all fair game—and those are just a few of the many -ologies, -onomies, and -ographies you’ll learn about below. 

Press play to find out more Earth-shattering facts, and subscribe to the Mental Floss YouTube channel for more fact-filled videos here.