Boa constrictors don’t so much suffocate prey as break their hearts. It turns out that the snakes kill like demon blood pressure cuffs, squeezing down circulation to its final stop. The notion that constrictors slay by preventing breathing turns out to be wrong.
The snakes don’t need limbs, or even venom, to bring down an animal of their own size. “Imagine you’re killing and swallowing a 150-pound animal in one meal — with no hands or legs!” animal ecologist Scott Boback tells his students at Dickinson College in Carlisle, Pa., to convey what extraordinary hunters snakes are. Speed matters with prey flailing claws, hooves or other weaponry the snake lacks. Embracing prey into heart failure is faster than suffocating it and appeared in different forms multiple times in snake history. Ambushing birds, monkeys and a wide range of other animals from Mexico south to Argentina, the iconic Boa constrictor attacks in much the same way each time. The snake cinches a loop or two around the upper body of prey, pressing against its victim hard enough to starve organs of oxygenated blood.
“It’s not some unbelievable amount of pressure,” says Boback, whose arms get snaked now and then. “It stings a little — you can kind of feel the blood stop,” he says. Within six seconds of looping around an anesthetized lab rat, a boa constrictor squeezes enough to halve blood pressure in a rear-leg artery. Blood that should surge through the artery lies dammed behind snake coils in the rat’s upper body. And back pressure keeps the rat heart from pumping out new blood. Circulation falters and fails. Boas release their grip after about six minutes on average, Boback and his colleagues report in the July 15 Journal of Experimental Biology.
Then the boa swallows the catch whole. A rat about a quarter of the snake’s weight disappears down the gullet in a couple of minutes. Moveable bones in the head help the snake make the gulp, as does a dimple of stretchy cartilage that lets the chin open wide. But what people most often tell Boback — that snake jaws must separate at the back — is just another serpentine myth.
Icicles made from pure water give scientists brain freeze.
In nature, most icicles are made from water with a hint of salt. But lab-made icicles free from salt disobey a prominent theory of how icicles form, and it wasn’t clear why. Now, a study is helping to melt away the confusion.
Natural icicles tend to look like skinny cones with rippled surfaces — the result of a thin film of water that coats the ice, researchers think (SN: 11/24/13). As icicles grow, the film freezes. Any preexisting small bumps in the icicle get magnified into large ripples because the water layer is thinner above the bumps and can freeze more readily. But this theory fails to explain the salt-free variety, which have more irregular shapes reminiscent of drippy candles, says physicist Menno Demmenie of the University of Amsterdam. So Demmenie and colleagues grew icicles in the lab, adding a blue dye that was visible only when the water was liquid. Salted icicles not only had ripples, but they also were covered in a thin, blue film. Icicles made from pure water had no such film. Only small droplets of blue appeared on those icicles, the team reports in the February Physical Review Applied.
In icicles with salt, the temperature at which the water on the surface freezes is lowered, allowing a liquid layer to coat the entire icicle. Without the salt, icicles must build up drop by drop.
Tiny, pond-dwelling Halteria ciliates are virovores, able to survive on a virus-only diet, researchers report December 27 in Proceedings of the National Academy of Sciences. The single-celled creatures are the first known to thrive when viruses alone are on the menu.
Scientists already knew that some microscopic organisms snack on aquatic viruses such as chloroviruses, which infect and kill algae. But it was unclear whether viruses alone could provide enough nutrients for an organism to grow and reproduce, says ecologist John DeLong of the University of Nebraska–Lincoln. In laboratory experiments, Halteria that were living in water droplets and given only chloroviruses for sustenance reproduced, DeLong and colleagues found. As the number of viruses in the water dwindled, Halteria numbers went up. Ciliates without access to viral morsels, or any other food, didn’t multiply. But Paramecium, a larger microbe, didn’t thrive on a virus-only diet, hinting that viruses can’t satisfy the nutritional requirements for all ciliates to grow.
Viruses could be a good source of phosphorus, which is essential for making copies of genetic material, DeLong says. But it probably takes a lot of viruses to account for a full meal.
In the lab, each Halteria microbe ate about 10,000 to 1 million viruses daily, the team estimates. Halteria in small ponds with abundant viral snacks might chow down on about a quadrillion viruses per day.
These feasts could shunt previously unrecognized energy into the food web, and add a new layer to the way viruses move carbon through an ecosystem — if it happens in the wild, DeLong says (SN: 6/9/16). His team plans to start finding out once ponds in Nebraska thaw.
In full swing The swaying feeling in jazz music that compels feet to tap may arise from near-imperceptible delays in musicians’ timing, Nikk Ogasa reported in “Jazz gets its swing from small, subtle delays” (SN: 11/19/22, p. 5).
Reader Oda Lisa, a self-described intermediate saxophonist, has noticed these subtle delays while playing.“I recorded my ‘jazzy’ version of a beloved Christmas carol, which I sent to a friend of mine,” Lisa wrote. “She praised my effort overall, but she suggested that I get a metronome because the timing wasn’t consistent. My response was that I’m a slave to the rhythm that I hear in my head. I think now I know why.” On the same page Murky definitions and measurements impede social science research, Sujata Gupta reported in “Fuzzy definitions mar social science” (SN: 11/19/22, p. 10).
Reader Linda Ferrazzara found the story thought-provoking. “If there’s no consensus on the terms people use … then there can be no productive discussion or conversation. People end up talking and working at cross-purposes with no mutual understanding or progress,” Ferrazzara wrote.
Fly me to the moon Space agencies are preparing to send the next generation of astronauts to the moon and beyond. Those crews will be more diverse in background and expertise than the crews of the Apollo missions, Lisa Grossman reported in “Who gets to go to space?” (SN: 12/3/22, p. 20).
“It is great to see a broader recognition of the work being done to make spaceflight open to more people,” reader John Allen wrote. “Future space travel will and must accommodate a population that represents humanity. It won’t be easy, but it will be done.”
The story also reminded Allen of the Gallaudet Eleven, a group of deaf adults who participated in research done by NASA and the U.S. Navy in the 1950s and ’60s. Experiments tested how the volunteers responded (or didn’t) to a range of scenarios that would typically induce motion sickness, such as a ferry ride on choppy seas. Studying how the body’s sensory systems work without the usual gravitational cues from the inner ear allowed scientists to better understand motion sickness and the human body’s adaptation to spaceflight.
Sweet dreams are made of this A memory-enhancing method that uses sound cues may boost an established treatment for debilitating nightmares, Jackie Rocheleau reported in “Learning trick puts nightmares to bed” (SN: 12/3/22, p. 11).
Reader Helen Leaver shared her trick to a good night’s sleep: “I learned that I was having strong unpleasant adventures while sleeping, and I would awaken hot and sweaty. By eliminating the amount of heat from bedding and an electrically heated mattress pad, I now sleep well without those nightmares.” Pest perspectives In “Why do we hate pests?” (SN: 12/3/22, p. 26), Deborah Balthazar interviewed former Science News Explores staff writer Bethany Brookshire about her new book, Pests. The book argues that humans — influenced by culture, class, colonization and much more — create animal villains.
The article prompted reader Doug Clapp to reflect on what he considers pests or weeds. “A weed is a plant in the wrong place, and a pest is an animal in the wrong place,” Clapp wrote. But what’s considered “wrong” depends on the humans who have power over the place, he noted. “Grass in a lawn can be a fine thing. Grass in a garden choking the vegetables I’m trying to grow becomes a weed. Mice in the wild don’t bother me. Field mice migrating into my house when the weather cools become a pest, especially when they eat into my food and leave feces behind,” Clapp wrote.
The article encouraged Clapp to look at pests through a societal lens: “I had never thought of pests in terms of high-class or low-class. Likewise, the residual implications of [colonization]. Thanks for provoking me to consider some of these issues in a broader context.”
As far back as roughly 25,000 years ago, Ice Age hunter-gatherers may have jotted down markings to communicate information about the behavior of their prey, a new study finds.
These markings include dots, lines and the symbol “Y,” and often accompany images of animals. Over the last 150 years, the mysterious depictions, some dating back nearly 40,000 years, have been found in hundreds of caves across Europe.
Some archaeologists have speculated that the markings might relate to keeping track of time, but the specific purpose has remained elusive (SN: 7/9/19). Now, a statistical analysis, published January 5 in Cambridge Archeological Journal, presents evidence that past people may have been recording the mating and birthing schedule of local fauna. By comparing the marks to the animals’ life cycles, researchers showed that the number of dots or lines in a given image strongly correlates to the month of mating across all the analyzed examples, which included aurochs (an extinct species of wild cattle), bison, horses, mammoth and fish. What’s more, the position of the symbol “Y” in a sequence was predictive of birth month, suggesting that “Y” signifies “to give birth.”
The finding is one of the earliest records of a coherent notational system, the researchers say. It indicates that people at the time were able to interpret the meaning of an item’s position in a sequence and plan ahead for the distant future using a calendar of sorts — reinforcing the suggestion that they were capable of complex cognition. “This is a really big deal cognitively,” says Ben Bacon, an independent researcher based in London. “We’re dealing with a system that has intense organization, intense logic to it.”
A furniture conservator by day, Bacon spent years poring through scientific articles to compile over 800 instances of these cave markings. From his research and reading the literature, he reasoned that the dots corresponded to the 13 lunar cycles in a year. But he thought that the hunter-gatherers would’ve been more concerned with seasonal changes than the moon.
In the new paper, he and colleagues argue that rather than pinning a calendar to astronomical events like the equinox, the hunter-gatherers started their calendar year with the snowmelt in the spring. Not only would the snowmelt be a clear point of origin, but the meteorological calendar would also account for differences in timing across locations. For example, though snowmelt would start on different dates in different latitudes, bison would always mate approximately four lunar cycles — or months — after that region’s snowmelt, as indicated by four dots or lines.
“This is why it’s such a clever system, because it’s based on the universal,” Bacon says. “Which means if you migrate from the Pyrenees to Belgium, you can just use the same calendar.”
He needed data to prove his idea. After compiling the markings, he worked with academic researchers to identify the timing of migration, mating and birth for common Ice Age animals targeted by hunter-gatherers by using archaeological data or comparing with similar modern animals. Next, the researchers determined if the marks aligned significantly with important life events based on this calendar. When the team ran the statistical analysis, the results strongly supported Bacon’s theory.
When explaining the markings, “we’ve argued for notational systems before, but it’s always been fairly speculative as to what the people were counting and why they were counting,” says Brian Hayden, an archaeologist at Simon Fraser University in Burnaby, British Columbia, who peer-reviewed the paper. “This adds a lot more depth and specificity to why people were keeping calendars and how they were using them.”
Linguistic experts argue that, given the lack of conventional syntax and grammar, the marks wouldn’t be considered writing. But that doesn’t make the finding inherently less exciting, says paleoanthropologist Genevieve von Petzinger of the Polytechnic Institute of Tomar in Portugal, who wasn’t involved in the study. Writing systems are often mistakenly considered a pinnacle of achievement, when in fact writing would be developed only in cultural contexts where it’s useful, she says. Instead, it’s significant that the marks provide a way to keep records outside of the mind.
“In a way, that was the huge cognitive leap,” she says. “Suddenly, we have the ability to preserve [information] beyond the moment. We have the ability to transmit it across space and time. Everything starts to change.”
The debate over these marks’ meanings continues. Archaeologist April Nowell doesn’t buy many of the team’s assumptions. “It boggles my mind why one would need a calendar … to predict that animals were going to have offspring in the spring,” says Nowell, of the University of Victoria in British Columbia. “The amount of information that this calendar is providing, if it really is a calendar, is quite minimal.”
Hayden adds that, while the basic pattern would still hold, some of the cave marks had “wiggle room for interpretation.” The next step, he says, will be to review and verify the interpretations of the marks.
