Snakes can’t really unhinge their jaws, but for some, that doesn’t get in the way of swallowing large prey. And new research indicates that relative to their size, the snakes that can gulp down the largest meals are harmless, 3-foot-long egg eaters.
“This particular group of snakes may be No. 1 when it comes to big mouths,” said Bruce Jayne, a biology professor at the University of Cincinnati and the author of a paper on the subject published in the Journal of Zoology.
The snakes in question, of the genus Dasypeltis, are found throughout Africa. They’re small, skinny, and nearly toothless since teeth prove to be a hindrance to their food of choice: bird eggs.
To test the snakes’ mouth-opening capabilities, Jayne measured the maximum open mouth area, or “gape,” of 15 Dasypeltis gansi egg-eaters and found that Dasypeltis gansi “has spectacularly stretchy skin,” enabling it to “add more than 50 percent of that gape area,” he said. A previous study by Jayne showed that Burmese pythons’ jaws allow them to expand their gape by 43%. Jayne suspects that Dasypeltis might have the biggest relative gap among snakes.
Bryan Maritz, an associate professor of biology at the University of the Western Cape in South Africa, who was not involved with the study, said Jayne’s study stood out because it upended traditional thinking with regard to estimating the size of prey a snake could swallow. “We’ve said, ‘Well, gape is correlated broadly with head length, and so you can measure a snake’s head length and you can estimate its gape,’” Maritz said. “And this study really shows that that’s not the case.” — KATE GOLEMBIEWSKI
What Goes Up a Tree Must Evolve the Ability to Climb Back Down
Millions of years ago, a simian ancestor decided to climb a tree. Although that ancestral primate must have solved the problem of coming back down, scientists have a lot of work to do in understanding that, and how it relates to the evolution of our species.
“Everyone focuses on climbing up, because that’s a difficult thing to do,” said Nathaniel Dominy, an evolutionary biologist at Dartmouth. “No one bothered to study climbing down, because gravity doesn’t care whether you’re climbing up or down.”
In a study published in the journal Royal Society Open Science, Dominy, and colleagues found that apes and our ancient human ancestors probably developed flexible shoulder and elbow joints to counteract the effects of gravity. The researchers posit that this adaptation persisted even as early humans swapped out trees for grassland habitats, their versatile upper limbs making it possible to forage, hunt, and defend.
A key insight came from Mary Joy, a co-author of the study and at the time a Dartmouth undergraduate. She had been watching videos of chimpanzees, which are human’s closest living relatives, and sooty mangabeys, an Old World monkeys native to West and Central Africa, and noticed that both animals climbed up trees with the same effort. The downward climb, however, was different.
Employing software typically used to analyze the movements of human athletes, Joy saw that when chimpanzees climbed down a tree, they extended their shoulders and elbows above their heads to a far greater degree than the smaller monkeys. Compared with the sooty mangabeys, the chimps flexed their shoulders about 14 degrees more, and extended their elbows about 34 degrees more, when climbing down (versus up) a tree.
“The mangabeys had a sort of similar motion to how they climbed up, a pretty angled way to hold their arms,” Joy said. For the chimps, it was like they were in a controlled fall, while also using a full range of motion to go as quickly as possible.
Susan Larson, a professor of anatomical sciences at Stony Brook University in New York, who was not involved in the study, said the new findings offered critical insight into the hominid evolution from trees to land. “I think it does give us a way of thinking about why early humans would retain these features for a long time, until they sort of abandoned trees and became bipedal hunters,” she said. — MIRIAM FAUZIA
Mars Lander Serves Up Surprise: the Red Planet Is Spinning Faster
For reasons unknown, the spin of Mars is speeding up.
In a paper published in June in the journal Nature, scientists working on NASA’s InSight lander mission on Mars reported findings gleaned from tiny shifts in the frequencies of radio transmissions between Earth and InSight.
The measurements showed the expected undulations of the planet’s rotation, quickest during winter and summer and slowest during spring and fall, as the distribution of frozen carbon dioxide in the ice caps shifted with the seasons.
When including the NASA Viking mission’s Doppler measurements from 47 years ago, the scientists found a slight speeding up in the spin of Mars, which has led to a shortening of a Martian day by about 1.5 millionths of a second per Martian year.
“It was a surprise,” Bruce Banerdt, the principal investigator for the InSight mission, said. “We did not expect to see that at all.”
It is known that one of the Martian moons, Phobos, is gradually falling, and that indeed is speeding up the rotation of Mars, but that is not big enough to explain what was observed. Banerdt said the most likely cause was a long-term accumulation of ice at the poles. — KENNETH CHANG
This article originally appeared in The New York Times.
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