Welcome to a new year of the Altmetric High Five!
On a monthly basis, my High Five posts examine a selection of the most popular research outputs Altmetric has seen attention for that month.
This month’s theme is changing history. The top scientific papers this month according to Altmetric.com all have big implications for our understanding of human, and celestial, history.
Paper #1. Beyond Pluto: Planet Nine?
Our top High Five paper this month is titled “Evidence for a distant giant planet in the solar system,” published in The Astronomical Journal on January 20. In the article, authors Konstantin Batygin and Michael Brown provide evidence for a bold theory – that somewhere out in the distant reaches of our own solar system, another planet lurks.
Did scientists just discover Planet Nine of our solar system?!
Not quite, or at least not yet. There is no data related to a direct detection of a ninth planet in the far solar system. But Batygin and Brown provide evidence that points to the possibility of such a planet, based on patterns in the movement of other small celestial bodies suggesting they are being affected by the gravity another large object – a planet-sized object.
The study was picked up by over 300 news outlets and dozens of blogs. The New York Times headlined, “Ninth Planet May Exist Beyond Pluto, Scientists Report.”
There might be a ninth planet in the solar system after all, and it is not Pluto. Two astronomers reported on Wednesday that they had compelling signs of something bigger and farther away — something that would satisfy the current definition of a planet, where Pluto falls short. “We are pretty sure there’s one out there,” said Michael E. Brown, a professor of planetary astronomy at the California Institute of Technology. […] In a paper published in The Astronomical Journal, Dr. Brown and Dr. Batygin laid out a detailed circumstantial argument for the planet’s existence in what astronomers have observed: a half-dozen small bodies in distant elliptical orbits. – Kenneth Chang, New York Times
The study authors conducted an AMA on Reddit in late January, inviting readers to ask questions about their latest discovery.
“[H]ow did we not observe this planet before?” one Redditor asked.
“It’s too far,” Brown responded.
“How confident are you that Planet Nine is real? If you had to put a percentage on it?” another Redditor asked.
“100000000000000000%,” Batygin responded.
“All those people who are mad that Pluto is no longer a planet can be thrilled to know that there’s a real planet out there, still to be found,” Brown said in a Scientific American 60-second Science podcast. Brown is also known as the “Pluto Killer,” because his research contributed to the reclassification of Pluto, as not a planet.
So what makes these researchers so sure that the new mysterious Planet Nine is really a planet? The video below provides an explanation for how the signs point to a new planet, not just a “new Pluto.”
But other scientists and science writers are careful to point out that currently Planet Nine is “just a theory.”
Emily Lakdawalla writes for her blog at The Planetary Society:
We still don’t know for sure if it’s out there, but it’s looking likelier that there is an undiscovered planet orbiting beyond the Kuiper belt. If it’s there, it’s big, far, and slow. It would be roughly 10 times the mass of Earth (or about half the mass of Neptune), likely never gets closer to the Sun than about 100 200 AU, and takes more than 10,000 years to orbit the Sun. The presence of such a planet would explain two odd clusters of Kuiper belt orbits, including distant detached objects Sedna and 2012 VP113, and the perpendicularly tilted ones of several newly discovered small worlds. – Emily Lakdawalla, Theoretical evidence for an undiscovered super-Earth at the edge of our solar system
“If there’s going to be another planet in the solar system, I think this is it,” Greg Laughlin of the University of California, Santa Cruz was quoted as saying by Nadia Drake at National Geographic. “It would be quite extraordinary if we had one. Fingers crossed. It would be amazing.”
Only time will tell if textbooks, solar system graphics and planetary mobiles hanging in your room should include a ninth, gaseous planet circling the sun in the far distance.
- Scientists Find Evidence for Ninth Planet in Solar System, by Nadia Drake, National Geographic
- Strong Evidence Suggests a Super Earth Lies beyond Pluto, by Michael Lemonick, Scientific American
- Evidence grows for giant planet on fringes of Solar System, by Alexandra Witze, Nature
Paper #2. You are mostly human
Our next High Five paper busts the myth that our human bodies contain more bacteria than they do our own human cells. The study, “Revised estimates for the number of human and bacteria cells in the body,” was posted on the preprint server bioRxiv on January 25. In the study, a team of researchers searched through the scientific literature for actual measurements of the number of human cells in the body and number of microbes in various human tissue samples, including stool samples (because where else to find a huge number of microbes from inside the human body?) What they found, though, looked more like a 1:1 ratio of microbes to human cells.
A ‘reference man’ (one who is 70 kilograms, 20–30 years old and 1.7 metres tall) contains on average about 30 trillion human cells and 39 trillion bacteria, say Ron Milo and Ron Sender at the Weizmann Institute of Science in Rehovot, Israel, and Shai Fuchs at the Hospital for Sick Children in Toronto, Canada. Those numbers are approximate — another person might have half as many or twice as many bacteria, for example — but far from the 10:1 ratio commonly assumed. – Alison Abbott, Nature
“You’re probably not mostly microbes,” The Atlantic headlined an article written by Ed Yong. Yong breaks down the history behind the famous 10:1 ratio of bacteria to human cells in the human body.
This 10:1 ratio crops up everywhere. It appears in scientific papers, blog posts, magazine stories, TED talks, and popular science books—sometimes, even in the very title. It is undoubtedly one of the most famous statistics about the microbiome. And it’s probably wrong. It’s the result of a back-of-the-envelope calculation that became enshrined as hard fact based on little more than its catchy nature and its sounds-about-right-ness. – Ed Yong, The Atlantic
“We have ~30 trillion cells & ~30 trillion bacteria. Throw out the old 10:1 ratio?” science writer Carl Zimmer wrote on Twitter. “The very fact that scientists are still so unsure of how many cells & bacteria are in each of us is pretty remarkable.”
But as one science blogger aptly points out, viruses are a different batter. “The number of viruses in your body vastly outnumber all the cells,’ AJ Cann writes on MicrobiologyBytes. Just a little perspective!
- Counting Cells, by Jef Akst, TheScientist
- How Much Bacteria Does The Human Body Really Contain? by Ben Taub, posted on IFLScience
Paper #3. A New geological era of human impact
Our third High Five paper this month documents the arrival of a new era of human impact on the planet. “The Anthropocene is functionally and stratigraphically distinct from the Holocene,” was published in Science magazine this month.
Humans are undoubtedly altering many geological processes on Earth—and have been for some time. But what is the stratigraphic evidence for officially distinguishing this new human-dominated time period, termed the “Anthropocene,” from the preceding Holocene epoch? Waters et al. review climatic, biological, and geochemical signatures of human activity in sediments and ice cores. Combined with deposits of new materials and radionuclides, as well as human-caused modification of sedimentary processes, the Anthropocene stands alone stratigraphically as a new epoch beginning sometime in the mid–20th century. – Science summary
Over 70 news outlets and over 25 blogs covered the study. According to The Guardian, “There is now compelling evidence to show that humanity’s impact on the Earth’s atmosphere, oceans and wildlife has pushed the world into a new geological epoch, according to a group of scientists.”
Wildlife […] is being pushed into an ever smaller area of the Earth, with just 25% of ice-free land considered wild now compared to 50% three centuries ago. As a result, rates of extinction of species are far above long-term averages. But the study says perhaps the clearest fingerprint humans have left, in geological terms, is the presence of isotopes from nuclear weapons testing that took place in the 1950s and 60s. – Adam Vaughan, The Guardian
This is the first time a new epoch has been observed in the making by modern-day researchers, the authors say. What kind of impact on the geological record are we leaving for future generations to find?
- Dawn of the Anthropocene: five ways we know humans have triggered a new geological epoch, by Jan A. Zalasiewicz and Mark Williams, The Conversation
Paper #4. Warfare among early hunter-gatherers
Our next High Five paper is “Inter-group violence among early Holocene hunter-gatherers of West Turkana, Kenya,” published in Nature magazine this month. The study authors report on a case of violence between hunter-gatherers during the late Pleistocene and early Holocene period – before the existence of warfare as we know it today. Or so we thought.
The nature of inter-group relations among prehistoric hunter-gatherers remains disputed, with arguments in favour and against the existence of warfare before the development of sedentary societies. […] Ten of the twelve articulated skeletons found at Nataruk show evidence of having died violently at the edge of a lagoon, into which some of the bodies fell. The remains from Nataruk are unique, preserved by the particular conditions of the lagoon with no evidence of deliberate burial. They offer a rare glimpse into the life and death of past foraging people, and evidence that warfare was part of the repertoire of inter-group relations among prehistoric hunter-gatherers. – Lahr et al. 2016
Nearly 100 news outlets and a dozen blogs picked up the study. The New York Times headlined, “Is Warfare in Our Bones?”
What scientists found at a place called Nataruk on what was once the shore of a lagoon on Lake Turkana in Kenya were skeletons showing unmistakable evidence of violent deaths — crushed skulls, imbedded arrow or spear points and the like. According to a report of the find in the journal Nature, one man had been hit in the front of the head and stabbed in the neck; the skeleton of a pregnant woman looked like she had been tied up before she was killed. It was obviously a terribly violent encounter. But was it war? The skeletons, alas, do not provide a conclusive answer, the scientists acknowledged. War, broadly defined as large-scale violent clashes, was fairly common between settled societies, and it is not clear whether the dwellers on the fertile land around Lake Turkana at the time of the Nataruk clash were already forming such societies, which would make a violent encounter less surprising, or whether the foraging groups banded together to fight. “In either case,” write the scientists, “the deaths at Nataruk are testimony to the antiquity of inter-group violence and war.” – The Editorial Board, New York Times
Update: However, other science writers covered this study with a skeptical eye toward the claim that the data supports a “deep-roots theory” of human warfare. John Horgan writes for Scientific American, “The evidence is overwhelming that war, far from being an innate behavior that evolved millions of years ago, was a cultural innovation – an “invention,” as Margaret Mead put it – that emerged relatively recently in our prehistory, toward the end of the Paleolithic era.”
- Prehistoric Carnage Site Is Evidence of Earliest Warfare, by Bret Stetka, Scientific American
- 10,000-year-old mass killing is still a mystery, by Annalee Newitz, ArsTechnica
- Attack 10,000 years ago is earliest known act of warfare, by Bruce Bower, ScienceNews
Paper #5. Ancient Use of Advanced Geometry
Our final High Five paper is a report published in Science magazine on January 29, “Ancient Babylonian astronomers calculated Jupiter’s position from the area under a time-velocity graph.” The study investigates how Ancient Babylonian astronomers managed to track Jupiter’s position – a very long time ago.
Ancient Babylonian astronomers developed many important concepts that are still in use, including the division of the sky into 360 degrees. They could also predict the positions of the planets using arithmetic. Ossendrijver translated several Babylonian cuneiform tablets from 350 to 50 BCE and found that they contain a sophisticated calculation of the position of Jupiter. The method relies on determining the area of a trapezium under a graph. This technique was previously thought to have been invented at least 1400 years later in 14th-century Oxford. This surprising discovery changes our ideas about how Babylonian astronomers worked and may have influenced Western science. – Science summary
The study has been picked up by over 100 different news outlets in the past few days. The New York Times headlined, “Knowing All the Angles: Ancient Babylonians Used Tricky Geometry.”
Ancient Babylonian astronomers were way ahead of their time, using sophisticated geometric techniques that until now had been considered an achievement of medieval European scholars. That is the finding of a study published on Thursday that analyzed four clay tablets dating from 350 to 50 BC featuring the wedge-shaped ancient Babylonian cuneiform script describing how to track the planet Jupiter‘s path across the sky. “No one expected this,” said Mathieu Ossendrijver, a professor of history of ancient science at Humboldt University in Berlin, noting that the methods delineated in the tablets were so advanced that they foreshadowed the development of calculus.
- Humans Calculated Paths of Planets 1,400 Years Earlier Than We Thought, By Grennan Milliken, Popular Science
- Babylonians tracked Jupiter with sophisticated geometrical math, by John Timmer, ArsTechnica
What other changes in our understanding of human history are on the horizon?