What Is a Planet? - GLORIA DICKIE
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Polar Bears Hunt With Weapons | Ice Gets Bent Out of Shape
MAGAZINE OF THE SOCIETY FOR SCIENCE s AUGUST 28, 2021
What Is
a Planet?
Fifteen years after
Pluto lost its title,
scientists still
don’t agree
cover_pluto.indd 1 8/11/21 1:42 PM
ON FIRE AND UNDER WATER
SOLUTIONS FOR OUR BURNING PLANET AND ITS RISING OCEANS
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—David Wallace-Wells, author of relationship with fire, updated for the —Kirkus Reviews
The Uninhabitable Earth climate-change generation.
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responsibilities—to our beaches written, demonstrating the author’s
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working . . . to better understand —CHOICE
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_C2.indd 2 7/29/21 3:59 PM
VOL. 200 | NO. 4
Features
20 Pluto’s Place
COVER STORY Fifteen years after astronomers voted
to redefine “planet,” some scientists say it’s time to
revisit that definition. A look back shows the term’s
meaning has been ever-changing. By Lisa Grossman
24 The Debate Over
Gender-Affirming Health Care
As some states seek to limit transgender youths’
access to gender-affirming health care, researchers
are studying the mental health effects of age-
24
appropriate care. By Maria Temming
News
6 Microscopic fossils push 10 The dino-killing asteroid 18 News in Brief
back the start of animal unleashed a tsunami An odd gamma-ray burst
life, a scientist contends that may have left may have been the death
giant ripple marks under knell of a massive star
7 The moon’s magnetic field
Louisiana
lasted for just a blip in The coronavirus razes
geologic time, a study hints 12 Viruses help moth a crucial cell barrier to
4
8 Sea level change can cause caterpillars combat cause severe COVID-19
killer parasites
a sea change in Santorini’s
volcanic activity 14 How speedy squirrels
Black holes born with
magnetic “hair” quickly
Departments
Colliding light might jump from tree to tree shed it, computer 2 EDITOR’S NOTE
demonstrate Einstein’s without falling simulations suggest
4 NOTEBOOK
equation E=mc2 Ice can bend without
16 For some polar bears, To survive harsh winters,
FROM TOP: DREW ANGERER/GETTY IMAGES; ALMA/ESO, NAOJ AND NRAO, M. BENISTY ET AL;
9 Pterosaurs may have stone and ice may be the pikas slow down their breaking; a baby exoplanet
taken to the air soon after perfect tools for hunting metabolism and snack on could be making moons
hatching walruses yak poop 30 REVIEWS & PREVIEWS
A new book tackles
JOHN CAPINERA/UNIV. OF FLORIDA, BUGWOOD.ORG (CC BY-NC 3.0 US)
pseudoscience; another
looks at the Big Bang
theory’s origins
34 FEEDBACK
36 SCIENCE VISUALIZED
See how a glass sponge
alters the flow of water
COVER Pluto rises above
the horizon of its largest
moon, Charon, in this
illustration. Mark Garlick/
Science Photo Library/Getty
12 Images Plus
www.sciencenews.org | August 28, 2021 1
toc.indd 1 8/11/21 2:03 PM
EDITOR’S NOTE
Debate over Pluto’s planet
publisher Maya Ajmera
editor in chief Nancy Shute
editorial
status still carries on editor , special projects Elizabeth Quill
news director Macon Morehouse
digital director Kate Travis
features editor Cori Vanchieri
Fifteen years ago, Pluto was kicked out of the planet club. managing editor , magazine Erin Wayman
deputy news editor Emily DeMarco
On August 24, 2006, members of the International associate news editor Ashley Yeager
associate editor Cassie Martin
Astronomical Union voted in favor of a new definition of associate digital editor Helen Thompson
audience engagement editor Mike Denison
what constitutes a planet. What was once considered the astronomy Lisa Grossman
solar system’s ninth planet no longer qualified. behavioral sciences Bruce Bower
biomedical Aimee Cunningham
The public outcry was immediate. “In changing the definition of planet, the earth and climate Carolyn Gramling
life sciences Susan Milius
International Astronomical Union is messing with something much bigger than molecular biology, senior writer Tina Hesman Saey
neuroscience , senior writer Laura Sanders
it is,” one Science News reader complained in a letter to the editor. “Think of all physics , senior writer Emily Conover
social sciences Sujata Gupta
the dictionaries, encyclopedias, textbooks and websites that will need revision.” staff writers Erin Garcia de Jesús, Jonathan Lambert
editorial assistant Aina Abell
Many planetary scientists were upset too, though mostly for other reasons. As science writer interns Jaime Chambers, Nikk Ogasa
contributing correspondents
astronomy writer Lisa Grossman explains in this issue (Page 20), some research- Laura Beil, Tom Siegfried, Alexandra Witze
ers thought the new definition — that a planet is a spherical body that orbits the design
chief design officer Stephen Egts
sun (which Pluto is) and has cleared other objects out of its orbit (which Pluto design director Erin Otwell
art director Tracee Tibbitts
hasn’t) — was too restrictive. Some scientists still lobby for a broader definition. assistant art director Chang Won Chang
The debate over classifying solar system objects reminds me of another classifi- science news for students
cation challenge: categorizing the diversity of life on Earth. As a child, I remember editor Janet Raloff
managing editor Sarah Zielinski
learning about the five kingdoms of life: animals, plants, fungi, protists (things assistant editor Maria Temming
web producer Lillian Steenblik Hwang
like algae) and monerans (bacteria). Though there was never a vote (that I’m society for science
aware of ), that system was superceded. In the 1990s, biologists proposed new president and ceo Maya Ajmera
chief of staff Rachel Goldman Alper
groups such as domains — bacteria, archaea (unicellular organisms that had once chief marketing officer Kathlene Collins
chief program officer Michele Glidden
been considered bacteria) and eukaryotes. More recently, scientists have debated chief, events and operations Cait Goldberg
chief communications officer Gayle Kansagor
how to organize eukaryotes, organisms that store DNA within a cell nucleus. For chief advancement officer Bruce B. Makous
chief technology officer James C. Moore
example, did you know you’re an opisthokont? According to some biologists, all chief financial officer Dan Reznikov
animals, fungi and some single-celled eukaryotes fall into that “supergroup” board of trustees
chair Mary Sue Coleman
(SN: 8/8/15, p. 22). The name, roughly meaning “rear pole,” references the fact vice chair Martin Chalfie treasurer Hayley Bay Barna
secretary Paul J. Maddon at large Christine Burton
that many opisthokonts have at least some cells powered by a whiplike tail. Ani- members Craig R. Barrett, Adam Bly, Mariette DiChristina,
Tessa M. Hill, Tom Leighton, Alan Leshner, W.E. Moerner,
mals, for instance, have sperm. But I doubt many schoolchildren would cry if we Dianne K. Newman, Thomas F. Rosenbaum, Gideon Yu,
lost our membership in this group, as they did over Pluto’s “demotion.” Feng Zhang, Maya Ajmera, ex officio
advertising and subscriber services
Categorizing life is an ongoing process, and even the definition of life itself advertising Daryl Anderson
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2 SCIENCE NEWS | August 28, 2021
ed note.indd 2 8/11/21 2:15 PM
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NOTEBOOK
Some soil samples collected
near Shackleton Glacier in
Excerpt from the Antarctica (shown) were
August 28, 1971 seemingly devoid of microbial
issue of Science News life, an unexpected finding.
50 YEARS AGO THE SCIENCE LIFE
The shrinking Missing microbes hint at limits on the search for E.T.
mass of Pluto Even in the harshest environments, though the air around Shackleton Glacier
Pluto was the last of the plan- microbes always seem to get by. They is so cold and so arid that he often left his
ets to be discovered (in 1930). thrive everywhere from boiling-hot damp laundry outside to freeze-dry.
If astronomers continue to seafloor hydrothermal vents to high on Surprisingly, some of the coldest,
make it lighter, it may be the Mount Everest. Clumps of microbial cells driest soils didn’t seem to be inhabited
first to disappear.… [The lat- have even survived for years in outer space by microbes at all, Fierer and colleagues
est measurement] brings (SN: 9/26/20, p. 10). report in the June Journal of Geophysical
Pluto down to 0.11 of Earth’s There was no reason for microbial ecolo- Research: Biogeosciences. To Fierer’s
mass, less than an eighth of gist Noah Fierer to expect that any of the knowledge, this is the first time that sci-
its former self.… The wide 204 soil samples he and colleagues had entists have found soils that don’t appear
discrepancies among the collected near Antarctica’s Shackleton to support any kind of microbial life.
figures presented for the Glacier would be different. A spoonful of The findings suggest that exceedingly
mass of Pluto illustrate the typical soil could easily contain billions cold and arid conditions might place a hard
particular difficulties of mea- of microbes, and Antarctic soils from limit on microbial habitability and raise
suring its mass.… If a planet other regions host at least a few thousand questions about how negative scientific
has satellites, its mass can be per gram. Fierer assumed that all of his results should be interpreted, especially in
determined from studying samples would host at least some life, even the search for life on other planets. “The
their motions.… But Pluto
has no known satellites.
HOW BIZARRE
UPDATE: The discovery of
Pluto’s moon Charon in 1978
Ice gets flexible in lab experiments
(SN: 7/15/78, p. 36) finally Ice’s well-established reputation for being stiff and brittle may
FROM TOP: ALMA/ESO, NAOJ AND NRAO, M. BENISTY ET AL; COURTESY OF N. FIERER
allowed astronomers to ac- be ruined. Thin, pristine threads of ice are bendy and elastic,
curately calculate the planet’s scientists report in the July 9 Science.
mass: about 0.2 percent of To create the flexible ice, nanoscientist Peizhen Xu of
Earth’s mass. Decades after Zhejiang University in Hangzhou, China, and colleagues used
scientists resolved Pluto’s heft, A tiny thread a needle with an electric voltage applied to it, which attracted
of ice (shown
the planet received arguably in a micro- water vapor within a chilled chamber. The resulting ice whis-
the greatest demotion of scope image) kers were a few micrometers in diameter or less. Ice usually
all — a downgrade to dwarf can bend into contains defects: tiny cracks, pores or misaligned sections of
FROM TOP: N. FIERER; P. XU ET AL/SCIENCE 2021
a curve and
planet (SN: 9/2/06, p. 149). spring back crystal. But the ice threads consisted of near-perfect crystals,
Some astronomers have since to its original giving the threads atypical properties. Between –70° and
proposed alternate definitions shape when –150° Celsius, scientists could curve the ice into a partial circle
released.
for the term “planet” that, if with a radius of tens of micrometers. When the team released
widely adopted, would restore the bending force, the fibers sprang back to their original
Pluto to its former rank (see shape. Bending the fibers compresses the ice on its inside
Page 20). edge, inducing the ice to take on a different structure. That
discovery could give researchers a new way to study ice’s prop-
erties when squeezed. — Emily Conover
4 SCIENCE NEWS | August 28, 2021 Watch a video of ice bending at bit.ly/SN_IceSpring
notebook.indd 4 8/11/21 11:31 AM
challenge comes back to this sort of another method to try, he says.
philosophical [question]: How do you Polar microbiologist Jeff Bowman
prove a negative?” says Fierer, of the sees the findings as an indication that
University of Colorado Boulder. current technology can’t detect very
Proving a negative result is notori- low levels of life, which can lead to
ously difficult. No measurement is false-negative results. “Certainly, there
perfectly sensitive, so there’s always a were things there,” says Bowman, of the
possibility that a well-executed experi- Scripps Institution of Oceanography in
ment will fail to detect something that is La Jolla, Calif. “This is Earth. This is an
actually there. It took nearly two years environment that is massively contami-
of experiments based on multiple meth- nated with life.”
ods before Fierer and his University of Even if there were a few microbes in
Colorado colleague Nick Dragone finally the soil, that wouldn’t undermine the
felt confident enough to announce that team’s evidence that cold and aridity PICTURE THIS
they’d found seemingly microbe-free pose a serious challenge to life, Dragone
soils. And the scientists intentionally says. “It’s the combination of multiple
A forming exoplanet
stated only that they were unable to very challenging environmental condi- could make moons
detect life in their samples, not that the tions that restricts life more than just
soils were naturally devoid of life. “We one acting by itself.” New telescope images may provide
can’t say the soils are sterile. Nobody As scientists search for evidence of the first view of moons forming out-
can say that,” Fierer says. There’s always life beyond Earth, they will be forced side the solar system.
to walk the line between evidence The Atacama Large Millimeter/
Microbe-free soil of absence and absence of evidence. submillimeter Array, or ALMA, in
samples raise questions “What we’re trying to do on Mars is Chile glimpsed a dusty disk of poten-
about how to interpret kind of the reverse of what we’ve tried tially moon-forming material around
negative results, says
researcher Noah Fierer. to do on Earth,” says polar microbiolo- a baby exoplanet about 370 light-
d gist Lyle Whyte of McGill University in years from Earth. The Jupiter-like
Montreal. On Earth, claiming that an world is surrounded by enough mate-
environment is lifeless is a tough scien- rial to make up to 2.5 Earth moons,
n tific sell. On Mars, it will be the other researchers report in the July 20
way around. — Elise Cutts Astrophysical Journal Letters.
ALMA observed a planet dubbed
PDS 70c circling the star PDS 70
THE –EST (center, above) in July 2019. Unlike
most known exoplanets, this world
A skeleton unearthed in Peru vies for the title is still forming, gobbling up material
y of oldest known shark attack victim from the disk of gas and dust swirling
FROM TOP: ALMA/ESO, NAOJ AND NRAO, M. BENISTY ET AL; COURTESY OF N. FIERER
When news broke in June that the oldest known case of a person killed by a shark around its star. During this forma-
involved a member of Japan’s Jōmon culture around 3,000 years ago (SN Online: tion process, planets are expected to
7/23/21), two researchers took special notice. wrap themselves in their own debris
Back in 1976, bioarchaeologist Robert Benfer of the University of Missouri in disks, which control how planets
Columbia and anthropological archaeologist Jeffrey Quilter of Harvard University pack on material and form moons.
helped excavate a roughly 17-year-old boy’s skeleton at a Peruvian village site Around PDS 70c, ALMA spotted
called Paloma. The remains bore signs of a fatal shark encounter: One of the boy’s a disk of dust (small dot, right of the
legs was missing, and his hip and forearm bones displayed deep bite marks char- star) about as wide as Earth’s orbit
FROM TOP: N. FIERER; P. XU ET AL/SCIENCE 2021
acteristic of those made by sharks. Radiocarbon dating indicated that the teen around the sun. With previously
died around 6,000 years ago, Benfer says. That could make the teen the real oldest reported exomoon sightings still
e known shark attack victim. controversial (SN Online: 4/30/19),
Quilter described the youth’s shark-related injuries in two paragraphs in the the new observations offer some of
1989 book Life and Death at Paloma. But the results were never published in an the best evidence yet that planets
academic journal. Quilter and Benfer e-mailed the excerpt to the Jōmon research- orbiting other stars have moons.
ers on July 26. “We were unaware of their claim until now but are keen to speak to — Maria Temming
- them about it in more detail,” says archaeologist J. Alyssa White of the University
of Oxford, who led the Jōmon team. — Bruce Bower
g www.sciencenews.org | August 28, 2021 5
notebook.indd 5 8/11/21 11:32 AM
News
LIFE & EVOLUTION
Oldest animal fossil claim stirs debate
Squiggly alleged sponge hints at a much earlier start for animals
BY JAKE BUEHLER the Cambrian Period, when an extreme tubes in 1992 in rocks from Little Dal, an
Pale, wormlike tubes in 890-million- burst in the evolution of animal diversity ancient reef system formed by cyano-
year-old rock may be ancient sea sponges, began (SN: 9/7/13, p. 12). Some other ani- bacteria, in northwestern Canada’s
a new study concludes. If confirmed, that mals are known from nearly 20 million Mackenzie Mountains. “I found this
controversial claim would push back the years earlier, but go too much further thing that was totally out of place,” she
origin of the earliest sponges by about back in time and the fossils’ classifica- says. “It was much more complex in
350 million years and make the micro- tion as animals becomes less certain terms of its structure than anything that
scopic squiggles the oldest known fossils (SN: 4/4/15, p. 12). Based on genetic could be made by cyanobacteria.”
of animals. data and sponges’ relative simplicity, the She would have reported the curious
Crucially, these fossils would imply creatures are generally thought to have squiggles then, but without much else
that animals emerged in environmental been the earliest form of animal life. to tie the fossils to sponges besides a
conditions previously thought unwork- But some scientists aren’t convinced general resemblance, Turner moved on.
able for animal life, geologist Elizabeth that the newly described tubes are More than a decade later, other scientists
Turner reports July 28 in Nature. sponge fossils. “Organisms from any- published research showing that sponges
Early in Earth’s history, the ocean where on the tree of life can make wiggly, preserved in rock could appear similar
mostly lacked oxygen. It wasn’t until little [branching and rejoining] struc- to the pallid wiggles at Little Dal, so she
about 800 million to 540 million years ago tures,” says paleobiologist Jonathan returned to her find.
that a large pulse of the gas to the atmo- Antcliffe of the University of Lausanne Turner argues that many modern
sphere, known as the Neoproterozoic in Switzerland. The fossils lack features sponges don’t have spicules. If ancient
Oxidation Event, brought atmospheric such as mineralized skeletal parts called creatures were similar, the newly
oxygen levels to within 10 to 50 percent spicules that would identify the crea- described fossils could be sponges. And
of modern levels. That event boosted the tures as sponges, he says. she suggests that sponges predating the
amount of oxygen in surface ocean waters What’s more, the finding doesn’t fit Neoproterozoic Oxidation Event may
(SN: 1/18/20, p. 7). Until that point, oxy- with what scientists know about the have scraped out an existence in “oxygen
gen levels were thought to be too low to availability of nutrients, biominerals oases” along microbial reefs, living in
sustain animal life. “But sponges are dif- and oxygen in the whole ocean ecosystem holes and reef flanks.
ferent from other animals,” says Turner, before the Cambrian Period, Antcliffe It’s possible that early sponges
of Laurentian University in Sudbury, says. “Everything we know about the emerged much earlier than the rest of
Canada. “Some sponges in the modern Earth’s oceans in this interval of time animal life and remained in a kind of evo-
world and in the rock record are known to tells us that animals originated around lutionary stasis in low-oxygen conditions,
be tolerant of comparatively low oxygen 540 [million to] 550 million years ago. Turner says. The evolution of more com-
relative to modern ocean levels.” It’s a legion of evidence, and to overturn plex animals would have had to wait until
Until now, the earliest, unambigu- such an enormously strong paradigm, oxygen became more abundant.
ous fossilized sponges date to about you need more than ‘might be a sponge.’ ” Scientists have known about odd types
540 million years ago to the beginning of Turner first found the network of of fossils in the Little Dal reef for a while,
says paleobiologist James Schiffbauer of
the University of Missouri in Columbia.
And previous genetic analyses have sug-
gested that sponges evolved well before
the Cambrian Period. “It has just been
a matter of finding them if they were
indeed preserved,” Schiffbauer says.
Future research could help confirm the
fossils’ identity. Turner says she plans to
E.C. TURNER/NATURE 2021
continue studying the ancient tubes, add-
ing that more answers may come from
100 µm 100 µm
looking in the right places. “We need to be
A skeletal fragment of a modern bath sponge (Spongia officinalis) has a characteristic branched looking for similar material with a really
structure. What’s claimed to be an ancient sponge fossil (inset) sports a similar structure. open mind in rocks of similar age.” s
6 SCIENCE NEWS | August 28, 2021
worm-fossil.indd 6 8/11/21 11:55 AM
ATOM & COSMOS
Lunar rocks hint at fleeting magnetism
The moon’s magnetic field lasted 500 million years at most
BY CAROLYN GRAMLING magnetic field for at least 4 billion years.
A lunar magnetic field may have The magnetization of the bit of glass
persisted for only a blip in geologic time, happened due to the meteorite impact
a new study suggests. that also formed the glass itself, Tarduno
Shortly after the moon formed about and colleagues suggest. 1 mm
4.5 billion years ago, it may have begun The idea that a meteorite impact can
generating a magnetic field, a protec- produce strong magnetization in rocks Lunar glass that formed in a meteorite strike
about 2 million years ago (example shown)
tive sheath that can deflect charged has been discussed in previous scientific probably was magnetized by the impact rather
particles from the sun. Now, analyses of studies, Tarduno says. As a meteorite than a magnetic field from the moon’s core.
moon rocks suggest that any lunar mag- punches into the lunar surface at super-
netic field was gone by at least 4 billion fast speeds, the impact can partially lingered until as recently as 1 billion
years ago, researchers report August 4 ionize particles on the surface, creating years ago (SN: 9/16/17, p. 10).
in Science Advances. thick, magnetized plasma. “The glass, Geodynamicists have wrangled over
Magnetized lunar rocks brought back as it was moving through this plasma, how the moon’s small core could have
by Apollo astronauts decades ago were acquired that strong magnetization,” sustained a magnetic field for billions
the first indication that the moon may he says. of years or even if the moon ever had a
have once had an internal dynamo — in The moon has been repeatedly bat- magnetic field at all, says paleomagne-
which molten, iron-rich rock swirls tered by meteorites over time (SN: tist Lisa Tauxe of the Scripps Institution
inside the core of a celestial body, giv- 6/6/20, p. 32). Relatively young and of Oceanography in La Jolla, Calif. Mod-
ing rise to a magnetic field (SN: 12/17/11, highly magnetized lunar samples that eling studies of the moon’s core “just
p. 17). But how long such a lunar dynamo researchers have puzzled over may have have a great deal of trouble generating
may have lasted has been unclear. gotten their magnetization in the same enough oomph to make a magnetic field,
The moon’s core is “really small,” way the glass did, Tarduno says. whereas you can do that pretty easily
says geophysicist John Tarduno of the If so, that may also help explain for the Earth.” The new study, she says,
University of Rochester in New York. results from recent studies, based on “presents a well-argued case against a
It’s not clear how that core could have analyses of the magnetization of a moon long-lived field.”
sustained a dynamo for long before cool- rock dating to between 2.5 billion and If any lunar magnetic field disap-
ing, he says. 1 billion years ago, that have suggested peared about 4 billion years ago, the
Tarduno and colleagues examined the the moon’s magnetic field might have lengthy bombardment of the moon’s
magnetization of a handful of the Apollo surface by the solar wind since then
rock samples. Analyzing the magnetism Earth’s moon has lacked a magnetic field, may have left a hidden wealth of
of tiny shards of metal trapped in crys- leaving it unprotected from the solar wind, for helium-3 and water buried in the lunar
at least 4 billion years, a study suggests.
tals in rock dating from 3.9 billion to soils (SN: 5/11/19 & 5/25/19, p. 8). Those
3.2 billion years ago showed that those are products that future moon expedi-
rocks were barely magnetized at all. tions may be able to mine for energy, as
But a piece of lunar glass that well as life support.
formed during a meteorite impact Drilling into those soils may also
about 2 million years ago had a give scientists an unprecedented
strong magnetic field, “just a lit- glimpse at past physical properties
FROM TOP: RORY COTTRELL; T. PESQUET/ESA, NASA
tle weaker than Earth’s today,” of the sun, Tarduno says, which
Tarduno says. That’s odd, could also help scientists better
because “everyone agrees there understand conditions on the
isn’t a magnetic field on the early Earth (SN: 6/25/16, p. 12).
moon now, and there wasn’t “[We] have the potential now to
one 2 million years ago,” he learn both about the ancient sun
says. “How does this happen?” and early Earth’s atmosphere,
Taken together, these findings which you’re not going to get in
point to one conclusion, the team any other way,” he says. “That’s really
says: The moon hasn’t generated a exciting stuff.” s
www.sciencenews.org | August 28, 2021 7
moon.indd 7 8/11/21 12:06 PM
NEWS
EARTH & ENVIRONMENT the volcano to cave in, forming a lagoon e
Sea level dips spur (SN: 3/10/12, p. 12).
To investigate how sea level might
o
v
volcanic eruptions influence the volcano, physical geogra-
pher Christopher Satow and colleagues
t
p
Santorini flare-ups are linked created a computer simulation of S
to periods of low sea level Santorini’s magma chamber, which sits w
about four kilometers beneath the volca- u
BY MARIA TEMMING no’s surface. When the sea level dropped
When sea level drops far below the at least 40 meters below the present-day a
present-day level, the island volcano level, the crust above the magma chamber o
Santorini in Greece gets ready to rum- splintered, the simulation showed. That a
ble. A comparison of the activity of the allows magma stored under the volcano Sea level seems to influence eruptions from s
the partially submerged volcano of Santorini
volcano with sea levels over the last to “move up through these fractures and (shown from above) in Greece. Lower sea lev- o
360,000 years suggests that when the sea make its way to the surface,” says Satow, els are historically linked to more eruptions. I
level dips more than 40 meters, it triggers of Oxford Brookes University in England. s
a fit of eruptions. During times of higher Those magma-filled cracks should and your hands’ inward pressure is the ly
sea level, the volcano is quiet, researchers take about 13,000 years to reach the sur- weight of the ocean. As someone else v
report in the August Nature Geoscience. face and awaken the volcano, the team pumps air into the balloon — like magma
Since more than half of the world’s found. After the water rises again, the building up under Earth’s crust — the le
volcanic systems are in or near oceans, cracks should take about 11,000 years to pressure of your hands helps prevent the d
sea levels probably similarly influence close, stopping eruptions. balloon from popping. “As soon as you a
other volcanoes, the researchers say. It may seem counterintuitive that start to release the pressure with your m
Santorini is a ring of islands surround- lowering the amount of water atop the hands, [like] taking the sea level down, t
ing the central tip of a volcano poking magma chamber would cause the crust to the balloon starts to expand,” Satow says, q
out of the Aegean Sea. The entire vol- splinter. Satow compares the scenario to and ultimately the balloon breaks. v
cano used to be above water, but a violent wrapping your hands around an inflated The team tested the simulation’s s
eruption around 1600 B.C. caused part of balloon, where the rubber is Earth’s crust predictions by comparing Santorini’s le
MATTER & ENERGY Predicted more than 80 years ago, Photons from a common source of B
Light is caught the Breit-Wheeler process had never
been directly observed. New measure-
light, such as a lightbulb or a laser, are
considered real. But the bona fides of o
making matter ments from the STAR experiment at
Brookhaven National Laboratory in
Brandenburg and colleagues’ photons are
up for debate because the light the team
W
L
But the result depends on New York match predictions for the elu- collided came from an unusual source: O
whether the photons are ‘real’ sive transformation, physicist Daniel the electromagnetic fields of two atomic a
Brandenburg and colleagues report in nuclei that race around Brookhaven’s
BY EMILY CONOVER the July 30 Physical Review Letters. Relativistic Heavy Ion Collider. d
Collide light with light, and poof, you get “The idea that you can create mat- Normally, photons from such elec- t
matter and antimatter. It sounds like a ter from light smashing together is an tromagnetic fields are virtual. But in the
simple idea, but it turns out to be sur- interesting concept,” says Brandenburg, experiment, the photons act as if they t
prisingly hard to prove. of Brookhaven. It’s a striking demon- are real due to the high speeds at which S
A team of physicists is now claiming stration of the physics immortalized the two nuclei are zipping along. In cases L
the first direct observation of the long- in E instein’s equation E=mc2, which where the nuclei barely miss one another, a
sought Breit-Wheeler process, in which revealed that energy and mass are two their electromagnetic fields overlap and H
two particles of light, or photons, crash sides of the same coin. two photons from those fields can collide. s
into one another and produce an elec- Whether the observation truly quali- So the team looked for near-misses that
NASA EARTH OBSERVATORY
tron and its antimatter counterpart, a fies depends on whether the photons spit out one electron and one positron. t
positron. But the detection’s significance are considered “real,” as demanded by Measurements of angles between p
hinges on whether the light is “real.” the Breit-Wheeler process, or “virtual.” those particles, which depend on t
MARK WITTON
Some physicists argue the photons don’t In particle physics, virtual particles are whether real or virtual photons collided, t
qualify as real, raising questions about ones that appear for only instants and matched expectations for real photons, h
the observation’s implications. don’t carry their normal masses. suggesting that the team had seen the li
8 SCIENCE NEWS | August 28, 2021
volcano-fossil-light.indd 8 8/11/21 12:08 PMeruption history with geologic evidence LIFE & EVOLUTION
of past sea levels. All but three of the
volcano’s 211 well-dated eruptions in Newly hatched pterosaurs took flight
the last 360,000 years happened during A strong wing bone suggests the baby reptiles were agile fliers
periods of low sea level, as predicted.
Such periods of low sea level occurred BY CAROLYN GRAMLING flight are strong bones, sufficient muscle
when more of Earth’s water was locked Pterosaur hatchlings may have been able mass to stay in the air for a long time and
up in glaciers during ice ages. to fly right out of the shell. A new analysis sturdy keratin fibers in the skin of the
“It’s really intriguing and interesting, of the fossilized wing bones of embryonic, wings, analogous to bird feathers, Padian
and perhaps not surprising, given that newly hatched and adult pterosaurs sug- says. “We know little about the last two.”
other studies have shown that volcanoes gests the baby creatures were strong and Paleontologist Darren Naish of the
are sensitive to changes in their stress nimble fliers from the start, researchers University of Southampton in England
state,” says geophysicist Emilie Hooft report July 22 in Scientific Reports. and colleagues turned to bones, com-
of the University of Oregon in Eugene. Pterosaurs were a diverse group of paring fossilized embryo and hatchling
Icelandic volcanoes, for instance, have flying reptiles that lived alongside dino- wing measurements with those of adults
shown an uptick in eruptions after over- saurs from 228 million to 66 million from two species: Pterodaustro guinazui
lying glaciers have melted, relieving the years ago during the Triassic and and Sinopterus dongi. The team zeroed
volcanic systems of the weight of the ice. Cretaceous periods. The group includes in on one wing bone, the humerus, that
As for Santorini, the last time sea Quetzalcoatlus northropi, the larg- offers key information on whether a
level was 40 meters below the present- est creature known to take wing, and pterosaur was capable of getting off the
day level was near the end of the last ice Kunpengopterus antipollicatus, which ground.
age — and sea level is rising due to cli- had opposable thumbs that enabled it to Relative to hatchlings’ size, their
mate change — so Satow’s team expects climb trees (SN: 5/8/21 & 5/22/21, p. 16). humerus bones were stronger than those
the volcano to enter a period of relative Scientists know relatively little about of many of the adults, and hatchlings also
quiet. But two major eruptions in the whether young pterosaurs could actively had shorter, broader wings, suggesting
volcano’s history did happen amid high flap their wings or only glide — which that youngsters might have been capable
sea levels, the team says, so future vio- might mean they stayed under paren- of nimbly changing direction and speed,
lent eruptions aren’t off the table. s tal care until they were flight-ready. But and possibly flying long distances. Agile
relatively recent revelations increasingly flying may have helped the hatchlings
point toward early independence, or pre- escape predators and chase tricky prey
Breit-Wheeler process. cociality, for the reptiles. For instance, such as insects, all while navigating
Strictly speaking, the experiment is researchers have found flight mem- dense vegetation, the team suggests.
one step removed from the true Breit- branes on the wings of an embryonic It isn’t unusual in the animal world
Wheeler process, says particle physicist pterosaur and the remains of a juvenile for young to fend for themselves, Padian
Lucian Harland-Lang of the University of that was capable of long-distance flying says. “Precociality is the rule, not the
Oxford. While the photons behave almost long before it had grown to adult size. exception, in vertebrates,” he says.
as if real, they are technically virtual. “Baby pterosaurs almost certainly Only animals with extended parental
Brandenburg and colleagues take a didn’t glide,” they flew, says paleontolo- care, such as songbirds and primates,
different view, in which the reality of gist Kevin Padian of the University of can afford to be helpless for prolonged
the photon is based on how it behaves. California, Berkeley. The three keys to periods. s
The scientists’ measurements back
that up, says laser plasma physicist A flamingo-like pterosaur, Pterodaustro guinazui
S tuart Mangles of Imperial College (shown in this artist’s rendition), could fly
from the moment it emerged from its shell,
London. “Everything they’re measuring new research suggests.
about it makes it look like a real photon.”
However, Mangles says, the photons are
still virtual by some definitions.
Mangles and others are working
NASA EARTH OBSERVATORY
toward detecting the Breit-Wheeler
process with lasers, which produce light
that’s as real as the light allowing you
MARK WITTON
to read this article. That, physicists are
hoping, will clinch the case for colliding
light making matter. s
www.sciencenews.org | August 28, 2021 9
volcano-fossil-light.indd 9 8/11/21 12:09 PMNEWS
When the Chicxulub asteroid (illustrated)
slammed into Earth millions of years ago, the
impact formed a tsunami that may have left
ripples in rock under present-day Louisiana.
there should be a tsunami.”
The ripple marks were preserved all
this time thanks to the depth at which
they formed underwater, Kinsland says.
Other studies suggest that this region
was 60 meters below the sea surface at
the time. At that depth, the ripples would
have been beyond the reach of tumultu-
EARTH & ENVIRONMENT ous storms that could have erased them.
Dino-killing asteroid had a ripple effect Then, over millions of years, other sedi-
ments slowly buried the marks.
An impact-induced tsunami may have left behind giant ridges A smaller, analogous set of struc-
tures may exist off the east coast of
BY NIKK OGASA which was underwater at the time Japan. There, a repeating sequence of
The asteroid impact that slew the dino- (SN: 11/25/17, p. 14). But no one had ever underwater dunes was reported to have
saurs may have also indirectly sculpted before found ripple marks formed by the appeared after the 2011 Tohoku earth-
the largest ripple marks ever found on sprawling wave. quake and tsunami (SN: 2/25/12, p. 22).
Earth. Geologist Kaare Egedahl discovered Except for the dunes’ size, they look
A series of ridgelike structures more the ripples while searching for coal nearly identical to the ripple marks
than three stories high and spaced deposits. Studying at the University buried beneath L ouisiana, K insland
nearly two Eiffel Towers apart appear of Louisiana at Lafayette at the time, says. That supports the idea that the
to be buried about 1.5 kilometers E gedahl had been combing through taller structures were also produced by
beneath central Louisiana. The over- seismic reflection data — 3-D images of a tsunami, though one of a much larger
sized features are megaripples shaped buried rock and soil that were generated magnitude.
by a massive tsunami generated by the by underground sound waves — provided Still, there is contention over whether
Chicxulub asteroid impact, researchers by the Devon Energy company. Egedahl, the features beneath Louisiana really are
argue in the Sept. 15 Earth and Planetary now at the oil and gas company Cantium megaripples formed by the Chicxulub-
Science Letters. in Covington, La., found the ripples atop induced tsunami.
“It’s just interesting that something a layer of rock thought to have formed “It’s hard to see how such a high-
that happened 66 million years ago could from debris shaken up by the Chicxulub energy event could form ripple marks
be so well preserved, buried 5,000 feet asteroid impact. He then shared his find- because they are usually associated
down in the sediments of Louisiana,” ing with Kinsland. with much calmer environments,” says
FROM TOP: MARK GARLICK/SCIENCE PHOTO LIBRARY/GETTY IMAGES; MARTELL STRONG
says geologist Gary Kinsland of the “I knew where that layer was from sedimentologist Pedro J.M. Costa of
University of Louisiana at Lafayette. in geologic time, and I knew what hap- the University of Coimbra in Portugal.
Ripple marks are repeating sequences pened there,” Kinsland says. “I knew And ripple marks typically form from
of ridges typically found on sandy frequent and recurring wave motion,
beaches or stream bottoms and form These are the ripples (most pronounced near while tsunamis don’t have many waves,
as wind or water flows over and moves the red line in this reconstruction) beneath he explains. Costa, who studies tsunami
Louisiana that a group of geologists say were
loose sediment. But ripple marks on the created by an asteroid-induced tsunami. deposits, says that reconstructing the lay
beach are often centimeters in height, of the seafloor at the time of the impact
m
while the structures found by Kinsland’s 11.3 k and conducting experiments in water-
team have an average height of 16 meters filled wave tanks could help unravel
and are spaced about 600 meters apart. the origins of the structures found by
The structures’ shape, size, ori- Kinsland’s team.
17.7
entation and location suggest that This new work is important because
km
they formed after the Chicxulub it opens a discussion, Costa says. Maybe
asteroid crashed into the Yucatán the Chicxulub impact “was such a high-
Peninsula in Mexico, generating a tsu- magnitude event that what we see in
nami that washed across the Gulf of normal tsunami events don’t apply to
Mexico and what is now Louisiana, this one.” s
10 SCIENCE NEWS | August 28, 2021
ripples.indd 10 8/11/21 11:57 AMSTEM
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A DV E RTI SE M E NT
_p11.indd 11 7/29/21 4:07 PMNEWS
LIFE & EVOLUTION insect virologist Madoka Nakai of the instructions from another host
Sick caterpillars Tokyo University of Agriculture and
Technology. A parasitoid wasp would kill
remains unclear, he says.
Researchers discovered in the 1970s
keep wasps at bay a host that the virus needs to survive, so
the virus fights for its home. “It’s very
that virus-infected caterpillars could
kill parasitoid wasp larvae using an
Viruses stop young moths clever,” Nakai says. unknown viral protein. In the new study,
from becoming wasp nurseries What’s more, some moth caterpillars Herrero, Nakai and colleagues identi-
make the wasp-killing proteins them- fied PKF as wasp-killing proteins. The
BY ERIN GARCIA DE JESÚS selves, the team found. It’s possible that team infected moth caterpillars with
When parasitic wasps come calling, in the distant past, a few moths survived a one of three insect viruses that carry
some caterpillars have a surprising ally: viral infection and “got some presents” in the genetic blueprints to make the
a viral infection. the form of genetic instructions for how proteins. Then the researchers either
Insects called parasitoid wasps lay to make the proteins, says insect pathol- allowed wasps to lay their eggs in the
their eggs inside young moth larvae, ogist and geneticist Salvador Herrero caterpillars or exposed wasp larvae to
turning the caterpillars into unwitting, of the University of Valencia in Spain. hemolymph — the insect equivalent of
destined-to-die incubators for possibly Those insects could have then passed blood — from infected caterpillars.
hundreds of wasp offspring. That’s bad the ability on to offspring. In this case, Virus-infected caterpillars were poor
news for viruses trying to use the cat- “what doesn’t kill you makes you stron- hosts of the parasitoid wasp Cotesia
erpillars as replication factories. Viral ger,” Herrero says. kariyai. Most young wasps died before
infections can be lethal for the caterpil- Previous studies had shown that they had the chance to emerge from the
lars, but their chances of surviving with viruses and insects, including moths, caterpillars into the world. Hemolymph
a virus are probably higher than if wasps can swap genes with each other. The new from infected caterpillars was also an
use them as a living nursery. finding is one of the latest examples of efficient killer of wasp larvae, typically
Now, a study shows how certain this activity, says entomologist Michael destroying more than 90 percent of
viruses can help caterpillars stymie Strand of the University of Georgia in offspring.
parasitoid wasps. A group of proteins Athens who was not involved in the C. kariyai wasp larvae also didn’t
dubbed parasitoid killing factor, or PKF, research. survive in caterpillars, including the
that is found in some insect viruses are “Parasite-host relationships are very beet armyworm (Spodoptera exigua),
incredibly toxic to young parasitoid specialized,” Strand says. “Factors like that make their own PKF. When the
wasps, researchers report in the July 30 [PKF] are probably important in defin- researchers blocked the genes for the
Science. ing which hosts can be used by which proteins in these caterpillars, the wasps
The finding shows that viruses and parasites.” But whether caterpillars stole lived, a sign that the proteins are key for
caterpillars can come together to the genetic instructions for the proteins the caterpillars’ defenses.
fight off a common wasp enemy, says from viruses or viruses originally stole Some parasitoid wasps, including
Meteorus pulchricornis, weren’t affected
Some moth caterpillars, such as beet armyworms (one by PKF from the viruses or the beet army-
shown), possess viral proteins that kill the larvae of worms, allowing the wasp offspring to
parasitoid wasps incubating inside them, a study finds. thrive inside caterpillars. That finding
suggests that the wasp-fighting ability is
species specific, says Elisabeth Herniou,
JOHN CAPINERA/UNIV. OF FLORIDA, BUGWOOD.ORG (CC BY-NC 3.0 US)
an insect virologist at CNRS and the
University of Tours in France who was
not involved in the work. Pinpointing
why some wasps aren’t susceptible could
reveal the details of a long-held evolu-
tionary battle between all three types of
organisms.
The study highlights that “single
genes can interfere with the outcome
of [these] interactions,” Herniou says.
“One virus may have this gene and the
other virus doesn’t have it,” and that can
change what happens when virus, cater-
pillar and parasitoid all collide. s
12 SCIENCE NEWS | August 28, 2021
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A DV E RTI SE M E NT
_p13.indd 13 8/11/21 1:58 PMNEWS
decisions, the researchers found some-
thing interesting: Branch flexibility had
about six times as great an influence on
when squirrels decided to jump as did
the length of the gap. If squirrels had
cared more about distance, they would
have jumped from about the same spot
on the rod, regardless of its give.
“We were surprised to see squirrels
weighing both of these things simul-
As they jump,
fox squirrels taneously, but in different amounts,”
make quick Hunt says.
calculations to The researchers upped the ante for five
balance trade-offs
between tree limb squirrels by increasing the flexibility of
flexibility and distance branches as well as gap distance. Initial
between limbs. leaps were less than graceful. No squirrels
fell, but most had clunky landings at first,
LIFE & EVOLUTION environments to navigate,” says Hunt, grasping the peg they leaped to with their
Leaping squirrels an integrative biologist at the University
of Nebraska Omaha.
front paws and swinging around to pull
themselves up instead of landing neatly
use parkour tricks When jumping between bendy
branches, a squirrel must assess how far
on all fours. But within five trials, “squir-
rels learned to compensate for their
Obstacle course reveals how it has to jump and know when to leap as initial error,” Hunt says, which they did
the animals navigate jumps it moves along a branch. Jump too early by modifying their initial velocity.
and the squirrel will fall short. Too late, If squirrels regularly encounter the
BY JONATHAN LAMBERT and the squirrel will find itself out on a same branches, such quick learning
Parkour enthusiasts need look no fur- part of the branch too flimsy from which “might explain how they move so fluidly
ther than up in the trees for inspiration. to launch. Hunt wondered, “How are and rapidly” across particular branches,
Squirrels’ aerial acrobatics make the they sensitive to that trade-off, manag- Hunt explains. The rodents might be
rodents masters of the form. ing to make accurate leaps?” such quick navigators, he says, because
A detailed look at how squirrels navi- To find out, he and colleagues “they’ve already learned what they need
gate narrow branches that bend and designed an artificial forest obstacle to know about that branch.”
sway with the wind — where the smallest course on the outskirts of the University The squirrels surprised the research-
error could spell death — shows that the of California, Berkeley campus. Then the ers in other ways too. For longer jumps,
rodents make split-second calculations team used peanuts to coax free-ranging or those that necessitated landing higher
to balance trade-offs between branch fox squirrels (Sciurus niger) into run- or lower than the starting point, many
bendiness and the distance between tree ning and jumping through a series of squirrels rotated midair, using their legs
limbs. And for particularly tricky jumps, acrobatic tests. to “jump” off an adjacent vertical wall in
squirrels improvise parkour-style moves First, the unwitting subjects learned a parkour-style maneuver. More often
to stick the landing, researchers report to leap from artificial branches of high, than not, squirrels employed parkour
in the Aug. 6 Science. medium or low stiffness across a gap to to slow down if they were coming in too
This research is “a great example reach a prize: a peanut at the end of a hot to a landing. “It’s an additional point
of how cool ‘normal’ animals can be landing peg. High-speed video captured of control,” Hunt says.
in their biomechanics,” says Michelle details of the jumps, from launch point For many arboreal animals, “jumping
Graham, a biomechanist at Virginia Tech to landing accuracy, for 12 squirrels between limbs is such a common thing,
in Blacksburg who was not involved with spanning 96 leaping trials. and yet we so frequently only study it in
the work. “We’ve all seen squirrels do Unsurprisingly, the squirrels leaped pieces,” Graham says, such as looking
crazy stuff in nature, but no one ever from more bendy branches earlier — just at the launch but not the landing.
pays any attention to it.” presumably to maximize jumping This study’s holistic look reveals “some-
JUDY JINN/UC BERKELEY
That is unless you’re like Nathaniel force — even though that increased the thing really interesting about squirrels,
Hunt, who has been mesmerized by distance that the animals must clear, that they take greater account of [branch
watching squirrels flash through the Hunt says. By comparing what the bendiness] than the gap distance,” she
overstory since graduate school. “Tree squirrels actually did with statistical notes. “I don’t know that I would’ve
canopies are incredibly challenging models that simulated optimal jumping guessed that.” s
14 SCIENCE NEWS | August 28, 2021 Watch squirrels leap through an obstacle course at bit.ly/SN_Squirrels
squirrel.indd 14 8/11/21 11:59 AMYou can also read
