Just beyond the tip of the Antarctic Peninsula lies an iceberg graveyard.

There, in the Scotia Sea, many of the icebergs escaping from Antarctica begin to melt, depositing sediment from the continent that had been trapped in the ice onto the seafloor. Now, a team of researchers has embarked on a two-month expedition to excavate the deposited debris, hoping to discover secrets from the southernmost continent’s climatic past.

That hitchhiking sediment, the researchers say, can help piece together how Antarctica’s vast ice sheet has waxed and waned over millennia. And knowing how much the ice melted in some of those warmest periods, such as the Pliocene Epoch about 3 million years ago, may provide clues to the ice sheet’s future. That includes how quickly the ice may melt in today’s warming world and by how much, says paleoclimatologist Michael Weber of the University of Bonn in Germany.
Weber and Maureen Raymo, a paleoclimatologist at Lamont-Doherty Earth Observatory in Palisades, N.Y., are leading the expedition, which set sail on March 25.

“By looking at material carried by icebergs that calved off of the continent, we should be able to infer which sectors of the ice sheet were most unstable in the past,” Raymo says. “We can correlate the age and mineralogy of the ice-rafted debris to the bedrock in the section of Antarctica from which the bergs originated.”
Icebergs breaking off from the edges of Antarctica’s ice sheet tend to stay close to the continent, floating counterclockwise around the continent. But when the bergs reach the Weddell Sea, on the eastern side of the peninsula, they are shunted northward through a region known as Iceberg Alley toward warmer waters in the Scotia Sea.

Because so many icebergs from all around the continent converge in one region, it is the ideal place to collect sediment cores and take stock of the debris that the bergs have dropped over millions of years.

“That area in the Scotia Sea is so exciting, because it’s a focus point between South America and the Antarctic Peninsula where the currents flow through, and there are a lot of icebergs,” says Gerhard Kuhn, a marine geologist at the Alfred Wegener Institute in Bremerhaven, Germany. “You get a picture of more or less [all of] Antarctica in that area,” says Kuhn, who has studied the region but is not aboard the current cruise.
The expedition, known as leg 382 of the International Ocean Discovery Program, plans to drill at six different sites in the Scotia Sea. At three sites, the team plans to penetrate about 600 meters into the seafloor. “That would likely bring us back to the mid-Miocene, which could translate into 12 million to 18 million years back in time,” Weber says.

At another site, the team plans to drill even deeper, 900 meters, to go further back in time, in hopes of finding sediments that date to the opening of the Drake Passage about 41 million years ago. That passage, a body of water that now lies between South America and Antarctica, opened a link between the Atlantic and Pacific oceans and may have played a role in building up Antarctica’s ice sheets at different times in its history.

A graveyard turned crystal ball
How much a melting Antarctica might have contributed to global sea-level rise following the last great ice age, which ended about 19,000 years ago, has been a subject of debate. Seas rose by about 130 meters from 19,000 to 8,000 years ago, Weber says, and much of the melting happened in the northern hemisphere.

But Antarctica may have played a larger role than once thought. In a study published in Nature in 2014, Kuhn, Weber and other colleagues reported that ice-rafted debris from that time period, as recorded in relatively short sediment cores from Iceberg Alley, often occurred in large pulses lasting a few centuries to millennia. Those data suggested that the southernmost continent was shedding lots of bergs much more quickly during those times than once thought.

Now, the researchers want to see even further into the past, to understand how quickly Antarctica’s ice sheet might have melted during even warmer periods, and how much it may have contributed to episodes of past sea-level rise.

The new drilling expedition targets several periods when the climate is thought to have warmed dramatically. One is a warm period in the middle Pliocene about 3.3 million to 3 million years ago, when average global temperatures were 2 to 3 degrees warmer than today; another is the ending of an older ice age about 130,000 years ago, when sea levels rose by about 5 to 9 meters.

Such periods may serve as analogs to the continent’s future behavior due to anthropogenic global warming. Currently, global average temperatures on Earth are projected to increase by between about 1.5 degrees and 4 degrees Celsius relative to preindustrial times, depending on greenhouse gas emissions to the atmosphere over the next few decades (SN: 10/22/18, p. 18).

“The existing [ice core] record from Iceberg Alley taught us Antarctica lost ice through a threshold reaction,” Weber says. That means that when the continent reached a certain transition point, there was sudden and massive ice loss rather than just a slow, gradual melt.

“We have rather firm evidence that this threshold is passed once the ice sheet loses contact with the underlying ocean floor,” he says, adding that at that point, the shedding of ice becomes self-sustaining, and can go on for centuries. “With mounting evidence of recent ice-mass loss in many sectors of West Antarctica of a similar fashion, we need to be concerned that a new ice-mass loss event is already underway, and there is no stopping it.”

This is what a black hole looks like.

A world-spanning network of telescopes called the Event Horizon Telescope zoomed in on the supermassive monster in the galaxy M87 to create this first-ever picture of a black hole.

“We have seen what we thought was unseeable. We have seen and taken a picture of a black hole,” Sheperd Doeleman, EHT Director and astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., said April 10 in Washington, D.C., at one of seven concurrent news conferences. The results were also published in six papers in the Astrophysical Journal Letters.

“We’ve been studying black holes so long, sometimes it’s easy to forget that none of us have actually seen one,” France Córdova, director of the National Science Foundation, said in the Washington, D.C., news conference. Seeing one “is a Herculean task,” she said.
That’s because black holes are notoriously hard to see. Their gravity is so extreme that nothing, not even light, can escape across the boundary at a black hole’s edge, known as the event horizon. But some black holes, especially supermassive ones dwelling in galaxies’ centers, stand out by voraciously accreting bright disks of gas and other material. The EHT image reveals the shadow of M87’s black hole on its accretion disk. Appearing as a fuzzy, asymmetrical ring, it unveils for the first time a dark abyss of one of the universe’s most mysterious objects.

“It’s been such a buildup,” Doeleman said. “It was just astonishment and wonder… to know that you’ve uncovered a part of the universe that was off limits to us.”

The much-anticipated big reveal of the image “lives up to the hype, that’s for sure,” says Yale University astrophysicist Priyamvada Natarajan, who is not on the EHT team. “It really brings home how fortunate we are as a species at this particular time, with the capacity of the human mind to comprehend the universe, to have built all the science and technology to make it happen.” (SN Online: 4/10/19)

The image aligns with expectations of what a black hole should look like based on Einstein’s general theory of relativity, which predicts how spacetime is warped by the extreme mass of a black hole. The picture is “one more strong piece of evidence supporting the existence of black holes. And that, of course, helps verify general relativity,” says physicist Clifford Will of the University of Florida in Gainesville who is not on the EHT team. “Being able to actually see this shadow and to detect it is a tremendous first step.”

Earlier studies have tested general relativity by looking at the motions of stars (SN: 8/18/18, p. 12) or gas clouds (SN: 11/24/18, p. 16) near a black hole, but never at its edge. “It’s as good as it gets,” Will says. Tiptoe any closer and you’d be inside the black hole — unable to report back on the results of any experiments.
“Black hole environments are a likely place where general relativity would break down,” says EHT team member Feryal Özel, an astrophysicist at the University of Arizona in Tucson. So testing general relativity in such extreme conditions could reveal deviations from Einstein’s predictions.

Just because this first image upholds general relativity “doesn’t mean general relativity is completely fine,” she says. Many physicists think that general relativity won’t be the last word on gravity because it’s incompatible with another essential physics theory, quantum mechanics, which describes physics on very small scales.
The image also provides a new measurement of the black hole’s size and heft. “Our mass determination by just directly looking at the shadow has helped resolve a longstanding controversy,” Sera Markoff, a theoretical astrophysicist at the University of Amsterdam, said in the Washington, D.C., news conference. Estimates made using different techniques have ranged between 3.5 billion and 7.22 billion times the mass of the sun. But the new EHT measurements show that its mass is about 6.5 billion solar masses.

The team has also determined the behemoth’s size — its diameter stretches 38 billion kilometers — and that the black hole spins clockwise. “M87 is a monster even by supermassive black hole standards,” Markoff said.

EHT trained its sights on both M87’s black hole and Sagittarius A, the supermassive black hole at the center of the Milky Way. But, it turns out, it was easier to image M87’s monster. That black hole is 55 million light-years from Earth in the constellation Virgo, about 2,000 times as far as Sgr A. But it’s also about 1,000 times as massive as the Milky Way’s giant, which weighs the equivalent of roughly 4 million suns. That extra heft nearly balances out M87’s distance. “The size in the sky is pretty darn similar,” says EHT team member Feryal Özel.
Due to its gravitational oomph, gases swirling around M87’s black hole move and vary in brightness more slowly than they do around the Milky Way’s. “During a single observation, Sgr A* doesn’t sit still, whereas M87 does,” says Özel, an astrophysicist at the University of Arizona in Tucson. “Just based on this ‘Does the black hole sit still and pose for me?’ point of view, we knew M87 would cooperate more.”

After more data analysis, the team hopes to solve some long-standing mysteries about black holes, such as how M87’s behemoth spews a bright jet of charged particles thousands of light-years into space.

This first image is like the “shot heard round the world” that kicked off the American Revolutionary War, says Harvard University astrophysicist Avi Loeb who isn’t on the EHT team. “It’s very significant; it gives a glimpse of what the future might hold, but it doesn’t give us all the information that we want.”
Hopes are still high for a much-anticipated glimpse of Sgr A*. The EHT team was able to collect some data on the Milky Way’s behemoth and are continuing to analyze that data, in the hopes of adding its image to the new black hole portrait gallery.

Since the appearance of that black hole changes so quickly, the team is having to develop new techniques to analyze the data. “We’re very excited to work on Sgr A*,” Daniel Marrone, an astrophysicist at the University of Arizona in Tucson, said in the Washington, D.C., news conference. “We’re doing that shortly. We’re not promising anything but we hope to get that very soon.”

Studying such different environments could reveal more details of how black holes behave, Loeb says. “The Milky Way is a very different galaxy from M87.”
The next look at the M87 and Milky Way behemoths will have to wait.

Scientists got a lucky stretch of good weather at all eight sites that made up the Event Horizon Telescope in 2017. Then bad weather in 2018 and technical difficulties, which cancelled the 2019 observing run, stymied the team.

The good news is that by 2020, there will be more observatories to work with. The Greenland Telescope joined the consortium in 2018, and the Kitt Peak National Observatory outside Tucson, Ariz., and the NOrthern Extended Millimeter Array (NOEMA) in the French Alps will join EHT in 2020.

Adding more telescopes could allow the team to extend the image, to better capture the jets that spew from the black hole. The researchers also plan to make observations using light of slightly higher frequency, which can further sharpen the image. And even bigger plans are on the horizon: “World domination is not enough for us; we also want to go to space,” Doeleman said.

These extra eyes may be just what’s needed to bring black holes into even greater focus.

WASHINGTON — In 2021, wildfires pillaged the world’s carbon-rich snow forests.

That year, burning boreal forests released 1.76 billion metric tons of carbon dioxide, researchers reported March 2 in a news conference at the annual meeting of the American Association for the Advancement of Science.

That’s a new record for the region, which stores about one-third of the world’s land-based carbon. “It’s also roughly double the emissions in that year from aviation,” said earth system scientist Steven Davis of the University of California, Irvine. The trend, if it continues, threatens to make fighting climate change even more difficult.
Boreal forests are part of the taiga, a vast region that necklaces the Earth just south of the Arctic Circle. Blazes in tropical forests like the Amazon tend to garner more attention for their potential to contribute large amounts of climate-warming gases to the atmosphere (SN: 9/28/17). But scientists estimate that on a per area basis, boreal forests store about twice as much carbon in their trees and soils as tropical forests.

Climate change is causing the taiga to warm about twice as fast as the global average. And wildfires are growing more widespread in the region, releasing more of the trapped carbon, which in turn can worsen climate change (SN: 5/19/21).

Davis and his colleagues analyzed satellite data on carbon emissions from boreal regions from 2000 to 2021. In 2021, emissions from boreal wildfires made up a whopping 23 percent of all the CO2 emitted by wildfires around the world, the researchers report in the March 3 Science. In contrast, CO2 emissions during an average year from 2000 to 2021 were about 10 percent.

The record-breaking emissions coincided with widespread heat waves and droughts in Siberia and northern Canada, probably fueled by human-caused climate change.

There’s no data yet to show if 2022 saw a similar surge in emissions. But, Davis said, “there’s not actually that much evidence that this record will stand for long.”

Full-grown snapping shrimp were already known to have some of the fastest claws under the waves. But it turns out they’re nothing compared with their kids.

Juvenile snapping shrimp produce the highest known underwater accelerations of any reusable body part, researchers report February 28 in the Journal of Experimental Biology. While the claws’ top speed isn’t terribly impressive, they go from zero to full throttle in record time.

To deter predators or competitors, snapping shrimp create shock waves with their powerful claws. The shrimp store energy in the flexing exoskeleton of their claw as it opens, latching it in place much like a bow-and-arrow mechanism, says Jacob Harrison, a biologist at Georgia Tech in Atlanta.
Firing the claw and releasing this elastic energy produces a speeding jet of water. Bubbles form behind it and promptly implode, liberating a huge amount of energy, momentarily flashing as hot as the sun and creating a deafening crack (SN: 10/3/01).

But it was unclear how early in their lives the shrimp could use this weaponry. “We knew that the snapping shrimp did this really impressive behavior,” Harrison says. “But we really didn’t know anything about how this mechanism developed.”

While a grad student at Duke University, Harrison and his adviser, biomechanist Sheila Patek, reared bigclaw snapping shrimp (Alpheus heterochaelis) from eggs in the laboratory. At 1 month old, the tiny shrimp — less than a centimeter long — began firing their claws when disturbed. The researchers took high-speed video footage of these snaps and calculated their speed.

The wee shrimp could create the collapsing bubbles just like adults. Despite being a tenth the adults’ size or smaller, the juveniles’ claws accelerated 20 times as fast when firing. This acceleration — about 600 kilometers per second per second — is on “the same order of magnitude as a 9-millimeter bullet leaving a gun,” Harrison says.
Dracula ants (Mystrium camillae) and some termites produce more explosive bites but aren’t pushing against water. The stinging cells of jellyfish launch their venomous harpoons about 100 times as fast, but their firing mechanism is inherently single use. Snapping shrimp, on the other hand, can fire their claws again and again.
The juveniles’ firing and bubble creation weren’t very reliable at the smallest sizes, but the shrimp routinely tried snapping anyway. The team wonders if the young shrimp could be practicing and training the necessary musculature.

If so, that training might ultimately be crucial to the claw’s function, says Kate Feller, a visual ecologist at Union College in Schenectady, N.Y., who studies similarly ultrafast mantis shrimp and was not involved in the new study. “If you were to somehow manipulate the claws so that they couldn’t properly close and they couldn’t snap,” she wonders, “would that affect their ability to develop these mechanisms?”

Understanding the storage of elastic energy in biological materials and how it flows through them is “tricky,” Harrison says. Figuring out how such tiny claws store so much energy without fracturing may help researchers illuminate this superpower.

Memory Transfer Seen — Experiments with rats, showing how chemicals from one rat brain influence the memory of an untrained animal, indicate that tinkering with the brain of humans is also possible.

In the rat tests, brain material from an animal trained to go for food either at a light flash or at a sound signal was injected into an untrained rat. The injected animals then “remembered” whether light or sound meant food.
Update:
After this report, scientists from eight labs attempted to repeat the memory transplants. They failed, as they reported in Science in 1966.

Science fiction authors and futurists often predict that a person’s memories might be transferred to another person or a computer, but the idea is likely to remain speculation, says neuroscientist Eric Kandel, who won a Nobel Prize in 2000 for his work on memory. Brain wiring is too intricate and complicated to be exactly replicated, and scientists are still learning about how memories are made, stored and retrieved.

Large-scale climate patterns that can impact weather across thousands of kilometers may have a hand in synchronizing multicontinental droughts and stoking wildfires around the world, two new studies find.

These profound patterns, known as climate teleconnections, typically occur as recurring phases that can last from weeks to years. “They are a kind of complex butterfly effect, in that things that are occurring in one place have many derivatives very far away,” says Sergio de Miguel, an ecosystem scientist at Spain’s University of Lleida and the Joint Research Unit CTFC-Agrotecnio in Solsona, Spain.
Major droughts arise around the same time at drought hot spots around the world, and the world’s major climate teleconnections may be behind the synchronization, researchers report in one study. What’s more, these profound patterns may also regulate the scorching of more than half of the area burned on Earth each year, de Miguel and colleagues report in the other study.

The research could help countries around the world forecast and collaborate to deal with widespread drought and fires, researchers say.

The El Niño-Southern Oscillation, or ENSO, is perhaps the most well-known climate teleconnection (SN: 8/21/19). ENSO entails phases during which weakened trade winds cause warm surface waters to amass in the eastern tropical Pacific Ocean, known as El Niño, and opposite phases of cooler tropical waters called La Niña.

These phases influence wind, temperature and precipitation patterns around the world, says climate scientist Samantha Stevenson of the University of California, Santa Barbara, who was not involved in either study. “If you change the temperature of the ocean in the tropical Pacific or the Atlantic … that energy has to go someplace,” she explains. For instance, a 1982 El Niño caused severe droughts in Indonesia and Australia and deluges and floods in parts of the United States.

Past research has predicted that human-caused climate change will provoke more intense droughts and worsen wildfire seasons in many regions (SN: 3/4/20). But few studies have investigated how shorter-lived climate variations — teleconnections — influence these events on a global scale. Such work could help countries improve forecasting efforts and share resources, says climate scientist Ashok Mishra of Clemson University in South Carolina.

In one of the new studies, Mishra and his colleagues tapped data on drought conditions from 1901 to 2018. They used a computer to simulate the world’s drought history as a network of drought events, drawing connections between events that occurred within three months of each other.

The researchers identified major drought hot spots across the globe — places in which droughts tended to appear simultaneously or within just a few months. These hot spots included the western and midwestern United States, the Amazon, the eastern slope of the Andes, South Africa, the Arabian deserts, southern Europe and Scandinavia.
“When you get a drought in one, you get a drought in others,” says climate scientist Ben Kravitz of Indiana University Bloomington, who was not involved in the study. “If that’s happening all at once, it can affect things like global trade, [distribution of humanitarian] aid, pollution and numerous other factors.”

A subsequent analysis of sea surface temperatures and precipitation patterns suggested that major climate teleconnections were behind the synchronization of droughts on separate continents, the researchers report January 10 in Nature Communications. El Niño appeared to be the main driver of simultaneous droughts spanning parts of South America, Africa and Australia. ENSO is known to exert a widespread influence on precipitation patterns (SN: 4/16/20). So that finding is “a good validation of the method,” Kravitz says. “We would expect that to appear.”
In the second study, published January 27 in Nature Communications, de Miguel and his colleagues investigated how climate teleconnections influence the amount of land burned around the world. Researchers knew that the climate patterns can influence the frequency and intensity of wildfires. In the new study, the researchers compared satellite data on global burned area from 1982 to 2018 with data on the strength and phase of the globe’s major climate teleconnections.

Variations in the yearly pattern of burned area strongly aligned with the phases and range of climate teleconnections. In all, these climate patterns regulate about 53 percent of the land burned worldwide each year, the team found. According to de Miguel, teleconnections directly influence the growth of vegetation and other conditions such as aridity, soil moisture and temperature that prime landscapes for fires.

The Tropical North Atlantic teleconnection, a pattern of shifting sea surface temperatures just north of the equator in the Atlantic Ocean, was associated with about one-quarter of the global burned area — making it the most powerful driver of global burning, especially in the Northern Hemisphere.

These researchers are showing that wildfire scars around the world are connected to these climate teleconnections, and that’s very useful, Stevenson says. “Studies like this can help us prepare how we might go about constructing larger scale international plans to deal with events that affect multiple places at once.”

Some fish can recognize their own faces in photos and mirrors, an ability usually attributed to humans and other animals considered particularly brainy, such as chimpanzees, scientists report. Finding the ability in fish suggests that self-awareness may be far more widespread among animals than scientists once thought.

“It is believed widely that the animals that have larger brains will be more intelligent than animals of the small brain,” such as fish, says animal sociologist Masanori Kohda of Osaka Metropolitan University in Japan. It may be time to rethink that assumption, Kohda says.
Kohda’s previous research showed that bluestreak cleaner wrasses can pass the mirror test, a controversial cognitive assessment that purportedly reveals self-awareness, or the ability to be the object of one’s own thoughts. The test involves exposing an animal to a mirror and then surreptitiously putting a mark on the animal’s face or body to see if they will notice it on their reflection and try to touch it on their body. Previously only a handful of large-brained species, including chimpanzees and other great apes, dolphins, elephants and magpies, have passed the test.

In a new study, cleaner fish that passed the mirror test were then able to distinguish their own faces from those of other cleaner fish in still photographs. This suggests that the fish identify themselves the same way humans are thought to — by forming a mental image of one’s face, Kohda and colleagues report February 6 in the Proceedings of the National Academy of Sciences.

“I think it’s truly remarkable that they can do this,” says primatologist Frans de Waal of Emory University in Atlanta who was not involved in the research. “I think it’s an incredible study.”

De Waal is quick to point out that failing the mirror test should not be considered evidence of a lack of self-awareness. Still, scientists have struggled to understand why some species that are known to have complex cognitive abilities, such as monkeys and ravens, have not passed. Researchers have also questioned whether the test is appropriate for species like dogs that rely more on scent, or like pigs that may not care enough about a mark on their bodies to try to touch it.

The mixed results in other animals make it all the more astonishing that a small fish can pass. In their first mirror test studies, published in 2019 and 2022, Kohda’s team exposed wild-caught cleaner fish in separate tanks to mirrors for a week. The researchers then injected brown dye just beneath the scales on the fish’s throats, making a mark that resembles the parasites these fish eat off the skin of larger fish in the wild. When the marked fish saw themselves in a mirror, they began striking their throats on rocks or sand in the bottom of the tank, apparently trying to scrape off the marks.

In the new study, 10 fish that passed the mirror test were then shown a photo of their own face and a photo of an unfamiliar cleaner fish face. All the fish acted aggressively toward the unfamiliar photo, as if it were a stranger, but were not aggressive toward the photo of their own face.

When another eight fish that had spent a week with a mirror but had not previously been marked were shown a photo of their own face with a brown mark on the throat, six of them began scraping their throats just like the fish that passed the mirror test. But they did not scrape when shown a photo of another fish with a mark.
Animals that recognize their reflection in the mirror most likely first learn to identify themselves by seeing that the movement of the animal in the mirror matches their own movement, researchers think. Because the cleaner fish were also able to recognize their own faces in still images, they, and possibly other animals that have passed the mirror test, may be able to identify themselves by developing a mental image of their own face that they can compare to what they see in the mirror or photos, the authors say.

“I think it’s a great next step,” says comparative cognitive psychologist Jennifer Vonk of Oakland University in Rochester, Mich., who wasn’t involved in the study. But she would like to see more research before drawing conclusions about what’s being represented in the mind of a nonverbal being like a fish. “As with most other studies, it still leaves some room for further follow-up.”

Kohda’s lab has more experiments planned to continue to probe what’s going on in the brain of the cleaner fish, and to try the new photo-recognition method on another popular research fish, the three-spined stickleback (Gasterosteus aculeatus).

Animal behaviorist Jonathan Balcombe, author of the book What a Fish Knows, is already convinced, describing the new study as “robust and quite brilliant.” People shouldn’t be surprised that fish could be self-aware given that they have already been shown to have complex behavior including tool use, planning and collaboration, Balcombe says. “It’s time we stopped thinking of fishes as somehow lesser members of the vertebrate pantheon.”

Fritillaria plants should be simple to spot.

The usually bright green plants often stand alone amid the jumbled scree that tops the Himalayan and Hengduan mountains in southwestern China — easy pickings for traditional Chinese medicine herbalists, who’ve ground the bulbs of wild Fritillaria into a popular cough-treating powder for more than 2,000 years. The demand for bulbs is intense, since about 3,500 of them are needed to produce just one kilogram of the powder, worth about $480.

But some Fritillaria are remarkably difficult to find, with living leaves and stems that are barely distinguishable from the gray or brown rocky background. Surprisingly, this plant camouflage seems to have evolved in response to people. Fritillaria delavayi from regions that experience greater harvesting pressure are more camouflaged than those from less harvested areas, researchers report November 20 in Current Biology.

The new study “is quite convincing,” says Julien Renoult, an evolutionary biologist at the French National Centre for Scientific Research in Montpellier who wasn’t involved in the study. “It’s a nice first step toward demonstrating that humans seem to be driving the very rapid evolution of camouflage in this species.”
Camouflaged plants are rare, but not unheard of, says Yang Niu, a botanist at the Kunming Institute of Botany in China, who studies cryptic coloration in plants. In wide open areas with little cover, like mountaintops, blending in can help plants avoid hungry herbivores (SN: 4/29/14). But after five years of studying camouflage in Fritillaria, Niu found few bite marks on leaves, and he did not spot any animals munching on the plants. “They don’t seem to have natural enemies,” he says.

So Niu, his colleague Hang Sun and sensory ecologist Martin Stevens of the University of Exeter in England decided to see if humans might be driving the evolution of the plants’ camouflage. If so, the more heavily harvested a particular slope, the more camouflaged the plants that live there should be.

In an ideal world, to measure harvesting pressure “you’d have exact measures of exactly how many plants had been collected for hundreds of years” at multiple sites, Stevens says. “But that data is practically nonexistent.”

Luckily, at seven study sites, local herbalists had noted the total weight of bulbs harvested each year from 2014 to 2019. These records provided a measure of contemporary harvesting pressure. To estimate further back in time, the researchers assessed ease of harvesting by recording how long it took to dig up bulbs at six of those sites, plus an additional one. On some slopes, bulbs are easily dug up, but in others they can be buried under stacks of rocks. “Intuitively, areas where it’s easier to harvest should have experienced more harvesting pressure” over time, Stevens says.

Both measures revealed a striking pattern: The more harvested, or harvestable, a site, the better the color of a plant matched its background, as measured by a spectrometer. “The degree of correlation was really, really convincing for both metrics we used,” Stevens says.
Human eyes also had a harder time spotting camouflaged plants in an online experiment, suggesting that the camouflage actually works.

Hiding in plain sight may present some challenges for the plant. Pollinators might have a harder time finding camouflaged plants, and the gray and brown coloration could impair photosynthetic activity. Still, despite those potential costs, these F. delavayi show just how adaptable plants can be, Steven says. “The appearance of plants is much more malleable than we might have expected.”