Trish Tran narrates her life in staccato notes.

“I remember carrying my little sister on my back because she’s too tired and walking through the huge sunflower fields … and me feeling so tired I didn’t think I could walk another step.”

“I remember being in a taxi with my mother, coming back to the man who had been violently abusive to all of us…. Her words to me were, ‘Just trust me, Trish. Just trust me.’ ”
“I’m waiting at a train station … to meet my mother who I haven’t seen in many years…. Hours pass and eventually I try to call her … and she says to me, ‘I’m sorry, Trish. My neighbor was upset, and I needed to stay back with them.’ And her voice was slurring quite a lot, so I knew she had been drinking.”

Tran, who lives in Perth, Australia, is dispassionate as she describes a difficult childhood. Her account lacks what are generally considered classic signs of trauma: She makes no mention of flashbacks, appears to have a generally positive outlook and speaks with relative ease about distressing events. Yet she narrates her life growing up and living in the Australian Outback as a series of disconnected events; her life story lacks connective glue.

Two photos of Trish Tran. On the left is a black and white family photo with Tran as a small child sitting on her fathers lap while to their right her mother holds a baby and her three siblings stand. The photo on the right is Tran as an adult holding a microphone and smiling.
That disjointed style is not how people, at least people in the West, tend to talk about themselves, says psychologist Christin Camia. Autobiographical accounts, like any good narrative, typically contain a curation of key past experiences, transitions linking those experiences and larger arcs about where life is headed. People use these stories to make sense of their lives, says Camia, of Zayed University’s Abu Dhabi campus in the United Arab Emirates.

But a growing body of evidence from fields as wide-ranging as psychology, neuroscience, linguistics, philosophy and literary studies suggests that, as with Tran, trauma can shatter the narrative coherence of one’s life. People lose the plot.

Life’s crises can trigger an existential crisis, Camia says. People think: “I don’t know who I am, and I don’t know where I go from here.”
One therapy now in testing aims to re-tether traumatized individuals to their mental timelines, or their sense of themselves as connected across past, present and future. The therapy focuses on the future, which once rife with possibilities now appears as a void. It asks: What would it take for someone like Tran, or anyone traumatized by war, abuse, mass shootings, the ongoing pandemic and other calamities, to flip their life script, to say that they know who they are and where they go from here?

People maintain a sense of self across time
In a nod to an established research approach, I have asked Tran to tell me her story in two parts. First, she should narrate seven snapshots of key moments in her life. Second, Tran, who is a lecturer on mental health recovery at Curtin University in Perth, should stitch those snapshots together to tell me how she became who she is today.

The first task comes easy. The second task eludes her. She switches to generalities. “I’ve always been a highly reflective person,” she says. “I’ve had to rely on my brains to keep myself and my family alive.”

I try to nudge her toward specifics, but her timeline disintegrates. She repeatedly attempted suicide. Her mother brought home many violent men.

The developer of this two-question approach, psychologist Tilmann Habermas, wasn’t focused on people who had experienced trauma. Habermas, now at Goethe University Frankfurt, wanted to understand how adolescents develop a narrative identity and then sustain that sense of self over time.

In 2003, Habermas launched a study that would follow participants for up to 16 years. Participants came into the lab every four years and dictated their life story in roughly 20-minute increments, using the two-task format I tried with Tran. Habermas analyzed the resulting transcripts line by line, coding them for emotion, tense, transitions and other features.

With few psychologists at the time studying autobiography as a window into the mind, Habermas turned to theorists from other fields for guidance. “After I read psychology, I read narratology, literary theory, linguistics, social linguistics,” he says. “I had to steal … all these concepts from the other areas.”

One of Habermas’ questions was how people retain their sense of self in the face of life’s many disturbances, such as divorce, illness, job loss or moving to a new location.

Philosophers have been puzzling over this question for millennia. “Your body has changed. Your experiences have changed. Your knowledge has changed. And yet, people generally think of themselves as being the same person … in the past and future,” says psychologist Yosef Sokol of Touro University in New York City. “That’s a hard problem.”

This general belief in self-continuity appears universal, even though how it is constructed may differ across cultures.
In the third wave of Habermas’ long-term study, when 150 participants were ages 16, 20, 28, 44 and 69, Habermas and Camia, who joined Habermas’ lab in 2009, also analyzed the transcripts for a type of thinking called autobiographical reasoning. This reasoning links the self across space and time.

“Autobiographical reasoning is this conscious reflection. How did my past impact me? How did I become the person I am today, and what does it mean for my future?” Camia says. Such reasoning tends to stem from change, she adds. “If there is perfect stability in life, you don’t do a lot of autobiographical reasoning … it’s the changes and the crises that compel meaning-making.”

The researchers divvied such reasoning into eight categories, such as turning points, lessons learned, generalized insights and using an event to explain a change in personality.

Participants also filled out two surveys. One survey summed up the number of big life changes experienced over the previous four years. The other gauged self-continuity, with participants rating the truth of statements such as, “When I look at pictures of myself four years back, it feels a little unfamiliar” and “I have the feeling that at the core I am the same person I was four years ago.”

Researchers then compared the three variables: autobiographical reasoning, levels of life change and sense of self-continuity. As expected, levels of autobiographical reasoning showed no discernible pattern among participants who experienced few changes in life, the team reported in 2015 in Memory.

But when the researchers zoomed in on the quarter of participants reporting the greatest level of change, more autobiographical reasoning came with higher levels of self-continuity. “Constructing continuity in the life story buffers against the effect of change in your life,” Habermas says. Other teams have made similar findings.
Most disruptions, however, do not rise to the level of trauma — such as that experienced by Tran. Several years later, Camia would study how traumatic events, notably being forced to flee one’s home and the resulting isolation and bereavement, affect people’s sense of self.

Trauma messes with our sense of time
“What does war change first? One’s sense of time, one’s sense of space,” said Ukrainian writer Serhiy Zhadan in an October speech translated to English in the online magazine LitHub.

Zhadan speaks from experience. But the idea that trauma disrupts time perception is also borne out by research. Researchers have found that emotions frequently dictate whether we experience time as passing fast or slow. And traumatic events, which come with intense emotions, can cause people to experience time in slow motion, researchers reported in 2012 in Frontiers in Psychology.

During a car accident, for instance, a person’s whole body is ready to act, says Marc Wittmann, a psychologist with the Institute for Frontier Areas of Psychology and Mental Health in Freiburg, Germany. “Your inner workings, your processing, is speeded up. Relative to that, your outside slows down.”

What’s more, says health psychologist Alison Holman of the University of California, Irvine, in that moment or moments of crisis, you do not think about the past or future. All that matters is survival.

Zhadan speaks directly to this idea in his speech: “People in a war-torn space try not to plan for the future or think too much about what the world will be like tomorrow. What’s happening to you here and now is all that matters, just the people and things that will be with you tomorrow morning — tops. That’s if you survive and wake up.”

That narrow focus can wreak havoc on mental health. “[When] that present moment is so intense that it sears into your mind … it may set up the likelihood that you will have a hard time moving past it,” Holman says. “The past never passes.”

Such breakdowns in time can show up in language, particularly among those most severely affected by trauma. For instance, Habermas and his team compared the speech patterns of 14 women diagnosed with post-traumatic stress disorder following a singular shocking event, such as physical or sexual abuse, and 14 women without such a diagnosis. The women with PTSD used more immersive language. They quoted people directly and spoke of the past as if it was ongoing, says Habermas, who reported the findings in 2014. “Instead of saying, ‘He hit me,’ they would say, ‘He hits me.’ ”

This immersive language dominates Tran’s narration. She is “carrying” her little sister. Her mother is “coming” back to the violent man. She is “walking many kilometers to school in the rain and then opening up my newspaper-wrapped wet and warm tomato sandwiches. They’re so wet, but I’m so hungry that I know I have to eat them otherwise I’ll never make the walk back.”

And always there, her mother’s voice: “Just trust me, Trish. Just trust me.”

“I don’t think I will ever forget those words,” Tran says.

Traumatized people can lose their life story
Tran remembers her mother’s words exactly, but other details of the abuse she experienced as a child are fuzzier. That’s common among people who experience trauma. People with trauma “have both an excess and depletion of memory,” says cognitive neuroscientist Elisa Ciaramelli of the University of Bologna in Italy.

How memory changes among trauma survivors remains controversial, write the authors of a 2021 opinion piece in Frontiers in Psychology. But mounting evidence suggests that people tend to remember stressful memories in detail. As the mind fixates on those traumatic memories, memories unrelated to the trauma seem to fade, while new memories fail to register.

For example, when asked to describe memories associated with a specific word, such as “beach,” people who do not have PTSD offer detailed reports, describing what they were wearing, what they said and who they were with, Ciaramelli says. People who have PTSD, on the other hand, typically provide general memories with little color.

Other memories can’t find a foothold. In one study, researchers asked 52 participants — 26 people with PTSD and 26 people who had experienced trauma but not developed PTSD — to keep a diary recording their memories over the course of a week. Participants also responded to questions about the memory, such as whether or not it related to their trauma, how central it was to their current life and how far away in time the memory felt.

Participants without PTSD recorded an average of 21.4 memories across the week while participants with PTSD recorded an average of just 11 memories, the team reported in 2017 in Clinical Psychological Science. The PTSD participants had more trauma-related memories than the non-PTSD group.

Tran recognizes this paucity of detail in her own life story. “My memories are lightbulb memories,” she says. “They are always attached to significant events like trauma or happy times. I may have 57 years of life, but you could truncate them into a chapter.”

Everyone’s memory has imprecision of course. That imprecision allows us to cut extraneous details and make sense of our story. The traumatized person’s relative lack of memories, though, both in clarity and quantity, means they struggle to construct a cohesive narrative of their past and to envision themselves moving forward.

“Ten years ago, people have found that the same brain regions that are activated and are necessary for remembering the past are also necessary to imagine the future,” Ciaramelli says. “We need memories to imagine the future.”

Camia’s work with refugees shows what can happen to the sense of self as people struggle and fail to reconcile a traumatic experience with the larger story of their life. Her central aim, which built on work with Habermas, was to see if the same autobiographical arguments people used to buffer against life’s everyday changes could help those facing traumatic disruptions. She and Rida Zafar, a psychology student at New York University Abu Dhabi, recruited 31 refugees living in Germany and asked them to narrate their life stories, plus fill out the life change and self-continuity surveys used in the 2015 study.

Among the 16 refugees who experienced relatively less change since arriving in Germany, such as fewer upheavals in relationships and fewer moves, more autobiographical reasoning did correlate with higher self-continuity, the team reported in 2021 in Frontiers in Psychology. Refugees who experienced high change also used autobiographical reasoning, but their sense of self-continuity remained low.

These individuals cannot settle their trauma, Camia explains, so their reckoning with the past leads not to resolution but rumination. They are stuck.

Therapy could restore the future self
For most of her adult life, Tran grappled with that sense of stagnation. “My identity was rooted in the past, and I couldn’t move forward,” she says. “Time was this eternal loop. Every time a problem came up, it felt like a replication of a past problem. I couldn’t see that I could change anything.”

Over and over again, unable to envision a viable escape, Tran tried to kill herself.

Suicide attempts serve as the clearest signal that a person’s future has gone blank, says Sokol, the psychologist at Touro University. The thinking here is intuitive. “If you think you have a meaningful life into the future, you’re not going to kill yourself,” he says.

Conventional therapies for treating people struggling with suicidal thinking often fail to meet their needs because the therapies do not directly address people’s future self, Sokol and his team wrote in 2021 in the Journal of Cognitive Psychotherapy. For instance, dialectical behavior therapy emphasizes focusing on the present to cope with stress and manage emotions. Narrative therapy likewise aims to help patients incorporate traumatic and other events into a continuous timeline, but focuses on linking past to present, not present to future.

So Sokol developed a therapy that incorporates elements of past- and present-oriented treatments but prioritizes future thinking. It’s known as continuous identity cognitive therapy. His goal is to help military veterans struggling with mental illness re-create the plot in the mental timeline of their lives, to answer those foundational questions: Who am I? Where do I go from here?

Sokol tested an initial version of the therapy in a four-week pilot study with 17 veterans. The program contains many work-arounds for participants struggling to access or make sense of their memories. The specific memory is less important than the larger story, or the broader values contained within that memory, Sokol says. “I have all sorts of techniques to help people tap into something that they find important, meaningful.”

In the first week, participants are asked to define their core values. The hope is that those values, rather than specific past events, will form the core of a person’s life story. To get to that core, participants review negative and positive experiences from their past and identify choices they made.

Many veterans struggle with what are called moral injuries — choices they made that don’t seem to align with who they wish to be, Sokol says. So veterans push those memories away. With the values approach, he hopes participants can start to see that they made the best choices they could under challenging circumstances. One way to access those values is to have participants identify people they admire, and the values those people embody. Participants can then use those people’s experiences to identify their own core values.

The focus of the second week shifts to the future. Participants assemble possible futures by reflecting on how life might play out if they work with, or against, their stated values. Participants also actively construct self-continuity. For instance, they write letters to themselves across different time points, such as from their present self to their future self or vice versa.

In week three, participants learn to differentiate between external life stories, the series of events outside their control, and internal life stories made up of choices in line with their stated values. By week four, participants should be able to visualize their future self overcoming an issue that their present self faces.
Tran came across Sokol’s research while embarking on her own journey to healing. That process began when Tran realized how her trauma was hurting the people she loved most. “I’m just causing my children and everybody near and dear trauma. I’m going to take [suicide] off the table,” she eventually realized. “This is not my pathway anymore. If it’s not my pathway, what am I going to do with the next 50 years of my life?”

Tran felt lost. So she dug into research on trauma survivors, eventually stumbling upon Sokol’s project. She was moved by the idea that participants did not have to reconstruct the past to build a new future. “This is true. My soul knows this to be true,” she remembers thinking.

Tran, who is also a trainer with DISCHARGED, a nonprofit organization that provides peer group support for people experiencing suicidal thoughts, and an occasional adviser to researchers writing about suicide, reached out to Sokol and offered to help him make the language used in his program more sensitive to people who have experienced trauma. For instance, she suggested changing references to “you” to “we” to give people a greater sense of belonging and agency. The two still work together.

Research on the therapy remains limited to Sokol’s lab, but initial results are promising. The pilot study showed that the program decreased previously reported levels of suicidal ideation and depression. Those levels stayed low one month after completion. Now Sokol has received a five-year, $1.1 million grant from the U.S. Department of Veterans Affairs to scale up the program and eventually roll out a randomized controlled trial. In its newer iteration, the program will run for three months instead of one.

With input from Tran and veterans in the program, Sokol made another substantial modification to the pilot program. Participants will now identify how their own story intersects with the stories of other people in their lives. That addition makes sense to Tran, who has become engrossed in research showing the intergenerational nature of trauma. She now sees her life as part of a larger story with many characters, each on their own often troubled journey.

She says her story will always be truncated. But even without a clean narrative arc, she has managed to sever time’s eternal loop. “You can change your relationship with your past experiences in a way that makes living a future possible,” Tran says.

Setting sail into a plastic sea — Science News, February 10, 1973

Scientists on an oceanographic voyage in the Central North Pacific last August became startled about the number of manmade objects littering the ocean surface. [Far from civilization and shipping lanes], they recorded 53 manmade objects in 8.2 hours of viewing. More than half were plastic. They go on to compute that there are between 5 million and 35 million plastic bottles adrift in the North Pacific.

Update
The Great Pacific Garbage Patch is larger now than it was in 1973, containing an estimated 1.8 trillion pieces of plastic within an area twice the size of Texas (SN Online: 3/22/18). In recent years, marine biologists have started seeing evidence that garbage is disrupting ocean ecosystems. For instance, large pieces of trash have helped species cross into new territories (SN: 10/28/17, p. 32). But an even greater threat may lurk beneath the waves. Tiny bits of plastic concentrate hundreds of meters deep where they can be eaten by filter feeders and potentially make their way into the guts of larger predators (SN: 7/6/19 & 7/20/19, p. 5).

Antarctica’s most vulnerable climate hot spot is a remote and hostile place — a narrow sliver of seawater, beneath a slab of floating ice more than half a kilometer thick. Scientists have finally explored it, and uncovered something surprising.

“The melt rate is much weaker than we would have thought, given how warm the ocean is,” says Peter Davis, an oceanographer at the British Antarctic Survey in Cambridge who was part of the team that drilled a narrow hole into this nook and lowered instruments into it. The finding might seem like good news — but it isn’t, he says. “Despite those low melt rates, we’re still seeing rapid retreat” as the ice vanishes faster than it’s being replenished.
Davis and about 20 other scientists conducted this research at Thwaites Glacier, a massive conveyor belt of ice about 120 kilometers wide, which flows off the coastline of West Antarctica. Satellite measurements show that Thwaites is losing ice more quickly than at any time in the last few thousand years (SN: 6/9/22). It has accelerated its flow into the ocean by at least 30 percent since 2000, hemorrhaging over 1,000 cubic kilometers of ice — accounting for roughly half of the ice lost from all of Antarctica.

Much of the current ice loss is driven by warm, salty ocean currents that are destabilizing the glacier at its grounding zone — the crucial foothold, about 500 meters below sea level at the drilling location, where the ice lifts off its bed and floats (SN: 4/9/21).

Now, this first-ever look at the glacier’s underbelly near the grounding zone shows that the ocean is attacking it in previously unknown and troubling ways.
When the researchers sent a remote-operated vehicle, or ROV, down the borehole and into the water below, they found that much of the melting is concentrated in places where the glacier is already under mechanical stress — within massive cracks called basal crevasses. These openings slice up into the underside of the ice.

Even a small amount of melting at these weak spots could inflict a disproportionately large amount of structural damage on the glacier, the researchers report in two papers published February 15 in Nature.

These results are “a bit of a surprise,” says Ted Scambos, a glaciologist at the University of Colorado Boulder who was not part of the team. Thwaites and other glaciers are monitored mostly with satellites, which make it appear that thinning and melting happen uniformly under the ice.

As the world continues to warm due to human-caused climate change, the shrinking glacier itself has the potential to raise global sea level by 65 centimeters over a period of centuries. Its collapse would also destabilize the remainder of the West Antarctic Ice Sheet, triggering an eventual three meters of global sea level rise.

With these new results, Scambos says, “we’re seeing in much more detail processes that will be important for modeling” how the glacier responds to future warming, and how quickly sea level will rise.

A cold, thin layer shields parts of Thwaites Glacier’s underside
Simply getting these observations “is kind of like a moon shot, or even a Mars shot,” Scambos says. Thwaites, like most of the West Antarctic Ice Sheet, rests on a bed that is hundreds of meters below sea level. The floating front of the glacier, called an ice shelf, extends 15 kilometers out onto the ocean, creating a roof of ice that makes this spot almost entirely inaccessible to humans. “This might represent the pinnacle of exploration” in Antarctica, he says.

These new results stem from a $50 million effort — the International Thwaites Glacier Collaboration — conducted by the United States’ National Science Foundation and United Kingdom’s Natural Environment Research Council. The research team, one of eight funded by that collaboration, landed on the snowy, flat expanse of Thwaites in the final days of 2019.

The researchers used a hot water drill to melt a narrow hole, not much wider than a basketball, through more than 500 meters of ice. Below the ice sat a water column that was only 54 meters thick.

When Davis and his colleagues measured the temperature and salinity of that water, they found that most of it was about 2 degrees Celsius above freezing — potentially warm enough to melt 20 to 40 meters of ice per year. But the underside of the ice seems to be melting at a rate of only 5 meters per year, researchers report in one of the Nature papers. The team calculated the melt rate based on the water’s salinity, which reveals the ratio of seawater, which is salty, to glacial meltwater, which is fresh.

The reason for that slow melt quickly emerged: Just beneath the ice sat a layer of cold, buoyant water, only 2 meters thick, derived from melted ice. “There is pooling of much fresher water at the ice base,” says Davis, and this cold layer shields the ice from warmer water below.

Those measurements provided a snapshot right at the borehole. Several days after the hole was opened, the researchers began a broader exploration of the unmapped ocean cavity under the ice.

Workers winched a skinny, yellow and black cylinder down the borehole. This ROV, called Icefin, was developed over the last seven years by a team of engineers led by Britney Schmidt, a glaciologist at Cornell University.
Schmidt and her team piloted the craft from a nearby tent, monitoring instruments while she steered the craft with gentle nudges to the buttons of a PlayStation 4 controller. The smooth, mirrorlike ceiling of ice scrolled silently past on a computer monitor — the live video feed piped up through 3½ kilometers of fiber-optic cable.

As Schmidt guided Icefin about 1.6 kilometers upstream from the borehole, the water column gradually tapered, until less than a meter of water separated the ice from the seafloor below. A few fish and shrimplike crustaceans called amphipods flitted among otherwise barren piles of gravel.

This new section of seafloor — revealed as the ice thins, lifts and floats progressively farther inland — had been exposed “for less than a year,” Schmidt says.

Now and then, Icefin skimmed past a dark, gaping cleft in the icy ceiling, a basal crevasse. Schmidt steered the craft into several of these gaps — often over 100 meters wide — and there, she saw something striking.

Melting of Thwaites’ underbelly is concentrated in deep crevasses
The vertical walls of the crevasses were scalloped rather than smooth, suggesting a higher rate of melting than that of the flat icy ceiling. And in these places, the video became blurry as the light refracted through vigorously swirling eddies of salty water and freshwater. That turbulent swirling of warm ocean water and cold meltwater is breaking up the cold layer that insulates the ice, pulling warm, salty water into contact with it, the scientists think.

Schmidt’s team calculated that the walls of the crevasses are melting at rates of up to 43 meters per year, the researchers report in the second Nature paper. The researchers also found rapid melt in other places where the level ceiling of ice is punctuated by short, steep sections.

The greater turbulence and higher melt also appear driven by ocean currents within the crevasses. Each time Schmidt steered Icefin up into a crevasse, the ROV detected streams of water flowing through it, as though the crevasse were an upside-down ditch. These currents moved up to twice as fast as the currents outside of crevasses.

The fact that melting is concentrated in crevasses has huge implications, says Peter Washam, an oceanographer on Schmidt’s team at Cornell: “The ocean is widening these features by melting them faster.”

This could greatly accelerate the years-long process by which some of these cracks propagate hundreds of meters up through the ice until they break through at the top — calving off an iceberg that drifts away. It could cause the floating ice shelf, which presses against an undersea mountain and buttresses the ice behind it, to break apart more quickly than predicted. This, in turn, could cause the glacier to spill ice into the ocean more quickly (SN: 12/13/21). “It’s going to have an impact on the stability of the ice,” Washam says.
These new data will improve scientists’ ability to predict the future retreat of Thwaites and other Antarctic glaciers, says Eric Rignot, a glaciologist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who assisted the team by providing satellite measurements of changes in the glacier. “You just cannot guess what the water structure might look like in these zones until you observe it,” he says.

But more work is needed to fully understand Thwaites and how it will further change as the world continues to warm. The glacier consists of two side-by-side fast-moving lanes of ice — one moving 3 kilometers per year, the other about 1 kilometer per year. Due to safety concerns, the team visited the slower lane — which still proved extremely challenging. Rignot says that scientists must eventually visit the fast lane, whose upper surface is more cracked up with crevasses — making it even harder to land aircraft and operate field camps.

The research reported today “is a very important step, but it needs to be followed by a second step,” the investigation of the glacier’s fast lane, he says. “It doesn’t matter how hard it is.”

Forget screwdrivers or drills. A stick and a straw make for a great cockatoo tool kit.

Some Goffin’s cockatoos (Cacatua goffiniana) know whether they need to have more than one tool in claw to topple an out-of-reach cashew, researchers report February 10 in Current Biology. By recognizing that two items are necessary to access the snack, the birds join chimpanzees as the only nonhuman animals known to use tools as a set.

The study is a fascinating example of what cockatoos are capable of, says Anne Clark, a behavioral ecologist at Binghamton University in New York, who was not involved in the study. A mental awareness that people often attribute to our close primate relatives can also pop up elsewhere in the animal kingdom.
A variety of animals including crows and otters use tools but don’t deploy multiple objects together as a kit (SN: 9/14/16; SN: 3/21/17). Chimpanzees from the Republic of Congo’s Noubalé-Ndoki National Park, on the other hand, recognize the need for both a sharp stick to break into termite mounds and a fishing stick to scoop up an insect feast (SN: 10/19/04).

Researchers knew wild cockatoos could use three different sticks to break open fruit in their native range of Indonesia. But it was unclear whether the birds might recognize the sticks as a set or instead as a chain of single tools that became necessary as new problems arose, says evolutionary biologist Antonio Osuna Mascaró of the University of Veterinary Medicine Vienna.

Osuna Mascaró and colleagues first tested whether the cockatoos could learn to smack loose a cashew placed inside a clear box and behind a thin paper barrier, akin to a chimpanzee’s hunt for termites. Six out of 10 cockatoos reliably knocked the nut out of the box using a pointy stick to poke through the membrane and a plastic straw to fish for the cashew.

Two birds managed the task in less than 35 seconds on their first try. Both — a male named Figaro and a female named Fini — are experienced tool users, Osuna Mascaró says.

Figaro, Fini and three fellow cockatoos were more likely to use both stick and straw only when the box had a paper barrier inside. If the team removed the barrier, the birds selected the straw instead of the stick as their tool.

Even when the birds had to walk or fly to reach the box, the birds brought along both tools every time the box had a barrier. If there was no paper, the cockatoos usually brought only one, a sign the cockatoos recognized when they needed their entire tool kit to swipe a snack.
Three of the birds even learned to put the stick inside the straw to carry both at the same time. That made for more efficient transport, meaning the birds didn’t have to make two trips and waste energy. Two birds, Kiwi and Pippin, transported both tools together every time the box had a barrier. Kiwi rarely brought along both tools if there wasn’t paper, and Pippin did so half as often.

Trading off which tools to bring may have to do with strength. After Figaro learned to combine transport, he grabbed both tools in 16 out of 18 trials. That may be because he’s one of the stronger birds in the group, Osuna Mascaró says. For him, grabbing both tools at once isn’t a big deal. Kiwi and Pippin, on the other hand, are weaker than Figaro.

Cockatoos raised in the lab probably display more abilities than a wild bird might use on an average day, Clark says. “Nevertheless, this means they can do it,” she says. “That doesn’t mean that the wild adult male … can do the same thing as Figaro. But he would have probably been capable of doing that had he been raised like Figaro.”

If you’ve noticed more lush medians and plant-covered roofs in cities, it’s not your imagination.

Incorporating more natural elements in urban landscapes is a growing management solution for the planet’s increasing climate hazards (SN: 3/10/22). Rain gardens, green roofs and landscaped drainage ditches are all examples of what’s known as green infrastructure, and are used to manage stormwater and mitigate risks like flooding and extreme heat. These strategies sometimes double as a community resource, such as a recreational space.
But a major problem with green infrastructure is that the planning processes for the projects often fail to consider equity and inclusion, says Timon McPhearson, an urban ecologist and director of the Urban Systems Lab in New York City, which researches how to build more equitable, resilient and sustainable cities. Without an eye on equity, plans might exclude those most vulnerable to climate disasters, which typically include low-income communities or minority groups (SN: 2/28/22).

There has been talk of fostering equity and inclusion in urban planning for some time, McPhearson says, but he wanted to know if there had been any follow-through. After analyzing 122 formal plans from 20 major U.S. cities, including Atlanta, Detroit and Sacramento, he and colleagues found that most government-affiliated green infrastructure plans are falling short. The researchers focused on plans produced or directly supervised by city governments, as non-profit organizations tend to be more inclusive, the study says.

Over 90 percent of plans didn’t use inclusive processes to design or implement green infrastructure projects, meaning communities targeted for upgrades often didn’t have a chance to weigh in with their needs throughout the process. What’s more, only 10 percent of plans identified causes of inequality and vulnerability in their communities. That matters because without acknowledging the roots of injustices, planners are unable to potentially address them in future projects. And only around 13 percent of plans even defined equity or justice, the researchers report in the January Landscape and Urban Planning.

Such inadequate plans can perpetuate existing inequalities that are part of an “ongoing legacy of historically racist policies,” McPhearson says, including limited access to heat- and pollution-relieving green spaces or proper stormwater management.

“We have an opportunity with green infrastructure to invest in a way that can help solve multiple urban problems,” McPhearson says. “But only if we focus it in the places where there is the most need.”

One reason behind poor urban planning practices is a lack of recognition that infrastructure can be harmful, says Yvette Lopez-Ledesma, the senior director for community-led conservation at The Wilderness Society in Los Angeles, who wasn’t involved in the study. For instance, when cities build stormwater channels but not bridges, locals are left without a way to safely cross. City planners also often lack the training and education to implement more inclusive methods.

But there’s hope. The researchers identified three areas that need more work. First, city planners need to clearly define equity and justice in planning documents to help guide their work. They also need to change planning practices to focus on inclusion by keeping communities informed and supporting their participation throughout the planning, decision-making and implementation processes. And plans need to address current and potential causes of inequality: For example, acknowledging sources of gentrification and identifying how green infrastructure could contribute to gentrification further if officials aren’t careful (SN: 4/18/19).

“If equity isn’t centered in your plans, then inequity is,” Lopez-Ledesma says. “You could be doing more harm.”

In shallow coastal waters of the Indian and Pacific oceans, a seagrass-scrounging cousin of the manatee is in trouble. Environmental strains like pollution and habitat loss pose a major threat to dugong (Dugong dugon) survival, so much so that in December, the International Union for Conservation of Nature upgraded the species’ extinction risk status to vulnerable. Some populations are now classified as endangered or critically endangered.

If that weren’t bad enough, the sea cows are at risk of losing the protection of a group who has long looked after them: the Torres Strait Islanders. These Indigenous people off the coast of Australia historically have been stewards of the dugong populations there, sustainably hunting the animals and monitoring their numbers. But the Torres Strait Islanders are also threatened, in part because sea levels are rising and encroaching on their communities, and warmer air and sea temperatures are making it difficult for people to live in the region.
This situation isn’t unique to dugongs. A global analysis of 385 culturally important plant and animal species found that 68 percent were both biologically vulnerable and at risk of losing their cultural protections, researchers report January 3 in the Proceedings of the National Academy of Sciences.

The findings clearly illustrate that biology shouldn’t be the primary factor in shaping conservation policy, says cultural anthropologist Victoria Reyes-García. When a culture dwindles, the species that are important to that culture are also under threat. To be effective, more conservation efforts need to consider the vulnerability of both the species and the people that have historically cared for them, she says.

“A lot of the people in the conservation arena think we need to separate people from nature,” says Reyes-García, of the Catalan Institution for Research and Advanced Studies and the Autonomous University of Barcelona. But that tactic overlooks the caring relationship many cultural groups – like the Torres Strait Islanders – have with nature, she says.

“Indigenous people, local communities, also other ethnic groups – they are good stewards of their biodiversity,” says Ina Vandebroek, an ethnobotanist at the University of the West Indies at Mona in Kingston, Jamaica, who was not involved in the work. “They have knowledge, deep knowledge, about their environments that we really cannot overlook.”

One way to help shift conservation efforts is to give species a “biocultural status,” which would provide a fuller picture of their vulnerability, Reyes-García and colleagues say. In the study, the team used existing language vitality research to determine a culture’s risk of disappearing: The more a cultural group’s language use declines, the more that culture is threatened. And the more a culture is threatened, the more culturally vulnerable its important species are. Researchers then combined a species’ cultural and biological vulnerability to arrive at its biocultural status. In the dugong’s case, its biocultural status is endangered, meaning it is more at risk than its IUCN categorization suggests.

This intersectional approach to conservation can help species by involving the people that have historically cared for them (SN: 3/2/22). It can also highlight when communities need support to continue their stewardship, Reyes-García says. She hopes this new framework will spark more conservation efforts that recognize local communities’ rights and encourage their participation – leaning into humans’ connection with nature instead of creating more separation (SN: 3/8/22).

CHICAGO – In January 2022, a cyclone blitzed a large expanse of ice-covered ocean between Greenland and Russia. Frenzied gusts galvanized 8-meter-tall waves that pounded the region’s hapless flotillas of sea ice, while a bombardment of warm rain and a surge of southerly heat laid siege from the air.

Six days after the assault began, about a quarter, or roughly 400,000 square kilometers, of the vast area’s sea ice had disappeared, leading to a record weekly loss for the region.
The storm is the strongest Arctic cyclone ever documented. But it may not hold that title for long. Cyclones in the Arctic have become more frequent and intense in recent decades, posing risks to both sea ice and people, researchers reported December 13 at the American Geophysical Union’s fall meeting. “This trend is expected to persist as the region continues to warm rapidly in the future,” says climate scientist Stephen Vavrus of the University of Wisconsin–Madison.

Rapid Arctic warming and more destructive storms
The Arctic Circle is warming about four times as fast as the rest of Earth (SN: 8/11/22). A major driver is the loss of sea ice due to human-caused climate change. The floating ice reflects far more solar radiation back into space than naked seas do, influencing the global climate (SN: 10/14/21). During August, the heart of the sea ice melting season, cyclones have been observed to amplify sea ice losses on average, exacerbating warming.

There’s more: Like hurricanes can ravage regions farther south, boreal vortices can threaten people living and traveling in the Arctic (SN: 12/11/19). As the storms intensify, “stronger winds pose a risk for marine navigation by generating higher waves,” Vavrus says, “and for coastal erosion, which has already become a serious problem throughout much of the Arctic and forced some communities to consider relocating inland.”

Climate change is intensifying storms farther south (SN: 11/11/20). But it’s unclear how Arctic cyclones might be changing as the world warms. Some previous research suggested that pressures, on average, in Arctic cyclones’ cores have dropped in recent decades. That would be problematic, as lower pressures generally mean more intense storms, with “stronger winds, larger temperature variations and heavier rainfall [and] snowfall,” says atmospheric scientist Xiangdong Zhang of the University of Alaska Fairbanks.

But inconsistencies between analyses had prevented a clear trend from emerging, Zhang said at the meeting. So he and his colleagues aggregated a comprehensive record, spanning 1950 to 2021, of Arctic cyclone timing, intensity and duration.

Arctic cyclone activity has intensified in strength and frequency over recent decades, Zhang reported. Pressures in the hearts of today’s boreal vortices are on average about 9 millibars lower than in the 1950s. For context, such a pressure shift would be roughly equivalent to bumping a strong category 1 hurricane well into category 2 territory. And vortices became more frequent during winters in the North Atlantic Arctic and during summers in the Arctic north of Eurasia.
What’s more, August cyclones appear to be damaging sea ice more than in the past, said meteorologist Peter Finocchio of the U.S. Naval Research Laboratory in Monterey, Calif. He and his colleagues compared the response of northern sea ice to summer cyclones during the 1990s and the 2010s.

August vortices in the latter decade were followed by a 10 percent loss of sea ice area on average, up from the earlier decade’s 3 percent loss on average. This may be due, in part, to warmer water upwelling from below, which can melt the ice pack’s underbelly, and from winds pushing the thinner, easier-to-move ice around, Finocchio said.

Stronger spring storms spell trouble too
With climate change, cyclones may continue intensifying in the spring too, climate scientist Chelsea Parker said at the meeting. That’s a problem because spring vortices can prime sea ice for later summer melting.

Parker, of NASA’s Goddard Space Flight Center in Greenbelt, Md., and her colleagues ran computer simulations of spring cyclone behavior in the Arctic under past, present and projected climate conditions. By the end of the century, the maximum near-surface wind speeds of spring cyclones — around 11 kilometers per hour today — could reach 60 km/h, the researchers found. And future spring cyclones may keep swirling at peak intensity for up to a quarter of their life spans, up from around 1 percent today. The storms will probably travel farther too, the team says.

“The diminishing sea ice cover will enable the warmer Arctic seas to fuel these storms and probably allow them to penetrate farther into the Arctic,” says Vavrus, who was not involved in the research.

Parker and her team plan to investigate the future evolution of Arctic cyclones in other seasons, to capture a broader picture of how climate change is affecting the storms.

For now, it seems certain that Arctic cyclones aren’t going anywhere. What’s less clear is how humankind will contend with the storms’ growing fury.

Our modern lives depend on rare earth elements, and someday soon we may not have enough to meet growing demand.

Because of their special properties, these 17 metallic elements are crucial ingredients in computer screens, cell phones and other electronics, compact fluorescent lamps, medical imaging machines, lasers, fiber optics, pigments, polishing powders, industrial catalysts – the list goes on and on (SN Online: 1/16/23). Notably rare earths are an essential part of the high-powered magnets and rechargeable batteries in the electric vehicles and renewable energy technologies needed to get the world to a low- or zero-carbon future.
In 2021, the world mined 280,000 metric tons of rare earths — roughly 32 times as much as was mined in the mid-1950s. And demand is only going to increase. By 2040, experts estimate, we’ll need up to seven times as much rare earths as we do today.

Satisfying that appetite won’t be easy. Rare earth elements are not found in concentrated deposits. Miners must excavate huge amounts of ore, subject it to physical and chemical processes to concentrate the rare earths, and then separate them. The transformation is energy intensive and dirty, requiring toxic chemicals and often generating a small amount of radioactive waste that must be safely disposed of. Another concern is access: China has a near monopoly on both mining and processing; the United States has just one active mine (SN Online: 1/1/23).

For most of the jobs rare earths do, there are no good substitutes. So to help meet future demand and diversify who controls the supply — and perhaps even make rare earth recovery “greener” — researchers are looking for alternatives to conventional mining.

Proposals include everything from extracting the metals from coal waste to really out-there ideas like mining the moon. But the approach most likely to make an immediate dent is recycling. “Recycling is going to play a very important and central role,” says Ikenna Nlebedim, a materials scientist at Ames National Laboratory in Iowa and the Department of Energy’s Critical Materials Institute. “That’s not to say we’re going to recycle our way out of the critical materials challenge.”

Still, in the rare earth magnets market, for instance, by about 10 years from now, recycling could satisfy as much as a quarter of the demand for rare earths, based on some estimates. “That’s huge,” he says.

But before the rare earths in an old laptop can be recycled as regularly as the aluminum in an empty soda can, there are technological, economic and logistical obstacles to overcome.

Why are rare earths so challenging to extract?
Recycling seems like an obvious way to get more rare earths. It’s standard practice in the United States and Europe to recycle from 15 to 70 percent of other metals, such as iron, copper, aluminum, nickel and tin. Yet today, only about 1 percent of rare earth elements in old products are recycled, says Simon Jowitt, an economic geologist at the University of Nevada, Las Vegas.

“Copper wiring can be recycled into more copper wiring. Steel can just be recycled into more steel,” he says. But a lot of rare earth products are “inherently not very recyclable.”
Rare earths are often blended with other metals in touch screens and similar products, making removal difficult. In some ways, recycling rare earths from tossed-out items resembles the challenge of extracting them from ore and separating them from each other. Traditional rare earth recycling methods also require hazardous chemicals such as hydrochloric acid and a lot of heat, and thus a lot of energy. On top of the environmental footprint, the cost of recovery may not be worth the effort given the small yield of rare earths. A hard disk drive, for instance, might contain just a few grams; some products offer just milligrams.

Chemists and materials scientists, though, are trying to develop smarter recycling approaches. Their techniques put microbes to work, ditch the acids of traditional methods or attempt to bypass extraction and separation.

Microbial partners can help recycle rare earths
One approach leans on microscopic partners. Gluconobacter bacteria naturally produce organic acids that can pull rare earths, such as lanthanum and cerium, from spent catalysts used in petroleum refining or from fluorescent phosphors used in lighting. The bacterial acids are less environmentally harmful than hydrochloric acid or other traditional metal-leaching acids, says Yoshiko Fujita, a biogeochemist at Idaho National Laboratory in Idaho Falls. Fujita leads research into reuse and recycling at the Critical Materials Institute. “They can also be degraded naturally,” she says.

In experiments, the bacterial acids can recover only about a quarter to half of the rare earths from spent catalysts and phosphors. Hydrochloric acid can do much better — in some cases extracting as much as 99 percent. But bio-based leaching might still be profitable, Fujita and colleagues reported in 2019 in ACS Sustainable Chemistry & Engineering.

In a hypothetical plant recycling 19,000 metric tons of used catalyst a year, the team estimated annual revenues to be roughly $1.75 million. But feeding the bacteria that produce the acid on-site is a big expense. In a scenario in which the bacteria are fed refined sugar, total costs for producing the rare earths are roughly $1.6 million a year, leaving around just $150,000 in profits. Switching from sugar to corn stalks, husks and other harvest leftovers, however, would slash costs by about $500,000, raising profits to about $650,000.
Other microbes can also help extract rare earths and take them even further. A few years ago, researchers discovered that some bacteria that metabolize rare earths produce a protein that preferentially grabs onto these metals. This protein, lanmodulin, can separate rare earths from each other, such as neodymium from dysprosium — two components of rare earth magnets. A lanmodulin-based system might eliminate the need for the many chemical solvents typically used in such separation. And the waste left behind — the protein — would be biodegradable. But whether the system will pan out on a commercial scale is unknown.

How to pull rare earths from discarded magnets
Another approach already being commercialized skips the acids and uses copper salts to pull the rare earths from discarded magnets, a valuable target. Neodymium-iron-boron magnets are about 30 percent rare earth by weight and the single largest application of the metals in the world. One projection suggests that recovering the neodymium in magnets from U.S. hard disk drives alone could meet up about 5 percent of the world’s demand outside of China before the end of the decade.

Nlebedim led a team that developed a technique that uses copper salts to leach rare earths out of shredded electronic waste that contains magnets. Dunking the e-waste in a copper salt solution at room temperature dissolves the rare earths in the magnets. Other metals can be scooped out for their own recycling, and the copper can be reused to make more salt solution. Next, the rare earths are solidified and, with the help of additional chemicals and heating, transformed into powdered minerals called rare earth oxides. The process, which has also been used on material left over from magnet manufacturing that typically goes to waste, can recover 90 to 98 percent of the rare earths, and the material is pure enough to make new magnets, Nlebedim’s team has demonstrated.

In a best-case scenario, using this method to recycle 100 tons of leftover magnet material might produce 32 tons of rare earth oxides and net more than $1 million in profits, an economic analysis of the method suggests.

That study also evaluated the approach’s environmental impacts. Compared with producing one kilogram of rare earth oxide via one of the main types of mining and processing currently used in China, the copper salt method has less than half the carbon footprint. It produces an average of about 50 kilograms of carbon dioxide equivalent per kilogram of rare earth oxide versus 110, Nlebedim’s team reported in 2021 in ACS Sustainable Chemistry & Engineering.
But it’s not necessarily greener than all forms of mining. One sticking point is that the process requires toxic ammonium hydroxide and roasting, which consumes a lot of energy, and it still releases some carbon dioxide. Nlebedim’s group is now tweaking the technique. “We want to decarbonize the process and make it safer,” he says.

Meanwhile, the technology seems promising enough that TdVib, an Iowa company that designs and manufactures magnetic materials and products, has licensed it and built a pilot plant. The initial aim is to produce two tons of rare earth oxides per month, says Daniel Bina, TdVib’s president and CEO. The plant will recycle rare earths from old hard disk drives from data centers.

Noveon Magnetics, a company in San Marcos, Texas, is already making recycled neodymium-iron-boron magnets. In typical magnet manufacturing, the rare earths are mined, transformed into metal alloys, milled into a fine powder, magnetized and formed into a magnet. Noveon knocks out those first two steps, says company CEO Scott Dunn.

After demagnetizing and cleaning discarded magnets, Noveon directly mills them into a powder before building them back up as new magnets. Unlike with other recycling methods, there’s no need to extract and separate the rare earths out first. The final product can be more than 99 percent recycled magnet, Dunn says, with a small addition of virgin rare earth elements — the “secret sauce,” as he puts it — that allows the company to fine-tune the magnets’ attributes.

Compared with traditional magnet mining and manufacturing, Noveon’s method cuts energy use by about 90 percent, Miha Zakotnik, Noveon’s chief technology officer, and other researchers reported in 2016 in Environmental Technology & Innovation. Another 2016 analysis estimated that for every kilogram of magnet produced via Noveon’s method, about 12 kilograms of carbon dioxide equivalent are emitted. That’s about half as much of the greenhouse gas as conventional magnets.

Dunn declined to share what volume of magnets Noveon currently produces or how much its magnets cost. But the magnets are being used in some industrial applications, for pumps, fans and compressors, as well as some consumer power tools and other electronics.
Rare earth recycling has logistical hurdles
Even as researchers clear technological hurdles, there are still logistical barriers to recycling. “We don’t have the systems for collecting end-of-life products that have rare earths in them,” Fujita says, “and there’s the cost of dismantling those products.” For a lot of e-waste, before rare earth recycling can begin, you have to get to the bits that contain those precious metals.

Noveon has a semiautomated process for removing magnets from hard disk drives and other electronics.

Apple is also trying to automate the recycling process. The company’s Daisy robot can dismantle iPhones. And in 2022, Apple announced a pair of robots called Taz and Dave that facilitate the recycling of rare earths. Taz can gather magnet-containing modules that are typically lost during the shredding of electronics. Dave can recover magnets from taptic engines, Apple’s technology for providing users with tactile feedback when, say, tapping an iPhone screen.

Even with robotic aids, it would still be a lot easier if companies just designed products in a way that made recycling easy, Fujita says.

No matter how good recycling gets, Jowitt sees no getting around the need to ramp up mining to feed our rare earth–hungry society. But he agrees recycling is necessary. “We’re dealing with intrinsically finite resources,” he says. “Better we try and extract what we can rather than just dumping it in the landfill.”

Shape-shifting liquid metal robots might not be limited to science fiction anymore.

Miniature machines can switch from solid to liquid and back again to squeeze into tight spaces and perform tasks like soldering a circuit board, researchers report January 25 in Matter.

This phase-shifting property, which can be controlled remotely with a magnetic field, is thanks to the metal gallium. Researchers embedded the metal with magnetic particles to direct the metal’s movements with magnets. This new material could help scientists develop soft, flexible robots that can shimmy through narrow passages and be guided externally.
Scientists have been developing magnetically controlled soft robots for years. Most existing materials for these bots are made of either stretchy but solid materials, which can’t pass through the narrowest of spaces, or magnetic liquids, which are fluid but unable to carry heavy objects (SN: 7/18/19).

In the new study, researchers blended both approaches after finding inspiration from nature (SN: 3/3/21). Sea cucumbers, for instance, “can very rapidly and reversibly change their stiffness,” says mechanical engineer Carmel Majidi of Carnegie Mellon University in Pittsburgh. “The challenge for us as engineers is to mimic that in the soft materials systems.”

So the team turned to gallium, a metal that melts at about 30° Celsius — slightly above room temperature. Rather than connecting a heater to a chunk of the metal to change its state, the researchers expose it to a rapidly changing magnetic field to liquefy it. The alternating magnetic field generates electricity within the gallium, causing it to heat up and melt. The material resolidifies when left to cool to room temperature.

Since magnetic particles are sprinkled throughout the gallium, a permanent magnet can drag it around. In solid form, a magnet can move the material at a speed of about 1.5 meters per second. The upgraded gallium can also carry about 10,000 times its weight.

External magnets can still manipulate the liquid form, making it stretch, split and merge. But controlling the fluid’s movement is more challenging, because the particles in the gallium can freely rotate and have unaligned magnetic poles as a result of melting. Because of their various orientations, the particles move in different directions in response to a magnet.

Majidi and colleagues tested their strategy in tiny machines that performed different tasks. In a demonstration straight out of the movie Terminator 2, a toy person escaped a jail cell by melting through the bars and resolidifying in its original form using a mold placed just outside the bars.
On the more practical side, one machine removed a small ball from a model human stomach by melting slightly to wrap itself around the foreign object before exiting the organ. But gallium on its own would turn to goo inside a real human body, since the metal is a liquid at body temperature, about 37° C. A few more metals, such as bismuth and tin, would be added to the gallium in biomedical applications to raise the material’s melting point, the authors say. In another demonstration, the material liquefied and rehardened to solder a circuit board.
Although this phase-shifting material is a big step in the field, questions remain about its biomedical applications, says biomedical engineer Amir Jafari of the University of North Texas in Denton, who was not involved in the work. One big challenge, he says, is precisely controlling magnetic forces inside the human body that are generated from an external device.

“It’s a compelling tool,” says robotics engineer Nicholas Bira of Harvard University, who was also not involved in the study. But, he adds, scientists who study soft robotics are constantly creating new materials.

“The true innovation to come lies in combining these different innovative materials.”

Birds that dive underwater — such as penguins, loons and grebes — may be more likely to go extinct than their nondiving kin, a new study finds.

Many water birds have evolved highly specialized bodies and behaviors that facilitate diving. Now, an analysis of the evolutionary history of more than 700 water bird species shows that once a bird group gains the ability to dive, the change is irreversible. That inflexibility could help explain why diving birds have an elevated extinction rate compared with nondiving birds, researchers report in the Dec. 21 Proceedings of the Royal Society B.
“There are substantial morphological adaptations for diving,” says Catherine Sheard, an evolutionary biologist at the University of Bristol in England, who was not involved with the study. For instance, birds that plunge into the water from the air, such as gannets and some pelicans, may have tweaks to the neck muscles and the bones in the chest.

It’s possible that some diving birds are evolving under an evolutionary “ratchet,” where adaptations to exploit a certain food source or habitat unlock some new opportunities, but also encourage ever more specialized evolutionary tailoring. These birds may become trapped in their ways, increasing their risk of extinction. That’s especially true if their habitat rapidly changes in some negative way, possibly because of human-caused climate change (SN: 1/16/20).

Evolutionary biologists Josh Tyler and Jane Younger investigated the evolution of diving in Aequorlitornithes, a collection of 727 water bird species across 11 bird groups. The team divided species into either nondiving birds, or one of three diving types: foot-propelled pursuit (such as loons and grebes), wing-propelled pursuit (like penguins and auks) and the plunge divers.

Diving has evolved at least 14 separate times in the water birds, but there were no instances where diving birds reverted to a nondiving form, the researchers found.

The scientists also explored the link between diving and the development of new species, or their demise, in various bird lineages. Among 236 diving bird species, 75, or 32 percent, were part of lineages that are experiencing 0.02 more species extinctions per million years than the generation of new species. This elevated extinction rate was more common in the wing-propelled and foot-propelled pursuit divers compared with plunge divers. Bird lineages that don’t dive, on the other hand, generated 0.1 more new species per million years than the rate of species dying out.

“The more specialized you become, the more reliant you are on a particular diet, foraging strategy or environment,” says Tyler, of the University of Bath in England. “The range of environments available for foraging is much larger for the nondiving birds than for the specialist divers, and this may play into their ability to adapt and thrive.”

Within diving bird groups, the less specialized, the better. Take penguins, a group that has become the subject of a fair share of conservation concern (SN: 8/1/18). The researchers point out that gentoo penguins (Pygoscelis papua) — which have a broad diet — have larger population sizes than related chinstrap penguins (P. antarcticus) that eat mostly krill, and may actually be as many as four very recently diverged species.
The International Union for the Conservation of Nature considers both penguin species to be of “least concern” in terms of imminent extinction risk. But chinstrap numbers are declining in some areas, while gentoo population numbers remain generally stable.

If some diving birds are being trapped in their environments by their own adaptations, that doesn’t bode well for their long-term survival, say Tyler and Younger, who is at the University of Tasmania in Hobart.

According to the IUCN, 156 species, or about one-fifth, of the 727 species of water birds are considered vulnerable, endangered or critically endangered. The researchers calculate that of the 75 diving bird species from lineages with heightened extinction rates, 24 species, or nearly one-third, are already listed as threatened.