In August 1941, the British government received a very unwelcome piece of analysis from an economist named David Miles Bensusan-Butt. A careful review of photographs suggested that the Royal Air Force’s Bomber Command was having trouble hitting targets in Germany and France; in fact, only one in three pilots who claimed to have attacked the targets seemed to have dropped their bombs within five miles of the sites. The Butt report is a landmark in the history of “bomb damage assessment,” or, as we now call it, “battle damage assessment.”
This recondite term has come back into public usage because of the dispute over the effectiveness of the June 22 American bombing of three Iranian nuclear facilities. President Donald Trump said that American bombs had “obliterated” the Iranian nuclear program. A leaked preliminary assessment from the Defense Intelligence Agency on June 24 said that the damage was minimal. Whom to believe? Have the advocates of bombing again overpromised and underdelivered?
Some history is in order here, informed by a bit of personal experience. From 1991 to 1993 I ran the U.S. Air Force’s study of the first Gulf War. In doing so I learned that BDA rests on three considerations: the munition used, including its accuracy; the aircraft delivering it; and the type of damage or effect created.
Of these, precision is the most important. World War II saw the first use of guided bombs in combat. In September 1943, the Germans used radio-controlled glide bombs to sink the Italian battleship Roma as it sailed off to surrender to the Allies. Americans developed similar systems with some successes, though none so dramatic. In the years after the war, precision-guided weapons slowly came to predominate in modern arsenals. The United States used no fewer than 24,000 laser-guided bombs during the Vietnam War, and some 17,000 of them during the 1991 Gulf War. These weapons have improved considerably, and in the 35 years since, “routine precision,” as some have called it, has enormously improved the ability of airplanes to hit hard, buried targets.
Specially designed ordnance has also seen tremendous advances. In World War II, the British developed the six-ton Tallboy bomb to use against special targets, including the concrete submarine pens of occupied France in which German U-boats hid. The Tallboys cracked some of the concrete but did not destroy any, in part because these were “dumb bombs” lacking precision guidance, and in part because the art of hardening warheads was in its infancy. In the first Gulf War, the United States hastily developed a deep-penetrating, bunker-busting bomb, the GBU-28, which weighed 5,000 pounds, but only two were used, to uncertain effect. In the years since, however, the U.S. and Israeli air forces, among others, have acquired hardened warheads for 2,000-pound bombs such as the BLU-109 that can hit deeply buried targets—which is why, for example, the Israelis were able to kill a lot of Hezbollah’s leadership in its supposedly secure bunkers.
The aircraft that deliver bombs can affect the explosives’ accuracy. Bombs that home in on the reflection of a laser, for example, could become “stupid” if a cloud passes between plane and the target, or if the laser otherwise loses its lock on the target. Bombs relying on GPS coordinates can in theory be jammed. Airplanes being shot at are usually less effective bomb droppers than those that are not, because evasive maneuvers can prevent accurate delivery.
The really complicated question is that of effects. Vietnam-era guided bombs, for example, could and did drop bridges in North Vietnam. In many cases, however, Vietnamese engineers countered by building “underwater bridges” that allowed trucks to drive across a river while axle-deep in water. The effect was inconvenience, not interdiction.
Conversely, in the first Gulf War, the U.S. and its allies spent a month pounding Iraqi forces dug in along the Kuwait border, chiefly with dumb bombs delivered by “smart aircraft” such as the F-16. In theory, the accuracy of the bombing computer on the airplane would allow it to deliver unguided ordnance with accuracy comparable to that of a laser-guided bomb. In practice, ground fire and delivery from high altitudes often caused pilots to miss. When teams began looking at Iraqi tanks in the area overrun by U.S. forces, they found that many of the tanks were, in fact, undamaged.
But that was only half of the story. Iraqi tank crews were so sufficiently terrified of American air power that they stayed some distance away from their tanks, and tanks immobilized and unmaintained for a month, or bounced around by near misses, do not work terribly well. The functional and indirect effects of the bombing, in other words, were much greater than the disappointing physical effects.
Many of the critiques of bombing neglect the importance of this phenomenon. The pounding of German cities and industry during World War II, for example, did not bring war production to a halt until the last months, but the indirect and functional effects were enormous. The diversion of German resources into air-defense and revenge weapons, and the destruction of the Luftwaffe’s fighter force over the Third Reich, played a very great role in paving the way to Allied victory.
At a microlevel, BDA can be perplexing. In 1991, for example, a bomb hole in an Iraqi hardened-aircraft shelter told analysts only so much. Did the bomb go through the multiple layers of concrete and rock fill, or did it “J-hook” back upward and possibly fail to explode? Was there something in the shelter when it hit, and what damage did it do? Did the Iraqis perhaps move airplanes into penetrated shelters on the theory that lightning would not strike twice? All hard (though not entirely impossible) to judge without being on the ground.
To the present moment: BDA takes a long time, so the leaked DIA memo of June 24 was based on preliminary and incomplete data. The study I headed was still working on BDA a year after the war ended. Results may be quicker now, but all kinds of information need to be integrated—imagery analysis, intercepted communications, measurement and signature intelligence (e.g., subsidence of earth above a collapsed structure), and of course human intelligence, among others. Any expert (and any journalist who bothered to consult one) would know that two days was a radically inadequate time frame in which to form a considered judgment. The DIA report was, from a practical point of view, worthless.
An educated guess, however, would suggest that in fact the U.S. military’s judgment that the Iranian nuclear problem had suffered severe damage was correct. The American bombing was the culmination of a 12-day campaign launched by the Israelis, which hit many nuclear facilities and assassinated at least 14 nuclear scientists. The real issue is not the single American strike so much as the cumulative effect against the entire nuclear ecosystem, including machining, testing, and design facilities.
The platforms delivering the munitions in the American attack had ideal conditions in which to operate—there was no Iranian air force to come up and attack the B-2s that they may not even have detected, nor was there ground fire to speak of. The planes were the most sophisticated platforms of the most sophisticated air force in the world. The bombs themselves, particularly the 14 GBU-57s, were gigantic—at 15 tons, more than double the size of Tallboys—with exquisite guidance and hardened penetrating warheads. The targets were all fully understood from more than a decade of close scrutiny by Israeli and American intelligence, and probably that of other Western countries as well.
In the absence of full information, cumulative expert judgment also deserves some consideration—and external experts such as David Albright, the founder of the Institute for Science and International Security, have concluded that the damage was indeed massive and lasting. Israeli analysts, in and out of government, appear to agree. They are more likely to know, and more likely to be cautious in declaring success about what is, after all, an existential threat to their country. For that matter, the Iranian foreign minister concedes that “serious damage” was done.
One has to set aside the sycophantic braggadocio of Secretary of Defense Pete Hegseth, who seems to believe that one unopposed bombing raid is a military achievement on par with D-Day, or the exuberant use of the word obliteration by the president. A cooler, admittedly provisional judgment is that with all their faults, however, the president and his secretary of defense are likely a lot closer to the mark about what happened when the bombs fell than many of their hasty, and not always well-informed, critics.
*Photo-illustration by Jonelle Afurong / The Atlantic. Sources: Alberto Pizzoli / Sygma / Getty; MIKE NELSON / AFP / Getty; Greg Mathieson / Mai / Getty; Space Frontiers / Archive Photos / Hulton Archive / Getty; U.S. Department of Defense.
Scientists have discovered a heartbeat-like pulse emanating from inside the Earth beneath the continent of Africa, which they believe will one day rip the continent into pieces.
In a new study published today in the journal Nature Geoscience, a team of European and African scientists explain how they used chemical signatures to examine this inner-Earth heartbeat, explaining that molten chunks of mantle — the rocky layer found between the Earth’s surface and core — are surging together through rift zones, or weak areas of volcanos where magma is likeliest to break through our planet’s crust.
These internal surges have settled into rhythmic bursts of pulsing plumes. Which, while fascinating to imagine, effectively means that bursts of molten rock are pushing against the African continent’s crust — and over millions of years, will likely tear the continent apart, making way for a new ocean basin.
Researchers focused on the Afar region of Ethiopia, a volcanic area where multiple rift zones are located, collecting and analyzing around 130 samples of volcanic rock.
“We found that the mantle beneath Afar is not uniform or stationary,” said Emma Watts, a Swansea University geologist and lead author of the study, in a statement. “It pulses, and these pulses carry distinct chemical signatures.”
Deep Understanding
As the Independent notes, the research is significant because while scientists have believed for some time that the region’s mantle was being pushed against its crust and causing it to expand, they didn’t quite know why.
This new research offers scientists a deeper understanding of that process. What’s more, it reveals that the Earth’s plates actually have a huge influence on the movements of the molten magma located beneath them.
“These pulses appear to behave differently depending on the thickness of the plate, and how fast it’s pulling apart,” said study co-author Tom Gernon, a geologist at the University of Southampton, in a statement. “In faster-spreading rifts like the Red Sea, the pulses travel more efficiently and regularly like a pulse through a narrow artery.”
Excitingly, the researchers believe their discovery will pave the way for more breakthroughs in how we understand and study volcanic activity, the dynamic inner workings of our planet, and what activity found today means for Earth’s future.
“This has profound implications,” said the University of Southampton’s Derek Keir, an earth sciences professor and study co-author, in a statement, “for how we interpret surface volcanism, earthquake activity, and the process of continental breakup.”
More on planet Earth: A Strange Darkness Is Spreading Throughout the Oceans
A new study published in the journal Death Studies suggests that positive childhood experiences can reduce the impact of trauma-related stress on suicidal thoughts in young adults. Researchers found that even among college students who reported symptoms of posttraumatic stress disorder and a history of adverse childhood experiences, those who recalled more supportive, affirming experiences from childhood were less likely to report suicidal ideation.
The findings offer evidence that early-life support may serve as a protective factor for suicide risk later in life—even in the presence of trauma. The study underscores the importance of both preventing early adversity and fostering positive relational experiences during childhood, especially in light of growing mental health concerns among college-aged populations.
Posttraumatic stress disorder, or PTSD, is a mental health condition that can develop in response to traumatic events. Symptoms include distressing memories, avoidance of reminders, emotional numbness, negative changes in beliefs and mood, and feelings of disconnection from others. These symptoms can cause psychological pain and lead to a sense of hopelessness, both of which are known contributors to suicidal ideation.
Suicidal ideation refers to thoughts about ending one’s life. These can range from vague feelings of despair to detailed plans. In the United States, suicide is the second leading cause of death among people aged 15 to 24. According to national data, nearly one in four college students has had suicidal thoughts in the past year.
Previous studies have shown that both PTSD and childhood trauma—often measured by a history of adverse childhood experiences, such as abuse or neglect—are associated with higher rates of suicidal thoughts. On the other hand, positive experiences during childhood, such as having a caring adult or feeling safe at home, may help buffer the negative impact of early adversity.
The new study was designed to explore how these factors interact. Specifically, the researchers wanted to find out whether benevolent childhood experiences could lessen the relationship between PTSD symptoms and suicidal ideation—even in those who had experienced high levels of adversity.
The study involved 837 undergraduate students at a university in the Southeastern United States. The average age of participants was 19, and most identified as White (88%) and female (76%). Participants completed a series of online questionnaires that measured posttraumatic stress symptoms, suicidal ideation, adverse childhood experiences, and benevolent childhood experiences.
To measure PTSD symptoms, the researchers used a widely accepted checklist that asks about the severity of different trauma-related symptoms over the past month. Suicidal ideation was assessed using a scale that includes both passive and active thoughts about death, such as wishing one were dead or making a plan to end one’s life.
Adverse childhood experiences were measured using a 10-item questionnaire that included questions about abuse, neglect, and household dysfunction before age 18. Participants answered “yes” or “no” to each item. The more “yes” answers, the higher their score.
Benevolent childhood experiences were measured with a similar 10-item scale that asked about positive early life experiences, such as having a good friend or feeling that their parents believed they were important.
The researchers then analyzed how all three factors—PTSD symptoms, adverse childhood experiences, and benevolent childhood experiences—interacted to predict suicidal ideation. They used a statistical method that allowed them to examine the combined effects of these variables across different levels.
About 27% of participants reported some degree of suicidal ideation in the past year. Around 17% had experienced four or more adverse childhood experiences, a threshold often associated with higher risk for mental health problems. At the same time, the vast majority—nearly 80%—reported high levels of benevolent childhood experiences.
As expected, participants with more severe PTSD symptoms were more likely to report suicidal ideation. Higher levels of adverse childhood experiences also increased suicide risk. But the presence of positive early experiences consistently reduced this risk.
The most important finding came from the three-way interaction analysis. The researchers discovered that benevolent childhood experiences reduced the strength of the relationship between PTSD symptoms and suicidal ideation—regardless of how many adverse experiences a participant had faced.
In other words, students with PTSD symptoms were less likely to think about suicide if they had also experienced supportive and affirming interactions in childhood. This buffering effect held true across all levels of adversity. Even those with high trauma exposure appeared to benefit from positive early relationships.
These results align with a well-supported psychological theory known as the Three-Step Theory of Suicide. This theory proposes that suicidal ideation emerges from the combination of psychological pain and hopelessness and intensifies when a person lacks a sense of connectedness to others or to meaningful aspects of life. Benevolent childhood experiences may provide a foundation for that sense of connectedness, even in the face of later trauma.
There are limitations to consider. The research was cross-sectional, meaning it captured a snapshot in time. Because of this, it cannot determine whether PTSD symptoms cause suicidal thoughts or whether benevolent experiences directly prevent them. Longitudinal studies following individuals over time would help clarify the direction of these relationships.
Another limitation is the study’s reliance on retrospective self-reporting. Participants were asked to recall childhood experiences, which could be subject to memory biases. People may remember or interpret past events differently depending on their current mental state.
The sample was also limited in diversity. Most participants were White, heterosexual, and cisgender women enrolled in college. These findings may not generalize to more diverse populations, including people with different racial, cultural, educational, or socioeconomic backgrounds.
Finally, while the study is consistent with the Three-Step Theory of Suicide, it did not directly measure the theory’s core components—such as hopelessness, psychological pain, or connectedness. Future research could incorporate more direct assessments of these concepts to better test the theory.
Some years ago I published a book called New York City of Trees. On facing pages of photographs and text, it presented portraits of fifty-five trees in the city’s five boroughs. One was of a Callery pear in the Chelsea neighborhood of Manhattan. A mid-sized tree covered in white blossoms each spring, glossy green leaves in the summer, and a mass of orange-yellow leaves in the fall, the species is a familiar sight in cities across the US. At the time of my book’s publication it was the second most widely planted species in Manhattan, after the honey locust.
Growing on the east side of Eleventh Avenue between 25th and 26th Streets, this particular tree stood out for the way its rounded crown, framed by the brick building behind it, glowed in a shaft of late afternoon sun filtered between a post office building and a sanitation depot across the street. I first saw it while walking with my wife, Katherine, in late April 2002, and in that aura of sun the leaves shone with the fresh kind of green that new leaves have in the spring. At Katherine’s suggestion, a few days later I retraced our steps and took a picture. I came back again to make portraits of the tree in the fall, winter, and early spring.
Benjamin Swett
The four seasons of the Callery pear, 2002–2003
I had recently left a job at the New York City Parks Department to try to make a living as a freelance photographer, particularly of trees. The four photographs of the Callery pear became something of a signature series for me. Friends sent me their own pictures of the tree taken from different angles and e-mailed me about things they had observed when they passed by—a number of plastic bags caught in its branches; a bicycle chained to its trunk, missing gears and tires; a phoebe singing in an upper branch; a street vendor selling used books on a blanket in its shade.
As I noted in my book, one day in 2008 I drove by and the Callery pear was gone. From friends at the Parks Department I learned that it had been cut down at the request of the Metropolitan Transportation Authority as part of the planned extension of the 7 subway line to Hudson Yards, then in development. Three new buildings necessary for the subway would be built on the lot behind the tree. The Parks Department had approved the removal in exchange for a restitution payment of $22,500, which would cover the cost of planting thirty new trees elsewhere in the neighborhood.
Benjamin Swett
The site of the Callery pear, 2008
During the years that followed, as I watched heavy equipment move in and transform the lot, I found myself rationalizing the loss. The city has procedures to calculate replacement values for trees in cases of construction conflicts, and extending the subway to Eleventh Avenue was hardly a bad thing. Callery pears are not even considered a long-lived or sustainable species. Introduced from East Asia in the early twentieth century and widely planted as ornamental street trees, they have weak branches that break easily under stress and a habit of spreading quickly in wild places, crowding out other plant life. They are now considered an invasive species in several states; most American cities actively discourage planting them. I did not think there was anything I could have done about the one on Eleventh Avenue and decided that the point was to appreciate its uniqueness in memory—and in photographs.
I had pretty much accepted this idea when, six years ago, I happened to walk by the spot again. Instead of the proposed three buildings, it turned out that the MTA had constructed just one—a five-story, windowless cement structure on the northern side of the lot. Occupying the southern side was a sculpture by Mark di Suvero. The Callery pear—which had been growing roughly in front of where the sculpture now stood—would not have been in the way of the MTA building; with protections in place, construction vehicles could have accessed the site without disturbing it. The tree had, it seemed to me, been cut down for nothing.
Benjamin Swett
The site of the Callery pear, 2019
New York City’s urban forest contains about seven million trees, distributed along streets, highways, and shorelines; in parks and cemeteries; in the backyards of private homes; in genuine forests; and in numerous other places, such as the edges of parking lots. City law codifies a system for removing any of these trees before the start of a new construction project—and then for replacing them with trees of an equivalent value in or near the original location after the project’s completion. “Any person that intends to remove any tree” within the jurisdiction of the Parks Department commissioner, according to Title 18-107 of the New York City Administrative Code, needs to obtain a permit and pay a fee “sufficient to cover the cost of replacing any tree proposed to be removed.” At a minimum, the law says, the new tree should “equal one caliper inch of replacement tree for each caliper inch of tree removed,” but the Parks Department has leeway to set a higher replacement value if one seems merited—and it usually does. To establish those values the agency has to follow guidelines “set forth in the most recent edition of the guide for plant appraisal.”
The International Society of Arboriculture (ISA) has been publishing and regularly updating its Guide for Plant Appraisal, now in its tenth edition, since 1957. At 170 pages, it offers formulas and standards to help arborists establish monetary values for trees lost to storms or for “inventory, tree preservation, insurance, casualty loss, income, accounting, tax, finance, and litigation purposes.” Years ago, in consultation with the New York chapter of the ISA, the Parks Department modified the formulas to arrive at its own Tree Valuation Protocol, which sets a tree’s monetary value “based on its size (as measured by the cross-sectional area of the trunk) and then adjusts for the tree’s condition, species, and location.”
The Parks Department’s Tree Valuation Protocol, which it calls “both a science and an art,” is one of the strictest in the country. The base standard for most municipalities is a wood-for-wood replacement for the species involved: a twelve-inch diameter pin oak, for instance, is said to be equivalent to four three-inch diameter pin oaks. Forest scientists and tree advocates speak of New York City’s protocol with admiration because it goes beyond such equivalencies to try to assess how trees actually contribute to the places where they grow. It takes into account not only the condition of a tree and the suitability of its species for the location but also ecological, aesthetic, and social factors: “pollution reduction, stormwater mitigation, promotion or inhibition of flora and fauna…form and structure, opportunities provided for recreation, and contributions to social cohesion and community revitalization.”
But despite the respect the city’s protocol garners and the higher replacement fees it imposes, tree removals such as that of the Callery pear on Eleventh Avenue continue unabated. In most cases planners and developers simply factor New York City’s higher removal costs into projects from the beginning as part of the price of doing business. And no amount of tree replacement math can substitute for just leaving a tree where it is.
Nobody knows how many trees are removed in New York City each year. Just 53.5 percent of trees in the city fall under the protection of the Parks Department, and even in the agency no single database compiles information about all the trees being worked on or removed at any given time. The rest of New York’s trees fall under the jurisdiction of other city agencies, New York State, the federal government, and especially private property owners, who only have to acquire permits for work on trees in public rights of way like sidewalks. In a 2022 report on the state of New York City’s urban forest, the Nature Conservancy concluded that “segmented ownership and limited data” make it “difficult to analyze the urban forest as a whole…or to arrive at an exact count of trees in the city from which to derive a more complete understanding.”
Benjamin Swett
Dawn Redwood, East River Park, 2023
Some idea of the scale of annual tree losses can be gleaned by considering the number and variety of projects that regularly lead to removals: road widenings, building development, public housing improvements, utility work, flood-control initiatives, park reconstructions, urban renewal projects, and requests by individual property owners for curb cuts and construction access. For example, despite protests from advocates, 991 healthy, mostly mature trees are being removed from East River Park in Lower Manhattan as I write so that the park can be rebuilt as a floodwall. With apparently less public controversy, 450 trees, again most of them healthy and mature, were recently removed from the Red Hook Houses public housing project in Brooklyn for another flood control project. More than a thousand—mature oaks, London planes, and honey locusts in excellent condition, with trunk diameters greater than twenty inches—were removed as part of the widening of the Van Wyck Expressway in Queens.
In its report the Nature Conservancy offered a more comprehensive view of tree losses and gains around the city by using satellite images to compare tree canopy cover between 2010 and 2017, the longest period over which such information was then available. The results showed that during the period a gross gain of 9,730 acres was offset by a loss of 6,477 acres, for a net increase of 3,253 acres—from 20.36 percent of the city to 22.04 percent. Gains in some neighborhoods were, however, undercut by losses in others. The distribution of trees in the city, the Conservancy found, reflected “inequity across communities.” Although a portion of the overall gain during the period could be attributed to Mayor Michael Bloomberg’s highly publicized Million Trees project, which ran from 2007 to 2015, the Nature Conservancy estimated that as much as 86 percent of the increase actually came from the natural growth of existing trees. Some of the overall loss, meanwhile, was due to a single natural disaster, Hurricane Sandy, which the Parks Department estimated had damaged or downed approximately 11,000 street and park trees.
It is meaningful that the canopy did grow overall during the period the study tracks. But it grew a lot less than it would have without the loss of those 6,477 acres—thousands of healthy, larger trees, covering an area roughly seven and a half times the size of Central Park, in a pollution-filled, ever-hotter city with an inequitable distribution of resources. The Conservancy worries that “even in cases where replacement is required, it can take decades to recover the associated canopy and benefits of larger, old trees that are removed.”
We ought to worry, too. With stronger tree retention requirements in place and different design standards, many proposed tree removals could, for one thing, be avoided with relatively little difficulty. For most projects, the technical problems trees pose are minor inconveniences. If it were standard practice to keep trees in place and protect them rather than cut them down and replace them later, and if builders and designers took the time to work out protocols for doing so, more of the city’s canopy could be preserved—and more of it could grow.
The MTA’s request to remove the Callery pear from the sidewalk on Eleventh Avenue to construct what I later found out to be a subway ventilation building is a case in point. The extension of the 7 line, of which the vent building was a part, was itself part of a bigger deal arranged by Mayor Bloomberg to encourage the project that came to be known as Hudson Yards. As has been well documented, with Bloomberg’s prodding two developers, the Related Companies and Oxford Properties, agreed to build a skyscraper-supporting platform over the Long Island Railroad’s Eleventh Avenue train yards. In total $6 billion in state and city concessions ended up going to the development; among them was the subway extension, providing direct public transportation to the building complex that the Related Companies now advertises as “the largest private real estate development in the history of the United States.” If the Parks Department had required that the Callery pear be left standing, I’m pretty sure the MTA could still have figured out a way to install what turned out to be that single vent building on the site. The Callery pear was the only tree along the Eleventh Avenue side of the block; part of the southern and the full northern half of the block were open—and access from the side streets was free as well. With roots, trunk, and crown protected by wood barriers, and of course with proper attention, the tree could still be growing there.
Benjamin Swett
American Elm, Bay Ridge, Brooklyn, 2012
But even if removal restrictions were as burdensome as developers sometimes claim, it would still be worth putting a high priority on preserving as many healthy, mature trees as we can. Design and construction practices in New York City tend to operate on the assumption that growing things in general and trees in particular are inanimate objects, like lampposts or guardrails or even buildings and bridges, that can be removed, replaced, added, subtracted, rearranged, “put in,” “taken out,” and generally made to fit into an idea of order that is not an order in which growing things grow. In the alchemy of New York City’s current tree replacement procedures, trees can be changed into money and money back into trees. In the process the trees themselves become costs to be covered or fees to be paid. Once the fee is paid the tree can be removed without loss.
But this is false. Mature, healthy trees that have been growing in one place for a long time have concrete, measurable advantages over the saplings usually planted to replace them. They are far better at cooling the city in the summer, absorbing pollution and excess rainwater, baffling sound, sequestering carbon, even creating oxygen. Neighborhoods with a larger number of mature trees are healthier than those with fewer. Meanwhile, as the Nature Conservancy points out, replacement trees take decades to begin to provide benefits on a par with those of the original trees, and the arboreal churning allowed by the city’s current replacement policies only slows down attempts to increase its tree canopy and cool its neighborhoods, even as the world heats up. To suggest that the replacements are in some sense equivalent to the originals only confuses neighbors into thinking that what is put in will somehow make up, in their lifetimes, for what has been taken away.
Mature, healthy trees also have more intangible effects. Simply by its presence on the side of a street, in a park, along a highway, or even in an airshaft, a tree provides benefits to people in a city that nothing else can offer, not even a sculpture by Mark di Suvero: the sounds of birds chirping outside one’s window, the unusual shapes and locations of branches and trunks as they lodge themselves in one’s mind, unconscious connections between certain trees and emotions during periods of one’s life, or an expanded sense of time in the presence of living things older than oneself. These effects are mostly unconscious until one day you happen by and see that the tree is gone.
In 1970 the New York City Landmarks Preservation Commission designated a southern magnolia in Bedford Stuyvesant, Brooklyn, as a city landmark, citing the anomaly of its survival so far north of its usual range. It is one of only two trees in the city ever to have been formally designated a landmark. (The other, the country’s first Weeping Beech, in Flushing, Queens, died around 2000.) Rare and lovely, with extraordinary white flowers each June, the Magnolia at 677 Lafayette Avenue still thrives today, nearly a century and a half since its original planting, protected from removal in a planned development by its landmark status.
New York has quite a few extraordinary trees that are especially large or old or botanically unusual, or that are associated with famous figures or moments in the country’s history, against whose protection few would argue. Revolutionary-era elms in Washington Heights and Greenwich Village, gigantic tulip trees in Staten Island and Queens, a ginkgo associated with an Underground Railroad association in Bedford Stuyvesant: these are just a few of the 120 trees around the city that the Parks Department has designated as “great.” But it is not just such officially designated trees that have value. As recent research has shown, trees grow best in forest systems, and the benefits of a grove of trees far outweigh those of any single one.
In New York City, forest systems take unusual forms. Genuine forested landscapes such as those in Inwood Hill Park, the New York Botanical Garden, and Alley Pond and Pelham Bay Parks, with their connected roots and layers of mycelium-filled duff, are by far the most efficient at sequestering carbon and combating pollution. But as the Nature Conservancy’s report highlights, what we call the urban forest is a distinctive kind of ecosystem that also includes trees planted along streets, around ballfields, at private houses, in new developments, in community gardens, and even taking root spontaneously in vacant lots and on the rooftops of abandoned buildings.
In many cases the trees in question belong to vastly different species that might not grow together in the wild. And yet just by surviving together for a number of years in a particular spot in the city they will have joined—may even have become central to—complex and unique networks of plant, animal, and human life. A lone oak on a street corner may not sequester as much carbon as it would among others of its kind in a forest, but its shade is of disproportionate value to those who shelter under it in the summer. These systems, idiosyncratic and unquantifiable, should be valued as wholes, and to survive as wholes they must be protected in their parts.
Simply putting saplings, no matter how climate-resilient, in place of healthy, full-grown trees is counterproductive to increasing the benefits of urban forest systems. Consider the question of carbon emissions. Study after study has shown that mature trees are exponentially more effective at absorbing carbon from the atmosphere than are the saplings typically planted to replace them. One study determined that a single large tree can absorb as much carbon in a year as an entire mid-sized tree will have absorbed in its lifetime. When you consider not only the loss of the carbon-sequestering power when a mature tree is removed but the added carbon footprint of raising, transporting, and planting the replacement saplings (not to mention the carbon footprint of cutting down the original tree and chipping it up), many years must pass before saplings can grow large enough to begin to make up for the loss of the tree they have replaced.
New York City’s tree law specifies how soon replacement trees must be planted after projects are completed. But as far as I know the replacement formula does not account for the number of years that sites could remain treeless during extended projects. If it did factor in the loss of a given tree’s benefits between the time of its removal and the time of its replacement, as well as the estimated time that it would actually take the new trees to grow big enough to approximate their predecessors’ contributions, then the beginnings of a more realistic tree replacement formula might emerge. The psychological effects of sudden treelessness on neighbors and the health effects of unchecked wind and hotter, louder streets—not to mention of unabsorbed pollution from traffic during the treeless interim—are harder to quantify but should also be included in the formula.
In the document that explains its valuation methods, the Parks Department includes tables for foresters to rate a given tree according to its expected longevity and canopy size and its potential contributions to the place where it grows. Trees of some species are assigned less value than others; Callery pears, for example, rate relatively low. It would seem, in theory, that including such ratings as a part of tree valuation would strengthen the urban forest by causing smaller or shorter-lived trees—such as Callery pears—to be replaced over time with new, longer-lived ones, such as oaks or ginkgos. In practice, however, the effect is to sanctify the more immediate removal of perfectly healthy, if less perfect, trees that may still contribute to their surroundings for many years in a human lifetime.
Benjamin Swett
American Elm, Crotona Park, the Bronx, 2024
A more beneficial scheme would be to keep the mature trees whenever possible, no matter what their ratings, and plant high-rated saplings in empty spaces nearby to augment them. Eventually, when the mature trees fail or enter senescence, the saplings will have had a chance to grow to maturity and start serving as meaningful replacements. The result would be a stronger, faster-growing urban forest system. If the new trees are chosen for future climate conditions—hickories, oaks, dawn redwoods, bald cypress—then that system will also be more resilient.
To take the measure of how limiting these abstract longevity ratings and financial formulas can be, I often think of the Survivor Tree at the World Trade Center memorial site in downtown Manhattan. Now designated a Great Tree, this Callery pear, its roots snapped and branches broken, was removed from the wreckage about a month after September 11, 2001, and transplanted to a Parks Department nursery in the Bronx where it was nurtured back to health over the next nine years. Replanted among 420 swamp white oaks at the World Trade Center Memorial site in 2010, this representative of a weak-limbed, brittle-branched invasive species—near the bottom of the Parks Department’s published hierarchy—is now more than thirty feet tall and grows happily there still.
Efforts to reduce tree removals in New York City will not succeed until the law adjusts to demand them. To ensure that projects factor preservation and accommodation—rather than removal and replacement—into the cost of doing business will require changes to the administrative code. Those changes are especially necessary now that the pressing need for more affordable housing is leading the city to relax certain construction regulations.
Some of these relaxations are welcome developments: as the city moves to a congestion pricing model for cars in parts of Manhattan and encourages the use of public transit to combat carbon pollution, it makes sense to remove a requirement that new developments provide sufficient parking for all residents. For those same reasons, however, it hardly makes sense to let developers remove pollution-absorbing trees from a sidewalk in the name of temporary construction efficiency, or to design buildings with footprints too expansive to accommodate trees already growing in front of a building site. Requiring space for crown and roots, trees are incompatible not with buildings (which can be designed to give them space) but with the practice of maximizing real estate values by bringing building footprints right up to the edge of a sidewalk.
Other US cities have by now moved ahead of New York in legislating tree protections. In 2019, declaring tree canopy a health issue affecting everyone within its borders, Cambridge, Massachusetts, extended municipal protections to any healthy tree with a diameter greater than six inches on private or public property, regardless of species. In 2021 Nashville created a panel of representatives from different city agencies with a mandate to review proposed tree removals on city land “for compliance with the replacement standards,” “pursue retention where feasible,” and “provide a recommendation of an alternate plan.” Seattle passed new regulations in 2023 that extend protections to trees on private property and specify levels of protection for different sizes of trees and types of projects.
In 2022 New York City Council Member Christopher Marte tried to strengthen the city’s tree protections by sponsoring a law that would have made it a misdemeanor to remove or harm a “heritage tree” (i.e., a tree with a circumference greater than one hundred inches) on public or private property. That law failed, but the following year the City Council took a step in the right direction by passing Local Law 1065, which requires a city agency selected by the mayor to develop an Urban Forest Plan that would “expand the tree canopy from the current 22 percent coverage to 30 percent coverage” and recommend strategies to mitigate urban forest loss.
The task of developing such a plan fell to the Mayor’s Office of Climate and Environmental Justice. In early February I spoke with Paul Lozito, a deputy director at MOCEJ, who told me that the agency expects to have a draft ready for public review by the summer. When I asked whether the draft will recommend changes to city law to help reduce tree removals, and whether it will extend protections to trees on private property, he said that they are considering all options. In the meantime, MOCEJ, in partnership with the City Parks Foundation, has been conducting a series of lively community listening events around the five boroughs to solicit ideas and concerns from tree advocates. Advocacy organizations such as the Forest for All Coalition—a group of around 150 organizations convened by the Nature Conservancy to advocate for the city’s forest—and the Regional Plan Association have all proposed ways to monitor and expand the canopy; in its 2022 report the Nature Conservancy made a point of calling for the city to “better prevent removal of healthy, larger trees on public lands.” None of these groups, however, has gone on record to propose legal changes as particular or extensive as the law that Christopher Marte had introduced to protect larger, older trees.
Benjamin Swett
Japanese Pagoda Tree, St. Mary’s Park, the Bronx, 2024
In the interest of moving the conversation forward, let me therefore propose four changes the City Council could make to the Administrative Code to reduce unnecessary tree loss and better protect New Yorkers from the effects of a warming planet.1First, the city could go ahead and extend protections to cover not just the 53.5 percent of trees growing on land under the Parks Department’s jurisdiction but also the 35 percent of trees on private property. In the interest of fairness, as Cambridge has done, fees for permitted tree replacements on private property could be reduced for homeowners whose incomes fell below a certain level. Any legal challenges to these expanded protections could be met on the grounds that the benefits of trees are shared by a community—preserving them is a matter of protecting the health of the neighborhood as a whole.
Second, the Council could create an independent Tree Board, similar to the Landmarks Preservation Commission, with a mandate to help designers and builders develop plans to retain established healthy trees—and with the power to deny permit applications for those that don’t. One of the crucial weaknesses of the city’s current tree law is that its designated enforcer, the parks commissioner, is a political appointee who serves at the mayor’s discretion. Any projects known to have mayoral backing—and most development projects generally do—are difficult for a parks commissioner even to seem to oppose. Many larger projects, from Hudson Yards to the East River Park renovation, originate in the executive branch. Creating an independent agency with disapproval powers would help the proposers of projects look beyond removal and replacement as an automatic response.
Third, the council could more unequivocally require the retention and accommodation of existing trees by requiring developers to get the Tree Board’s approval before removing any of three types of trees: what I would call established trees (trees with diameters greater than ten inches) growing within fifteen feet of a curb; working trees (any given tree with a diameter greater than twenty inches, or a group of six or more whose average diameters are greater than ten inches), and heritage trees (those with diameters greater than thirty inches). If the Tree Board grants approval, the applicant would follow the current rules governing tree replacement. If the board requests changes, the applicant would need to work with them to redesign the plans. In the interest of fairness, currently allowed caps on the Parks Department’s tree replacement requirements in certain residential zoning districts would be eliminated.
Finally, the council could require public notification of proposed tree work involving established, working, or heritage trees, and open a fourteen-day comment period during which affected neighbors could submit their concerns about proposed removals to the Tree Board. Along with this, the Parks Department could be required (and given the necessary funds) to establish a comprehensive, publicly accessible, easily searchable database and map of proposed, upcoming, and completed tree work on public and private property, including work that is part of its own capital projects. These measures would both keep neighbors abreast of proposed changes and create a single collecting point for data about tree work and tree removals.
Reducing tree loss is ultimately a matter less of taking on arduous new work or paying steeper costs than it is of changing one’s state of mind. If politicians, planners, designers, engineers, and property owners knew from the beginning that retaining trees was often a requirement, not just something you could pay a fee to avoid, they would make plans accordingly. From my own observation, whether of large capital projects such as the renovation of East River Park or of development projects that involve local street trees, alternative designs and construction practices could allow many trees to remain.
Benjamin Swett
American Sycamore, Corlear Avenue, Kingsbridge, the Bronx
This has been shown to work right here in New York. After a developer announced plans to construct condominium apartments in a parking lot occupied by a famous old American sycamore—a designated Great Tree—on Corlear Avenue in Kingsbridge, neighbors rallied to save the tree. Whether because it had always intended to or because it deferred to the intense community pressure (and articles in The New York Times and the Riverdale Press), the developer ended up designing the building with a U-shaped courtyard to accommodate the tree, and even went so far as to name the building the Sycamore Court Condos.
Now the building’s residents live among the tree’s leaves and hear birds in its branches. In summer visitors pass through a shady courtyard on their way to and from the lobby and the medical offices on the ground floor. The building superintendent waters the tree in dry periods and the neighbors who originally fought to save it watch over it and make sure it stays healthy. And because it is a designated Great Tree, the Parks Department keeps an eye on it, too.
The Callery pear on Eleventh Avenue was not a designated Great Tree, and the only constituency it could be said to have had was the neighbors, gallery-goers, and post office and sanitation workers who passed by it every day. Nearly two decades since its removal, hardly anyone probably remembers it now. But I do, and since 2019 I have gone back every couple of years to see what is happening on the block where it grew.
Benjamin Swett
The site of the Callery pear, 2021
Benjamin Swett
The site of the Callery pear, 2023
Benjamin Swett
The MTA’s completed vent building on 11th Avenue, carrying an advertisement for a planned development, 2023
By 2021 the di Suvero sculpture was gone and the lot was blocked off by orange barrels and plastic barriers. The spot on the sidewalk where the Callery pear had grown was occupied by heavy stacks of construction supplies. By 2023 the entire lot, including the vent building on the north side, was fenced off as a new construction site. Around the vent structure stretched an advertisement for a new “Arts Building” to be erected along the block.
Benjamin Swett
A detail of the developer’s rendering for the planned arts hub on 11th Avenue, 2023
From the computer rendering it was apparent that the windowless vent building would be incorporated into the new development, whose glass front came right up to the edge of the sidewalk, leaving no space either for the lush crown of my remembered Callery pear or for its roots. Inside the building, in the developer’s imagination, people in various styles of dress went about their business on different floors in well-lit office spaces. A few trees grew in planters on the roof. Out front along the street, however, not a single tree grew.
Ta-Nehisi Coates delivers a searing and deeply personal examination of Black life in America through Between the World and Me, a book structured as an extended letter to his teenage son. This National Book Award winner transcends traditional memoir boundaries, weaving together personal narrative, historical analysis, and urgent social commentary into a work that demands confrontation with uncomfortable truths about American society.
The Power of Epistolary Intimacy
Coates constructs his argument through the intimate framework of paternal guidance, addressing his son Samori directly throughout the text. This epistolary approach transforms what could have been another academic treatise on race into something far more visceral and immediate. The father-son dynamic infuses every observation with stakes that feel life-and-death urgent, because for Black bodies in America, they often are.
The author’s voice carries the weight of someone who has survived the “streets” of Baltimore, navigated the intellectual awakening of Howard University, and emerged as a clear-eyed observer of American racial dynamics. His prose style borrows from the urgency of journalism—his primary profession—while maintaining the lyrical quality necessary for memoir. Coates writes with controlled fury, each sentence carefully constructed to build an overwhelming case about the precarious nature of Black existence in America.
The Body as Central Metaphor
Throughout the work, Coates returns obsessively to the concept of “the body”—specifically, the Black body as a site of violence, control, and destruction. This isn’t abstract theorizing; it’s grounded in concrete experiences from his Baltimore childhood, where physical safety required constant vigilance and the navigation of unwritten codes that could mean the difference between life and death.
The author’s discussion of his educational experiences reveals how both “the streets” and “the schools” served as mechanisms of control over Black bodies. His analysis of how traditional education failed to address the fundamental questions about Black existence in America resonates with particular power. Coates describes his intellectual awakening at Howard University—which he calls “The Mecca”—as a revelation of Black intellectual and cultural diversity that had been systematically hidden from him.
The Howard University sections represent some of the book’s most compelling writing. Coates captures the intoxicating discovery of Black intellectual tradition, the diversity of Black experience across the diaspora, and the formation of his own analytical framework. His description of the campus as a space where he could see “everything I knew of my black self multiplied out into seemingly endless variations” demonstrates his ability to render personal transformation in vivid, accessible terms.
Historical Reckoning and Contemporary Violence
Coates skillfully weaves historical analysis throughout his personal narrative, refusing to treat slavery and its aftermath as distant history. His examination of how wealth extraction from Black bodies built American prosperity reads as both economic analysis and moral indictment. The connection he draws between historical plantation violence and contemporary police brutality isn’t metaphorical—it’s direct lineage.
The book’s emotional center emerges in Coates’s discussion of Prince Jones, a Howard University friend killed by police. This section transforms from personal grief into broader analysis of how American society systematically devalues Black life. Coates’s interview with Prince’s mother, Dr. Mable Jones, provides one of the book’s most devastating passages, revealing how even middle-class success cannot protect Black families from state violence.
The author’s treatment of contemporary events—Eric Garner, Michael Brown, Trayvon Martin—avoids both sensationalism and false comfort. Instead, he places these deaths within the broader historical pattern of American violence against Black bodies, arguing that such killings represent features, not bugs, of the American system.
Challenges and Limitations
While Between the World and Me succeeds brilliantly as both memoir and historical analysis, it faces certain limitations that some readers may find frustrating. Coates’s rejection of hope and redemptive narratives, while intellectually honest, can feel overwhelming in its relentlessness. His explicit rejection of religious faith and traditional civil rights optimism may alienate readers seeking more uplifting perspectives on racial progress.
The book’s focus on Black male experience, while understandable given its father-son framework, occasionally marginalizes Black women’s perspectives. Though Coates acknowledges that Black women face additional vulnerabilities, the analysis remains primarily centered on masculine experiences of racial violence.
Additionally, Coates’s sometimes abstract language around concepts like “the Dream” (his term for white American mythology) can feel unnecessarily opaque. While this abstracting serves rhetorical purposes, it occasionally distances readers from the concrete realities he’s describing.
Literary Achievement and Cultural Impact
Between the World and Me demonstrates Coates’s evolution from his earlier memoir The Beautiful Struggle, showing greater narrative sophistication and analytical depth. Where his first book focused primarily on his relationship with his father and coming-of-age in Baltimore, this work expands to encompass broader questions of American identity and global perspective.
The book’s international scope—particularly the Paris sections where Coates examines American racial dynamics from outside the country—provides crucial perspective. His observations about feeling “alien” in France, yet paradoxically more free, illuminate how American racial categories shape Black experience in profound ways.
Coates’s journalism background serves him well here, particularly in sections dealing with housing discrimination and police violence. His ability to synthesize complex policy analysis with personal narrative creates a reading experience that feels both intellectually rigorous and emotionally immediate.
Contemporary Relevance and Legacy
Written in the immediate aftermath of Ferguson and published during ongoing national conversations about police violence, Between the World and Me arrived at a crucial cultural moment. The book’s refusal to offer easy solutions or false comfort challenged readers across racial lines to confront uncomfortable truths about American society.
The work’s influence extends beyond literary circles into academic, political, and activist spaces. Its unflinching analysis of how white supremacy operates through institutions rather than individual prejudice has shaped contemporary discussions about systemic racism.
Essential Reading Recommendations
Readers drawn to Coates’s analysis should explore:
The Fire Next Time by James Baldwin—the clear literary predecessor to Coates’s epistolary approach
Stamped from the Beginning by Ibram X. Kendi—for deeper historical analysis of racist ideas
The Warmth of Other Suns by Isabel Wilkerson—for understanding the Great Migration’s impact
Just Mercy by Bryan Stevenson—for contemporary perspectives on criminal justice
How Long ‘Til Black Future Month? by N.K. Jemisin—for speculative fiction engaging similar themes
Final Assessment
Between the World and Me succeeds as both intimate family document and sweeping social analysis. Coates’s achievement lies in making the personal political without sacrificing the specificity that gives memoir its power. His refusal to provide false comfort or easy answers may frustrate some readers, but it also represents the book’s greatest strength—its commitment to truth-telling over consolation.
The work demands active engagement from readers, particularly white readers who may find their assumptions challenged at every turn. This discomfort is intentional and necessary, part of Coates’s project of forcing America to confront the reality of how it has been built and maintained.
While the book offers no easy path forward, it provides something potentially more valuable: clarity about where we actually stand. In a cultural moment often characterized by wishful thinking about racial progress, Between the World and Me insists on the importance of seeing clearly before attempting to move forward. For readers willing to engage with its unflinching analysis, the book offers both devastating critique and profound insight into the American experience.
We love microlending, don’t we, folks? Unlike old-school credit cards, with their days-long approval processes and prior credit minimums, buy-now, pay-later (BNPL) apps — companies like Klarna and Afterpay — offer hard-up customers instant financing options to buy the junk they crave the instant they see it.
In the United States, purchases made with these apps currently don’t even affect your FICO credit score — or at least, they never used to.
That’s all about to change this fall, when Fair Isaac Corp, one of the largest credit scoring bureaus, is slated to begin factoring BNPL data into individual credit scores, as first reported by the Wall Street Journal.
The move is a huge deal for the financial sector and US consumers, marking the first time FICO has ever specifically reckoned with a particular type of loan — as opposed to treating all loans equally — FICO vice president of scores and predictive analytics Ethan Dornhelm told the WSJ.
Up until now, lenders have mostly been kept in the dark regarding how much debt individual consumers have taken on. Though companies like Affirm have recently begun sharing BNPL data with credit bureaus, the industry hasn’t agreed on how to use it.
Per Wired, BNPL has become an essential part of the economy in developed countries, with over half of all Americans using it to finance stuff like lunch deliveries and school supplies. The cumulative effect is significant: as early as 2022, BNPL apps had already caused a “permanent increase” in household retail spending.
Behind that growth arecompanies like the aforementioned Klarna, which have grown BNPL from a relatively niche financial market in 2020 to a $94 billion pit-o-money in 2024. By this year, the WSJ notes, the BNPL market is expected to reach $108 billion in value.
As some economists have noted, the model could have upsides for borrowers who pay their debt on time. But there will also be huge consequences for the credit scores of those who’ve fallen behind on payments, or who’ve chained multiple microloans on top of each other. Unfortunately, those borrowers likely make up a huge piece of the BNPL pie.
As the US Federal Reserve outlined in a May survey, low-income households bringing in less than $50,000 a year make up the biggest users of BNPL services. And as the BNPL market grows — taking advantage of cash-poor workers — so too does the number of borrowers using it to finance basic necessities, like groceries.
And unsurprisingly, when more and more desperate people turn to BNPL as a last-minute payday loan, the number of late payments skyrocket.
Between 2024 and 2025, the rate of late payments in the US grew by 7 percent, as the amount of regular BNPL users financing groceries jumped from 14 to 25 percent. Meanwhile, 40 percent of BNPL borrowers reported stacking multiple loans together at a time.
“I do think it’s going to get worse, at least in the short term,” Matt Schulz, a consumer financial analyst told CNBC. “I don’t know that there’s a whole lot of reason to expect these numbers to get better in the near term.”
As BNPL debt grows, so too can inflation and the risk of a systemic banking crisis. The resulting loss of credit scores that might stem from FICO’s decision can have huge impacts on the economy, affecting the housing and labor markets while dramatically increasing consumer debt.
Whether the data hidden within the BNPL market causes a widespread debt crisis is largely up to the credit models used, and the consumers themselves. One thing’s for sure: with BNPL regulation a long way off, consumer debt isn’t going anywhere but up.
More on FinTech: Dystopia Intensifies as Startup Lets You Take Out a Micro-Loan to Get Fast Food
A new study by neuroscientists at the Massachusetts Institute of Technology sheds light on how the brain creates internal maps of space. Their research in mice reveals that while some brain cells quickly encode specific locations, it takes a broader ensemble of neurons and repeated experiences—along with sleep—to form a coherent mental map of the environment.
The study, published in Cell Reports, supports the idea that cognitive maps are built through a gradual process involving not just specialized “place cells” in the hippocampus, but also a group of neurons that initially respond only weakly to specific locations. Over several days of exploration and sleep, these weakly tuned neurons begin to work together with place cells, forming coordinated patterns that reflect the layout of an environment.
The researchers were interested in a longstanding question in neuroscience: How does the brain go from recognizing individual places to constructing a complete internal map? Since the 1970s, scientists have known that certain hippocampal neurons fire when an animal is in a specific location. But a map requires more than isolated waypoints—it needs a network that connects them. Psychologist Edward Tolman first proposed the idea of cognitive maps in 1948, and while the discovery of place cells supported his theory, the exact process by which the brain links individual locations into a full map remained poorly understood.
“I’m interested in this project because how memory is formed in the brain is one of the most fundamental questions in neuroscience,” said study author Wei Guo, a research scientist at the Picower Institute of Learning and Memory, working under the supervision of Professor Matthew Wilson.
To investigate, the team used mice that freely explored unfamiliar mazes over several days. Importantly, the animals did not receive rewards or punishments in the mazes, allowing the researchers to study how the brain learns spatial layouts without reinforcement. The focus was on a form of passive learning known as latent learning, where knowledge is acquired without immediate behavioral changes.
To track brain activity, the researchers used advanced calcium imaging. They genetically modified hippocampal neurons to produce a fluorescent protein that signals activity, and implanted tiny lenses and microscopes into the mice’s brains. This setup allowed them to record activity from hundreds of neurons in the hippocampus while the mice explored the mazes or rested in their home cages.
Using a technique called manifold learning, the researchers created simplified visual representations of neural activity patterns over time. On the first day in a maze, each neuron had its own spatial firing pattern, but the ensemble of neurons did not yet form a recognizable map. By day five, however, the overall neural activity could be organized into a low-dimensional shape—called a “neural manifold”—that resembled the structure of the maze. This shift showed that over time, the brain began to represent the entire environment, not just individual spots.
The researchers found that this transformation was especially dependent on sleep. In one part of the study, mice explored the maze twice in one day, with a three-hour break in between. Some mice were allowed to sleep during the break, while others were gently kept awake. Only the sleeping mice showed improvements in how well their neural activity matched the maze layout. This indicated that sleep helped reorganize the hippocampal neural patterns into a more coherent map.
To understand what was changing in the brain, the researchers focused on two types of neurons. Some neurons, called strongly spatial cells, had clear place fields—they reliably fired when the mouse visited specific parts of the maze, even from the first session. These cells remained stable across days and did not significantly change their behavior during learning. In contrast, weakly spatial cells had less defined firing patterns early on but gradually increased their spatial tuning over time. More importantly, these weakly tuned cells became more coordinated with the rest of the neural network, particularly during sleep.
The researchers measured each neuron’s “mental field”—how its activity related not to physical space, but to the broader neural state. This helped them identify which neurons were becoming more integrated into the ensemble. They found that weakly spatial neurons, even if they never became strong place cells, played a key role in shaping the overall structure of the cognitive map. These cells developed correlations with other neurons, contributing to a network that could represent not just isolated locations but the relationships between them.
When the researchers tried to reconstruct the neural map using only the strong place cells, the resulting patterns showed little change over time. Only when they included the weakly spatial neurons did the full map-like structure emerge. This suggests that while place cells provide the building blocks, it’s the subtle and often-overlooked shifts in less specialized neurons that help assemble the full mental picture.
The study points to a broader role for weakly tuned neurons in learning. Rather than being noise or irrelevant, these cells help the brain build flexible, interconnected representations. They appear to respond not just to places, but to combinations of activity across the network. Over time, their activity becomes more synchronized with the rest of the ensemble, helping to stitch together a map of the environment.
“I was surprised that a subset of previously overlooked neurons that had weak activity turned out to be pivotal to memory formation,” Guo told PsyPost.
Sleep appeared to amplify this process. During rest after maze exploration, neural activity patterns resembled those seen during navigation, a phenomenon known as replay. This replay likely helps the brain reinforce connections between different places. The researchers found that after sleep, neural states during rest were more similar to those during maze runs, suggesting that the brain was using sleep to reinforce and refine the map.
This work supports the idea that memory formation is not limited to fast, discrete events. It often involves slower, distributed changes that rely on experience and sleep. The findings also highlight that “sleep is very important in transforming your experience into memory,” Guo said.
As with all research, the study has some limitations. The researchers relied on calcium imaging, which offers slower and less precise readings than direct electrical recordings. Their recordings were also limited to one part of the hippocampus and did not include other brain areas that may contribute to spatial memory.
Looking forward, Guo plans “to further investigate the local circuit in the hippocampus as well as their interactions with other brain regions during memory formation.”
This week, Robert F. Kennedy Jr. used his address to a global vaccine summit to disparage global vaccination. The conference was organized by Gavi, the world’s leading immunization program, and in a recorded speech, Kennedy accused the organization of collaborating with social-media companies to stifle dissenting views on immunization during the coronavirus pandemic and said it had “ignored the science” in its work. He criticized Gavi for recommending COVID-19 shots to pregnant women, and went deep on a discredited study that purported to find safety issues with a tetanus vaccine commonly used in the developing world. “In its zeal to promote universal vaccination,” Kennedy claimed, Gavi “has neglected the key issue of vaccine safety.”
Kennedy’s remarks confirmed what The New York Times first reported in March: that the United States, Gavi’s third-largest donor, would stop pledging money to the organization. (Congress, which has always had final say over Gavi funding, has not yet weighed in.) They are also the first indication that the U.S.’s rejection of global vaccine campaigns stems from the Trump administration’s opposition not only to foreign aid, but to vaccination itself. For the first time, Kennedy has managed to use the anti-vaccine agenda to guide American foreign policy.
Gavi, at its most basic level, is Costco for immunizations, wielding its massive purchasing power to buy vaccines in bulk for cheap. National governments and private philanthropies pledge funding to it every five years. The United Kingdom and the Gates Foundation are its largest donors; the United Nations distributes the shots. The poorest countries pay 20 cents per vaccine, and prices rise along with national income. Since the partnership was launched, in January 2000, 19 countries—including Ukraine, Congo, and Guyana—have gone from relying on Gavi to paying for vaccinations entirely on their own. Indonesia, which accepted donations from Gavi as recently as 2017, pledged $30 million to the organization this funding cycle.
Gavi, by its own estimate, has saved about 19 million lives and vaccinated 1 billion children. At the conference this week, the director of the World Health Organization noted that since 2000, the number of children who die each year before they reach the age of 5 has fallen by more than half, largely due to the power of vaccines. By Gavi’s estimates, the U.S. canceling its Biden-era pledge to provide $1.2 billion this donation cycle could lead to the deaths of more than 1 million children who otherwise would have lived. (The Department of Health and Human Services did not respond to a request for comment.) In his recorded remarks, Kennedy said America would not send the money until Gavi can “re-earn the public trust” by “taking vaccine safety seriously.”
Cutting off millions of children’s only access to routine vaccines is “the most emphatic globalization of the anti-vaxxer agenda,” Lawrence Gostin, the faculty director of Georgetown’s O’Neill Institute for National and Global Health Law, told me. Tom Frieden, the former director of the CDC, told me that after he heard Kennedy’s remarks, “I was literally sick to my stomach,” because “unscientific, irresponsible statements like this will result in the deaths of children.” (The U.S. has run an international anti-vaccine campaign before: According to an investigation by Reuters, in 2020, the Pentagon unleashed bot accounts on multiple social-media platforms that impersonated Filipinos and discouraged uptake of China’s Sinovac vaccine—the first COVID vaccine available in the Philippines—using a hashtag that read, in Tagalog, “China is the virus.” The goal was not to combat vaccines, but to undermine China’s influence.)
Read: RFK Jr. is barely even pretending anymore
Kennedy’s prerecorded address held back his harshest critiques of Gavi. In his 2021 book, The Real Anthony Fauci, Kennedy paints “Bill Gates’s surrogate group Gavi” (the Gates Foundation co-founded Gavi) as nothing more than a profiteering “cabal” and a facilitator of “African Genocide.” To hear Kennedy tell it, “virtually all of Gates’s blockbuster African and Asian vaccines—polio, DTP, hepatitis B, malaria, meningitis, HPV, and Hib—cause far more injuries and deaths than they avert.”
Decades’ worth of safety and efficacy studies have proved him wrong. In his remarks to Gavi this week, Kennedy focused on the DTP (diphtheria, tetanus, and pertussis) shot, describing at length a “landmark” 2017 study that found the vaccine increased all-cause mortality among girls in Guinea-Bissau. But as Frieden pointed out, this was in fact a relatively small observational study. In 2022, a randomized, double-blind, placebo-controlled trial of more than 50,000 newborns found that the DTP vaccinesignificantly decreased infant mortality. Frieden compared the evidence: “Hundreds of kids versus 50,000 kids. Poorly done; well done.”
Kennedy made efforts to take his anti-vaccine advocacy global before he became America’s health secretary. In 2021, he delivered a webinar on the importance of expanding an “international movement” for Children’s Health Defense, the anti-vaccine organization he founded. In 2019, when Samoa was experiencing a major dip in measles immunization after an improperly prepared vaccine killed two children, Kennedy visited the prime minister and, on behalf of Children’s Health Defense, reportedly offered to build an information system the country could use to track the health effects of vaccines and other medical interventions. When a deadly measles outbreak took hold later that year, Kennedy sent a letter to the prime minister suggesting that widespread vaccination might make unvaccinated Samoan children more likely to die of measles. (In an interview for a 2023 documentary, Kennedy said that “I had nothing to do with people not vaccinating in Samoa” and that his conversations about vaccines with the prime minister had been “limited.”)
Read: The U.S. is going backwards on vaccines, very fast
Now, it seems, Kennedy has gained the power to realize his ambitions both domestically and abroad. Earlier this month, Kennedy dismissed all 17 members of the CDC’s vaccine advisory committee, then replaced them with a group that includes several allies who have spread misinformation about the harms of vaccines. This week, as other countries pledged their support for Gavi, Kennedy’s brand-new, handpicked panel convened for a discussion of the dangers of thimerosal, a vaccine ingredient that is a frequent target of anti-vaxxers despite having been found safe. The committee has formed a working group to review the “cumulative effect” of childhood vaccination in the United States. As Kennedy said in his address to Gavi, “Business as usual is over.”
Welcome to the Saturday edition of Today in Books, where it’s all Book Riot, all the time. Here are the biggest news stories we covered this week.
Meet The Freedom to Read Teen Advocacy Toolkit, a robust program and toolkit built for library workers, educators, and community organizations working with today’s young people to support and bolster teen advocacy and activism.
While intellectual freedom and library support are the focus of The Freedom to Read Teen Advocacy Toolkit, it is adaptable and flexible to meet the interests and concerns in any community.
Presented annually since 1967, the Boston Globe-Horn Book Awards are among the most prestigious given to books for young readers. They are given every year in June in three categories–picture book, fiction, and nonfiction–to books published in the United States between June 2024 and May 2025. Three judges, selected by the editor in chief of The Boston Globe, choose the slate of winners and honorees in each category.
The 2025 awards were announced on June 23.
Love speculative fiction? Then you’re going to want to get your paws on the winners of this year’s Locus Awards. These books represent the best of the best as voted on by readers in science fiction, fantasy, and horror, and they’re given by Locus Magazine, which allows any reader to vote on the winners of the awards.
The awards were present at the Locus Awards Weekend on June 21, 2025. Here are the winners in 17 categories, ranging from best in genre to excellence in editing.
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