Global team of researchers, including three New York botanical garden scientists, publish ground-breaking study of plant evolution with many potential uses, from plant conservation to the discovery of new medicines

DNA of over 9,500 species sequenced to create largest-ever tree of life for flowering plants, mapping evolutionary and genetic relationships of plants

THE NEW YORK BOTANICAL GARDEN

 

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AN INTERNATIONAL TEAM OF RESEARCHERS, INCLUDING THREE NEW YORK BOTANICAL GARDEN (NYBG) SCIENTISTS, USED GENETIC CODE FROM MORE THAN 9,500 FLOWERING PLANT SPECIES TO CREATE THE MOST DETAILED EVOLUTIONARY TREE OF LIFE FOR THIS GROUP OF PLANTS TO DATE.

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CREDIT: ROYAL BOTANIC GARDENS, KEW

Bronx, NY—A new paper published today in the journal Nature by an international team of 279 researchers, including three New York Botanical Garden (NYBG) scientists, presents the most up-to-date understanding of the evolutionary and genetic relationships of the flowering plants, which represent about 90 percent of known plant life.

Using 1.8 billion letters of genetic code from over 9,500 species covering almost 8,000 plant genera (groups of closely related species), the research team was able to create the most detailed tree of life—a graphic depiction of species relationships similar to a genealogical family tree—to date for this group of plants, shedding new light on the evolutionary history of flowering plants and their rise to ecological dominance on Earth. The study’s authors believe the data will aid future attempts to identify new species, refine plant classification, uncover new medicinal compounds, and conserve plants in the face of the dual biodiversity and climate crises.

Contributing to this major milestone in plant science were Fabián Michelangeli, Ph.D., Abess Curator of Tropical Botany and Director of NYBG’s Institute of Systematic Botany; Gregory M. Plunkett, Ph.D., Director and Curator of NYBG’s Cullman Program for Molecular Systematics; and John D. Mitchell, NYBG Affiliated Scientist. 

“While the main goals of this large-scale project were to understand the relationships of all flowering plant genera, it also sheds light on the timing of major events in the evolution of complex flower forms and life histories,” Dr. Michelangeli said. “Large analyses such as this can provide context for conservation strategies, sustainable agriculture, and many other applications that need basic biodiversity knowledge. Understanding how organisms are related is the building block of all biodiversity science and applications.”

The research team—led by the Royal Botanic Gardens, Kew, and involving 138 organizations internationally—used 15 times more data than any comparable studies of the flowering plant tree of life. Among the species included in the study, the DNA of more than 800 had never been sequenced before. The sheer amount of data unlocked by this research, which would take a single computer 18 years to process, is a huge stride towards building a tree of life for all 330,000 known species of flowering plants.

Drs. Michelangeli and Plunkett and Mr. Mitchell provided expertise on the plant families they study as well as expertly identified samples for a variety of plant groups, with a large proportion coming from the Melastomataceae family of tropical plants, which is Dr. Michelangeli’s specialty, and the Apiaceae (parsley or carrot) and Araliaceae (ginseng) families, which Dr. Plunkett studies.

Unlocking Historic Herbarium Specimens for Cutting-Edge Research

The flowering plant tree of life, much like a family tree, enables scientists to understand how different species are related to each other. The tree of life is uncovered by comparing DNA sequences between different species to identify changes (mutations) that accumulate over time like a molecular fossil record. Science’s understanding of the tree of life is improving rapidly in tandem with advances in DNA-sequencing technology. For this study, new genomic techniques were developed to magnetically capture hundreds of genes and hundreds of thousands of letters of genetic code from every sample, orders of magnitude more than earlier methods.

A key advantage of the team’s approach is that it enables a wide diversity of plant material, old and new, to be sequenced, even when the DNA is badly damaged. The vast treasure troves of dried, preserved plants in the world’s herbarium collections, which comprise nearly 400 million specimens, can now be studied genetically. Using such specimens, the team successfully sequenced a sandwort (Arenaria globiflora) collected nearly 200 years ago in Nepal and, despite the poor quality of its DNA, were able to place it on the tree of life. The team even analysed extinct plants, such has the Guadalupe Island olive (Hesperelaea palmeri), which has not been seen alive since 1875. In fact, 511 of the species sequenced are already at risk of extinction, according to the Red List, the authoritative compilation of the world’s threatened plant, fungal, and animal species maintained by the International Union for Conservation of Nature.

Across all 9,506 species sequenced, over 3,400 came from material sourced from 163 herbaria in 48 countries. Additional material from plant collections around the world such as DNA banks, seeds, and living collections have been vital for filling key knowledge gaps to shed new light on the history of flowering plant evolution. The team also benefited from publicly available data for over 1,900 species, highlighting the value of the open science approach to future genomic research.

Illuminating Darwin’s “Abominable Mystery”

Flowering plants account for about 90 percent of all known plant life on land and are found virtually everywhere on the planet—from the steamiest tropics to the rocky outcrops of the Antarctic Peninsula. And yet our understanding of how these plants came to dominate the scene soon after their origin has baffled scientists for generations, including Charles Darwin. Flowering plants originated over 140 million years ago after which they rapidly overtook other vascular plants, including their closest living relatives—the gymnosperms, non-flowering plants that have naked seeds such as cycads, conifers, and ginkgo.

Darwin was mystified by the seemingly sudden appearance of such diversity in the fossil record. In an 1879 letter to Joseph Dalton Hooker, his close confidant and Director of the Royal Botanic Gardens, Kew, he wrote, “The rapid development as far as we can judge of all the higher plants within recent geological times is an abominable mystery.”

Using 200 fossils, the researchers scaled their tree of life to time, revealing how flowering plants evolved across geological time. They found that early flowering plants exploded in diversity, giving rise to over 80 percent of the major lineages that exist today shortly after their origin. However, this trend then declined to a steadier rate for the next 100 million years until another surge in diversification about 40 million years ago, coinciding with a global decline in temperatures. These new insights would have fascinated Darwin and will surely help today’s scientists grappling with the challenges of understanding how and why species diversify.

Assembling a tree of life this extensive would have been impossible without the collaboration of scientists across the globe. In total, 279 authors were involved in the research, representing many different nationalities from 138 organizations in 27 countries. International collaborators shared their unique botanical expertise as well as many invaluable plant samples from around the world that could not be obtained without their help. The comprehensive nature of the tree is in no small part a result of this wide-ranging partnership.

“Efforts like this show how the international scientific community can come together to collaborate and produce something that no one research group or institution can do alone,” Dr. Michelangeli said.

Putting the Flowering Plant Tree of Life to Good Use

The flowering plant tree of life has enormous potential in biodiversity research. This is because, just as one can predict the properties of an element based on its position in the periodic table, the location of a species in the tree of life allows scientists to predict its properties. The new data will thus be invaluable for enhancing many areas of science and beyond.

To enable this, the tree and all of the data that underpin it have been made openly and freely accessible to both the public and scientific community, including through the Kew Tree of Life Explorer. The study’s authors believe such open access is key to democratising access to scientific data across the globe. 

Open access will also help scientists to make the best use of the data such as combining it with artificial intelligence to predict which plant species may include molecules with medicinal potential. Similarly, the tree of life can be used to better understand and predict how pests and diseases might affect the world’s plants in the future. Ultimately, the authors note, the applications of the data will be driven by the ingenuity of scientists.

About The New York Botanical Garden

The New York Botanical Garden (NYBG) has been a connective hub among people, plants, and the shared planet since 1891. For more than 130 years, NYBG has been rooted in the cultural fabric of New York City, in the heart of the Bronx, its greenest borough. NYBG has invited millions of visitors to make the Garden a part of their lives, exploring the joy, beauty, and respite of nature. NYBG’s 250 acres are home to renowned exhibitions, immersive botanical experiences, art and music, and events with some of the most influential figures in plant and fungal science, horticulture, and the humanities. NYBG is also a steward of globally significant research collections, from the LuEsther T. Mertz Library collection to the plant and fungal specimens in the William and Lynda Steere Herbarium, the largest such collection in the Western Hemisphere.

The plant people of NYBG—dedicated horticulturists, enthusiastic educators, and scientific adventurers—are committed to helping nature thrive so that humanity can thrive. They believe in their ability to make things better, teaching tens of thousands of kids and families each year about the importance of safeguarding the environment and healthy eating. Expert scientists work across the city, the nation, and the globe to document the plants and fungi of the world—and find actionable, nature-based solutions to the planet’s dual climate and biodiversity crises. With eyes always looking forward, they train the next generation of botanists, gardeners, landscape designers, and environmental stewards, ensuring a green future for all. At NYBG, it’s nature—or nowhere.

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JOURNAL

Nature

DOI

10.1038/s41586-024-07324-0 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Phylogenomics and the rise of the angiosperms

ARTICLE PUBLICATION DATE

24-Apr-2024

Vast DNA tree of life for flowering plants revealed by global science team

Scientists use 1.8 billion letters of genetic code to build groundbreaking tree of life

UNIVERSITY OF MICHIGAN

Images

The most up-to-date understanding of the flowering plant tree of life is presented in a new study published today in the journal Nature by an international team of 279 scientists, including three University of Michigan biologists.

 

Using 1.8 billion letters of genetic code from more than 9,500 species covering almost 8,000 known flowering plant genera (ca. 60%), this achievement sheds new light on the evolutionary history of flowering plants and their rise to ecological dominance on Earth.

 

Led by scientists at the Royal Botanic Gardens, Kew, the research team believes the data will aid future attempts to identify new species, refine plant classification, uncover new medicinal compounds, and conserve plants in the face of climate change and biodiversity loss.

 

The major milestone for plant science, involving 138 organizations internationally, was built on 15 times more data than any comparable studies of the flowering plant tree of life. Among the species sequenced for this study, more than 800 have never had their DNA sequenced before.

 

The sheer amount of data unlocked by this research, which would take a single computer 18 years to process, is a huge stride toward building a tree of life for all 330,000 known species of flowering plants—a massive undertaking by Kew's Tree of Life Initiative.

 

"Analyzing this unprecedented amount of data to decode the information hidden in millions of DNA sequences was a huge challenge. But it also offered the unique opportunity to reevaluate and extend our knowledge of the plant tree of life, opening a new window to explore the complexity of plant evolution," said Alexandre Zuntini, a research fellow at Royal Botanic Gardens, Kew.

 

Tom Carruthers, postdoctoral researcher in the lab of U-M evolutionary biologist Stephen Smith, is co-lead author of the study with Zuntini, who he previously worked with at Kew. U-M plant systematist Richard Rabeler is a co-author.

 

"Flowering plants feed, clothe and greet us whenever we walk into the woods. The construction of a flowering plant tree of life has been a significant challenge and goal for the field of evolutionary biology for more than a century," said Smith, co-author of the study and professor in the U-M Department of Ecology and Evolutionary Biology. "This project moves us closer to that goal by providing a massive dataset for most of the genera of flowering plants and offering one strategy to complete this goal."

 

Smith had two roles on the project. First, members of his lab—including former U-M graduate student Drew Larson—traveled to Kew to help sequence members of a large and diverse plant group called Ericales, which includes blueberries, tea, ebony, azaleas, rhododendrons and Brazil nuts.

 

Second, Smith supervised the analyses and construction of the project dataset along with William Baker and Felix Forest of the Royal Botanic Gardens, Kew, and Wolf Eisenhardt of Aarhus University.

 

"One of the biggest challenges faced by the team was the unexpected complexity underlying many of the gene regions, where different genes tell different evolutionary histories. Procedures had to be developed to examine these patterns on a scale that hadn't been done before," said Smith, who is also director of the Program in Biology and an associate curator in biodiversity informatics at the U-M Herbarium.

 

As co-leader of the study, Carruthers' main responsibilities included scaling the evolutionary tree to time using 200 fossils, analyzing the different evolutionary histories of the genes underlying the overall evolutionary tree, and estimating rates of diversification in different flowering plant lineages at different times.

 

"Constructing such a large tree of life for flowering plants, based on so many genes, sheds light on the evolutionary history of this special group, helping us to understand how they came to be such an integral and dominant part of the world," Carruthers said. "The evolutionary relationships that are presented—and the data underlying them—will provide an important foundation for a lot of future studies."

 

The flowering plant tree of life, much like our own family tree, enables us to understand how different species are related to each other. The tree of life is uncovered by comparing DNA sequences between different species to identify changes (mutations) that accumulate over time like a molecular fossil record.

 

Our understanding of the tree of life is improving rapidly in tandem with advances in DNA sequencing technology. For this study, new genomic techniques were developed to magnetically capture hundreds of genes and hundreds of thousands of letters of genetic code from every sample, orders of magnitude more than earlier methods.

 

A key advantage of the team's approach is that it enables a wide diversity of plant material, old and new, to be sequenced, even when the DNA is badly damaged. The vast treasure troves of dried plant material in the world's herbarium collections, which comprise nearly 400 million scientific specimens of plants, can now be studied genetically.

 

"In many ways this novel approach has allowed us to collaborate with the botanists of the past by tapping into the wealth of data locked up in historic herbarium specimens, some of which were collected as far back as the early 19th century," said Baker, senior research leader for Kew's Tree of Life Initiative.

 

"Our illustrious predecessors, such as Charles Darwin or Joseph Hooker, could not have anticipated how important these specimens would be in genomic research today. DNA was not even discovered in their lifetimes. Our work shows just how important these incredible botanical museums are to groundbreaking studies of life on Earth. Who knows what other undiscovered science opportunities lie within them?"

 

Across all 9,506 species sequenced, more than 3,400 came from material sourced from 163 herbaria in 48 countries.

 

"Sampling herbarium specimens for the study of plant relationships makes broad sampling from diverse areas of the world much more feasible than if one had to travel to get fresh material from the field," said U-M's Rabeler, a research scientist emeritus and former collection manager at the U-M Herbarium.

 

For the tree of life project, Rabeler helped verify the identity of herbarium specimens selected for sampling and analyzed the resulting data.

 

Flowering plants alone account for about 90% of all known plant life on land and are found virtually everywhere on the planet—from the steamiest tropics to the rocky outcrops of the Antarctic Peninsula. And yet, our understanding of how these plants came to dominate the scene soon after their origin has baffled scientists for generations, including Darwin.

 

Flowering plants originated more than 140 million years ago after which they rapidly overtook other vascular plants including their closest living relatives—the gymnosperms (nonflowering plants that have naked seeds, such as cycads, conifers and ginkgo).

 

Darwin was mystified by the seemingly sudden appearance of such diversity in the fossil record. In an 1879 letter to Hooker, his close confidant and director of the Royal Botanic Gardens, Kew, he wrote: "The rapid development as far as we can judge of all the higher plants within recent geological times is an abominable mystery."

 

Using 200 fossils, the authors scaled their tree of life to time, revealing how flowering plants evolved across geological time. They found that early flowering plants did indeed explode in diversity, giving rise to more than 80% of the major lineages that exist today shortly after their origin.

 

However, this trend then declined to a steadier rate for the next 100 million years until another surge in diversification about 40 million years ago, coinciding with a global decline in temperatures. These new insights would have fascinated Darwin and will surely help today's scientists grappling with the challenges of understanding how and why species diversify.

 

Assembling a tree of life this extensive would have been impossible without Kew's scientists collaborating with many partners across the globe. In total, 279 authors were involved in the research, representing many different nationalities from 138 organizations in 27 countries.

 

"The plant community has a long history of collaborating and coordinating molecular sequencing to generate a more comprehensive and robust plant tree of life. The effort that led to this paper continues in that tradition but scales up quite significantly," said U-M's Smith.

 

The flowering plant tree of life has enormous potential in biodiversity research. This is because, just as one can predict the properties of an element based on its position in the periodic table, the location of a species in the tree of life allows us to predict its properties. The new data will thus be invaluable for enhancing many areas of science and beyond.

 

To enable this, the tree and all of the data that underpin it have been made openly and freely accessible to both the public and scientific community, including through the Kew Tree of Life Explorer.

 

Open access will help scientists to make the best use of the data, such as combining it with artificial intelligence to predict which plant species may include molecules with medicinal potential.

 

Similarly, the tree of life can be used to better understand and predict how pests and diseases are going to affect plants in the future. Ultimately, the authors note, the applications of this data will be driven by the ingenuity of the scientists accessing it.

Study: Phylogenomics and the rise of the Angiosperms (DOI: 10.1038/s41586-024-07324-0)

 

Written by Royal Botanic Gardens, Kew.

 

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JOURNAL

Nature

DOI

10.1038/s41586-024-07324-0 

 

UT School of Natural Resources team receives grant to remove ‘forever chemicals’ from water

Student team led by assistant professor Mi Li to participate in the EPA’s national student design expo

UNIVERSITY OF TENNESSEE INSTITUTE OF AGRICULTURE

 

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MI LI, ASSISTANT PROFESSOR IN THE UT CENTER FOR RENEWABLE CARBON (CENTER), RECEIVED A GRANT FROM THE U.S. ENVIRONMENTAL PROTECTION AGENCY TO RESEARCH REMOVING HARMFUL CHEMICALS FROM WATER. KAILONG ZHANG, A PH.D. STUDENT IN THE SCHOOL OF NATURAL RESOURCES (LEFT), AND RYAN BASKETTE, AN UNDERGRADUATE IN THE DEPARTMENT OF BIOCHEMISTRY AND CELLULAR AND MOLECULAR BIOLOGY, ARE MEMBERS OF THE TEAM. 

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CREDIT: PHOTO COURTESY UTIA.

Mi Li, assistant professor in the University of Tennessee Center for Renewable Carbon and the UT School of Natural Resources, received a $75,000 research grant from the U.S. Environmental Protection Agency (EPA) for a two-year project using a cellulose-functionalized adsorbent to remove per- and polyfluoroalkyl substances (PFAS) from water. Li has built a student team to work on this project including Kailong Zhang, a Ph.D. student in the School of Natural Resources, and Ryan Baskette, an undergraduate student in the Department of Biochemistry and Cellular and Molecular Biology.

The grant comes from the EPA’s People, Prosperity, and the Planet Program, which provided almost $1.2 million to 16 college student teams across the U.S. to develop solutions for environmental and public health challenges. The team plans to create a cellulose-metal organic frameworks (Cello-MOFs) hybrid adsorbent to remove PFAS from water. PFAS are synthetic chemicals that resist heat, oil, stains, grease, and water. “They’re forever chemicals. They’re applied almost everywhere from firefighting foams to nonstick cooking utensils to textiles and cosmetics. After leaching, they accumulate in the soil, water, and environment, and they’ve been there for a long time, harming the environment, wildlife, and humans,” Li said.

The team will demonstrate how their judiciously designed adsorbent cleans water contaminated with PFAS at the EPA’s National Student Design Expo in 2025. “Our team aims to functionalize naturally derived cellulose with MOFs to capture these substances and contribute to a cleaner and safer environment,” Li said.

Li said the showing at the expo could lead to additional funding for the project or its commercialization. The team also plans to put the project’s results in a technical manuscript for a peer-reviewed journal. Li added, “Having one or two co-authored, peer-reviewed journal publications will benefit the students when applying for graduate school or jobs. It is a big deal!”

“I am thrilled to be a part of the U.S. EPA P3 project as a graduate student team member. This project offers more than just an opportunity for my academic research exploration. It is a valuable hands-on learning experience crucial for my future academic pursuits,” Zhang said.

“As an undergraduate, the lab skills and research experience I have gained as part of this team will be invaluable to my future endeavors. Working on sustainable solutions to environmental and health issues, like PFAS pollution, has been fulfilling and impactful,” Baskette said.

The project will continue through December 2025.

The UT School of Natural Resources is part of the Herbert College of Agriculture, UT AgResearch and UT Extension at the University of Tennessee Institute of Agriculture. The curricula focus on a mastery learning approach, emphasizing practical, hands-on experiences. The School’s faculty, staff and students conduct research and extension that advances the science and sustainable management of our natural resources. For more information, visit naturalresources.tennessee.edu.

Through its mission of research, teaching and extension, the University of Tennessee Institute of Agriculture touches lives and provides Real. Life. Solutions. utia.tennessee.edu

 

How light can vaporize water without the need for heat

Surprising “photomolecular effect” discovered by MIT researchers could affect calculations of climate change and may lead to improved desalination and drying processes.

MASSACHUSETTS INSTITUTE OF TECHNOLOGY

 

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RESEARCHERS AT MIT HAVE DISCOVERED A NEW PHENOMENON: THAT LIGHT CAN CAUSE EVAPORATION OF WATER FROM ITS SURFACE WITHOUT THE NEED FOR HEAT. PICTURED IS A LAB DEVICE DESIGNED TO MEASURE THE “PHOTOMOLECULAR EFFECT,” USING LASER BEAMS.

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CREDIT: BRYCE VICKMARK

It’s the most fundamental of processes — the evaporation of water from the surfaces of oceans and lakes, the burning off of fog in the morning sun, and the drying of briny ponds that leaves solid salt behind. Evaporation is all around us, and humans have been observing it and making use of it for as long as we have existed. 

And yet, it turns out, we’ve been missing a major part of the picture all along.

In a series of painstakingly precise experiments, a team of researchers at MIT has demonstrated that heat isn’t alone in causing water to evaporate. Light, striking the water’s surface where air and water meet, can break water molecules away and float them into the air, causing evaporation in the absence of any source of heat.

The astonishing new discovery could have a wide range of significant implications. It could help explain mysterious measurements over the years of how sunlight affects clouds, and therefore affect calculations of the effects of climate change on cloud cover and precipitation. It could also lead to new ways of designing industrial processes such as solar-powered desalination or drying of materials.

The findings, and the many different lines of evidence that demonstrate the reality of the phenomenon and the details of how it works, are described in the journal PNAS, in a paper by Carl Richard Soderberg Professor of Power Engineering Gang Chen, postdocs Guangxin Lv and Yaodong Tu, and graduate student James Zhang.

The authors say their study suggests that the effect should happen widely in nature— everywhere from clouds to fogs to the surfaces of oceans, soils, and plants — and that it could also lead to new practical applications, including in energy and clean water production. “I think this has a lot of applications,” Chen says. “We’re exploring all these different directions. And of course, it also affects the basic science, like the effects of clouds on climate, because clouds are the most uncertain aspect of climate models.” 

A newfound phenomenon

The new work builds on research reported last year, which described this new “photomolecular effect” but only under very specialized conditions: on the surface of specially prepared hydrogels soaked with water. In the new study, the researchers demonstrate that the hydrogel is not necessary for the process; it occurs at any water surface exposed to light, whether it’s a flat surface like a body of water or a curved surface like a droplet of cloud vapor.

Because the effect was so unexpected, the team worked to prove its existence with as many different lines of evidence as possible. In this study, they report 14 different kinds of tests and measurements they carried out to establish that water was indeed evaporating — that is, molecules of water were being knocked loose from the water’s surface and wafted into the air — due to the light alone, not by heat, which was long assumed to be the only mechanism involved.

One key indicator, which showed up consistently in four different kinds of experiments under different conditions, was that as the water began to evaporate from a test container under visible light, the air temperature measured above the water’s surface cooled down and then leveled off, showing that thermal energy was not the driving force behind the effect.

Other key indicators that showed up included the way the evaporation effect varied depending on the angle of the light, the exact color of the light, and its polarization. None of these varying characteristics should happen because at these wavelengths, water hardly absorbs light at all — and yet the researchers observed them.

The effect is strongest when light hits the water surface at an angle of 45 degrees. It is also strongest with a certain type of polarization, called transverse magnetic polarization. And it peaks in green light — which, oddly, is the color for which water is most transparent and thus interacts the least.

Chen and his co-researchers have proposed a physical mechanism that can explain the angle and polarization dependence of the effect, showing that the photons of light can impart a net force on water molecules at the water surface that is sufficient to knock them loose from the body of water. But they cannot yet account for the color dependence, which they say will require further study.

They have named this the photomolecular effect, by analogy with the photoelectric effect that was discovered by Heinrich Hertz in 1887 and finally explained by Albert Einstein in 1905. That effect was one of the first demonstrations that light also has particle characteristics, which had major implications in physics and led to a wide variety of applications, including LEDs. Just as the photoelectric effect liberates electrons from atoms in a material in response to being hit by a photon of light, the photomolecular effect shows that photons can liberate entire molecules from a liquid surface, the researchers say.

“The finding of evaporation caused by light instead of heat provides new disruptive knowledge of light-water interaction,” says Xiulin Ruan, professor of mechanical engineering at Purdue University, who was not involved in the study. “It could help us gain new understanding of how sunlight interacts with cloud, fog, oceans, and other natural water bodies to affect weather and climate. It has significant potential practical applications such as high-performance water desalination driven by solar energy. This research is among the rare group of truly revolutionary discoveries which are not widely accepted by the community right away but take time, sometimes a long time, to be confirmed.”

Solving a cloud conundrum

The finding may solve an 80-year-old mystery in climate science. Measurements of how clouds absorb sunlight have often shown that they are absorbing more sunlight than conventional physics dictates possible. The additional evaporation caused by this effect could account for the longstanding discrepancy, which has been a subject of dispute since such measurements are difficult to make.

“Those experiments are based on satellite data and flight data,“ Chen explains. “They fly an airplane on top of and below the clouds, and there are also data based on the ocean temperature and radiation balance. And they all conclude that there is more absorption by clouds than theory could calculate. However, due to the complexity of clouds and the difficulties of making such measurements, researchers have been debating whether such discrepancies are real or not. And what we discovered suggests that hey, there’s another mechanism for cloud absorption, which was not accounted for, and this mechanism might explain the discrepancies.”

Chen says he recently spoke about the phenomenon at an American Physical Society conference, and one physicist there who studies clouds and climate said they had never thought about this possibility, which could affect calculations of the complex effects of clouds on climate. The team conducted experiments using LEDs shining on an artificial cloud chamber, and they observed heating of the fog, which was not supposed to happen since water does not absorb in the visible spectrum. “Such heating can be explained based on the photomolecular effect more easily,” he says.

Lv says that of the many lines of evidence, “the flat region in the air-side temperature distribution above hot water will be the easiest for people to reproduce.” That temperature profile “is a signature” that demonstrates the effect clearly, he says.

Zhang adds: “It is quite hard to explain how this kind of flat temperature profile comes about without invoking some other mechanism” beyond the accepted theories of thermal evaporation. “It ties together what a whole lot of people are reporting in their solar desalination devices,” which again show evaporation rates that cannot be explained by the thermal input.

The effect can be substantial. Under the optimum conditions of color, angle, and polarization, Lv says, “the evaporation rate is four times the thermal limit.”

Already, since publication of the first paper, the team has been approached by companies that hope to harness the effect, Chen says, including for evaporating syrup and drying paper in a paper mill. The likeliest first applications will come in the areas of solar desalinization systems or other industrial drying processes, he says. “Drying consumes 20 percent of all industrial energy usage,” he points out.

Because the effect is so new and unexpected, Chen says, “This phenomenon should be very general, and our experiment is really just the beginning.” The experiments needed to demonstrate and quantify the effect are very time-consuming. “There are many variables, from understanding water itself, to extending to other materials, other liquids and even solids,” he says.

The work was partly supported by an MIT Bose Award. 

“We’re exploring all these different directions,” Chen says. “And of course it also affects the basic science, like the effects of clouds on climate, because clouds are the most uncertain aspect of climate models.”

CREDIT

Bryce Vickmark

Written by David L. Chandler, MIT News

Paper: “Photomolecular effect: visible light interaction with air-water interface”

https://www.pnas.org/doi/10.1073/pnas.2320844121

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JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2320844121 

ARTICLE TITLE

“Photomolecular effect: visible light interaction with air-water interface”

 

Human activities have an intense impact on Earth's deep subsurface fluid flow

UNIVERSITY OF ARIZONA

The impact of human activities – such as greenhouse gas emissions and deforestation – on Earth's surface have been well-studied. Now, hydrology researchers from the University of Arizona have investigated how humans impact Earth's deep subsurface, a zone that lies hundreds of meters to several kilometers beneath the planet's surface.

"We looked at how the rates of fluid production with oil and gas compare to natural background circulation of water and showed how humans have made a big impact on the circulation of fluids in the subsurface," said Jennifer McIntosh, a professor in the UArizona Department of Hydrology and Atmospheric Sciences and senior author of a paper in the journal Earth's Future detailing the findings. 

"The deep subsurface is out of sight and out of mind for most people, and we thought it was important to provide some context to these proposed activities, especially when it comes to our environmental impacts," said lead study author Grant Ferguson, an adjunct professor in the UArizona Department of Hydrology and Atmospheric Sciences and a professor in the University of Saskatchewan's School of Environment and Sustainability.

In the future, these human-induced fluid fluxes are projected to increase with strategies that are proposed as solutions for climate change, according the study. Such strategies include: geologic carbon sequestration, which is capturing and storing atmospheric carbon dioxide in underground porous rocks; geothermal energy production, which involves circulating water through hot rocks for generating electricity; and lithium extraction from underground mineral-rich brine for powering electric vehicles. The study was done in collaboration with researchers from the University of Saskatchewan in Canada, Harvard University, Northwestern University, the Korea Institute of Geosciences and Mineral Resources, and Linnaeus University in Sweden.

"Responsible management of the subsurface is central to any hope for a green transition, sustainable future and keeping warming below a few degrees," said Peter Reiners, a professor in the UArizona Department of Geosciences and a co-author of the study. 

With oil and natural gas production, there is always some amount of water, typically saline, that comes from the deep subsurface, McIntosh said. The underground water is often millions of years old and acquires its salinity either from evaporation of ancient seawater or from reaction with rocks and minerals. For more efficient oil recovery, more water from near-surface sources is added to the salt water to make up for the amount of oil removed and to maintain reservoir pressures. The blended saline water then gets reinjected into the subsurface. This becomes a cycle of producing fluid and reinjecting it to the deep subsurface. 

The same process happens in lithium extraction, geothermal energy production and geologic carbon sequestration, the operations of which involve leftover saline water from the underground that is reinjected.

"We show that the fluid injection rates or recharge rates from those oil and gas activities is greater than what naturally occurs," McIntosh said. 

Using existing data from various sources, including measurements of fluid movements related to oil and gas extraction and water injections for geothermal energy, the team found that the current fluid movement rates induced by human activities are higher compared to how fluids moved before human intervention. 

As human activities like carbon capture and sequestration and lithium extraction ramp up, the researchers also predicted how these activities might be recorded in the geological record, which is the history of Earth as recorded in the rocks that make up its crust. 

Human activities have the potential to alter not just the deep subsurface fluids but also the microbes that live down there, McIntosh said. As fluids move around, microbial environments may be altered by changes in water chemistry or by bringing new microbial communities from Earth's surface to the underground.

For example, with hydraulic fracturing, a technique that is used to break underground rocks with pressurized liquids for extracting oil and gas, a deep rock formation that previously didn't have any detectable number of microbes might have a sudden bloom of microbial activity. 

There remain a lot of unknowns about Earth's deep subsurface and how it is impacted by human activities, and it's important to continue working on those questions, McIntosh said. 

"We need to use the deep subsurface as part of the solution for the climate crisis," McIntosh said. "Yet, we know more about the surface of Mars than we do about water, rocks and life deep beneath our feet."

---

JOURNAL

Earth's Future

DOI

10.1029/2024EF004496 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Acceleration of Deep Subsurface Fluid Fluxes in the Anthropocene

 

Use of acid reflux drugs linked to higher risk of migraine

AMERICAN ACADEMY OF NEUROLOGY

MINNEAPOLIS – People who take acid-reducing drugs may have a higher risk of migraine and other severe headache than people who do not take these medications, according to a study published in the April 24, 2024, online issue of Neurology® Clinical Practice, an official journal of the American Academy of Neurology. The acid-reducing drugs include proton pump inhibitors such as omeprazole and esomeprazole, histamine H2-receptor antagonists, or H2 blockers, such as cimetidine and famotidine, and antacid supplements.

The study does not prove that acid-reducing drugs cause migraine; it only shows an association.

Acid reflux is when stomach acid flows into the esophagus, usually after a meal or when lying down. People with acid reflux may experience heartburn and ulcers. People with frequent acid reflux may develop gastroesophageal reflux disease, or GERD, which can lead to cancer of the esophagus.

“Given the wide usage of acid-reducing drugs and these potential implications with migraine, these results warrant further investigation,” said study author Margaret Slavin, PhD, RDN, of the University of Maryland in College Park. “These drugs are often considered to be overprescribed, and new research has shown other risks tied to long-term use of proton pump inhibitors, such as an increased risk of dementia.”

For the study, researchers looked at data on 11,818 people who provided information on use of acid-reducing drugs and whether they had migraine or severe headache in the past three months.

A total of 25% of participants taking proton pump inhibitors had migraine or severe headache, compared to 19% of those who were not taking the drugs. A total of 25% of those taking H2 blockers had severe headache, compared to 20% of those who were not taking those drugs. And 22% of those taking antacid supplements had severe headache, compared to 20% of those not taking antacids.

When researchers adjusted for other factors that could affect the risk of migraine, such as age, sex and use of caffeine and alcohol, they found that people taking proton pump inhibitors were 70% more likely to have migraine than people not taking proton pump inhibitors. Those taking H2 blockers were 40% more likely and those taking antacid supplements were 30% more likely.

“It’s important to note that many people do need acid-reducing medications to manage acid reflux or other conditions, and people with migraine or severe headache who are taking these drugs or supplements should talk with their doctors about whether they should continue,” Slavin said.

Slavin noted that the study looked only at prescription drugs. Some of the drugs became available for over-the-counter use at non-prescription strength during the study period, but use of these over-the-counter drugs was not included in this study.  

Other studies have shown that people with gastrointestinal conditions may be more likely to have migraine, but Slavin said that relationship is not likely to fully explain the tie between acid-reducing drugs and migraine found in the study.

A limitation of the study is that a small number of people were taking the drugs, especially the H2 blockers.

Learn more about headache at BrainandLife.org, home of the American Academy of Neurology’s free patient and caregiver magazine focused on the intersection of neurologic disease and brain health. Follow Brain & Life® on Facebook, Twitter and Instagram.

When posting to social media channels about this research, we encourage you to use the hashtags #Neurology and #AANscience.

The American Academy of Neurology is the world's largest association of neurologists and neuroscience professionals, with over 40,000 members. The AAN’s mission is to enhance member career fulfillment and promote brain health for all. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as Alzheimer's disease, stroke, concussion, epilepsy, Parkinson's disease, multiple sclerosis, headache and migraine.

For more information about the American Academy of Neurology, visit AAN.com or find us on Facebook, Twitter, Instagram, LinkedIn and YouTube.

---

JOURNAL

Neurology Clinical Practice

 

For immigrants to Canada, risk of MS increases with proportion of life spent there

AMERICAN ACADEMY OF NEUROLOGY

MINNEAPOLIS – Immigrants to Canada who have spent a greater proportion of their lives in Canada have a greater risk of developing multiple sclerosis (MS) than people who have spent a smaller proportion of their lives there, according to a study published in the April 24, 2024, online issue of Neurology®, the medical journal of the American Academy of Neurology. The study does not prove that an increased proportion of life in Canada causes MS; it only shows an association.

“Other studies have shown that immigrants tend to have better health than long-term residents, which is thought to be because healthy people are more likely to choose to immigrate,” said study author Manav V. Vyas, MBBS, MSc, PhD, of St. Michael’s Hospital in Toronto, Canada and a member of the American Academy of Neurology. “We wanted to see if the lower risk of MS declines over time as people adopt some of the unhealthy lifestyles of their new country or are exposed to other environmental factors that increase their risk.”

The study involved 1.5 million immigrants who arrived in Canada between 1985 and 2003 and were covered by health insurance for at least two years with no diagnosis of MS. The people were then followed through 2016.

During that time, 934 people were diagnosed with MS. This is a rate of 0.44 cases per 100,000 person-years. The overall rate of MS in Canada based on previous research is estimated to be 15 to 17 cases per 100,000 person-years. Person-years represent both the number of people in the study and the amount of time each person spends in the study.

The person’s age at arrival in Canada and the amount of time since they immigrated were used to determine the proportion of life spent in Canada. Overall, people had spent an average of 20% of their lives in Canada.

Researchers found that people who had spent 70% of their lives in Canada were 38% more likely to develop MS than people who had spent 20% of their lives there. This result took into account other factors that could affect the risk of MS, such as sex, age and other health conditions.

The researchers did not find any differences between men and women or based on which of Canada’s immigration classes people belonged to: family, refugee or economic.  

“Our data did not include information on various environmental factors associated with MS, but our theories include that this increase in the risk of MS over time may be due to lifestyle factors such as higher rates of smoking and changes in diet, environmental factors such as sunlight exposure and biological factors such as the composition of the gut microbiome that have been previously associated with an increased risk of MS,” Vyas said. “Some immigrants may be more susceptible to these risk factors due to social determinants of health such as income, education, neighborhood and access to nutritious food.”

A limitation of the study is that new cases of MS were determined by use of the health care system, and immigrants may differ from non-immigrants in seeking care for their symptoms by cultural background, age, time spent in the country, familiarity with language or other factors related to the health care system.

The study was supported by the MS Society of Canada and the Consortium of Multiple Sclerosis Centers.

Learn more about multiple sclerosis at BrainandLife.org, home of the American Academy of Neurology’s free patient and caregiver magazine focused on the intersection of neurologic disease and brain health. Follow Brain & Life® on Facebook, X and Instagram.

When posting to social media channels about this research, we encourage you to use the hashtags #Neurology and #AANscience.

The American Academy of Neurology is the world's largest association of neurologists and neuroscience professionals, with over 40,000 members. The AAN’s mission is to enhance member career fulfillment and promote brain health for all. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as Alzheimer's disease, stroke, concussion, epilepsy, Parkinson's disease, multiple sclerosis, headache and migraine.

For more information about the American Academy of Neurology, visit AAN.com or find us on Facebook, X, Instagram, LinkedIn and YouTube.

---

JOURNAL

Neurology

 

Q&A: How TikTok’s ‘black box’ algorithm and design shape user behavior

UNIVERSITY OF WASHINGTON

TikTok’s swift ascension to the upper echelons of social media is often attributed to its recommendation algorithm, which predicts viewer preferences so acutely it’s spawned a maxim: “The TikTok algorithm knows me better than I know myself.” The platform’s success was so pronounced it’s seemed to spur other social media platforms to shift their designs. When users scroll through X or Instagram, they now see more recommended posts from accounts they don’t follow.

Yet for all that influence, the public knows little about how TikTok’s algorithm functions. So Franziska Roesner, a University of Washington associate professor in the Paul G. Allen School of Computer Science & Engineering, set about researching both how that algorithm is personalized and how TikTok users engage with the platform based on those recommendations.

Roesner and collaborators will present two papers this May that mine real-world data to help understand the “black box” of TikTok’s recommendation algorithm and its impact.

Researchers first recruited 347 TikTok users, who downloaded their data from the app and donated 9.2 million video recommendations. Using that data, the team initially looked at how TikTok personalized its recommendations. In the first 1,000 videos TikTok showed users, the team found that a third to half of the videos were shown based on TikTok’s predictions of what those users like. The researchers will publish the first paper May 13 in the Proceedings of the ACM Web Conference 2024.

The second study, which the team will present May 14 at the ACM CHI Conference on Human Factors in Computing Systems in Honolulu, explored engagement trends. Researchers discovered that over the users’ first 120 days, average daily time on the platform increased from about 29 minutes on the first day to 50 minutes on the last.

UW News spoke with Roesner about how TikTok recommends videos; the impact that has on users; and the ways tech companies, regulators and the public might mitigate unwanted effects.

What is it important for us to understand about how TikTok’s algorithm functions?

Franziska Roesner: TikTok users often have questions like: “Why was I shown this content? What does TikTok know about me? How is it using what it knows about me? And is it?” So we looked at what TikTok shows people and by what criteria. If we better understand how the algorithm functions, then we can ask whether we like how it works.

For example, if the algorithm is exploiting people's weaknesses around certain types of content, if it predicts that I'm more likely to be susceptible to a certain type of misinformation, it could be pushing me down certain rabbit holes that might be dangerous to me. Maybe they mislead me, or they exacerbate mental health challenges or eating disorders. The algorithm is such a black box, to the public and to regulators. And to some extent, it probably is to TikTok itself. It's not like someone is writing code that's targeting a person who’s vulnerable to an eating disorder. The algorithm is just making predictions from a bunch of data. So we as researchers are interested in the features that it is using to predict, because we can't really understand if and why a prediction is problematic without understanding those.

We also looked at how people engage with TikTok’s algorithm as we understand it. These considerations go hand in hand. As a security and privacy person, I'm always really interested in how people interact with technologies and how their designs shape what we read and believe and share. So researching the human experience helps to understand the impact of the algorithm and the platform design.

What did you learn from these studies?

FR: One thing that surprised me a little was that those of us who use TikTok — and I do use TikTok — probably spend more time on it than we wish to admit. I was also a little surprised that people watch only about 55% of videos to the end. We debated whether this was high or low. Is this part of the platform’s design, that once you've got whatever you wanted to get out of this video you move on? Or is it a sign that even this highly tuned recommendation algorithm is not doing that well? I don't know which it is. But it's useful to at least have a baseline to compare future findings against.

Another important takeaway was looking at what features influence what videos the algorithm shows you. How much agency is TikTok potentially taking from us? How good is it at predicting what we're likely to want to watch? How rabbit hole-y do those things get? In the study, we labeled each video within a user's timeline as an “exploration video” or an “exploitation video.” An exploration video is not linked to videos that the user has seen before — for instance, there are no similar hashtags or creators. The idea is that there's some value in the algorithm showing you new stuff. Maybe there’s societal value to not putting you down a rabbit hole. There's also probably value for TikTok, because the more you see the same stuff, the more bored you get. They want to throw some spaghetti at the wall and see what sticks.

The exploitation videos are the ones that are more like, “We know what you like, we're going to show you more videos that are related to these.” In the study, we looked at what fraction of the videos are explorative versus exploitative. We found that in the first 1,000 videos users saw, TikTok exploited users’ interests between 30% and 50% of the time. We then looked at how the videos differed and how TikTok treated them. For example, if you're following someone, you're significantly more likely to see videos from them. That's probably not surprising. However, based on our data, scrolling past a video faster does not seem to impact as much what the algorithm is doing.

We also found that people finished watching the videos from accounts they were following less, but engaged with them more. We hypothesized that if someone sees a video from their friend, maybe they’re not that interested and don’t want to watch, but they still want to show support, so they engage.

In these papers you make several suggestions to mitigate the potential negative effects of TikTok’s design. Could you explain a few of those?

FR: We found that the data donations were not complete enough for us to be able to answer all the questions that we had. So there's some lack of transparency in the data users could download and about the algorithm overall. We’ve seen this in other studies. People have looked at Facebook's ad-targeting disclosures. If you ask why you’re seeing this ad, it usually offers the broadest criteria that were included — that you're over 18 and in the United States, for instance. Yes, but also because you visited this product website yesterday. But the company isn't sharing that. I’d like to see more transparency about how people’s data is used. Whether that would change what an individual would do is a different question. But I see it as the duty of the platform to help us understand that.

That also connects to regulation. Even if that information doesn't change an individual's behavior, it’s vital to be able to do studies that show, for example, how a vulnerable population is being disproportionately targeted with a certain type of content. That kind of targeting is not necessarily intentional, but if you don't know that's happening, you can't stop it. We don't know how these platforms are auditing internally, but there's always a value in having external auditors with different incentives.

Before we had these platforms, we understood more about how certain content got to certain people because it came in newspapers or on billboards. Now we have a situation where everybody's got their own little reality. So it’s hard to reason about what people are seeing and why and how that all fits together — let alone what to do about it — if we can't even see it.

What is important for people to know about TikTok?

FR: Awareness is helpful. Remember that the platform and the algorithm kind of shape how you view the world and how you interact with the content. That's not always bad, that can be good. But the platform designs are not neutral, and they influence how long you watch and what you watch, and what you're getting angry or concerned about. Just remember that the algorithm shows you stuff in large part because it’s predicting what you might want to see. And there are other things you're not seeing.

Additional co-authors on the papers included Karan Vombatkere of Boston University; Sepehr Mousavi, Olivia Nemes-Nemeth, Angelica Goetzen and Krishna P. Gummadi of Max Planck Institute for Software Systems; Oshrat Ayalon of University of Haifa and Max Planck Institute for Software Systems; Savvas Zannettou of TU Delft; and Elissa M. Redmiles of Georgetown University.

For more information, contact Roesner at franzi@cs.washington.edu.

---

DOI

10.1145/3589334.3645600 

ARTICLE TITLE

TikTok and the Art of Personalization: Investigating Exploration and Exploitation on Social Media Feeds

ARTICLE PUBLICATION DATE

13-May-2024

Why the US and EU are going after TikTok

Stephanie Höppner 

DW

Video-sharing platform TikTok faces a US ban unless it is sold. And the EU accuses the app of posing a mental health risk.

TikTok's dance video are very appealing to young girls

Image: ROBIN UTRECHT/picture alliance

TikTok is one of the most popular apps with children and young people worldwide, but it has also sparked considerable controversy. The Chinese video-sharing platform has been in the news recently as both the United States and the European Union have taken action against it.
What steps is the US taking against TikTok?

US President Joe Biden has signed a bill into action that forces TikTok's Chinese parent company to sell the app or face a US ban. This comes after the US Senate voted in favor of bill on Tuesday.

The bill stipulates that parent company ByteDance must sell off TikTok within 270 days, though provides a possibility for a 90-day extension if progress is made. Failing to do so, TikTok will be removed from the Apple app store and Google's Play Store.

The US move stems from data protection concerns. Chinese TikTok parent company ByteDance is suspected of giving or being forced into passing on user data to the Chinese Communist Party. In the US, some 170 million people currently use the app. There are also concerns China could use TikTok to spread propaganda and disinformation. TikTok itself rejects these accusations.
Why is the EU taking aim at TikTok?

The EU has also set its sights on TikTok, albeit for entirely different reasons. A probe will examine whether TikTok Lite's reward function — allowing users to earn money for certain tasks — endangers the mental health of young app users and thus violates EU rules. The new app has been available in France and Spain since April.

Many teens are hooked on social media

Zacharie Scheurer/dpa-tmn/picture alliance

Large social media platforms such as Facebook, X, Instagram and TikTok have had to comply with the EU's Digital Services Act (DSA) since August 2023. The DSA is intended to prevent illegal or harmful online practices. The EU also prohibits "dark patterns" designed to keep users coming back to online platforms.

The EU Commission criticizes TikTok for launching the new TikTok Lite app in France and Spain without having sufficiently assessed the risks beforehand. TikTok had until April 18 to submit a risk report but initially missed the deadline. It was then given another deadline and submitted a risk assessment this Tuesday, according to TikTok.

In doing so, TikTok has for now avoided steep EU fines. The bloc, after all, can impose fines of up to 1% percent of total annual company revenue. The EU could also block TikTok Lite's controversial reward function.

Back in February, the EU already launched a probe into TikTok over child protection concerns.

Why is TikTok Lite considered so addictive?

TikTok Lite differs from the standard TikTok app in that is builds on a rewards system. Anyone who watches videos, likes content and invites friends to join TikTok Lite can earn digital coins in return, which can be exchanged for Amazon vouchers and other rewards. This rewards system is highly addictive, says the EU Commission.

TikTok Lite, which also features many music and dance videos, is particularly popular with children and young people. According to the terms of use, individuals must be at least 13 years old to use the app. Anyone under the age of 18 also needs either their parents or legal guardians to give their consent, although it is not clear whether the platform checks users' age, according to the Commission.
Is TikTok more addictive than other social media platforms?

The video-sharing platform's algorithms are slightly different than those used by other social media platforms and may therefore get users hooked faster. TikTok displays videos that other users find appealing instead of primarily focusing on content from accounts that a user subscribes to.

TikTok's algorithms are extremely intelligent. The more time users spend on TikTok, the more precisely the platform can predict what content they might like.

How does social media cause stress?

This is not without consequences. In March 2023, US daily The Washington Post cited a study which found that almost half of all adolescent girls on TikTok reported feeling addicted to the platform. Researchers found that when girls use TikTok, they spend more than 2.5 hours on the platform, with those experiencing symptoms of depression logging even longer times. Some of these girls reported using the app practically all the time.

A Pew Research Center later that same year found that 17% of teens described their TikTok use as "almost constant." No other app seems to have such a strong pull on young people.

This article was originally written in German. It was updated on April 25.