Useful News for You

If you’ve ever talked to a baby, you’ve likely raised your pitch, made silly sounds, or used a sing-song voice. You’re not alone.

In a landmark study spanning six continents, researchers affiliated with the Music Lab found striking consistencies in the ways adults spoke and sang to infants. The findings, published this week in Nature Human Behaviour, point to possible common functions of certain kinds of speech and song patterns for infant development and parent-child bonding.

Over a period of three years, researchers coordinated the collection of 1,615 recordings from 21 cultures with varying degrees of connectedness to the rest of the world. From an urban English-speaking environment in San Diego to a Hadza hunter-gatherer society in East Africa, adults changed their speech patterns when interacting with infants. No previous study has compared infant-directed vocalizations across such a wide range of cultures.

“For about as long as people have been studying parents and babies, psychologists have theorized that there are special kinds of vocalizations for babies, but it’s difficult to study that trend in diverse groups of people all over the world,” said Samuel Mehr, who led the project as director of the Music Lab and a Harvard research associate before taking a new role as a senior scientist at Yale’s Haskins Laboratories. “Because of this big international collaboration, we were able to test this question rigorously in many different sites around the world.” 

New genetic research from remote islands in the Pacific offers fresh insights into the ancestry and culture of the world’s earliest transoceanic seafarers, including family structure, social customs, and the ancestral populations of the people living there today.

The work, described in the journal Science, reveals five previously undocumented migrations into a subregion of this area and suggests that about 2,500 to 3,500 years ago early inhabitants of these Pacific islands — including Guam in the northern region and Vanuatu in the southwest — had matrilocal population structures, ones in which women almost typically remained in their communities after marriage while men more often moved out of theirs to join them.

The practice is opposite of patrilocal societies, in which women typically relocate. These findings support the idea that these early seafarers were from cultures organized through female lineages.

The results come from a genome-wide analysis on 164 individuals from 2,800 to 300 years ago, as well 112 modern individuals. It was published by a team of researchers co-led by Harvard geneticists David Reich and Yue-Chen Liu, Ron Pinhasi at the University of Vienna, and Rosalind Hunter-Anderson, an independent researcher working in Albuquerque, New Mexico.

“It’s an unexpected gift to be able to learn about cultural patterns from genetic data,” said Reich, a professor in the Department of Human Evolutionary Biology and a professor of genetics at Harvard Medical School. “Today, traditional communities in the Pacific have both patrilocal and matrilocal population structures, and there was a debate about what the common practice was in the ancestral populations. These results suggest that in the earliest seafarers, matrilocality was the rule.”

The genetic analysis compared mitochondrial DNA sequences — which are inherited only from biological mothers — of the first seafarers from Guam to those of the first seafarers from the southwest islands of Vanuatu, and Tonga who lived 2,500-3,000 years ago. It revealed that the two lineages of the first Remote Oceanians derived from two distinctly different maternal lineages but that kind of stark differentiation didn’t exist in terms of the rest of their DNA.

When Ellis Monk’s wife became pregnant in 2019, the couple became curious about what skin tone their child might have. The subject was of more than passing interest to the sociology professor, some of whose work involves the role lighter and darker skin tones play in society. Monk’s wife noted that a comprehensive scale would be useful and urged him to develop one.

So he did, and last month Google adopted Monk’s namesake 10-shade scale as a standard in its digital products to make them more inclusive and diverse and to promote wider awareness of the problems and unintended bias associated with technologies that fail to recognize a wider range of skin tones.

Monk’s scale is already making an impact. It has been incorporated in Google’s online image searches and photo filters. The innovation will be particularly important for training artificial intelligence and machine learning applications, such as facial recognition and self-driving vehicle systems, which often have not performed as well with people with darker skin tones. And it could help reduce or eliminate some unintended algorithm bias in search engines and other products.

“She encouraged me to keep it going,” Monk said, crediting his wife. “Eventually, I delved in and put together the Monk Skin Tone Scale, taking the baton [and] building on what she had started.”

Monk’s scale is a rethinking of the Fitzpatrick Scale, which has been considered the online standard. Created by dermatologist Thomas B. Fitzpatrick at Harvard Medical School in 1975, the Fitzpatrick Scale was developed to classify six tones based on skin pigmentation and response to sun exposure. It was not created with diverse populations in mind but as a gauge of tolerance for ultraviolet light, Monk explained.

As food costs continue to rise and a global food crisis looms on the horizon, it’s staggering to think that some 30-40 percent of America’s food supply ends up in landfills, mostly due to spoilage. At the same time, the World Health Organization estimates that foodborne illness from microbial contamination causes about 420,000 deaths per year worldwide.

What if there were a way to package fresh foods that could extend their shelf life and eliminate microbial contamination?

Now, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences and the Harvard T.H. Chan School of Public Health have developed a biodegradable, antimicrobial food packaging system that does both.

“One of the biggest challenges in the food supply is the distribution and viability of the food items themselves,” said Kit Parker, the Tarr Family Professor of Bioengineering and Applied Physics at SEAS and senior author of the paper. “We are harnessing advances in materials science and materials processing to increase both the longevity and freshness of the food items and doing so in a sustainable model.”

The research was published in Nature Food.

From the battlefield to the farm

Surprisingly, the new food packing system has its roots in battlefield medicine. For more than a decade, Parker and his Disease Biophysics Group have been developing antimicrobial fibers for wound dressings. Their fiber manufacturing platform, known as Rotary Jet-Spinning (RJS), was designed specifically for the purpose.

RJS works likes a cotton candy machine — a liquid polymer solution is loaded into a reservoir and pushed out through a tiny opening by centrifugal force as the device spins. As the solution leaves the reservoir, the solvent evaporates, and the polymers solidify to form fibers, with controlled diameters ranging from microscale to nanoscale.

A summer dilemma worthy of Solomon: how to stay cool in days of high heat and humidity without turning to traditional air conditioning, which consumes vast amounts of electricity and emits potent climate-changing greenhouse gases.

The answer potentially involves a new class of solid-state refrigerants that could enable energy-efficient and emission-free cooling. And now researchers from the Department of Chemistry and Chemical Biology have developed an environmentally friendly mechanism to enable solid-state cooling with two-dimensional perovskites. Their findings are described in a new study in Nature Communications.

“Shifting away from the vapor compression systems that have been in use for a really long time is a crucial part of the overall push toward a more sustainable future,” said Jarad Mason, the paper’s senior author and assistant professor of chemistry and chemical biology. “Our focus is looking deeply at the intrinsic properties of these materials to see what is possible in terms of solid-state cooling as a sustainable alternative.”

Also known as barocaloric materials, the two-dimensional perovskites release and absorb heat in response to pressure changes as they expand and contract. The effect is based on a phenomenon you may be familiar with if you’ve ever stretched a balloon and felt it warm up against your lips. Similarly, these materials release heat when pressurized or stressed. Without releasing any harmful emissions, this mechanism can remove heat in the solid state using low driving pressures.

The work was led by members of Mason’s lab, including Jinyoung Seo, Ryan D. McGillicuddy, Adam H. Slavney, Selena Zhang ’22, Rahil Ukani, and Shao-Liang Zheng, director of the X-ray Laboratory. Advanced tests were also performed in collaboration with scientists at the Argonne National Laboratory in Lemont, Illinois.

This new mechanism for solid-state cooling has the potential to overcome the limitations of traditional vapor-compression cooling technology, which has remained largely unchanged since the early 20th century.

Any kind of refrigeration system runs in a cycle from a low-entropy state when a material can absorb heat, thereby cooling a space, to a high-entropy state when that energy can be released in a heat sink, where it dissipates. Vapor-compression air conditioners circulate a volatile fluid refrigerant that evaporates and condenses under varying pressure through metal coils to cool an enclosed space and eject heat outside. Running vapor-compression cycles is energy-intensive, responsible currently for almost 20 percent of electricity use in buildings around the world. In addition, leaking refrigerants are more than 1,000 times more potent greenhouse gases than carbon dioxide.

Why do we sleep? Scientists have debated this question for millennia, but a new study adds fresh clues for solving this mystery.

The findings, published in the Journal of Neuroscience, may help explain how humans form memories and learn, and could eventually aid the development of assistive tools for people affected by neurologic disease or injury. The study was conducted by Massachusetts General Hospital in collaboration with colleagues at Brown University, the Department of Veterans Affairs, and several other institutions.

Scientists studying laboratory animals long ago discovered a phenomenon known as “replay” that occurs during sleep, explains neurologist Daniel Rubin of the MGH Center for Neurotechnology and Neurorecovery, the lead author of the study. Replay is theorized to be a strategy the brain uses to remember new information. If a mouse is trained to find its way through a maze, monitoring devices can show that a specific pattern of brain cells, or neurons, will light up as it traverses the correct route. “Then, later on while the animal is sleeping, you can see that those neurons will fire again in that same order,” says Rubin.

Scientists believe that this replay of neuronal firing during sleep is how the brain practices newly learned information, which allows a memory to be consolidated — that is, converted from a short-term memory to a long-term one.

However, replay has only been convincingly shown in lab animals. “There’s been an open question in the neuroscience community: To what extent is this model for how we learn things true in humans? And is it true for different kinds of learning?” asks neurologist Sydney S. Cash, co-director of the Center for Neurotechnology and Neurorecovery at MGH and co-senior author of the study. Importantly, says Cash, understanding whether replay occurs with the learning of motor skills could help guide the development of new therapies and tools for people with neurologic diseases and injuries.

To study whether replay occurs in the human motor cortex — the brain region that governs movement — Rubin, Cash, and their colleagues enlisted a 36-year-old man with tetraplegia (also called quadriplegia), meaning he is unable to move his upper and lower limbs, in his case due to a spinal cord injury. The man, identified in the study as T11, is a participant in a clinical trial of a brain-computer interface device that allows him to use a computer cursor and keyboard on a screen. The investigational device is being developed by the BrainGate consortium, a collaborative effort involving clinicians, neuroscientists, and engineers at several institutions with the goal of creating technologies to restore communication, mobility, and independence for people with neurologic disease, injury, or limb loss. The consortium is directed by Leigh R. Hochberg of MGH, Brown University, and the Department of Veterans Affairs.

In the study, T11 was asked to perform a memory task similar to the electronic game Simon, in which a player observes a pattern of flashing colored lights, then has to recall and reproduce that sequence. He controlled the cursor on the computer screen simply by thinking about the movement of his own hand. Sensors implanted in T11’s motor cortex measured patterns of neuronal firing, which reflected his intended hand movement, allowing him to move the cursor around on the screen and click it at his desired locations. These brain signals were recorded and wirelessly transmitted to a computer.

That night, while T11 slept at home, activity in his motor cortex was recorded and wirelessly transmitted to a computer. “What we found was pretty incredible,” says Rubin. “He was basically playing the game overnight in his sleep.” On several occasions, says Rubin, T11’s patterns of neuronal firing during sleep exactly matched patterns that occurred while he performed the memory-matching game earlier that day.

“This is the most direct evidence of replay from motor cortex that’s ever been seen during sleep in humans,” says Rubin. Most of the replay detected in the study occurred during slow-wave sleep, a phase of deep slumber. Interestingly, replay was much less likely to be detected while T11 was in REM sleep, the phase most commonly associated with dreaming. Rubin and Cash see this work as a foundation for learning more about replay and its role in learning and memory in humans.

“Our hope is that we can leverage this information to help build better brain-computer interfaces and come up with paradigms that help people learn more quickly and efficiently in order to regain control after an injury,” says Cash, noting the significance of moving this line of inquiry from animals to human subjects. “This kind of research benefits enormously from the close interaction we have with our participants,” he adds, with gratitude to T11 and other participants in the BrainGate clinical trial.

Hochberg concurs. “Our incredible BrainGate participants provide not only helpful feedback toward the creation of a system to restore communication and mobility, but they also give us the rare opportunity to advance fundamental human neuroscience — to understand how the human brain works at the level of circuits of individual neurons,” he says, “and to use that information to build next-generation restorative neurotechnologies.”

Rubin is also an instructor in neurology at Harvard Medical School. Cash is an associate professor of neurology at HMS. Hochberg is a senior lecturer on neurology at HMS and professor of engineering at Brown University.

This work was supported by the Department of Veterans Affairs, the National Institute of Neurologic Disease and Stroke, the National Institute of Mental Health, Conquer Paralysis Now, the MGH-Deane Institute, the American Academy of Neurology, and the Howard Hughes Medical Institute at Stanford University.  

In the 1970s, as Evelynn Hammonds walked the halls of MIT’s physics department on her way to a Ph.D., faculty, students, and staff kept asking her the same question:

“Hi, Shirley, how’s your work going?”

Her name, of course, was Evelynn, not Shirley. A few years before, Shirley Jackson, the second African American woman to receive a Ph.D. in physics in the United States, had been the only Black woman in the department. But she was gone by the time Hammonds, also the only Black woman in MIT physics, arrived.

“As an African American woman, I carried the double burden,” Hammonds, the chair and professor of the history of science at Harvard, recalled in a recent interview with the Harvard Museums of Science and Culture. “The first two years, I just felt like I was constantly fighting to have people take me seriously.”

After she earned her degree, Hammonds took a leave of absence to grapple with questions physics couldn’t answer: “Where are the women? What’s going on?”

Today, on the 50th anniversary of Title IX, which prohibits sex-based discrimination at educational institutions that receive federal funding, she’s still asking why there aren’t more women in science, technology, engineering, and mathematics. “The attitudes and the culture haven’t changed as much as they absolutely have to,” she said.

Most people associate Title IX with anti-discrimination initiatives in athletics and efforts to reduce sexual harassment. But it was also intended to increase women’s access to higher education. This “big hammer,” as the chemist Debra Rolison calls it, could be used to put universities on alert: Fail to increase the representation of women in STEM, and the government might take away your federal funding.

“No money from the feds is death at the door,” said Rolison, who has been fighting for women’s equality since her male cousins excluded her from a baseball game when she was 5 years old. “I have never, ever appreciated that double standard,” she said. “And every time I can say or do something about it, I do.”

For decades, Rolison, who is head of the Advanced Electrochemical Materials section at the Naval Research Laboratory, has given talks to raise awareness about gender inequities in STEM. When words haven’t been enough, she has sought to force change by using the “big hammer” Title IX represents.

Since the law’s enactment, women have made some gains in science and engineering — they’ve gone from representing just 8 percent of STEM workers in 1970 to 27 percent in 2019. But men still dominate, making up half of all U.S. employees but 73 percent of the STEM workforce. A report published in 2018 made clear that sexual harassment was still an everyday reality for many women in science. Two years later, the American Association of University Women (AAUW) found that women in science earned about $15,000 less than their male colleagues.

“The gender gap that exists in the STEM workforce cannot be blamed on differences in academic preparation,” the National Coalition for Women and Girls in Education wrote in a report released this month. Research has shown that women are no less capable than men in science and mathematics. But, according to the AAUW, external factors, like a lack of role models, cultures that tend to exclude women, and persistent stereotypes about women’s intellectual abilities, reinforce a wide gender gap. Even today, teachers and parents underestimate girls’ STEM abilities from a young age. From a historical perspective, at least in certain fields, we seem to have regressed.

“In 1700, 14 percent of German astronomers were women,” said Londa Schiebinger, who earned her Ph.D. in history from Harvard and is now the John L. Hinds Professor of History of Science at Stanford University. As a student, she couldn’t stop wondering: “What happened to all the women?”

The were pushed out, she found, and men brandished biased science to justify keeping them out. Take the Harvard-trained physician Edward Hammond Clarke, who practiced in the late 1800s.

Clarke, Schiebinger noted, claimed that as a woman’s brain grows, her ovaries shrink — clear-cut evidence, he said, that a woman’s rightful place was in the home, bearing children. The first drawings of the female skeleton, also from the 19th century, depicted (inaccurately) small skulls and large pelvises — more evidence, male scientists thought, that a woman’s body was made for procreation. In the 1920s, men blamed female hormones for their inferior minds. A century later, when Schiebinger was a graduate student at Harvard, she still heard men argue that women were intellectually deficient and ill-suited for science.

The gender gap isn’t just about percentages or fairness; a lack of women (and other minorities) in a field affects the quality of the science, as Schiebinger has discovered.

Women are 47 percent more likely to be injured in a car crash, she said, because crash test dummies are just smaller versions of the male anatomy. “It’s a shrink-it and pink-it sort of thing,” Schiebinger said. Medical devices fail more often for women. Pulse oximeters, for example, which measure blood oxygen levels, tend to miscalculate these levels in women and people of color, putting them at risk of not receiving emergency care (an especially pernicious threat during the pandemic). Large datasets don’t have equal representation of women or different ethnic groups. Search algorithms, for example, show more high-paying jobs to men because that’s what their underlying data tells them: men earn more.

“It’s not like Title IX changed anything,” Schiebinger said. “It’s been the women’s movement, right? It’s the people who have been working nonstop on institutional reform. Some law doesn’t really change anything.”

A male-dominated culture — along with its unconscious biases and rewards for cutthroat pursuit of money and prestige — is still considered one of the biggest and most stubborn barriers women face in STEM, said Schiebinger.

Hammonds would agree.

“You’re in a culture where, on any given day, somebody might think you were a secretary, or a janitor, or anything but a graduate student in physics, so you had to live with that,” she said. “It was made very clear to us by some people that we didn’t fit, that we didn’t belong, that we were only there because of affirmative action, that we could never be successful. We were constantly finding those attitudes.”

Some people argue that women choose to avoid STEM careers because of long hours that can intrude on family responsibilities. It’s true, Rolison noted, that child care and parental leave are critical benefits that ensure women can have a family without sacrificing career ambitions.
But, she said, the particular demands and realities of a life in science are not the primary problem. “There’s plenty of work done to show that, no, it’s the culture. It’s always the culture. It’s not the low pay; it’s not the long hours; it’s the culture.”

To fix the culture, Schiebinger argues for a coordinated approach. Courses should teach awareness of social issues; journals and funding agencies shouldn’t accept research that doesn’t consider gender and sex; big hammers like Title IX should be used as levers to force stubborn institutions to do better.

“These have to be structural solutions. It’s not just getting this woman or that woman,” Schiebinger said. “You gotta do it everywhere. Start in the womb, I always say.”