In our culture, we tend to revere people whose work puts them in the limelight—actors, sports heroes, pop music stars, and the like. Yet there are many more people whose work involves little to no fanfare but profoundly impacts our collective lives. Scientists are among them. As we begin a new year, I’d like to remember some of the scientists we lost in 2024. Each one made indelible contributions to improving human health and to our understanding of ourselves and our planet. At a time when distrust of science is being fomented by many, it’s more important than ever to remember their achievements.

• Richard A. Cash, MD, physician/public health researcher, age 83. As a young physician in the late 1960s, Dr. Cash set to work on a daunting problem. Each year, millions of children worldwide were dying of cholera and other diarrhea-inducing infections—largely due to dehydration. In the impoverished countries that were hardest hit, the standard treatment (IV fluids) was often not feasible. So Dr. Cash and a colleague, Dr. David Nalin, developed a low-tech rehydration solution made of water, salt, and sugar that could be given as a drink. The simple approach was initially met with skepticism, but the doctors were undaunted. They first showed, in a small study, that the rehydration therapy was effective. Then they worked with a nonprofit in Bangladesh to teach parents there how to give the treatment at home. The therapy later spread to other countries, and today it’s credited with saving over 70 million lives and counting.
• John Clements, MD, pulmonary physiologist, age 101. There was a time when premature babies born in respiratory distress almost always died. Dr. Clements, who joined the faculty at the University of California, San Francisco, in 1961, was instrumental in turning that around. He and his colleagues discovered lung surfactant, a natural substance that keeps the lungs from collapsing, then later showed that preemies born in respiratory distress lack that substance. Though some other researchers in the field were doubtful early on, Dr. Clements and his team worked for years to develop a synthetic lung surfactant that gained approval by the Food and Drug Administration in 1990. Newer versions are still in use, and those treatments (along with other advances in newborn care) have increased tiny preemies’ survival rate from 5 percent in the 1960s to over 90 percent today.
• Helen Fisher, PhD, biological anthropologist, age 79. Dr. Fisher spent decades researching the neurological basis for human love—from lust, to romance, to the bonds that hold marriages together for decades. Using MRI imaging, she and her colleagues were able to confirm, for the first time, that matters of the heart are hard-wired in the brain. They showed, for example, that when you’re in the honeymoon phase of a relationship, an image of your beloved can cause specific areas of your brain to “light up” (the same areas associated with basic drives like hunger and thirst). Dr. Fisher held various research and academic positions, wrote six books (including Why We Love), and, fittingly, served as chief science advisor to the internet dating site Match.com.
• Leonard Hayflick, PhD, microbiologist/biomedical researcher, age 96. On occasion a scientist makes a discovery that’s so remarkable, it’s named after him or her. Dr. Hayflick was one of those individuals. Back in the early 1960s, as a young researcher at the University of Pennsylvania, he discovered a fundamental reason why humans (most likely) will never be immortal: Our body cells can only divide and replicate themselves so many times (40 to 60) before they lose that capacity. And as those “old” cells start to accumulate, the body ages. The phenomenon, later dubbed the “Hayflick limit,” turned a then-prevailing theory on aging on its head—that human cells were immortal, and aging was strictly the result of external causes, like bad diets and disease. Dr. Hayflick’s discovery was frustrating to those who had hoped that science would unravel the secret to eternal life. But it gave us a clearer understanding of why our time is finite.
• Edith P. Mitchell, MD, physician/cancer researcher, age 76. Called a “woman before her time” by her colleagues, Dr. Mitchell was an oncologist, researcher, and leader in the fight for healthcare equity. She enlisted in the Air Force in 1973, becoming a flight surgeon and, eventually, the first female physician to attain the rank of Air Force brigadier general. In the 1990s, Dr. Mitchell joined Thomas Jefferson University, in Philadelphia, where she directed the Center to Eliminate Cancer Disparities. In that role, Dr. Mitchell helped call attention to the national problem of racial inequities in healthcare, and she is remembered as a tireless advocate for improving care in underserved communities.
• Maxine Singer, PhD, biologist, age 93. In 1988, Dr. Singer became the first female president of the prestigious research institute Carnegie Science. But her career began in the 1950s, when a new field known as molecular biology was taking off. Just three years after the landmark discovery of the structure of DNA, Dr. Singer joined a small group of researchers at the National Institutes of Health, whose work would ultimately fuel the deciphering of the genetic code—paving the way for major advances in the understanding and treatment of many diseases. In 1992, Dr. Singer received the National Medal of Science, an honor bestowed by the president of the United States upon scientists who make significant contributions to their field.
• Warren Washington, PhD, climate scientist, age 88. Dr. Washington was a trailblazer from the beginning. When he received his PhD in meteorology in 1964, he became only the second Black individual in the United States to do so. Before long, Dr. Washington emerged as one of the first, and most influential, climate scientists of our time. He co-created critical computer models that allowed researchers to study the impact of human-induced climate change on the planet. And he was among the first scientists to sound the alarm on global warming—well before its existence was widely affirmed. Dr. Washington would serve as an advisor on climate change to five presidents, and he was part of the Intergovernmental Panel on Climate Change, which shared the Nobel Peace Prize with former vice president Al Gore in 2007.

While these scientists came from different fields and different backgrounds, they shared some things in common. Each had to surmount significant obstacles in their work—whether barriers related to race or gender, skepticism from their scientific peers, or political pushback. And they all had the curiosity and tenacity it takes to dedicate one’s life to asking questions and searching for answers. As Dr. Singer once said: “Science is not an inhuman or superhuman activity. It’s something that humans invented, and it speaks to one of our greatest needs—to understand the world around us.”