In 1999, the American Philosophical Society held a symposium that gathered experts from around the world to make predictions about humanity in the 21st century. One of those experts, demographer and statistician Joel Cohen, met with host Patrick Spero to discuss this millennium’s trends and if we got them right in 1999. In this episode of Useful Knowledge, Cohen reviews his 1999 predictions on topics like population growth, economic equality, immigration, family dynamics, and more to share the outcomes, for better or worse, making recommendations for the coming decades. 

Joel E. Cohen is the Abby Rockefeller Mauzé Professor of Populations at the Rockefeller University, New York. He studies the demography, ecology, epidemiology, and social organization of human and non-human populations using mathematical, statistical, and
computational concepts and tools. He earned doctorates in applied mathematics in 1970 and population sciences and tropical public health in 1973 from Harvard University. He has published 14 books and more than 480 papers and chapters. His books include How
Many People Can the Earth Support? and a book of scientific and mathematical jokes. He was named a MacArthur Fellow and a Guggenheim Fellow in 1981 and was elected to the U.S. National Academy of Sciences in 1997. In 1992, he received the Mindel C. Sheps Award of the Population Association of America.
 

Dr. Emily Sperou is an ecobiologist and researcher who spent her doctoral studies and the first years of her postdoctoral career studying one of the world’s most elusive apex predators: the leopard seal. She and her colleagues take arduous boat trips through Antarctica, searching for rare animals and studying their diets, reproduction, and their survival amid climate change, melting polar ice, and changing sea levels. Sperou’s work helps inform policymakers and teach conservation groups about how to protect leopard seals and what their livelihood and survival means for the vast polar food web beneath them.

Dr. Emily Sperou is a postdoctoral fellow at the University of Rhode Island in the Comparative Ecophysiology of Animals Lab, where she studies the ecophysiology of marine mammals to understand how they survive and thrive in a rapidly changing environment. Her research aims to answer fundamental questions about their health, adaptive capacity, and ecological roles by integrating multiple lines of evidence.

Currently, Dr. Sperou is leading projects investigating the reproductive biology of leopard seals through field observations, necropsy-based anatomical studies, and analyses of historical museum specimens to assess lifetime reproductive success and variation in reproductive strategies. This work is providing unprecedented insight into one of the least studied apex predators in the Southern Ocean and is helping to fill critical gaps in our understanding of how leopard seals may respond to ongoing environmental change. Her goal is to generate data that inform conservation strategies and improve our ability to forecast the future of polar marine ecosystems.

Dr. Sperou was awarded grants from the APS Lewis and Clark Fund in 2022 and 2024. She also joined us as a speaker in our April 2025 Member Meeting. 
 

Before becoming a respected biochemist, Michael Marletta was a child watching Sputnik crossing over Rochester, New York, imagining what it might be like to be a scientist one day. He was his mother’s helper in the kitchen, wondering how spices got their flavor and how they changed when mixed together and heated. He admired the periodic table and the unbelievable truth that those simple elements make up all of life on Earth. As he explored the field of chemistry, he realized the Earth itself is the best biochemist of all–putting all the elements together to shape life as we know it.

In this episode of Useful Knowledge, host Patrick Spero is joined by biochemist Michael Marletta (APS 2016) to discuss how he found his niche in biochemistry and the future of the field for budding scientists. They consider the fascinating history of biochemistry from its earliest days when scientists were encouraged to smell and even taste their creations, and the role of serendipity in scientific discovery. And, Marletta shares one of the foundational chemicals in his work–nitric oxide, which has widespread effects throughout the human body. 

Michael Marletta is a biochemist and Distinguished Professor of Chemistry and of Molecular and Cell Biology at the University of California, Berkeley. He has also served on the faculty at M.I.T. and the University of Michigan. While at Michigan, he was appointed to the Howard Hughes Medical Institute. He joined the faculty of The Scripps Research Institute in 2011 and served as it president and CEO until August 2014.

Marletta has been recognized with numerous honors including a MacArthur Fellowship (1995), election to the National Academy of Medicine (1999), the American Academy of Arts and Sciences (2001), the National Academy of Sciences (2006), the American Philosophical Society (2016), and the American Institute for Biological and Medical Engineers (2024). Since 2014 he has served a consultant on national security for the US Government. He sits on the Board of Directors for the Fredonia College Foundation and the Chabot Space and Science Center. He is a co-founder of Omniox, Inc.

Marletta's primary research interests lie at the interface of chemistry and biology with emphasis on the study of protein function, enzyme discovery and enzyme reaction mechanisms. He has made fundamental discoveries on the biological action of nitric oxide. His continued studies on NO signaling have led to a molecular understanding of general gas sensing mechanisms in biology. A new research direction involves novel oxidative enzymology of cellulose degradation with application to biofuel production and crop pathogenesis.
 

David Tatel grew up believing in the power of law and science to make life better for everyone. He began doing that work himself, launching a decades-long career as a civil rights lawyer and later, as a judge in the United States Court of Appeals for the D.C. Circuit. He fought and decided cases on various topics, notably education, voting rights, environmental law, and disability protections. Along the way, disability took on a personal meaning in his life as he was diagnosed with retinitis pigmentosa, a degenerative eye disease that began to take away his vision. For much of his decades-long career as a lawyer and judge, he hid his failing vision.

Writing his memoir, Vision: A Memoir of Blindness and Justice, gave Judge Tatel the time and space to reflect back on his 50 years in law and justice, and helped him rethink his relationship to his blindness. The book, along with his trusty guide dog, Vixen, helped him realize that his blindness is an essential part of his life and that "acknowledgement is better for everybody.”

In this episode of Useful Knowledge, Judge Tatel joins host Patrick Spero to reflect on his philosophy of judicial restraint, his concerns about the future of American law, and becoming the role model he never had. 

Judge David Tatel served on the United States Court of Appeals for the District of Columbia Circuit from 1994 to 2024. After graduating from the University of Michigan and the University of Chicago Law School (1966), he served as the founding director of the Chicago Lawyers’ Committee for Civil Rights Under Law and then director of the National Lawyers Committee. He headed the Office for Civil Rights of the US Department of Health, Education, and Welfare during the Carter administration (1977-1979) and then founded and led the education practice at Hogan Lovells (1979-1994), where he is now Senior Counsel. In addition to APS, Judge Tatel is a member of the American Philosophical Society and the American Academy of Arts and Sciences. In the past, he co-chaired the National Academy of Sciences’ Committee on Science, Technology and Law, and chaired the boards of The Spencer Foundation and The Carnegie Foundation for the Advancement of Teaching. Judge Tatel and his wife, Edie, live in Virginia and Washington, D.C. They have four children, eight grandchildren, and one great-grandchild.
 

Born-digital materials are files created and stored in a digital environment: from email inboxes, to Word documents, to photos on your phone. As life becomes more and more digital, so too are archival collections. Current and future research will rely on access to born-digital files.

Born-digital archiving at the American Philosophical Society is a nascent and ongoing project. Many collections at the APS contain born-digital materials, and the Digital Archivists are improving on existing processing and descriptive standards to preserve materials and make them accessible to researchers, both on-site in our Reading Room and through the digital library. Learn more about the born-digital program at the APS and explore resources pertaining to curating your born-digital materials below.

Distant, freezing, barren–it may seem that the icy regions of the Arctic and Antarctica have nothing to do with life in warmer homes. In this episode of Useful Knowledge, Neil Shubin, paleontologist, evolutionary biologist, and APS Member, joins host Patrick Spero to explain how much these regions can tell us about the history and future of life on our planet and beyond.

Shubin’s work has allowed him to crack open 380-million-year old rocks, uncovering histories of the times when the polar regions were tropical, meteorites and rocks from the Moon and Mars, and creatures that have evolved to survive in near-impossible conditions. What do scientists make of the freshwater lake hidden under Antarctica? Can polar ice release viruses onto our populace? What are the consequences of melting polar ice? In this episode, learn about these and other incredible findings. 
 

Neil Shubin (APS 2017) is a paleontologist, evolutionary biologist, and author. His most recent book, Ends of the Earth: Journeys to the Polar Regions in Search of Life, the Cosmos, and Our Future, is used as a touchpoint in this episode. Shubin is the Robert R. Bensley Professor of Organismal Biology and Anatomy, Associate Dean of Organismal Biology and Anatomy, and Professor on the Committee of Evolutionary Biology at the University of Chicago. Starting in July of 2026, he will be President of the National Academy of Sciences. He has conducted fieldwork in North America, China, Africa, and Antarctica, and famously co-discovered a 275-million-year-old-fossil of the Tiktaalik roseae, a fish that shows the transition between fish and land mammals, in 2004. 

Psychologist and author Daniel Gilbert (APS 2024) joins host Patrick Spero to discuss how humans imagine new possibilities and the subjective way we think about the future and the past. Inspired by the United States’ upcoming 250th birthday, Gilbert and Spero discuss what America’s Founders meant by the “Pursuit of Happiness” and what it might mean for Americans today. 

Daniel Gilbert is the Edgar Pierce Professor of Psychology at Harvard University. He has won numerous awards for his research and teaching. His popular book, Stumbling on Happiness, spent 6 months on the New York Times bestseller list and has been translated into more than 40 languages. Gilbert is the host and co-writer of the award-winning NOVA television series This Emotional Life which was seen by more than 10 million viewers in its first airing. He is a contributor to Time, The New York Times, and NPR's All Things Considered, and has been a guest on numerous television programs including The Today Show, The Colbert Report, and The Late Show. Gilbert’s three TED talks have more than 30 million views, and his first TED talk remains one of the most popular of all time.

Historian and APS Member Joyce Chaplin (APS 2020) joins host Patrick Spero to speak about Benjamin Franklin and the global significance of the Franklin stove.

Chaplin explores how Franklin’s efforts to heat his Philadelphia home during the Little Ice Age led to new ways of thinking about fuel efficiency, indoor climate, and the atmosphere itself. The conversation moves from colonial Pennsylvania and environmental change to Franklin’s broader scientific insights, including his ideas about convection, storms, and conservation.

Tracing the stove’s surprising spread across Europe, Chaplin reframes Franklin not only as a founder of the American Revolution, but also as a key figure in the Industrial Revolution and an early critic of wasteful fuel use. The episode reveals how a practical invention meant to warm a room reshaped ideas about science, climate, and modern life.

Joyce E. Chaplin is the James Duncan Phillips Professor of Early American History in the Department of History at Harvard
University, where she teaches the histories of science, climate, colonialism, and environment. She serves on the Faculty Executive Board of the Harvard Museums of Science and Culture and is a Trustee of the Massachusetts Historical Society, the first historical society in the United States. An award-winning author, her most recent book is The Franklin Stove: An Unintended American Revolution (2025), for which
she received a 2018 Guggenheim Fellowship. Her work has been translated into French, Japanese, Korean, Portuguese, Estonian, and, forthcoming, into Chinese. Her reviews and essays have appeared in the Times Literary Supplement, the New York Times Book Review, the London Review of Books, the Wall Street Journal and Aeon.