SERIES

Take a jaunt through a jungle of strange neurons underlying your sense of touch, hundreds of millions of years of animal evolution and the dense neural networks of brains and AIs.

Carlos Arrojo for Quanta Magazine

What Can a Cell Remember?

As I reflect on a year of Quanta biology stories to decide which of the many excellent ones to recommend, I am relying on memory. But what exactly does that mean?

“Memory” is a slippery word. It means one thing to a person striving to recall places, people or moments from the past, and another to someone searching their mind for a fact they swore they knew. A neuroscientist might consider a “memory” to be a physical connection between neurons or networks reactivated by cognitive processes, or the changes in an animal’s behavior in response to something it experienced in the past.

But what is memory to a cell biologist — or to a cell? This is what the writer Claire L. Evans explored in her scientific, philosophical, semantic journey through the long-forgotten and recently revived history of aneural, or brainless, forms of memory. She recounts decades-old and brand-new experiments that test whether individual cells record experiences, such as pulses of chemicals in their environments. In the process, these experiments challenge fundamental ideas in neuroscience. For a cell, Evans writes, “there’s no distinction between memory, the memorizer and the act of remembering.” Is that also true for us?

Here are some more stories from 2025 that I think are worth remembering.

Mark Belan/Quanta Magazine

A Biography of Earth Across the Age of Animals

One of the many things I love about biology is the way evolution situates us in the grand context of deep time. It connects us to billions of years of struggle, survival and adaptation; it places my ancestors in unrecognizable forms and almost incomprehensible worlds, and helps me appreciate the strangeness of our age, too. Usually we glimpse these ancient worlds one at a time: the Cambrian seas ruled by trilobites, the great Carboniferous swamps, the fantastic dinosaurs of the Jurassic. In Quanta’s special issue on basic climate science, Peter Brannen takes us on an extensive and fascinating journey through the latest advances in geologic climate modeling, which is trying to weave these stories of past worlds into a single narrative — the history of Earth for as long as animals have occupied it.

Telling such a tale is no small feat. To assemble this tour de force, Brannen had to compile far-flung details about past climates — the frozen and hothouse worlds through which animals lived and died — and situate them within the deductions scientists have made about evolution from fossil and genomic evidence. His effort paid off in a piece that spans 540 million years of interconnections between rocks, atmosphere, water and life, each of which makes and reshapes the others. He introduces us to the “pioneering forests [that] geoengineered the ancient world,” the “tropical coal swamps, streaked by titanic bugs, [that] were first buried in this age, moving carbon dioxide into the geologic abyss,” and the chalky plankton that drifted like snow to the seafloor and was “delivered to deep sea trenches, cooked and then released through the throats of volcanoes at the surface again as carbon dioxide.”

This perspective propels our story beyond biological evolution and into planetary evolution. It reveals that all we are and will ever know is ultimately part of Earth’s carbon cycle. And isn’t it glorious to be present as living, breathing, embodied carbon?

Irene Pérez for Quanta Magazine

AI Is Nothing Like a Brain, and That’s OK

Today we live surrounded by intelligent networks of electrified neurons that fire signals to process information, recall memories and create representations of the world using language. But wait — am I talking about living brains or the neural networks that power artificial intelligence?

To a biologist, such comparisons can feel like an abuse of neuroscience in service of tech marketing, but I still want to know: How do these two kinds of networked intelligences measure up? Is there anything to learn about the human brain by comparing it to AI, or vice versa?

A feature by staff writer Yasemin Saplakoglu delivers answers to these questions and more. “AI Is Nothing Like a Brain, and That’s OK” explores the origins of artificial neural networks in neuroscience models, and shows how decades of assumptions and simplifications by early computational neuroscientists have led to widespread misunderstanding of the complexity, diversity and networked nature of the human brain. Yes, artificial neurons fire and connect like biological ones — but the cells that make up our brains are “wicked complicated things,” Saplakoglu writes, “whose behaviors are controlled by a menagerie of molecules released on precise timescales.”

I now have a new understanding of AI, but more importantly, I feel a fresh appreciation for the complexity of the miraculous organ in my head, “the most complex piece of active matter in the known universe,” as one neuroscientist told Saplakoglu. This piece ran as part of Quanta’s series on artificial intelligence’s complex relationship with fundamental science. Check out the entire project here.

Rachel Bujalski for Quanta Magazine

How Paradoxical Questions and Simple Wonder Lead to Great Science

I’m a huge fan of ecologist Rachel Carson’s book The Sense of Wonder, published in 1965, a year after her death. In it she insists that every one of us is born a scientist, with innate curiosity about the world that gets drilled out of us as we become adults. Her argument has influenced my approach to science journalism, and I find it embodied in Manu Prakash, an engineer and microbiologist at Stanford University, who was the subject of a Quanta Q&A. Prakash’s philosophy compels him to spend “half his time studying urgent health issues with global impact and the rest pursuing questions ‘of no use to anyone,’” he told writer Molly Herring.

The conversation captures an endlessly creative and active scientist — one day reeling in strange plankton to investigate their biophysical mechanisms and the next inventing low-cost tools to diagnose malaria in the field. Prakash embraces and defends the basic science we cover at Quanta — research that is “not at the service of something, but the groundwork that is our entire society’s foundation,” he told Herring.

Courtesy of David Ginty

Touch, Our Most Complex Sense, Is a Landscape of Cellular Sensors

How does our sense of touch work? David Ginty, a neurobiologist at Harvard Medical School known to some colleagues as “the emperor of touch,” has dedicated his career to documenting the surprising menagerie of neurons that innervate our skin. “These strangely shaped cells are the reason why the experience of touch is so rich and multifaceted — why a buzzing cell phone feels different from a warm breeze or a lover’s caress, from raindrops or a mother’s kiss,” writes Quanta contributor Ariel Bleicher. “To realize that your body is covered in them — that they are a part of you — takes your breath away.”

When Bleicher pitched me this story, she described the touch neurons as evolved feats of engineering. They are little mechanical objects at the surface of our skin or just beneath it that, when activated by temperature or vibrations of various frequencies, send signals to our nervous system to generate perceptions — warmth and cold, pressure, pain, itchiness, pleasure, softness and hardness, and awareness of the body in space.

Bleicher’s descriptions of the neurons and their workings, paired with Ginty’s fluorescent portraits of the various cell types, convey an entire world operating beyond our perception. Once they help you see it, you won’t experience this nuanced, multidimensional sense the same way again.

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