Big Ideas Lab
Ancient footprints, unidentified remains, brain cells - they're all part of the story told through atoms.
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British Columbia, 1968. Detectives were at a loss.
Come in, dispatch. I think we found something.
A child's remains were discovered along the riverbank with no clear cause of death and no indication of who the child was.
Copy that, dispatch. Alert Central.
They couldn't figure out where the child was from.
Initial forensics at the time concluded that they had found the body of a seven-to-nine-year-old.
And there wasn't anybody in the area that matched that. There was no DNA at that time.
With no name, no missing persons match, and no DNA analysis available, the case faded into the archives of the John and Jane Does. Stories suspended in silence. Years passed, but in 2005, a forensic DNA analysis at Simon Fraser University reopened a case with a new discovery.
They misidentified the age.
The child wasn't even seven years old. He was about four and a half. Hundreds of miles away, Lawrence Livermore National Laboratory took the next step. With an advanced radiocarbon dating technique, scientists used the atomic signature of Cold War nuclear tests to pinpoint when the child was born and when he died. Key information that led to the end of the search and a legal identification for the child finally declared.
And it was like 40 years from the time that they found it. It was actually amazing.
It wasn't guesswork. It wasn't luck. It was a technique that hadn't even existed when the child's remains were first discovered. A technique perfected with the ultra-precise instruments at the Center for Accelerator Mass Spectrometry.
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The Center for Accelerator Mass Spectrometry, or CAMS, at Lawrence Livermore National Laboratory is one of the most advanced and prestigious facilities in the world for measuring various ultra-rare isotopes and investigating the information they provide. It houses an array of powerful machines that analyze tiny atomic markers and discover answers to questions that have long eluded science, from archaeology to national security to public health and forensic investigation. But one of CAMS' most unique strengths comes from its people.
We all come with different scientific backgrounds.
That's Bruce Buchholz, a staff scientist at Lawrence Livermore National Laboratory and a lead on multiple CAMS research initiatives.
We have some very specialized things that we can do.
The lab operates with a flat structure, where a dozen PhDs from a wide range of disciplines all work hands-on with the machines, pursuing their own lines of scientific inquiry and creating a diverse, multifaceted team.
It could be soil, it could be coral, wood, charcoal, anything. And the reason carbon is so useful is that everything that's alive has carbon.
Carbon 14 in particular plays a key role in radiocarbon dating. And that's where accelerator mass spectrometry, or AMS, comes in.
99% of carbon is carbon 12. About 1% of carbon is carbon 13. About one part per trillion of carbon out in the environment is carbon 14. So we're measuring variations off the one part per trillion natural concentration of carbon 14.
AMS is designed to detect and count those rare atoms by turning them into charged particles, accelerating them, and separating them based on their mass. When traveling through a magnetic field, heavier isotopes like carbon 14 bend less while lighter ones like carbon 13 and carbon 12 bend more. By measuring how much radioactive carbon 14 is left compared to stable carbon 13 and carbon 12, scientists can determine a sample's age, whether it's 400 or 4,000 years old. However, Bruce and the other CAM scientists use this process for far more than dating ancient charcoal or wood.
And I will do nuclear forensics and bomb poll stuff and a wide variety of things.
In many cases, AMS can help unlock the hidden history of human remains, breathing new life into cold cases and long-forgotten lives. That's exactly what happened in 2007 when police from Newfoundland, Canada were six years into an investigation with nothing but dead ends.
I was approached by Inspector in Newfoundland about a case. Hunter has found some remains in the woods somewhere in Newfoundland. They knew it was a murder based on other information. They had no idea who the person was.
The body had been deep in the Canadian woods for six years. Local investigators had done everything they could, but the leads had dried up, and the evidence, what little there was, was inconclusive. Authorities decided to try something different. Investigators in Newfoundland contacted Bruce after encountering research he had published, alongside collaborators from the Karolinska Institutet in Sweden, on using carbon dating to estimate the age of human remains. Bruce used the advanced machines at Lawrence Livermore National Laboratory, not to analyze fingerprints, but to analyze the atoms that history had left its fingerprints on.
Beginning in 1955, above-ground nuclear testing released increased amounts of neutrons into the atmosphere. These neutrons reacted with nitrogen to create carbon-14, which created a spike in the atmosphere: the radiocarbon bomb pulse. In 1963, the Partial Test Ban Treaty was signed, and the carbon-14 supply began decreasing.
That pulse basically started in 1955, went up, and reached a peak in 1963, and has been coming down since then.
For scientists like Bruce, the bomb pulse acts as a timestamp. The surge in carbon-14 gives post-1955 samples a precise fingerprint that narrows the age range of an organic sample as close as a few months. It's a level of chronological precision otherwise impossible with older remains, where timelines blur and the age uncertainties can stretch across decades.
We were able to determine that date of death was about 1996, approximately. Dated a couple of teeth, and we were able to determine a date of birth was 1958 to 1962.
The unidentified person in Newfoundland was likely born in 1958, plus or minus a few years, and died sometime between 1994 and 1997.
placing him in his 30s at the time of death. Combined with advances in genetic genealogy, investigators were eventually able to identify the unidentifiable. Temestockel Fernandez-Casas, a man originally from Cuba. A case spanning 15 years could finally be closed. The machines that made it possible contain their own history. A powerful lineup of accelerator systems, each one designed to perform a different kind of scientific investigation. Their principal machine is a 10MV particle accelerator, the most versatile and productive AMS system in the world. Susan Zimmerman is a staff scientist at Lawrence Livermore National Laboratory.
The big accelerator that we have, the 10MV machine, is a kind of equipment that was used by nuclear physicists.
In the late 1960s, nuclear physicists moved on to bigger facilities, leaving machines like the 10MV to find new missions.
Some of the big machines like that were modified from their nuclear physics backgrounds to do AMS.
Most radiocarbon work is done in universities and institutes that are focused on doing science, not nuclear physics and other national security work, positioning CAMs to take on more unique challenges.
So our mission and the kinds of things that we do and the support that we have from engineering and from the safety people is all, I think, different from other labs that do AMS.
The diversity of tasks CAMs accepts extends far beyond cold cases. The same scientific techniques that help law enforcement identify a missing person can also reach far deeper into the past. Sometimes the mystery isn't who someone was.
But when someone was? That was the question geologists were trying to answer when they turned to Susan, who led the team at CAMHS on investigating the age of the footprints discovered at White Sands National Park.
Radiocarbon is the most widespread fundamental way of dating things that happened in the last about 50,000 years.
A set of fossilized footprints were originally discovered in the park in 2006, footprints that told a story far more complex than we imagined about the first humans in North America.
The biggest thing when you're trying to reconstruct the past is to understand the timing of things. That would turn out to be much harder than we actually anticipated.
For the US Geological Survey team invited by the Park Service to investigate, dating the White Sands footprints presented a huge challenge. Researchers needed to find organic material that was not only reliable, but also clearly connected to the event itself.
This is from my perspective as a geochronologist, one of the really hard things about archaeology.
You can't just date the dirt around a footprint. The most accurate radiocarbon dating requires an organic sample that was growing using carbon from the atmosphere around the time the print was made.
If you find an arrowhead or something, the arrowhead is made of stone and you can't date the arrowhead with radiocarbon. And so you date a little piece of plant material from the rope that was associated with the arrowhead or some other organic material.
Without organic material containing carbon, radiocarbon dating can't be done. But buried in the same sediment layers containing the footprints, scientists discovered something small and powerful: seeds from an aquatic plant called Rupia serosa that were both directly associated with the fossilized footprints and radiocarbon-datable. These seeds were the key. They became the organic timestamp that scientists could use to peer into the past. And when the analysis was complete...
The dates shocked everyone.
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New evidence confirms that humans were walking across North America more than 20,000 years ago.
According to the rupiah seed measurements, the footprints found in White Sands National Park were between 21,000 and 23,000 years old. For decades, the scientific consensus had been that humans crossed into the North American continent around 13,000 years ago after the last Ice Age began to thaw. Newer investigations at various sites had begun pushing that date back to about 16,000 years ago. However, the new evidence that emerged from dating organic materials showed these footprints were laid down during the Ice Age, not after.
No one was expecting dates 23,000 years old.
It sparked immediate debate. Academic minds questioned whether the plant material truly reflected the age of the footprints or if it had been affected by a chemical disequilibrium between the water the rupiah was growing in and the atmosphere. The U.S. Geological Survey had to go deeper. The team continued searching for terrestrial materials that could be dated using AMS, and eventually, they found it: pollen.
The carbon trees used to make pollen comes from the atmosphere. One way of assuring reliable radiocarbon dates. But analyzing pollen isn't simple. It's a delicate, complex process that requires both precision and patience. This is when the US Geological Survey team called Susan. They knew she had been working on developing pollen dating for years.
The really critical thing about dating the pollen is you have to have really pure pollen. You can't have a bunch of algae or other aquatic material, or carbonate minerals, or things that are made in the lake water.
To perform AMS measurements on pollen, scientists need at least 50,000 pollen grains. And the more grains, the more precise the date. Thankfully, with the help of a flow cytometer, a machine that separates grains individually, producing pure pollen samples, the team at CAMs was able to isolate clean samples and send them to Susan for analysis.
It turned out that the pollen dates pretty much confirmed the rupiah seed dates. And so the footprints really are, as far as we know at the moment with the evidence we have, something like 23,000 years old.
Thanks to the ultra-sensitive isotope work at CAMs, these footprints are now considered the oldest reliable evidence of human presence in North America. Rewriting a key chapter in the story of human migration and adding 7,000 years to their history living there.
There has to be so much humility to say, "We don't know anything, anything about what people were doing in the Western Hemisphere for those 7,000 years, and what other people were doing 23,000 years in other places." Right? Suddenly, we have to go, "Oh, we know almost nothing." And that is pretty cool.
Members of the CAMs team at Lawrence Livermore National Laboratory aren't just unlocking the past. They're contributing to the future. Their work extends into biomedical research and drug development, like the new compound to aid in fentanyl recovery and prevention, mentioned in part two of our Forensic Science Center episode, or the biomedical breakthrough on what most scientists assumed was impossible.
Dating DNA.
No one had ever tried to date DNA because we always said, "Oh, it's too small. There's not enough there. You can't purify it."
However, Bruce Buchholz and his collaborators Jonas Sprezian and Kirsty Spalding at the Karolinska Institute decided to try. By dating DNA in the brain, they found that neurons don't turn over. The neurons you're born with are the ones you keep. With one exception.
Neurons in the hippocampus do turn over. And hippocampus is where memories get transferred from short term to long term.
By using accelerator mass spectrometry, scientists can trace the lifespan of brain cells with incredible precision, revealing when neurons are formed, how they age, and whether they regenerate. This discovery has helped shape how scientists understand the brain.
Some of the projects that we've been involved in really changed the way people think of things.
Accelerator mass spectrometry is helping scientists navigate concepts that feel unreachable: identifying unknown individuals, rewriting human history, tracing how our brains age, and beyond.
There's just lots of things that can be done now that couldn't be done 20 years ago. They're new tools all the time.
We're always trying to figure out what we can do better, what kind of scientific measurements we can make that we can't do now. If we would just modify or improve the accelerator system, what new science, what more science, what better science we can do.
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Page updated October 31, 2026 · transcript and summary are machine-generated