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How old are you? Or more precisely, how old are your cells...the cells in your liver, or your spleen, or your brain? It's a question that's harder to answer than you think. That’s because some cells are born after you are, sometimes many many years after, but we’re not really sure which ones, or when — it’s not as if there are cellular birthday parties, marked by balloons and cake. So the question of age remained relatively unanswered until the early aughts, when scientist Jonas Frisén, inspired by work from researcher Bruce Buchholz, had an idea: what if we just look up? In this story, producer Molly Webster travels back in time, to the Cold War; way up into the atmosphere; and deep inside our cells, where a secret little signal, from a very special type of carbon is helping to answer the question: how old are we? But it’s a journey that is pressured by time. 
Special thanks to Mark Lovell, Henrik Druid, Laura Kiessling, Phil Newmark, Marc Kirschner, and Thomas Pollard 



Bruce Buchholz, Jonas Frisén and Kirsty Spalding

Produced by:

Molly Webster

Comments [10]

Geneva from New Mexico

Good afternoon,, My question is "Why could we not just get cells and the elements of the bomb and do test on them that way?"

Jan. 28 2018 12:59 PM
Wil in Golden from United States

While Mary Webster has a very interesting analysis of tissue age, she is apparently unaware of the natural production of C-14 by cosmic rays in the upper atmosphere. Atomic testing that took place in the upper atmosphere has nothing to do with normal C-14 production. I'm surprised that she hasn't heard of "carbon dating" that is done by measuring the beta emission from all organic material discovered by Willard Libby in 1949. With a constant background of C-14 being incorporated from carbon dioxide into plant material we can see half the beta emission decreasing every 5,700 years. Go to Wikipedia "carbon-14" and see what it says. Yes, Ms. Mary can apologize for not knowing that atomic atmospheric testing is not necessary for her work.

Feb. 11 2017 10:06 PM
Kurt from 78628

Aug. 19 2016 01:15 AM
Kurt from Georgetown, TX

I really want to visit Marion Island with you. I think that we need to gather more evidence about the nuclear testing that may have happened there. It will be a challenge getting South Africa to get us credentials. I think it may be worth it. Not Kidding. We need to explore.

Aug. 19 2016 12:56 AM
Kurt from 78626

There might be one nuclear event that happened in 1979 that would skew your results. It was on Marion Island.

Aug. 17 2016 12:04 AM
Paddy from P-Town

having reached the level of a 3rd grade science education (at the age of 60) i really enjoyed the poem to magnesium.

"i'd go blind watching you burn, magnesium." I have such good memories of watching this old guy use magnesium as a fuse to set off a plastic bag of settling gas back when I was not much older than a 3rd grader. I know there was so much useful information discussed but it was the poem that got me to look up the podcast so I could copy and memorize the ode to M.

please keep up the good work!

May. 22 2016 06:22 PM

Ridiculous Mary. Most detonations were tests, and a lot more people have been harmed by Alzheimer's. If we need a test detonation to figure out how the disease progresses more accurately, I don't have a problem with that. If one was done in the middle of the ocean...unless it was would never even know. It does not affect you or anyone. And it could be fairly small. We don't have to blow up an island or anything. It could be detonated at high altitude so it does not even affect the fish.

Feb. 26 2016 07:41 AM
Timo from New York

Just a small comment. Although the hippocampus seems crucial in the formation of new memories, memories are generally thought to be stored in the cortex, not so much in the hippocampus.

Feb. 17 2016 04:51 PM
Chris Carter from Dallas

#science I have started to look for podcasts for my students to listen to to better understand the real world connections to science... they are 8th graders and always connected to the web, but seldom connect to their world beyond their small circles. These element podcasts connect A LOT of info to their 8th grade brains.

Feb. 15 2016 01:12 AM

I have been a faithful fan of Radiolab for past 5 years. I loved it so much to the point I started listening to episodes released before I became to know Radiolab. Not anymore after listening to this episode. As a family member of the victim of nuclear accident, I was extremely offended by multiple comments made during this show. One particular one was "I kind of want to detonate atomic bomb again." This is NOT ACCEPTABLE TO BE BROADCASTED IN PUBLIC RADIO STATION. Producer who made this episode should meet all innocent citizens who became a victim of nuclear accident and observe the degree of their suffering. If she doesn't change her mind, she is a psychopath. You have no right to criticize teenager drinking expensive latte because you are way worse than what they are. I truly want a formal apology from the team produced this episode to all patients currently suffering from their complications from nuclear accidents occurred all over the world. I have been donating to NPR every year. I will never do it unless I hear an apology from you.

Dec. 18 2015 03:03 PM

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