An artist’s rendering of Brazil when the Giant Sloths reigned. The picture appears on a poster featuring Alex’s work.

Master Dater

What it means to be a Geochronologist

“Do you know radiocarbon dating?” Dr. Alex Cherkinsky, a senior research scientist at CAIS, sees the answer in my guilty facial expression. He searches his desk for pen and scrap paper. “I will show you. If you’re going to work here you should know.”

He doesn’t seem like one to enthuse. He is stoic in the colloquial sense of the term. A gruff-seeming Russian with a thick, gravelly accent. But the lengths he goes to in order to explain the core of his life’s work— sketching graphs, comparing data from his own AMS tests, writing out figures and calculations, patiently watching my face for signs of confusion as he speaks — demonstrates a kind of passion that words can’t do justice.

Because radiocarbon dating relies on 14C (Carbon 14), the method is limited to mostly organic objects that are under 50,000 years old. Still, it is a useful tool in the endeavor to satisfy human curiosity about the past. How has the climate changed over the millennia? Why did certain species go extinct? How did ancient humans survive? Do these elements relate in a given place during a given time period?

Alex entered the field of geochronology over forty years ago. He specializes in determining the age of objects. At CAIS he has analyzed just about everything under the sun. In one instance, he re-determined the age of a mummified steppe bison called Blue Babe, an apt allusion to Paul Bunyan’s giant ox. Originally dated at 36,000 years old, Alex found it to exceed the limit of 50,000 years. Keeping with the theme of mega fauna, he has also researched the extinction of giant sloths in Brazil. From Puru, he’s dated Incan quipus, which are impressive pre-literate modes of record-keeping. And in a rare forensics case, he dated human scalps found in the basement of a drug dealer post-bust. He has even showed up on two documentary series — one about mummies and one about the controversy over digging up and testing Native American bones. I searched the Internet far and wide for clips of these documentaries to no avail.

Quipu are composed of one cord from which pendant cords hang. The knots in this quipu represent decimals.

When he came to CAIS in 2006, Alex was a seasoned veteran in his field. He started working with radiocarbon dating during his university years and continued that research on into his time at the Russian Academy of Sciences. RAS is an exclusive society of Russian scientists who are elected based on merit. So it’s a pretty big deal. The collapse of the USSR brought him to the U.S. and eventually he made his way into the CAIS laboratories where he immediately began applying his experience.

The University of Glasgow runs a program wherein labs across the world submit samples of their work in radiocarbon dating. The lab compiles all the samples and plots the data on a graph so that other labs can see where their precision ranks among competitors. It was Alex’s suggestion that CAIS participate in the program in order to check the precision of their methods and improve them where needed. It was also Alex who helped convince the team at CAIS to invest more into Accelerated Mass Spectrometry (AMS), an improved radiocarbon dating technique. With AMS, scientists can date sensitive material such as paintings and sculptures with minimum damage.

The skull of a steppe bison found in Alaska. Alex analyzed samples from the remains of a mummified steppe bison, preserved in ice for tens of thousands of years.

The application comes in handy. Alex has dated a few wooden sculptures, one from the Chinese Warring States Period and another from American colonial times. The latter, which he confirmed to be 400 years old, later sold at Christie’s in New York for an obscene amount of money. For those who haven’t heard of it, as I hadn’t, Christie’s is a posh organization that auctions off expensive and rare art.

“The thing was very primitive,” Alex said, laughing, “I wouldn’t buy it for even thirty dollars.”

He is candidly funny like that throughout our two-hour conversation. When I asked why dating old objects is important, he shrugged.

Alex Cherkinsky, geochronologist at CAIS

“Why are people interested in life 10,000 years ago? I don’t care about life even 100 years ago. How does it affect me?” Alex said.
Given his line of work, I’m not entirely convinced. He concedes, of course, that value lies in understanding climate change and its effect on environments, flora, fauna, and us. (See Carla Hadden’s application of radiocarbon dating to modern fisheries.) And while I’m sure he appreciates the practical applications of geochronology, I suspect the reason he’s worked in this field for four decades has more to do with this simple fact: he loves it.

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