Death Clock


National Institute of Allergy and Infectious Diseases

By Mollie Putzig

Life after death may reveal when someone died, and it might even help catch a killer.

Normally, clues like body temperature and insect larvae help forensic scientist determine time of death. But microbes, bacterial organisms found by the trillions throughout our bodies, may offer a more precise measurement–especially for longer time periods.

Some people donate their bodies to this research. Their corpses lie in the tall grass of a pine forest at the Southeast Texas Applied Forensic Science Facility, commonly called a human body farm. Scientists take samples of their skin and the soil beneath them to study how communities of microbes change as bodies decompose.

Jessica Metcalf, an evolutionary biologist working in the Knight Lab at the University of Colorado Boulder, researches the postmortem microbiome, those tiny organisms that decompose us after we die. By tracking these organisms over time, she’s building a microbial clock to calculate the time since something, or someone, died.

On a normal day, Metcalf studies the microbial communities of dead mice. By scrutinizing the organisms living on their skin, she can calculate the rodents’ time of death within a few days.

“With this experiment what we found is that we could actually build a model and predict with really, really high accuracy how long an unknown sample had been dead,” Metcalf said.

Metcalf recently visited the body farm to determine if humans have a microbial clock like she’d seen in the mice. She said the microbes in the skin and soil samples from the body farm look promising.

“One of the things we’re trying to understand is, ‘how much of the decomposer communities associated with the mice are shared with the decomposer communities associated with the humans out in Texas?’” Metcalf said.

She and Sybil Bucheli, a forensic entomologist with Sam Houston State University who works at the body farm, hope their research of living organisms that grow on the dead can someday assist criminal investigations.

Every person has a unique microbiome, a bacterial signature that can’t be forged, according to research from the Argonne National Lab. Everywhere we go, we leave behind some of the living community that makes up our microbiome, like a time-stamped fingerprint.

This could allow crime investigators to identify the last people to contact a body before or after the person died.

Metcalf is conducting a second study of decomposing mice and their microbes. In her first experiment she placed 40 dead mice on boxes of soil. To make sure the only difference between them was the amount of time since death, she used mice that were all males of the same age and breed that were fed the same food.

“We just want to understand if there’s a pattern there before we get to the question of, alright, how do these various variables interrupt it?” Metcalf said.

Once she found evidence of a microbial clock, she repeated the experiment using various soils to see if soil type affected which microbes grew. She found that placing mice on desert, grassland or alpine soil didn’t significantly alter microbe growth.

She also tested the soils 10, 20 and 30 days after removing the mice, to see if postmortem microbes remain in soil over time.

“They did,” Metcalf said. “So that’s a big part of our second paper.”

If distinct human decomposer microbes remain in the soil, then soil samples might even help locate a buried body.

That’s still a long way off, she said, but Metcalf is confident that studying the life that depends on death could lead scientists to a microbial death clock.

BMFF 2014: A Geography of Blood and The Last Ocean


Speakers Candace Savage and John Weller took audience members from the end of the road to the end of the world Thursday morning at the Banff Mountain Film and Book Festival, showcasing their respective work on the prairies of East End, Saskatchewan, and the Ross Sea in Antarctica.

Though some may herald the death of print, this year marked the first time the festival’s book events sold out in advance, noted MC Bruce Ramsay. And it was for obvious reason.

The Prairie

GeographyBloodJacket_Final_rep13.indd“Prairie bashing is as old as the written record.”

In the opening minutes of her presentation of her book A Geography of Blood: Unearthing Memory from a Prairie Landscape, Savage didn’t waste any time beating around the bush.

Her 2012 book, which she describes as a love affair with the landscape of Cypress Hills, Saskatchewan, may seem out of place at a festival dedicated to jagged mountain peaks and snow pack, but the flat-lander made it a point to mention East End still sits at a higher elevation than Banff itself.

“It’s funny that these little bumps are being included at Banff,” she says. “In Canada, the Cypress Hills are the highest landform between the Rockies and Quebec, but they’re not very rocky, and they’re not very mountainous.”

Regardless, Savage’s peaceful prose and contemplation on the 600-person town located in southwestern Saskatchewan (despite its name of East End) more than held its own among the mountain fare.

For thousands of years, the hills have been a refuge for people. Surviving teepee rings serve as an erosional remnant of the people and bison that once roamed the plains.

“The book is haunted by the question of “Who are we? The settlers of Western Canada,” says Savage. “Perhaps it’s time we reconsider where that story began and the ecological and humanitarian violence that occurred.”

Admittedly, the book’s memoir-style a bit of a departure for Savage who often writes in the removed third-person about nature and social history.

“With this book, I knew fairly early on that there was a story at the heart of the book that people like me avoid—we’ve been avoiding it successfully for 140 years,” she says. “I knew that in order to encourage my readers to face this story, to face these truths, I needed to be there as a presence.”

After an artist’s residence at famed historian Wallace Stegner’s boyhood home in East End, Savage and her partner returned to the arid landscape the next year and purchased a home.

“The second time we went there, it began just as a feeling of being there for a reason. And because I worked as a writer, the reason had to be writing,” she recalls.

Still, Savage spent nearly eight years working on the novel which would go on to win the Hilary Weston Writers’ Trust Prize for Nonfiction in 2012.

“The land did all the speaking, but there were many hours spent in reading microfilm,” she says of the process. “The land posed the questions, and sometimes the microfilm held the answers.”

For years, Savage pored of archives of Indian Affairs, even going so far as to meet with an elder from the Nekaneet First Nation, and members of the Narcisse Blood of the Kainai First Nation.

The story, Savage says, can be very dark.

“One of the things that we’ve done in this country is frame our story so it conveniently begins in an empty landscape, and that way we don’t have to take responsibility for the displacement and the destruction that made is possible for us, as settlers, to be here,” she says. “I’m not sure what the cost is for not owning that pain.”

Yet, there is still an abundance of beauty in the flat land. Part-memoir, part-history, part-geological survey, part-lament, Savage’s reading of her book left the audience transfixed by descriptions of nesting birds and paddling minks.

“I’m not a high adrenaline person,” notes Savage. “This is more of a high octane emotional journey that I’m offering. You can go higher, you can descend faster, but this is a chance to go deeper.”
The Ice 

51cW9t2GbxLIn Antarctica’s Ross Sea, time ceased to exist for photographer John Weller.

“All you can think about is not throwing up,” says Weller. “With 30 to 40 degree rolls among the waves, you can basically walk on the walls of the boat.”

The Ross Sea is the windiest, driest place on the planet, but also one of the most diverse.

Here, Emperor Penguins and Adelie Penguins coexist with killer whales and Antarctic tooth fish. More than 500 miles of jigsaw ice floes extend to the horizon, where they meet 1,800-foot high icebergs, rising up from the ocean like jagged teeth.

It’s also one of the last pristine oceans, says Weller, who spent nine years working on the project, aptly titled The Last Ocean.

After scrolling through countless photos of charismatic penguins, bursting forth from the ocean’s depths with a “bridal veil of bubbles,” and bizarre creatures that dwell under the ice, Weller stopped on two maps showing “Catch per Unit” effort in 1965 and 1995. Catch per unit shows the effort it takes to catch a fish with a single book. In the 1960s, only a few hotspots stood out on the map as areas where fish had been greatly depleted. By the mid-1990s, nearly all of the world’s oceans had reached this point, leading Weller to raise concerns about “The End of Fish.”

Since 1965, we’ve eaten between 70 and 90 percent of top fish, he says. “Our grandchildren could see the end of fish in their lifetime.”

His presentation led one audience member to conclude that much like the hundreds of thousands of bison which once roamed the prairie, fish, too, once so plentiful, may soon be ecologically extinct.

Banff Mountain Film & Book Festival: Radical Reels and Sufferfest 2

Screen Shot 2014-11-05 at 8.16.32 AMWhether you’re a dirtbag or a dreamer, it’s enough to make your stomach drop—thin ice, raging rapids, and daring heights. For the 39th year in a row, the Banff Mountain Film and Book Festival compiled a sweaty-palm series showcasing some of the “raddest” adventure athletes around, including big mountain skier Angel Collinson and “dangerous dork” climber Cedar Wright.

The film serves as a follow-up to Wright’s and famed climber Alex Honnold’s original jaunt around California, where they climbed each and every one of the state’s 14ers (mountains with elevations over 14,000 feet) while taking a blistering bike ride from peak to peak in just over 20 days.

This March, the duo chased desert towers in the Four Corners, travelling from southwestern Colorado to Utah to New Mexico, and lastly to Navajo land in Arizona, where they worked to install solar panels through The Honnold Foundation.