Podcast: Probing the odor of decomposition at a body farm

Research at body farms—research facilities dedicated to studying what happens to human bodies after death—supplies law enforcement with valuable information about the process of decomposition in various scenarios. This month, Stereo Chemistry is sharing an episode of Orbitals that features an interview with forensic chemist Shari Forbes, an expert in human decomposition who studies the odors of decomposition at a body farm in chilly Quebec.

Find more stories from Orbitals on the American Chemical Society’s website, acs.org, or wherever you listen to podcasts.

Subscribe to Stereo Chemistry on Apple Podcasts, Spotify, or wherever you get your podcasts.

The following episode transcript was provided in part by Orbitals.

Kerri Jansen: Hi, Stereo Chemistry listeners. While our show is on hiatus this summer, we’re sharing a selection of stories that have been curated just for you from some other podcasts we think you’ll love. So far we’ve brought you stories from My Fave Queer Chemist and Distillations, from the Science History Institute. This next one we sourced a little closer to home.

We’re about to hear an episode of Orbitals, a podcast from the American Chemical Society. ACS also publishes Chemical & Engineering News, which is the independent news outlet that powers Stereo Chemistry.

On Orbitals, host Sam Jones digs into chemistry tales you didn’t know you needed to know. In the upcoming episode, Sam talks with forensic chemist Shari Forbes about her work at a research facility that’s dedicated to studying the decomposition of human bodies—more commonly known as a body farm. Shari specializes in studying the odors a body emits during decomposition. In the episode, we’ll hear about how this smelly job can help law enforcement in homicide and missing-persons investigations and what surprising things decomposition research has revealed. And if you’re wondering, how exactly does a scientist collect odor molecules from a decomposing corpse? Well, we’ll hear that too.

You can find more stories from Orbitals on the American Chemical Society’s website or wherever you listen to podcasts.

And now, without further ado, Orbitals.

Sam Jones: Imagine a large, fenced-in field—maybe some trees, rolling hills, small bodies of water. Now imagine dozens of human corpses purposefully and strategically placed throughout that field. Some of these bodies are buried, some are above ground, some are clothed, some not, others are submerged in water or maybe placed in a car. This place is called a body farm.

This week on Orbitals, we’re talking about death—more specifically what we can learn from the decomposing bodies we leave behind.

The first body farm was created by anthropologist Dr. William Bass in 1981, at the University of Tennessee. It was named the University of Tennessee Anthropological Research Facility—“body farm” is the more casual term for facilities like these. On a body farm, scientists collect information from donated corpses every day and that helps them understand how things like weather and the positioning of a body will affect human decomposition. And the idea is that, if we can better understand the science underlying our decomposition, then that knowledge can be used to help law enforcement not only find the bodies of victims—who are often murdered—but figure out how they died.

Right now there are a dozen body farms across the world. Nine are in the US, one is in Australia, another in the Netherlands, and now a new facility is opening in Quebec, Canada. And it will be REALLY cold, which will allow researchers to monitor how a decomposing body is affected by snowfall and subzero temperatures, information important for law enforcement and forensics teams to know if they’re trying to figure out how long a victim has been dead and what caused their death in places as cold as Quebec.

The facility will be run by founding director and forensic chemist Dr. Shari Forbes. Shari studies the odors our bodies release as we decompose.

Shari Forbes: My research is focused very much on understanding probably the worst part of decomposition, which is the odor, and trying to determine how cadaver-detection dogs use that odor to search for and locate human remains. So the majority of my research is about trapping that odor, chemically profiling the odor, and then correlating what we see from a chemical perspective with what the dogs actually tell us in real life.

Sam: One of the compounds Shari and other researchers have detected when a corpse is decomposing is dimethyl sulfide, which has a characteristic rotten egg or cabbage smell. And cadaver dogs can pick up the scent, meaning it tells them: “hey, there’s a dead body here.” But dimethyl sulfide is just one compound of the many we emit as our body breaks down, and Shari is after all of them.

Shari Forbes: Because people can donate their bodies to the study of human decomposition, we can use these real scenarios to collect that odor on a daily basis. So once a donor arrives at our facility, we will place them in a scenario that would mimic some kind of search strategy that we would follow, whether that was looking for a missing person who had simply perished on the surface or a victim of homicide who may be concealed in a burial. And we’ll recreate that scenario and then we’ll visit every single day to collect the odor. Uh, we do that in very small tubes and then we take those tubes back to our laboratory. We chemically analyze the gases and we try to understand what comprises that odor. So in other words, we’re trying to identify the volatile compounds of which there are hundreds, how that changes with the decomposition process. And of those hundreds of compounds, which ones do the dogs actually use when they’re searching for human remains in an outdoor scenario.

Sam: So, I asked Shari, how does one go about collecting an odor? Because that was something I was having some serious difficulty wrapping my brain around.

Shari Forbes: Odor collection is challenging because it’s just present in the air. But what we do is we actually place a large aluminum hood over our donors for a very short period of time. It’s only 10 to 15 minutes.

Sam: So yes, imagine a large aluminum shell—or a range hood, if you’re familiar with that term—placed over a corpse to trap odors in.

Shari Forbes: And what that does is it contains the odor around the body and it gives us a targeted source that we can actually collect from rather than just collecting from the air naturally.

Sam: That air under that hood is then pumped into small tubes, which Shari then takes back to the lab to analyze what odorant molecules are in there.

Until I spoke with Shari I wasn’t aware of how hard it can be for a dog to sniff out a victim. I guess shows like Criminal Minds and CSI kind of warp our concept of reality. On TV, you see police dogs locate a body within hours of a murder. But in real life, it’s often not that quick or straightforward.

Shari Forbes: With the odor analysis and odor profiling, it is about enhancing the way we train the dogs. So I always say the dogs are only as good as the odor that they’re trained on. And if they’re not trained on real human decomposition odor, then we cannot expect them to find human decomposition odor. It’s about understanding which compounds they detect and then determining how we can incorporate that into their training so that they better identify those compounds and essentially ignore all the background compounds that they’re being exposed to on a daily basis. And the challenge in this scenario is ensuring that they can differentiate that human decomposition odor in challenging environments such as a mass disaster where we have a lot of naturally decaying organic matter that produces very similar odors.

Sam: So when Shari says mass disaster she’s talking about things like hurricanes or earthquakes, where a lot of people die but their bodies are often covered up by rubble, fallen trees, dirt, and all of the odors created by that [material] makes it more difficult for dogs to find the victims. Shari’s work will help law enforcement condition dogs to distinguish a decomposing human corpse from . . . all that other stuff.

So let’s say law enforcement does uncover a corpse. It’s hard to tell if it’s been there for 5 years, or 10, or even 50, and being out in snowy weather, partially submerged underwater, or buried in the ground, bring in additional factors that make that time-of-death window even blurrier. Ideally, police would find a corpse, find out how old it is, and then sift through the missing persons records from that time frame. Shari’s other work is trying to make this a reality.

She looks at what compounds break down and are created as we decompose. And she’s after the ones that have a predictable pattern. In other words, ones where we can say: “the tiny amount of this compound means this person has been dead for, at most, 4 years” or “wow a lot of this compound has built up—this person has been dead for at least a decade.” To do this, they collect tiny tissue samples from donors every day using a biopsy needle, and then often look at the fats and proteins in that sample because they actually stick around for a while. Shari says they’ve even found fat products in grave soil where a person was buried more than 50 years before.

In my conversation with Shari, I couldn’t help but ask her if there was anything she was shocked to see in the time she’s spent with decomposing bodies. And this next story really stuck with me:

Shari Forbes: So we’ve had a donor who underwent chemotherapy prior to death and that completely changed the rate of decomposition. The body is effectively toxic and insects, being extremely intelligent invertebrates, can recognize them. So they are not interested in approaching the remains as they normally would be. They don’t lay their eggs, we have no insect activity. And it completely changes the process in that the body preserves to a degree until it’s no longer toxic. And I can honestly say before we had these facilities, we would never have known that because we don’t have studies with animals who have had chemotherapy and we don’t have studies with animals with high levels of illicit drugs, which also has a similar impact. So there’s all these anomalies that we sometimes have to go back and look at the medical records and say, why is this occurring? And then once we understand it, we can, we can think about that for future, but we certainly can’t replicate it. Every donor is unique.

Sam: Death and what happens to our bodies after we die has always intrigued me, but I’ve also always had some trouble getting past the squeamish stuff that would come with studying it, and that kept me from ever pursuing that kind of research. So I found it really interesting to talk to someone who did. I asked Shari if she always knew this work was her calling or if she kinda just fell into it.

Shari Forbes: So I studied forensic science, specifically forensic chemistry when I was at university. I wanted to study a science degree that I could clearly understand what the application was going to be. So I studied forensic science before CSI and Bones and NCIS before anyone knew what forensic science was. And I think, to me, forensic science had a clear application to society so I could understand who I was helping in terms of the police and who they work for in terms of victims and their families. So that was the draw card for me. And then, when I was in my forensic science degree, we had to conduct a research project and I chose one that was completely new and different to what we’d done. This project was trying to understand why bodies in a cemetery in Sydney, Australia were not decomposing. And after studying these human remains in the cemetery I just loved the research and recognized that this was an area that needed a lot more research, particularly in the forensic field.

Sam: Now you may be wondering why those bodies weren’t decomposing. It turned out that the bodies in one corner of the cemetery were slightly downhill of the others and closer to groundwater. So, those particular bodies were becoming waterlogged, and that caused them to form something called adipocere—a waxy substance that comes from body fat and happens to preserve tissue. Why did this matter? Well, in Australia, grave plots are often leased—usually for between 25 and 75 years—and then the remains, which are often just bone, are removed so that the grave space can be reused for the next person. But these waterlogged bodies were making that swap difficult. Shari actually thinks they’ve now stopped using that corner of the cemetery. Seems like a good call.

So after graduating from the University of Technology Sydney, Shari became a professor and founding director of the undergraduate forensic science program at the University of Ontario Institute of Technology. And, following that, she returned to Sydney to spearhead efforts that led to the creation of the Australian Facility for Taphonomic Experimental Research whose acronym is A-F-T-E-R. After. Pretty clever. And now Shari’s back in Canada, as the director of the body farm in Quebec that will open later this year.

I was actually directed to Shari by a researcher at a different body farm, who focuses on forensic odontology—seeing what happens to our teeth as we decompose. He’s also optimizing victim DNA recovery . . . from maggots—in other words, getting a victim’s DNA from the digestive system of maggots that have been feeding on them. It’s a technique that’s especially important when a corpse is in a state that’s harder to recover DNA from, like if they were badly burned, or in the case that a victim’s body has recently been moved from its original location. If there are maggots left behind, law enforcement could identify the missing victim. Crazy, right? So, that made me made me wonder, how broad is the research done at a body farm?

Shari Forbes: The scope is enormous. I was previously the director of the Australian facility for taphonomic experimental research. And in the 3 years that I was the director, we had more than 30 disciplines who worked at that facility. So I’m a chemist and I collect odor, but we also had chemists focusing on fingerprint recovery. We had them looking at textile degradation, hairs, and fibers. Then we had biologists who would collect DNA. They would look at the microbiome, the bacteria influencing the body, the bacteria in the soil. We had geologists of course interested in the soil, anthropologists and odontologists and the list just goes on. And for us, these facilities are all about collecting the most data we can from every single donor that comes to us because their contribution is truly invaluable.

Sam: Body farms have now been around for almost 40 years. I asked Shari how far she thinks we’ve come in that time and what some of her hopes are for the future.

Shari Forbes: We have already made advances in terms of understanding the decomposition process since the 1980s when the first facility opened in Tennessee. So what we knew then was very little compared to what we know now. I would like to think that we can estimate time since death slightly better. Perhaps not as accurately as we would like, but we at least have a better understanding of how quickly a body will decompose in our local environment.

Sam: The future of Shari’s work, and the work done at every body farm requires . . . bodies. And those bodies are donated. So, I wanted to know—what’s that process like?

Shari Forbes: Many facilities have a radius in which they’ll accept donors. And so you need to live in that radius at the time of death. Other facilities such as the facility in Australia being the only facility currently in the country, our radius was most of Australia. We would take donors from all over because we wanted to have that opportunity available to anyone who was interested. But if a person decides they wish to donate, typically they will contact the directors such as me. They often ask, what’s the process? Can I send them the forms which we’ll do and we’ll ask that they contact us if they have questions, which they often do just out of interest or just wanting to know exactly what’s going to occur at the time of death so that they can share that information with their family. And once that person has consented to donate, they’re typically provided with a donor card, which looks kind of the same as a license. We ask that they carry it with them at all times, that they notify the relative or the relevant senior next of kin. If that’s a lawyer and just to ensure that at the time of death, the right people know who to contact and how to contact us.

Sam: But, even if someone is within the appropriate radius to donate their body, there are still certain circumstances that would keep them from being able to.

Shari Forbes: There are some exclusions which we always tell the donors about, particularly if they die of an infectious disease or some other limitations that are placed from a legislative point of view, usually based on provincial state or federal law. And we like to make sure the donors know that, so there’s no surprises for them or their family at the time. But otherwise it’s, it’s like filling any form, returning that form, and making sure that they understand what it is they’re donating to and that we address any questions or concerns they have before they actually consent.

Sam: Although much of our conversation focused on body decomposition and victim recovery, Shari continued to circle back to the gratitude she has for the donors who make her research, and the research of her colleagues, possible.

Shari Forbes: The thing that I’ve been most surprised about actually has nothing to do with decomposition. It’s about the generosity of our donors. And we honestly didn’t know how many people would be interested in donating to this type of research when we first started. And the numbers are huge. They just keep increasing. People are so excited about what we do; they understand what we do; they recognize the implications; and we get calls almost on a daily basis of people who just want to give back to society and particularly who say they want to help victims and their families. And I think from a general public perception, often as you mentioned early on, there’s a lot of morbidity associated with these facilities and people think, “oh, it’s gross”. “Why would anyone want to donate?” But the reality is it’s very different. We have thousands and thousands of people every year who want to donate to this cause.

Sam: And so my next question for Shari felt like a pretty obvious one. Does she plan to donate her body to a body farm?

Shari Forbes: I have written in my will and my family know, because I know the process, that I would like to donate to science. The reality is I move a lot for my work. I love new challenges and I don’t know where I’ll be at the time that I die. And so it’s difficult for me to sign into one facility, uh, particularly if I’m not in the same state or country. So I’ve just made a general commitment, which my husband of course knows, that I donate to science to the nearest facility, whether that’s forensic science, medical research, anatomical research, or perhaps we have a new type of research that we can donate to by that time. So that’s my commitment to science. Uh, of course I couldn’t do what I do if I wasn’t willing to make the same contribution that our donors make to us.

Sam: I found that having this conversation with Shari was enlightening in a bunch of ways. I’m not going to lie and say that I’ve come to terms with my mortality, but I will say that learning about body farms and the good that can come from them has provided me with something that I can think about when the thought of death is too overwhelming. It’s the idea that, even when we’re dead, we can still be contributing to something greater. We can be helping law enforcement and forensic teams bring peace to those who have lost loved ones and need answers.

Shari Forbes: It’s natural for the human condition, for our culture to feel that this is a taboo topic to talk about. And we understand that most people do have a fear of death or at least feel anxious when they think about that. But for me, yes, I deal with donors everyday. I deal with their families and I am exposed to death on a very regular basis. And I. . . I can certainly say it has changed my perspective. I’m much more comfortable talking about it to my family, to my friends on podcasts, whatever it might be. And I actually kind of enjoy talking about [it] because it does raise an awareness about the need for people to talk to their families and to know what they want at the time of death. Too often we have families saying, I don’t know if this is what they wanted. I don’t know what kind of research they wanted to contribute to. And so for me, it’s a good thing that we can talk about it more. Once people do talk about it, they actually realize it’s not that bad. It often reduces their anxiety. They can be quite scientific about it rather than emotional. And ultimately, our donors just focus on the positive, which is what they’re giving back to society. And I think the positive thing of body donation is the family then can focus on that positive as well. So even during their mourning process, they can be thinking, gosh, imagine what dad’s doing right now in terms of helping forensic science. Um, and that does bring a smile to most people’s face. So yeah, absolutely. It’s changed my perspective and I like to think I’m much better at talking about it now than I was 10 years ago.

Sam: Thanks for listening to this episode of Orbitals, a production of the American Chemical Society. If you liked this episode, please subscribe!

This episode was written and narrated by me, Sam Jones, and edited by David Vinson. Our executive producer is George Zaidan. Our guest was Dr. Shari Forbes. We’ll see you in December.

Kerri: You’ve been listening to an episode of Orbitals, presented by Stereo Chemistry. Stereo Chemistry is the official podcast of Chemical & Engineering News, which is published by the American Chemical Society. Thanks for listening.