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JED SPARKS: Might as well get started. My name is Jed Sparks. I'm a professor in ecology and evolutionary biology here at Cornell. Welcome. Thanks for coming out in the rain. You get used to the rain when you're here.
What I'm going to try to do today is talk about some work that I do, other people do, students do. Many of your students may participate in some of this. And the way I'm going to put this talk together is to give you some motivation, and hopefully tell you some cool stuff before I tell you how it all works. And you do that because how things work is kind of boring, so you want people to be in a good place when you tell them how it works.
So somebody's been murdered. Always start on a high note in any talk ever. You probably watch television a lot, and see these forensics kind of oriented television shows. And almost all of the methods that they present to you in those shows are true. What isn't true is the timeline at which they can do things. If I could do things at the rate they could, I'd have about three Nobel prizes, I think, about right now. But we can do a lot of the similar stuff.
So the murder I was talking about is a woman's found on the side of the freeway in Nebraska in 1985. She's still living. She's in a coma. She dies several weeks later. She's a Jane Doe for the next 18 years. And no one knows where she came from, who she is, anything about her life.
And police departments would really like to know where these people were living the six months or a year before they were killed. This allows them to focus their investigation, contact agencies and do those things. And so they contact us, and they provided us bone, hair, and fingernail material from this person. And we run what's called a stable isotope analysis on that material.
And we run two. We run one that was based on oxygen. And it has to do with the water that's found across our continent. And those waters have different signals in them. And that is all of the gray area you can see across the US. I mean, the black. Sorry, the darker black. Another isotope we use is strontium, which has to do with the age of the crust of the Earth's surface. Different ages of rock substrates have different strontium isotope ratios in them. And that's the gray area.
And so where it's red is where those two isotopes are both true in this woman's body material. So we can report back to the police that she is either from Northern California, New Mexico, upstate New York, or Vermont. And this allows them to go in. And it turned out she was from Vermont and she was a prostitute. And she had been picked up by a long-distance truck driver, and he was one of the more prolific serial killers in the US in the '80s. And he was very difficult to find because he would dump these bodies very far away. So stable isotopes were used to figure out where this person had lived before.
We do this because we can make maps of something like the US that tells you what those isotope ratios are. This is literally me and hundreds of other people around the world asking people to give us samples of their tap water, just right out of the tap in your kitchen or your bathroom. We run the isotope ratios of that, and then we can build maps of what the isotope ratios are. And we're interested in that because you're equilibrating to your tap water. What you drink and the water that's in the food that you eat is in your hair, it's in your nails, it's in every part of your body.
And you can see that a person who was living in Wyoming versus someone who's living in Florida would look isotopically very different. So we could tell the police department or, in other cases, any animal where it had been living. From an ecological, biological sense, we do much less depressing things, and ask where was a bird during the last six months, where does this mountain lion range, those kinds of things. Strontium is similar. You can measure strontium all across the US and obtain different ratios of strontium, and have a map that your body or any animal's body is going to equilibrate to where it exists.
It's not all doom and gloom. If you're not into dead bodies, you can be into fine wine. I find people fall into one of those two categories, they're either fascinated with dead bodies or fascinated with wine. The adulteration of where a wine comes from is really big business. So if you have a wine that's from the Appalachians in certain parts of France, that's a $500 or $1,000 bottle of wine. A wine grown in the Balkans is $7. But if you switch those two labels, you're suddenly selling your $7 bottle of wine for $500.
We can tell isotopically where the grapes were grown. And the wine industry loves us because we can take a syringe and we can pull the gas in the top headspace of the wine bottle without damaging the wine and tell them where the wine was grown. So things like Interpol, agencies like Interpol-- unfortunately, the business of wine and big money Appalachians isn't really relevant in the US all that much. It's not like people in the Willamette Valley are acting like they're from Napa. But in France, in Europe, it is huge, enormous, millions of dollars.
But we have looked at isotope ratios in the US. So this is sort of the wine isoscape of California, Oregon, and Washington. And so you can tell by these isotope ratios that something grown in Napa, down in Northern California, versus someone grown in the Willamette Valley in Oregon, we can tell where those grapes came from. And we can inform people.
While we're on a alcohol kind of oriented streak here, Reinheitsgebot is one of the oldest laws on Earth. It's a law in Germany. And in 1516, William of Bavaria decreed that beer can only contain hops, barley, water and yeast, nothing else. So in Germany, you can be prosecuted for having any other ingredient.
The main ingredient that's added to beer that isn't on that list is any kind of fast processing sugar, like rice or corn syrup. That allows them to make beer much faster and much cheaper. And it has a different isotopic composition than any of these. So I can tell you that wines in Germany, very few of them break the law. Every beer that you buy in the United States has yeast and corn syrup in it because they're making it as most inexpensive as they possibly can.
This was an alcoscape we built in 2015, which, if you're going to be in science and you have to sample something, beers of the world is not bad. So you send graduate students and colleagues around the world and you collect beers. And you then identify where they can come from and what they're made out of. And I will tell you that undergraduates, whoever look at my publication record, they want to know about the beer papers over everything else. So there's a high interest in beer in the undergraduate population, and so I tend to include it in lectures.
And one very fun thing is you can find out how truthful your advertising is. So if you're about my age, you grew up with every advertisement from Coors beer saying that it's stubbornly brewed in the same Golden, Colorado brewery with 100% Rocky Mountain water and high country barley since 1873. Golden, Colorado is a suburb of Denver. And so we can tell if every Coors beer on Earth is from Golden, Colorado.
If you go all the way here to the right, those two white bars, the first is what is the isotopic composition of tap water in Denver. The next one is the range of tap water values for all of the Rocky Mountains. The other are five different beers that we sampled from around the world. And one thing you can tell is three of those definitely were not brewed with water in Golden, Colorado. They were brewed somewhere else. And this is obvious. Coors is brewed in more locations than Golden, Colorado. But it basically shows they're a bunch of liars in their advertisements, which is fun.
You can look at yourself. So your body is telling the world isotopically what you eat. And if you look at a vegan compared to a vegetarian compared to an omnivore, on that scale on that side, the nitrogen scale, it's telling you where in trophic position are you eating on average.
So down at the bottom, where that number six is, that's kale. You're eating kale every day of your life. Up there at 9.5 or 10, you like polar bear steaks or something really, really top apex predator kind of thing. Along the bottom, that carbon scale is where does the carbon come from that you're eating. Towards the more negative side, that tends to be wheat, barley, flours. That's the European diet. To this less negative side, over a negative 18, that is corn and corn syrup. And the American diet is almost 100% based on corn, in one way or another.
So if you do your own dietary isotopes along there, you can tell, well, if I'm way over here, I'm eating a lot of processed foods. You know, I go to McDonald's a lot, I've never seen a farmers market to save my life, all that stuff. If you're way over there, you might be a vegan or vegetarian or you very much like fresh foods. You know, you're always going to the farmers market, you're never buying anything that's processed and has corn syrup added to it. Of course, you can trick people by eating fresh food, but you love corn and you eat it every day. You're still going to be over there.
So as an example, this is my friend Thure. Thure is an interesting guy. He was originally part of the Atomic Energy Commission, and then he studied carbonate chemistry. And they put him in the National Academy for Science for that. He got bored, and for the last 20 years, he's studied diets of elephants. So great guy.
And he was invited to go to Mongolia to look for fossils of ancient elephant species. And Thure said, of course I want to go. And he's a professor at the University of Utah. And what he did was, every day when he shaved, he took what was in his electric shaver and he put it in a little vial. And he brought it back and we ran it for stable isotopes. How close was his beard hair tracking changes in diet as he traveled around the world?
So if you start on this end, this is the days of the year. And he starts out in Salt Lake City. And that's Thure's normal sort of diet. He's around a negative 19. He gets on a plane, and he goes to Ulaanbaatar, which is the capital of Mongolia. Really significant shift. The diet that he's eating in Mongolia is much different, and immediately shows up in his hair.
They then take him out into the field, which, according to Thure, everything you eat is derived from a yak in one way or another. And his isotopes shift again. He goes back to Ulaanbaatar, and then back to Salt Lake City. So you have this instantaneous record of what Thure's been eating. And we can apply that to anything-- an animal that we're interested in, populations of humans. My advanced ecology class this week, they are all anonymously donating their hair and we're figuring out who's a vegan, who's a liar, who says they're vegan but they're not. And it's a really, really powerful tool.
In another forensic application, we work a lot with this amazing animal. I took this picture in Namibia two summers ago, this bull elephant. And he's been clipped on his tusks to avoid poaching. And the poaching of elephant ivory is a widespread problem across Africa. But ivory that's on the market comes in three different varieties. You have the elephants that are killed illegally in Africa, and their tusks are sawed off and they're smuggled somewhere. You have what's called ancient ivory. Any ivory that is older-- if it's 19th century ivory, when it was collected in the 19th or 17th or earlier, it's legal on the global market.
In the last 15 years, we have this new influx into the market. This is Siberia. And in Siberia, the permafrost is melting at such a rapid rate that people go there with large water pumps and they scour away the banks of this permafrost and they find prehistoric ivory. They find mastodon, mammoth ivory. And they put that on the market. And they each have legal issues around it, and people struggle with it a lot globally in the enforcement.
So the tools that we bring to that are radioisotopes. And this is a record of the amount of 14C carbon-- this is the radioactive nucleotide of carbon-- In the Earth's atmosphere put there by us through testing of weapons. So shortly after World War II, into the late '50s, early '60s, there was mass testing done around the world. And that led to this big spike in the amount of radioisotopes in our atmosphere. You had the SALT II treaty that occurred about 1978, 1980. And that shut down all at least above-ground testing worldwide, except for the few examples that we've seen in India, Pakistan, and other places.
And so you've had this steady decline in radio nucleotides. And we can use these radio nucleotides because that's recorded in the elephant ivory. And we can tell how old, to within four or five years, how old that ivory is. So we can tell Interpol this is ancient ivory, this is prehistoric ivory, or this is an elephant that's been illegally poached in Africa within the last five years.
You get involved with things, this is the mid '90s. This is one seizure of elephant ivory in Hong Kong when we were there. So these can be massive sales and massive seizures. And law enforcement not only wants to know its age to see if it's illegal ivory, they really want to know where this ivory is coming from, because in order to do enforcement, they need to know was this animal illegally killed in Kenya, was it killed in Zimbabwe, was it equatorial Africa, is it an Asiatic elephant. So they want those kinds of things answered. And we can do that isotopically, as well.
So in a similar way to how we figured out where that dead body was, we can tell where the elephants came from. This is work done by some of my German colleagues who work for German law enforcement. And this was a seizure in Europe of 15 tusks. And we can take small samples of the base of that tusk and look at the hydrogen and oxygen isotopes and know where in Africa that animal was living before it was killed. So of these 15, they go all the way from southern Zimbabwe all the way up into equatorial Africa. And it allows law enforcement to focus in on where animals are being poached and where these groups of people are doing that poaching.
So I hope you're nice and motivated to think this is just the coolest thing since sliced bread, because now I'm going to teach you some of the-- let you leave with some knowledge. So what in the world is a stable isotope? Well, if you remember back to high school chemistry or college chemistry, whenever you had that, every element is defined by the number of protons that it has in its nucleus.
Neutrons, on the other hand, in the nucleus can vary. So this is carbon, for example. It has six protons and six neutrons. That's the most common form of carbon on Earth. And that's a carbon-12. However, there are some carbons that have an extra neutron. If it has this extra neutron, it's a carbon-13. This is a stable isotope of carbon.
You can continue to add neutrons. If we add another one, such that we now have eight neutrons and six, this is now an unstable element. So this is a radio nucleotide. This is radioactive. It's decomposing. Believe it or not, this will actually become a nitrogen-15 once it gets through its half-life. So we have stable isotopes and we have radioisotopes. I work primarily with stable isotopes. Easier to get through airports, don't make your hair fall out. Much easier to deal with.
So why are they interesting? Why do we look at them? And it's all because, believe it or not, that extra neutron makes any element, any process that has to deal with it, it's energetically more difficult to deal with the heavier isotope. So you have some kind of energy hill.
So if you have a process, like you're eating food and you're turning it into your body material, it's easier for your body to utilize the carbon-12 over the carbon-13. So your ratio is going to be different compared to your food because you preferred to use that carbon-12. If we have a process like diffusion, some compound moving through water, every water molecule that has a heavier isotope as part of it diffuses slightly slower than the other ones. And we can use these differences to measure differences in process or tell where something was living because the isotope ratios are different there.
Then once you understand that, you just need a lot of money to buy some cool stuff. This is my lab. These are mass spectrometers. The technology inside this one box hasn't really changed since the Manhattan Project. The first time we started to separate isotopes from one another was really refined during the Manhattan Project because we needed enriched plutonium isotopes to build weapons. However, everything outside of it has changed a lot because this box needs a pure, clean, water-free gas that we can flow in a helium stream. So if we're interested in an elephant tusk, or your hair or your toenails or whatever we're interested in, we have to turn that into a clean gas. I started with the technology in 1985.
As an undergrad working in a lab, we did all of this cleaning with cryogenic lines. So it was like you were a mad scientist. You had giant apparatus. You burned things, you froze things, you did all this, and you worked all day and you'd get six samples. And you'd run to the bar in College Town and go, yay, we did six samples. Now in my lab, we run 300 samples a day. So we've automated a lot of this upfront kind of stuff to clean it up.
Once we have that clean gas and it goes into that box, this is what's inside. There's what we call a source. And that source has a cathode and an electron beam. And it's held at 500 kilovolts. So you don't touch it. It will kill you. And it ionizes that gas stream, puts a charge on it.
And then it flies down this what we call the flight tube, which is under Ultra-Torr vacuum. And it goes through a magnetic field. And because it has a charge and it has a mass, that magnetic field impacts it and bends it in an arc. The heavier it is, the less it bends. The lighter it is, the more it bends. So you can see those lines bending at slightly different degrees. That's because of different masses.
And at the end of the flight tube, they hit what are called Faraday cups. And each time one of those ions hit it, it induces a voltage. So the two that are right together, the difference between those is the weight of a single neutron. And we can measure that difference by the amount of impacts in each one of those cups.
So how it ends up working is like, if we're going to measure carbon in your hair, we're going to turn that into pure CO2. And then we're going to ionize it and it's going to go down that flight tube, and we're going to measure three masses because, in that CO2, there's both carbon and oxygen. So the most common one is going to be a carbon that is 12, so it only has six protons and six neutrons, and oxygen-16, which is the most common form of oxygen. But rarely, we're going to have something that has a 13 in the carbon position or we're going to have something that has an 18 in the oxygen position. And then we're going to compare the amounts of both of those, and get a ratio and be able to have our isotopic ratio number which we're going to use to figure things out.
So not everything is forensics. A lot of what I do and people in isotope ecology do are ask questions about the natural world with isotopes. So one question you could ask is here, in the Arctic, we want to know what do all the organisms in this environment eat. Who are the predators? Who are the producers? Who are the herbivores? How is everything connected?
And that sounds like maybe sort of an easy thing to do, but with my luck, my job would be they take me there and they say, we need to know what walruses eat. Walruses feed at about 650 feet under the Arctic Ocean. So that would be my job. I would have to go down and watch what walruses do. It would both be very cold, very expensive, and really hard.
And so getting numbers on who eats who is really difficult. And traditionally, the way it would be done would be either massive amounts of observations, like that bird, hiring tons and tons of undergraduates to go into the field with binoculars and say, OK, what are all the food items that this bird is bringing back to its nest, or it's sacrificing animals. So for instance, those seals have been sacrificed and their stomach contents have been analyzed to figure out what the seals are eating.
All of this is a lot of work, and we don't really want to do it. So probably 25 years ago, we began to use stable isotopes. And what we figured out was that the difference between someone's diet, any organism's diet and their own body tissue is predictable. On average, it's about 3.5 per mil. So that's just a unit of isotope difference. So we can begin to use that, because instead of having to do all these observations, if we can get body material from everyone in the ecosystem, we can tell who eats who and how it's all organized.
And we would do things like that. This is Lancaster Sound in Canada. And we collected everything from kelp all the way up to polar bears in this system. And you see how it's getting more positive along that line, where your apex predators are most positive. They're the most enriched because they're all the way at the top of this food chain. The least enriched are primary producers, so things like kelp and POM is particulate organic matter. So it's all this stuff that's making its own food. Basically, it's a plant, a photosynthetic organism.
And so here, without ever going into the field, other than to get these samples, I can now make a really good guess at what walruses eat, because if you look at walrus values right there, it's between about 12 and 14. And I know that whatever that walrus is eating is about 3.5 per mil less positive than the walrus. So if we move over 3.4, we'll see, well, that walrus is either eating copepods, bivalves or kelp.
Then we have to use natural history. So kelp, walruses, their mouth morphology just does not look like something that eats a lot of kelp. Everybody know what a copepod is? All you need to know is they're really, really tiny, microscopic. Unlikely a walrus is eating it. They don't have any baleen. They're not doing that kind of feeding behavior.
So what do they eat? Walruses eat bivalves. They go into the bottom. They use those teeth and mouth morphology to dig around in the substrate in the bottom, and then they break open those big bivalves like large clams and things like that. And that's what they eat. And you've gotten all of that just from a stable isotope number.
So say you're-- got to pay attention to this one because I'm going to give you a quiz at the end, analyzing your own data-- these are three species of gulls in South America. And we don't know anything about what these gulls do. All we know is where they're nesting. So we can collect feathers from them on their nesting site, and then we can run their isotopes. And we can look at the 15 N value and the delta 13 C value.
And it can tell us two things. One is, where in the trophic position are they eating? And the other is, what's the carbon source? So just like in humans, where you say Europeans are going to be one place and Americans are going to be another, animals that eat in a terrestrial place versus animals that eat in a marine place have different carbon values.
So we've never viewed what any of these birds eat. But if we look at them, if you see that open circle on the top, it's all the way at the top, right, so it's eating at a higher trophic position compared to the other birds. In fact, that bird, which is on the top there, likes to eat the bird that's in the triangle, which is the second bird. It tends to eat its chicks. It walks around and gobbles them down during the entire nesting season, and enriches itself above it.
The open circle, or the closed circle, the black circle, it's way over here on the carbon side. And that's because that is an open ocean feeding bird. It's going out and all of its resources are coming from the ocean. So it looks very ocean-like in its isotope values.
The triangles on the other side, it looks more terrestrial, but it's kind of spread out all over the place. This is a gull species that would be bothering you at the beach. This is a very adventitious bird. It'll eat stuff from the ocean. It'll eat stuff at McDonald's. It'll be in the dumpster. It'll steal your sandwich on the beach. So it's very broad feeding habits, and it looks terrestrial and pelagic.
We do tons of isotopic measurements in plants. I'm not going to completely bore you with fancy equations, except for one slide. But basically, one of the big questions we're always asking about a plant that we grow for food or one that we're concerned about is how does it deal with getting CO2 to do photosynthesis while it's losing water. How efficient it is at doing that is very important if you want to grow this plant in a place that experiences a drought.
And this is where you all groan in my lecture because I actually give you equations, but all this means is that we know everything about that plant in terms of isotopes except for this term ci ca. And that's just a measurement of how efficient it is in using CO2 in water. So the isotope values can give you a direct estimate of how drought tolerant a plant is. So that becomes incredibly useful. So if you're trying to select a genotype to grow in, say, West Africa, where you have droughts occurring all the time, you can pre-screen genotypes and figure out which one is going to be more drought tolerant, and make that recommendation for that planting in that area.
Remember I said there's a quiz? All right. These data were collected this summer by Cornell students at our marine station. I had them go out and measure nestlings on the Isle of Shoals, where we have our marine station. And then I ran all those values. So each one of these points represents a bird. And it represents the diet of that bird.
And there's two. One is the black-backed gull, the great black-backed gull. It's the largest gull species on Earth. Very amazing animal. And the herring gull. Herring gull is the one that's bugging you on the beach on the East Coast. All right? So I want to give you about 30 seconds to look at that. And then you guys are all isotope experts now, and you'll be able to tell me something about the ecology of these two birds. And you have to do what I say because I have a microphone and I'm up here, and you guys have nothing to do with it.
And like I tell my students, you talk to each other. That's how we learn.
All right, anybody have a brilliant idea? You can just go ahead and yell one out. What do we know about the bird that's in kind of the teal color?
AUDIENCE: [INAUDIBLE].
JED SPARKS: It doesn't [? feel it. ?] You're exactly right. Yeah, it's [INAUDIBLE] which, hopefully, a lot of [? your ?] students are doing. One of the amazing things is they have [INAUDIBLE], a very [INAUDIBLE]. How old were you when [INAUDIBLE] you were probably sitting in [INAUDIBLE] exams or something [INAUDIBLE].
AUDIENCE: Well, it's this bird calling to the other bird. And it says, oh god, [? Helen, ?] [INAUDIBLE] is eating the bird.
JED SPARKS: And so [INAUDIBLE] like [INAUDIBLE] run around in the heat [INAUDIBLE] all the time. And so they're feeding a higher trophic level all the time. What about the other bird? What about the herring gull? Thank you.
AUDIENCE: It's opportunistic.
JED SPARKS: Very opportunistic, so you can be in Portsmouth, New Hampshire, and if you're eating lunch and you stare at the dumpster, the herring gull will be there eating stuff. A little more nuanced things in there. By and large, the Black-backed is a more pelagic predator. So if you look on the carbon side, it's way over here, more positive, like a negative 15, negative 14. That's because most of the things it eats, that primary production is coming from the ocean rather than the land.
Herring gulls, they're everywhere. So they're way over here on terrestrial stuff, way over here. And probably, those crazy negative 14, negative 15 values have mostly to do with their eating corn syrup. So they're literally stealing your Big Mac, because that's a corn source, which is a very different isotopic value.
All right, so the point here is, just a bunch of students going around for an afternoon, collecting a bunch of feather samples at a nesting site for a bird, you can learn all kinds of things about their ecology-- what they eat, what they do, what their behaviors are, all from information stored in isotope values in their tissues, like feathers.
I want to leave tons of times for questions. My lab uses this technology in almost every way you can imagine, everything from the aircraft picture. We use isotopes to measure and evaluate hydraulic fracturing, so we do a lot of airborne kind of measurements. We do ocean things, desert things, have cool people in the lab who show off their muscles.
I have a very large fondness for snakes. This is me handling western diamondbacks in Arizona. And I just love them, as animals. But we do almost everything. And I'd be happy to take any questions you have about isotopes. I'm also a faculty in residence in the dorm, so if you want to know what it's like for your students to live in the dorm, I might be able to give you some insight. Yeah?
AUDIENCE: [INAUDIBLE] thinking about the qualitative value of [INAUDIBLE]?
JED SPARKS: It can in the sense that-- so there's no magic value, that you can say, oh, if you get this value of a healthier diet. But it can tell you, if you're worried about corn syrup, for example, processed foods, your-- the value of your body would tell you, OK, what proportion, so if you're-- and all that up there-- but say I tell you your value in carbon is a negative 14. That means you love Mountain Dew and processed foods. I mean, that's what you're doing.
If you're a negative 31, you're pretty much eating fresh food, you-- to get that value. So yes and no, there's no magic number. But you can get a lot of information about what you're eating and then make decisions based on it. Yeah?
AUDIENCE: Why does the [INAUDIBLE] have a different basal plane from the carbon in the atmosphere [INAUDIBLE]?
JED SPARKS: Yeah, it's a fantastic question.
AUDIENCE: Yeah, [INAUDIBLE].
JED SPARKS: So the major evolutionary advance in photosynthesis is called C4 photosynthesis. So 4 billion years ago, there was an enzyme called RuBisCO, which is the primary carbon fixing enzyme on Earth. At that time it was quite warm and oxygen levels were very low.
As the atmosphere in the Earth has evolved over the last 4 billion years, temperatures have gone up quite a bit and the amount of oxygen has gone up quite a bit. And that enzyme is not very good at its job. And it will accidentally use oxygen instead of carbon. And that's called photorespiration. And it can be a 50%, 60%, 70% wasted effort by a plant in photosynthesis.
So around 800,000 years ago there was an advance in photosynthesis where instead of fixing carbon only with RuBisCO, it isolated RuBisCO in one of its cells, and then it started fixing CO2 with another enzyme called PEP carboxylase. And then it started pumping it into that other cell, and it created this environment where CO2 concentrations were super high and this photorespiration couldn't happen anymore.
And those two photosynthetic pathways result in different isotopic values. And so that PEP carboxylase, as an enzyme, fractionates differently than the RuBisCO enzyme. So anything that's C4, that uses this special pumping mechanism, is very distinct from anything that doesn't.
And a lot of our agricultural crops, we want them to be highly productive, so they'll tend to be C4. And corn is one of those. And so it's very different. It's about 15 to 20 per mil difference in isotope space. When my mom asked me a question-- she says when I ask her-- she asked me what time it is, I tell her how to build a watch. So be careful what you ask.
[LAUGHTER]
Yeah?
AUDIENCE: People are often pretty bad at estimating their diets, when you ask them. So has there ever been a study where you looked at a person's [INAUDIBLE] relative to their life expectancy?
JED SPARKS: It's been done. I've never done it. People use it for health. In sulfur isotopes, interestingly enough, that's resulted in an amount of fish oil, an amount of marine inputs you have. And so there's been significant things that are correlated with the Asian diet and the Mediterranean European diet, which tends to be more reliant on those sources leading to lower rates of heart disease, diabetes, et cetera, but no direct correlation between the two.
In terms of perception of diet, I mean, I literally used to call my lab, on hair isotopes that I do with the students, vegetarians, vegans, and liars, because there is always someone in the course that says they're a vegan, and they're not. The isotopes don't lie. We're nice to them. We don't tell them, but I'm like, yeah, you're dreaming that you're a pure vegan. So you're getting up in the middle of the night and having corn dogs or something. I don't know what's going on.
[LAUGHTER]
Yeah?
AUDIENCE: How are different [INAUDIBLE] ages. It moves around, changes within their diet. And isn't it that something about it lasts, or [INAUDIBLE]?
JED SPARKS: Different parts of your body turn over at different rates. So if I wanted to know what you ate this morning, I'd want to look at your blood plasma. If I want to know what you've been eating over the last 30 days, you'd be mad, but I'd want a little piece of your liver, just a little one. If we wanted to get an integration of perhaps most of your life, we would look at bone because bone isn't turning over very fast.
The most common human tissue that we run is hair. And why we like hair is, with your length of hair you probably have a year and a half record of your diet. So we could take your entire hair length, cut it up into little pieces like that, and I could reconstruct where you've been. So if you-- like say you spend your summers in France. I can pick that up in your hair while you're on a French diet. Obviously, no one can tell where I've been.
[LAUGHTER]
So cut your hair so no one can tell. Yeah?
AUDIENCE: [INAUDIBLE].
JED SPARKS: I wish. Yeah, that would be a-- that would be a great parent weekend thing to do.
[LAUGHTER]
We should try and do that. We'll have two meetings. We'll find out who's lying about being a vegan. It'll be super fun.
It's about, for courses, like for example, I collected the students' hair on Wednesday, and I'll be able to give them their numbers on Monday. So it's pretty fast, but probably not in one day. Yeah?
AUDIENCE: Is there another isotope you can use over the [INAUDIBLE]?
JED SPARKS: Almost every element has an isotope. There's a few, just because of the chemistry, it doesn't-- phosphorus is a good example-- it doesn't have a stable isotope. But laboratories basically separate into two kinds-- the light isotope labs and the heavy isotope labs, biology forensics versus geology. So I look at carbon, hydrogen, oxygen, nitrogen, and sulfur. Those are the five that I use.
And then the instruments that I have, their magnetic capability and their ability to make something a gas are tuned to things that would be like that. We call it, what matrix is it in. So the hardest matrix that I deal with would be like a carbonate rock.
If you went down the hill to some of my colleagues in Earth and atmospheric sciences, they may be interested in what are the isotopic ratio of a piece of granite. I don't have the ability to make that into a vapor. I don't have ability to make it into a gas. Down there we use what's called an ICP, which is an ion cannon, which will actually vaporize rock. So you can measure an isotope ratio of almost anything, except for a few exceptions. But it would depend on whether or not you have the technology to make it into a gas or not. Yeah?
AUDIENCE: [INAUDIBLE] the same within the body?
JED SPARKS: Is it the same within your body? It varies because of these turnover times. So like if we tested every part of your body right now, things have probably changed through your lifetime. So it's very likely that your bone is different than your plasma is different than your muscle tissue because of turnover times. So one's turning over and equilibrating very quickly, and one's doing it very slowly. So there's quite a bit of variation through your body. Yeah?
AUDIENCE: [INAUDIBLE] analysis when you [? have ?] bleached hair, dyed hair, or graying hair?
JED SPARKS: Graying, not so much. Bleaching, especially really hard, rough hair treatments, can have an effect on it. So we try to steer clear of bleach blondes, I guess. Yeah, it can have an effect. So there's what's called isotope transfer. So the thing that you're interested in, some chemical treatment could have made some of those elements transpose with each other.
We run into it in things like fish that have been stored in alcohol for 100 years. Obviously, we'd really like to know the isotopic ratio of a 100-year-old fish. We have to be very careful because there's been some isotope switching with the formaldehyde or whatever it's stored in. Yeah?
AUDIENCE: In talking about tap water, and you said that's quite a bit, how fast is tap water [INAUDIBLE] tap water [INAUDIBLE].
JED SPARKS: So the isotopic value of something doesn't really have any relationship to how good it is. So I can only answer that question, that I lived on 42nd Street and Fifth Avenue for two years and my tap water was awesome.
[LAUGHTER]
So an interesting thing with tap water is in that whole, how big are people liars? The bottled water industry is really bad. So we can isotopically tell. And there's a reason that Evian is naive, if you spell it backwards. It's coming from all sorts of different sources. The one true producer of bottled water that we found is Fiji. Fiji water is from Fiji. So go buy Fiji water if you like fancy water because it is actually from Fiji. Yeah?
AUDIENCE: What is the-- are you measuring how climate change affects the regular climate-- the change--
JED SPARKS: Absolutely.
AUDIENCE: --when you go across the world and [INAUDIBLE] plants, animals, et cetera.
JED SPARKS: Yeah.
AUDIENCE: [INAUDIBLE].
JED SPARKS: Yeah, so many--
AUDIENCE: [INAUDIBLE] Biden's [INAUDIBLE] climate change in order to provide funding for government and commercial issues [INAUDIBLE]?
JED SPARKS: My understanding, most of what is in Biden's bill is policy-oriented rather than research-oriented. But the College-- this College, the College of Agricultural and Life Sciences, which you're standing in now, and the College of Arts and Sciences are both going to COPE 42 in Glasgow next week to lobby for that in the bill.
Back to your original question, isotope measurements play a big part in a lot of the estimates that we make in terms of climate change. We can tell how much fossil fuel carbon has entered the atmosphere because we can measure the isotopic value of the atmosphere. And it's changing as we add fossil fuels to it. So our estimate of how much is coming from fossil fuels is that way.
Things like carbon balances, this extra carbon-- basically, what climate change is in a nutshell is we have carbon on Earth that cycles on an annual to a 100-year timescale. That's photosynthesis, respiration, all that stuff. Then we have stuff that cycles on a multi-million-year time scale. That's volcanoes, erosion, biological pumping in the ocean to limestone subduction during plate tectonics.
Those two have never mixed together, had any problems with each other for our entire history until we extracted a part of that geologic cycle and put it into the biological cycle. And that was fossil fuels. So that's a pool. It's like 10 million-- it's supposed to sit there for about 10 million years, and we got it out in 150. And that's sort of the short circuit that has caused everything.
And because those different pools have different isotopes, we use that all the time to measure what the amount of that crossover is and all those sorts of things. So yeah, it's a big part. Yeah?
AUDIENCE: What kind of isotope analysis has it been with colony collapse in honey bees, if any.
JED SPARKS: Yeah, I'm not sure if anyone's approached the honeybee collapse with an isotope kind of approach. If someone asked me to, we could use it to look at, if you have inputs of resources to, honey bee diet that are changing, or are there differences between healthy colonies and declining colonies. But I'm not aware of anybody who's done that. Yeah?
AUDIENCE: Is there an isotopic signature in nitrogen, where you can tell the difference between [INAUDIBLE] or from the cancer?
JED SPARKS: Yes. So depending upon the kind of fertilizer, fertilizers have very unique-- I always get yelled at for that. I guess something can't be very unique-- they have unique signatures. So animal residues compared to-- most things are-- most fertilizers are made through what's called the Haber-Bosch process, which is synthetically creating fixed ammonia. And so a lot of nitrogen isotope work is in what I call the blame game.
So you have something bad-- you guys live on the coast and you're like, ick, the coast looks like hell because it's all ugly and nasty. And someone tells you, well, that's because you have too much nitrogen and phosphorus going into that. And then everyone goes, well, where does it come from?
People who have cows say it's not coming from us. People who have agriculture say it's not from us. Sewage treatment plants say it's not from us. And so we're often brought in to say we can tell, because isotopically you're each different, so we can then look back.
Right now, I'm doing that for the State of Florida. I'm in DeSantis's budget, of all people, to actually estimate pollution going to the coast. So I guess even if politically you're not too into ecology, if enough rich people yell at you that their golf courses look like hell, they'll hire me to figure out why. Yeah?
AUDIENCE: [INAUDIBLE]. How many people come to you to work for them privately versus you coming to [INAUDIBLE] find [INAUDIBLE]?
JED SPARKS: Yeah, it's the greatest job in the world, because everybody can see the power of the technique, and it's not easy to do. So my office door is getting opened all the time. I mean, it's amazing. Most scientists get really pigeonholed into something. I sit there and the phone rings, and some guy goes, hi. I'm the cold case detective in St. Louis. I want to talk to you. And I'm like, cool. Yeah, that would be awesome, where you have somebody go, we've just discovered some mummies in Chile and we're really interested in doing some isotopic work. So it is coming through the front door. So it's great.
I'm the primary runner of these kinds of isotopes for the whole Cornell community. And then we probably, on an annual basis, run samples from maybe 50 or 100 other universities, federal agencies, police departments, probably 25 or 30 countries. I've run carbonate samples for Iran, for example, which was weird because the embargo meant they couldn't pay us. And so I said, don't worry about it. And then we got this box with just cash in it.
[LAUGHTER]
Cash, and when you ship carbonates, they're little bags of white dust. So you don't want to get a box with some cash and some things of white dust in it. So I just told the lab manager, just put that in a drawer. Don't deal with that at all.
AUDIENCE: [? Where is the ?] research now?
JED SPARKS: What's that?
AUDIENCE: [? Current ?] research, what are you doing now?
JED SPARKS: Oh, a pretty broad variety of things. Across my graduate students it's crazy. They work on everything from the physiology of salamanders to the global modeling of how much carbon is stored in soils. Me personally, I love to get interested in pet projects. And my recent pet projects have been conservation of Pacific Islands. And so I spend a lot of time in Hawaii. And we use isotopes to figure out the best predictions we can make to get places to recover from invasive animals.
So Hawaii's been very badly damaged by pigs, goats, and sheep. And so we fence them out, and then we figure out ways that we can nudge along the natural community to make it come back in something that people want rather than kind of this nasty invasive species kind of thing. Is there something back there?
AUDIENCE: If an animal is extremely migratory, like a warbler that [INAUDIBLE] pass through most of the United States [INAUDIBLE] how do those isotope changes in those new places, if you relied on data to determine [INAUDIBLE]?
JED SPARKS: You pick up the isotope signal wherever you're growing your feathers. So what you have to do is first you have to figure out the molting and feather plan that a particular bird has. So like, for example, something like a warbler is wonderful because they go to one place and they completely molt and they completely grow new feathers. So we have this perfect signal of that one place that they go.
Something like a raven, it's horrible. They're continually losing feathers in this unpredictable way. So when we sample a raven, it's much more difficult to say where was that raven when it picked up that isotope signal? So it depends on the bird species. Anything else? You guys ready to go out in the rain?
AUDIENCE: [INAUDIBLE] you said can get within four years on a modern elephant tusk. How close can you get on the ancient Greeks who were [INAUDIBLE]?
JED SPARKS: So not that there were a lot of benefits to having a lot of testing of radioactive material, but that spike gives us a lot more resolution. And so if you don't have that recent spike in radioactivity, you're reliant on the decay of carbon-14 since the Big Bang. That kind of estimate we can get to within like a couple of thousand years.
So it's pretty easy to tell something-- if something's a million years or two million years old. But that kind of five-year time resolution is not possible with carbon-14 on that scale. But it is possible with the bomb spike that we've had over the last century. Yeah?
AUDIENCE: I'm just wondering, how are you gathering what happened in all this data then sharing it collaboratively locally with other interested in [INAUDIBLE]. Are you using the [INAUDIBLE]? Are you using [INAUDIBLE]?
JED SPARKS: Mostly, it's websites. So isoscape.org is our main data repository. And then we have another repository called IsoBank, where we're banking all the data. The isotope community worldwide is kind of like the mafia, I think. We all sort of came from a couple of dons or whatever. And we're all sort of related. And those guys call these big meetings.
My don, for example, is a guy named Jim Ehleringer, who's in the National Academy, who's at the University of Utah. And he was the pioneer for a lot of this stuff. And data repositories in general, not just isotopes, have become much more important and prevalent in the last 15 years. We used to not really worry about those kinds of things. And now we want all the data stored and all the data available for other people to use it. And so it's primarily done on these data repositories.
And then the way it's enforced is the funding agencies. So if you get money from the National Science Foundation or the National Institutes of Health, one of the requirements of the money that they give you is it will be deposited and be made available in whichever repository that particular data is supposed to go. So it's becoming very powerful and very efficient. Anything else? All right, well thank you guys so much for coming out.
[APPLAUSE]
And all of you have a great day. I have to go home and carve pumpkins with my kids, so.
[LAUGHTER]
Turn on the television any day and watch a scientist make a measurement suggesting the victim was killed elsewhere or track a compound found at the crime scene back to a particular manufacturer. How close is this to reality? Join Professor Jed Sparks, Ecology and Evolutionary Biology, who will explain the state of this science and how labs at Cornell and elsewhere use stable isotopes to help police departments determine the identity of victims, test that expensive bottle of wine to see if it really came from France, or determine whether an elephant tusk seized in Asia was from an animal killed in Kenya or South Africa.
