Science Club: David Hunt
In which DCist interviews area scientists, researchers, and academics on topics pertaining to natural and scientific interests. As Thomas Dolby would say: science!
David Hunt is the collections manager for physical anthropology for the Smithsonian Institution. He has researched and published on several subjects in physical anthropology, with special emphasis on skeletal biology, human morphometrics, bioarchaeology, and forensic anthropology. Dr. Hunt has analyzed mass graves, helped to perform facial reconstructions, and studied mummification, and he has taken part in archaeological excavations in Mongolia, Italy, and the U.S. He is an adjunct professorial lecture at George Washington University.
Dr. Hunt’s primary activities at the Smithsonian's National Museum of Natural History are curation, management, and conservation of the human skeletal collections, which includes more than 30,000 cataloged specimens. In addition, there are approximately 3,500 cataloged specimens of non-skeletal human materials—casts, busts, and a non-hard tissue repository of brains, organs, hair and dermal tissues—that Dr. Hunt oversees.
DCist: What are some common misconceptions about forensic anthropology?
David Hunt: We're not Quincy, M.E.. He's a coroner—coroners can't arrest anybody. Or on CSI, where the people are experts on bugs as well as doing DNA and other chemical analyses and residue and gunshot ballistics. We as forensic anthropologists—in any criminalist science—you have to know what other people are doing, so you know how they could help you. So if I'm working on a skeleton that's been around for more than 5 or 6 months, there will be insects that have left sign on the skeleton. I'm not an expert on forensic entomology, so I call someone.
When I work with a criminal investigative office, I'm a portion of the investigation—I'm not the investigation. I go to the morgue, I do an analysis of the skeleton, I do a description of what is present in the individualistic traits of the individual. Bones, tissues, male or female, what their apparent age or ancestry would be.
DCist: Is your work more often criminal investigation or research?
DH: Well, there are sometimes questions about a trauma or defect on the bone, and you may do an applied type of analysis, using a surrogate pig or cow bone where you may be testing stab wounds or gun-shot wounds or decay rates. There are tests, types of analyses where you try to test the hypothesis you have. That's a research question rather than a criminal investigation per se.
A forensic biologist is actually a skeletal biologist, a person who deals with skeletons either on an individual or population level. "Forensic" means nothing other than "argument." It's a medical-legal question. Forensic geologist, forensic botanist, forensic chemist.
DCist: What does it mean to study the skeleton at the population level?
DH: Most people who study physical anthropology and get a Ph.D. have studied skeletons that have come from a cemetery or a group with relation to migration or worldwide population change. They have used features in the skeleton to analyze population similarities or population studies.
This isn't particular to skeletons. It would be the same for hair color or blood type. What is the range of hair color in Washington, D.C.? Well, to find that out, you go running around Washington, D.C., looking for a range of hair color.
When a skeletal biologist or an entomologist is looking at something at the population level, you have to have access to that range. That's why at the Smithsonian Institution we have 8 million bugs, because scientists want to be able to study a range of something across the whole world.
DCist: Is the statistical process for arriving at a population sample of skeletons same for coming up with a statistical sample of live humans?
DH: When you poll—say, exit polls for the election. You're in a particular part of town. Ward 1 is not going to reflect the same exit polls as Ward 6, but when you combine the two, you get something far more accurate about Washington, D.C. If you were to look at a skeletal series from Massachusetts in 1800 and look at a skeletal series from southern Califronia from the 1900s, will you get the same thing? No. Because the Massachusetts base is much more European-based and the southern California sample is much more Hispanic based.
DCist: What kinds of tells can you draw from the skeleton?
DH: From our research of collections all over the world in the last 100-some years, we recognize differences primarily in the skull that will indicate population differences and ancestry differences. Race is a paradigm, it's what you think you are—but ancestry is what your parentage actually was. If you're from Africa and you've coe to the United States and you've been living here for 250 years, you're an African American. You'll have features that are particular to Africa. But there's genetic admixture, and those modifiers affect the phenotype, the physical expression in the skeleton. The nose, the cranium, the physical features of the teeth. There's a higher frequency of certain shapes of the teeth in some parts of the population. It's not totally exclusionary. It's not like people who are white will have some features that people of Asian ancestry won't have.
Postcranium, everything below the skull, the skeleton has fewer diagnostic features. The pelvis is going to be the most diagnostic for sex, due to certain features that have been promoted by natural selection: Men have smaller pelvises whereas women have larger pelvises. But not always: A female from Sweden will be a pretty big individual compared to a male from Peru.
DCist: Has immigration reduced the diagnostic capacity of skeletons?
DH: It has. A population within Peru might become sexually dimorphic if Swedes were to immigrate there.
When we're talking about "race," when someone says they are Hispanic or Latino—what does that mean? They have Hispanol background: from Mexico or Central or South America. But all of those people have genetic admixture, Spanish and Meso-American, with individualistic features in the skeleton.
DCist: So race doesn't matter in the skeletal tell?
DH: It doesn't because of hybridity. If you have an individual, you might see white features or black features. You will say that you see white and black admixture present. But you can't say, because you can't know for sure, whether this person would say, I'm white or I'm black or I'm Hispanic because the skeleton is going to have features that are variable.
But in skeletal analysis, people use karyotype analysis and DNA analysis and protein analysis that can be more specific for population groups.
DCist: How long can you extract DNA from bone?
DH: They're now able to extract fragments of DNA from neanderthals. There's some group that says that they're able to extract DNA information from dinosaur bone. I haven't read how they do their work. We are still in the fledgling stage of DNA analysis.
DCist: How is DNA derived from bone?
DH: DNA in any material is some sort of biological part. Bone is primarily mineral, but inside the mineral are the cells that made the hard structure. So scientists will take a bunch of bone and grind it all up and extract whatever DNA material that might be present. That then is amplified—where they use a chemical method to take that DNA and try to replicate it numerous times so you have something that you can actually analyze. The older that something is, the less that material can be preserved.
There are two types of DNA you're looking for: nuclear DNA or mitochondrial DNA . Mitochondrial are easier to find because there are multiple mitochondria within the cell. Mitochondrial DNA, you have three to seven chances within one cell. Mitochondrial DNA does not pass through the father to the children, however—it is maternally inherited.
DCist: Is the skeleton easier to analyze if the body has been mummified?
DH: Mummified remains or dessicated bodies are actually a greater thing, a more interesting thing to study than bones. There's more information there that's present to study. If you have dried organs, muscle tissue that's there, besides all the chemical information you can derive—you just have more information about the cause of death. So many people die from acute illnesses and the skeleton doesn't tell that.
Somebody gets shot in the stomach, it goes through and through and you're bleeding to death, and you're left out in the field somewhere for 2 years? Hopefully there is a remnant of clothes. If you just have the skeleton, you're going to have no idea what that someone died from.
DCist: Can you describe a case you worked on locally?
DH: There was the iron coffin, which was found up in Columbia Rd area. This was a body preserved since the 1850s—we were able to do a full autopsy on this boy and determine that he died of pneumonia because of gram-negative bacteria in his lung.
DCist: What's that?
DH: You can type bacteria as a positive or negative bacteria. Gram is a chemical you apply to the slide and you get a different coloration whether it's positive or negative. Gram-negative type are most consistent with pneumococcus. That determination was made.
DCist: Why the iron coffin?
DH: They weren't cheap. A wood coffin was $4 whereas an iron coffin was $45. If someone was going to be shipped somewhere before burial, this would be how they would do that. We expected to find someone quite high status, which this boy was not. He was orphaned. This boy was put in an iron coffin for one of two reasons: He was either going to be shipped back home to Accomack County, Virginia. Or he was very well liked by the students and the faculty of Columbia College and they paid for it for him. They all thought very highly of him.
DCist: What else did you discover about his death?
DH: There was mitral valve detect in his heart, we were able to see that as well. If it were just a skeleton and he was found in a remnant pine box, we'd have no idea what he died of. Now, he was a smaller-size guy for a kid his age, so we could make assumptions based on that, that this kid was a weaker kid and maybe had some kind of chronic or long-term illness. But having tissue gave us absolute identification of cause of death.
The iron coffin was found in 2005 by Columbia Road by a construction company putting in a gas line. That area used to be part of Columbia College, which used to be up there by the Columbia Pike area. In the late 1800s, Columbia College moved to where it is now, GW. When they moved the bodies to Rock Creek Park, this body was overlooked.
There was unfortunately no nameplate. It has either never been put on or it has come off the iron coffin. The autopsy was done and we did DNA sequences from blood and tissue. We were able to identify a time-frame from the coffin and clothing. The clothing was pre-Civil War, probably early- to mid-1850s, and the coffin type was one made between 1850 and 1852. We looked through death records for a late-teen individual who died some time between 1850 and 1855. Then we looked through the matrilineal line from three families and got the mitochondrial DNA from living relatives today.
We got DNA confirmation in September or October 2007. The most closely related family members he has recently made a decision to donate his body and his coffin and his clothing to the Smithsonian for future research and exhibit possibilities. He was William Taylor White, who died on January 25, 1852, born in Accomack County, Virginia, out on the Eastern Shore, whose guardian paid for him to start his education at Columbia College that year.