Forensic Anthropology Research

Laura Torres, Forensic Anthropology Center at Texas State

Not a Pretty Picture: An Internship Experience with Human Decomposition

In the Spring of 2015, I helped complete weather data spreadsheets with FACTS, or Forensic Anthropology Center at Texas State, director Dr. Daniel Wescott. He had been working on a side project that was focused on what variables affect the rate of decomposition based on accumulated degree days, and he invited me to help finish it. Although the project seemed intimidating, my main goal was to complete the 2009-2014 spreadsheets by finding the average humidity, average real humidity, real high, real low, and average solar radiation of every day for these years. The next step in the project included analyzing all of the data I collected. Dr. Wescott has hypothesized that solar radiation is the key factor in the increased rate of decomposition in the summer months, so we’re hoping that the analysis will provide a statistically significant answer. The final step in this research project will include writing an abstract with Dr. Wescott about our findings, and it will be submitted to the American Academy of Forensic Science. This report will give an insight into how weather affects the rate of decomposition, and how I was given the opportunity to explore the scientific reasoning behind the increased rate of decomposition in the summer months.

In the following research project described in this paper, I helped complete a data set that analyzed different factors that affect the rate of decomposition. These factors included temperature, humidity, solar radiation, and hours of sunlight.

Determining the rate of decomposition is an important part of forensic anthropology, because it helps estimate the postmortem interval, or PMI. The PMI is used to determine when a deceased individual died based on environmental factors and natural events. The rate of decomposition is especially important, because it provides specific benchmarks that correlate with an estimated time frame. Decomposition is the process in which organic substances break down into a simpler form of matter. Although this project didn’t focus on the rate of decomposition, it did focus on why these benchmarks occur when they do.

The study of decomposition divides the process into 4 broad categories: fresh, early decomposition, advanced decomposition, and skeletonization. The process of decomposition begins immediately after an individual perishes. Once the heart stops beating, the fresh stage begins, and the body stops receiving oxygen. Within the first three to seven minutes the brain cells begin dying, but the bone and skin cells will survive for several days (http://science.howstuffworks.com/body-farm1.htm).

Next, in the early decomposition stage, three processes known as livor mortis, rigor mortis, and algor mortis occur. Livor mortis happens when blood drains from the capillaries and pools in the lower-lying portions of the body. It creates pale appearances in some places and dark appearances in others. Rigor mortis, or stiffening of muscles, sets in about three hours after death but begins to subside within 72 hours. Algor mortis, loss of internal heat, begins around twelve hours after death, depending on the amount of body fat and external temperatures. This causes the body to feel cold. The third stage, advanced decomposition, includes autolysis, which begins when bacteria within the body starts breaking down. This causes the repugnant appearance and smell. As the gas pressure rises, it causes the eyes to bulge, blisters to form on the skin and burst, and the entire body to increase in size (Marks and Love 2000).

Decomposing tissue emits fluid and gasses such as methane and hydrogen sulfide. Then, the gases dissipate from the abdominal cavity, it caves in, and the internal organs begin to liquefy. Finally, the stage of skeletonization occurs when all the moisture in the body is gone, and the remains are left exposed to sunlight or extreme heat.

Forensic anthropologists give a point value that begins with 1—signifying fresh—and increases in value for each progressive stage. The total number of points received represents the amount of accumulated decomposition that has occurred (Megyesi et al 2005).

This process is known as total body scoring (Galloway et al 1989). There are two different systems of scoring developed by Megyesi and Galloway. Megyesi’s system is a modification that puts the stages into a sequential ranking system, removes the stage of adipocere development, and alters the stages to reflect the process as it occurs in a non-desert region.

The remains are scored independently in three specific areas of the body: the head and neck, which includes the cervical vertebrae; the trunk, which includes the thorax, pectoral girdle, abdomen, and pelvis; and the limbs, which include the hands and feet. Then, the scores of each anatomical region are combined to produce the total body score.

It has been found that decomposition is dependent on accumulated temperature, which is why I collected the data that I did. Although it is apparent that decomposition occurs at a higher rate during the summer months, the goal of this research project was to determine which factor or factors were causing this to happen.

My research project considered two important factors: humidity and solar radiation. Humidity is the percentage of water vapor in the air, and is a good indicator of dew, precipitation, or fog. Solar Radiation, or sunlight, is the portion of electromagnetic radiation given off by the sun. On Earth, solar radiation is filtered through Earth’s atmosphere and is divided into two categories: direct solar radiation and diffused solar radiation. Direct solar radiation refers to radiation not blocked by clouds, while diffused solar radiation describes sunlight when it’s blocked by clouds or reflects off other objects (https://firstgreenconsulting.wordpress.com/2012/04/26/differentiate-between-the-dni-dhi-and-ghi/).

Both of these factors are key in understanding why decomposition occurs at the rate it does because the location is unique. Although a great deal of research on the stages of decomposition exists (Schotsman et al 2014), individuals left to decompose in the sun at FACTS are subject to extreme dryness.  This leads to mummification, which involves both humidity and solar radiation. There aren’t many studies available at this time that specifically identify these variables because most decomposition research facilities don’t experience such a high number of mummified individuals. Our study is relevant to forensic anthropology because it will provide an analysis of variables affecting decomposition through 6 years of data, which could be helpful in determining why mummification is occurring at such a high rate in this location (Janaway et al 2009).

As an intern, I was given the responsibility of locating and entering precise weather data for the 2009-2014 spreadsheets. I began my data entry with a simple google search to determine which website would provide historical weather data. I chose the website called weatherunderground.com because it provided a simple layout of average humidity, high temperature, and low temperature.

I found the average high humidity by taking the max humidity of every day of that particular month, then using the “Average” function on Excel. I did the same thing when I was finding the real high temperature of every month. To find the solar radiation data, I used a NOAA database that provided the specific years needed to complete the spreadsheet.

Once I finished compiling all of this information, I then entered the information into the donor spreadsheet which showed when a specific individual was laid out and what the weather variables were that day. We expect for the results to show a strong correlation between the amount of solar radiation and the rate of decomposition. If our analysis does reflect this hypothesis, it will provide a scientifically sound explanation about the increased rate of decomposition in the summer months. Although, if the analysis doesn’t reflect our initial hypothesis, it will still provide an insight on the variables affecting the rate of decomposition in Texas. For example, the results might offer support for another variable that we hadn’t considered before, like humidity.

This research project will provide a solid base for other researchers who are interested in the post mortem interval because it gives an insight to what is happening at the decomposition research facility in San Marcos, Texas.

Throughout this semester, I was able to be a part of an active research project, and was given the opportunity to see the real side of research, which isn’t always entertaining. Research is very interesting to conduct and to analyze, but it was very tedious to collect. I spent my entire semester entering data and it proved to be a test of motivation. I was constantly reminding myself of the greater good this information would provide to the anthropological world, because it’s an important project that could shed light on a more precise post mortem index but it wasn’t the most hands-on. It took extreme patience and positivity because it just seemed like a never ending task.

Overall, I’m honored to be a part, even in the slightest, in a project that could help forensic anthropology, but I do warn those who are interested in becoming involved in a research project that it will not entirely be a fun time and it will be work. Although I am not pursuing a career in anthropology, I did learn that all work requires a good mentality, and I look forward to taking all that I’ve learned into my next step in the business world.

References

Janaway, Robert C., Andrew S.Wilson, Gerardo C. Diaz, Sonia Guillen. 2009 “Taphonomic

changes to the buried body in arid environments: an experimental case study in Peru.” Criminal and Environmental Soil Forensic, pp. 341–356.

Marks MK and JC Love. 2000. Taphonomy and Time: Estimating the Postmortem Interval.

Chapter 12 In: Steadman OW, editor. Case Studies in Forensic Anthropology. Prentice Hall

Megyesi, Mary S., Stephen P. Nawrocki, and Neal H. Haskell. May 2005. “Using Accumulated

Degree Days to Estimate the Postmortem Interval from Decomposed Human Remains.”

Journal of Forensic Science 50 (3)

Scheve, Tom.  18 June 2008 “How Body Farms Work”.  HowStuffWorks.com.

http://science.howstuffworks.com/body-farm.htm

Schotsmans, Eline M., John Denton, Jonathan N. Fletcher, Robert C. Janaway, and Andrew S.

Wilson. 2014. “Short-term effects of hydrated lime and quicklime on the decay of human remains using pig cadavers as human body analogues: Laboratory experiments.” Forensic Science International 238, 142.e1-142.e10.

Vashishtha, Sanjay. April 2012. “Differentiate between the DNI, DHI, and GHI.”

Firstgreenconsulting.com. https://firstgreenconsulting.wordpress.com/2012/04/26/differentiate-between-the-dni-dhi-and-ghi/

About the author

The Internship Coordinator

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