Chemistry of Human Decomposition
Hopewell Valley Student Podcasting Network
Chemistry Connections
You thought gluten made you bloated????
Episode #12
(Say it very quickly) Warning: There are gruesome topics mentioned in this podcast, so feelings of disgust is natural. This podcast is not meant to joke about human decomposition, but to explain the process in a light-hearted manner. We hope this podcast is educational and that you enjoy.
Welcome to Chemistry Connections, my name is Katie Laitusis and I’m Angela Choi and we are your hosts for episode number 12 called You thought gluten made you bloated???? Today we will be discussing Human Decomposition… yuck
Segment 1: Introduction to Human Decomposition
There are 5 stages of human decomposition: the fresh stage (aka autolysis), the bloat stage, active decay, advanced decay, and the dry or skeletonized stage. In this episode we will be focusing on our personal favorites: the bloat stage and advanced decay stage. To start, during the bloat stage the body may double in size, due to the gases, which is why it has a bloated look. During the advanced decay stage, gut bacteria digests intestines and then surrounding tissues, and cartilage. Hair, bones, and ligaments are the only parts of the body that are left over. Insects that chew are attracted to the body during advanced decay like dogs to a bone.
Segment 2: The Chemistry Behind Human Decomposition
Anyways, lets lighten the mood with a quick joke before we get into the chemistry. What do you do with a dead chemist? I don’t know, what? You Barium. HAHAHAHAHHAHAHAHAHAHAHHAHAHAHHAHAHAHAHHAHAH
We will now be talking about the chemistry behind these stages. In the bloating stage, we will talk about gas pressure and how it affects people during decomposition. During bloating, gasses build up and fluids are pushed outside of natural body openings. The bloat phase begins about 3-5 days after death and this occurs when bacteria shifts from aerobic to anaerobic bacteria, which is when they don’t require oxygen. The bacteria will feed on the body tissues, causing the sugars to ferment them to produce gaseous by-products… probably not the type of passing gas your familiar with. So then what type of gasses are we talking about? Some of the gases produced include methane, hydrogen sulphide, ammonia, carbon dioxide, and nitrogen. What else happens during the this stage?During bloating, this stage also will start to attract flies that lay eggs and produce maggots, which will feed on the dead tissue. As more bacteria accumulates, the abdomen and other body parts will grow in size. Anaerobic bacteria converts hemoglobin molecules, which once carried oxygen around the body, into sulfhemoglobin. The presence of this molecule in settled blood gives skin the marbled, greenish-black appearance characteristic of a body undergoing active decomposition. Ewwww… uhhh Cool? And, even better, as the gas pressure continues to build up inside the body, it causes blisters to appear all over the skin surface… and sometimes the abdomen will burst from the pressure. I’m never going to an open casket funeral then. So tell me about the advanced decay stage.
In the fourth stage, which is advanced decay, this process may start about 25-50 days after death. In advanced decay, we will talk about the effect that temperature has on the speed of reactions. During decomposition, the speed of the chemical reactions involved doubles with every 10°C rise in temperature, because when particles are heated, they move faster within the system, creating more collisions, and an increase in the rate of the reaction. So a cadaver will reach the advanced stage after 16 days or 1.14 fortnights at an average daily temperature of 25°C. However it will take 80 days to reach this stage at an average daily temperature of 5°C. Good thing I don’t live in the desert. The higher the temperatures, the more bacteria in the body will produce gas at a faster rate. This will create more openings in the skin for flies to lay their eggs. A decomposing human body in the earth will eventually release approximately 32g of nitrogen, 10g of phosphorus, 4g of potassium, and 1g of magnesium for every kilogram of dry body mass. Wow, that’s a lot of gas! Or is it? How much is a gram of gas? Anyways, that must have some effects on the area… right? Dead bodies can impact the environment, because of chemicals leaking into the soil, which can actchually make it more fertile. Who knew decaying corpses were the secret to solving climate change? Not me 😀
Segment 3: Personal Connections
Now its time to get personal…We have always been interested in forensics from watching TV shows like Criminal Minds, and took the Forensic Science course during high school. In this course we went over how people look during death such as rigor mortis, but never went over different stages of decomposition, and felt interested in this topic. You also never know when you might stumble across a dead body and want to know why it looks so bloated… and juicy 😉
Thank you for listening to this episode of Chemistry Connections. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.
Sources:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3377612/
Music Credits
Warm Nights by @LakeyInspired
Bodies (cover) by @Angela Choi and Katie Laitusis
Turn It Down For What (cover) @Angela Choi and Katie Laitusis
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