What do beef jerky, bogs, and Egyptian pharaohs have in common? No this isn’t the setup to a joke: they are all involved in preservation. Humans have been preserving things for thousands of years. In this mildly spooky article, we’ll explore the science and history behind all sorts of preservation.
Let’s start with something not spooky at all: food. In food science, preservation is key to keeping food safe to eat during times of low food production, like during winter. In ancient times, food preservation looked different than it does today and depended where you lived. If you were in colder climates, food could be preserved by letting the naturally freezing temperatures keep food frozen. In warmer climates, food could be dried out in the sun. Drying foods out limits bacterial growth by making the food very devoid of water, essentially dehydrating bacteria, forcing them to grow slowly, stop growing at all, or killing them outright. This is because of differences in osmotic potential between the bacteria and the food. Drying food using salt or sugar works the same way, which is why we have delicious honey, jams, and jellies.
Modern methods of preserving food will use chemical preservatives, or canning/pasteurization to keep decomposition bacteria at bay.
Moving on, we have bogs. Bogs are a wetland, typically found in cooler climates around poorly-draining lakes or ponds. They consist of mud and peat, which is essentially partially decayed biological gunk. Because of all of the peat, bogs are a significant sink of carbon, and important in the carbon cycle. How are bogs involved in preservation? The answer is bog people.
Bog people, also called bog bodies, are human remains which have been preserved and naturally mummified in a bog. Some of these mummies date back to as far as 8,000 B.C.E.! One unique factor about bog bodies is that the remains often include soft tissues, which normally aren’t preserved because of decomposition. Bogs are capable of mummifying mammalian remains because of their acidic environment. If the remains enter the bog during a cold season, bacteria won’t be able to begin decomposition, allowing the bog’s acid time to saturate the body. The process is similar to pickling. The result is well preserved tissue which can be studied thousands of years later.
Lastly, we have human-made mummies, famously those from ancient Egypt. How does this mummification compare to the natural method of a bog? The first step for a proper Egyptian mummification was the removal of organs. A hook-like instrument was carefully inserted up the nostrils and used to remove sections of the brain. Next, a large incision was made in the abdomen to remove internal organs. These were then placed into burial jars of their own, or sometimes wrapped and placed back into the body. Next, all water was removed from the body. This was done by placing the body in large amounts of salt. After many days, the now dried body was ready for wrapping until it looked like a true mummy.
The attentive reader will notice similarities across all of these methods. The goal is to keep decomposition to a minimum, which means keeping bacterial growth to a minimum. Whether in your food, in a bog, or in a sarcophagus, humans have been mastering the science of keeping these decomposers away for millennia.
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