How We Learn About Diseases In The Past

Humans have suffered from chronic and infectious illnesses for as long as we’ve existed, but how do we know that? In this post, you will find the YouTube video exploring how we learn about diseases in the past and a full video transcript (with relevant references and links).

YouTube Video

YouTube Video Transcript

Here, you will find the complete transcript of the video in the previous section with hyperlinked references/citations.

Introduction

Tuberculosis, osteoarthritis, tapeworm infection. None of these diseases are particularly pleasant. They’re also not new to humankind. In fact, humans have suffered from chronic and infectious illnesses for as long as we’ve existed.

But how do we know that? Hi, I’m Dr. Smiti Nathan, and I’m an archaeologist. In this video, we’re going to explore how we uncover diseases in the past, so let’s get into it.

Skeletal Remains

One of the most common ways we uncover ancient diseases is by analyzing skeletal remains.  Now, by looking at bones, we can estimate an individual’s age, sex, and height.

This is often what we do first before looking for clues about ancient health. Once we’ve recorded that basic information, or as much as we can gather from the bones at hand, using those bones, paleopathologists can then extrapolate information about ancient diseases.

Now, when it comes to paleopathology, the prefix paleo means old or ancient, while pathology refers to the study of disease, so this field refers to the study of ancient disease.

Paleopathologists come from different fields, and these can include medicine, biology, zoology, and yes, even archaeology.

They often work at cemeteries or other burial sites and may work alongside other specialists to create a fuller picture of health in the past, but more on that later.

Now, when it comes to bones, paleopathologists investigate both infectious and chronic diseases that impacted people in the past.

Infectious Diseases

Let’s start with infectious diseases, which are ailments that are caused by bacteria, viruses, or fungi, and are often contagious.

Certain infectious diseases leave distinctive marks on bones. For example, the sexually transmitted disease syphilis creates distinctive holes.

These marks give us insight into the diseases that impacted ancient people.

This is a good time to mention that I will be talking about human remains in this video, but I won’t show any actual images of them.

Instead, we’ll use drawings to illustrate certain points, just like we did before.

Okay, back to infectious diseases. 

 In the Sevan region of Armenia, archaeologists working at five early Bronze Age cemeteries analyzed the skeletal remains of 157 individuals and found bone damage consistent with Hansen’s disease, also known as leprosy.

In particular, the archaeologists noted damage to facial bones, meaning that over 2,000 years ago, these individuals likely suffered from the visible deformities of the face that are characteristic of this infectious disease.

Chronic Diseases

Now chronic diseases are conditions that are typically not infectious and can last for many years. Some common chronic diseases include heart disease, diabetes, and Alzheimer’s. The wear and tear of certain chronic diseases can leave permanent marks on bones, which archaeologists can then identify.

For example, archaeologists can uncover degenerative joint diseases like osteoarthritis and osteoporosis by analyzing remains for evidence of healed or broken bones.

Take this study in a rural central Russian settlement. It examined 26 individuals from a 14th and 15th-century cemetery. Archaeologists found that almost everyone, including children, showed signs of stress and chronic diseases like anemia and nutrient deficiencies.

Based on evidence gathered from skeletal remains, the people buried in the cemetery had short stature and poor nutrition, as well as bone lesions, spinal herniations, cavities, and ridges in their tooth enamel. 

Small holes near their eye sockets also suggest that children suffered from many infectious diseases, like malaria, which was common in the area. However, about 28 percent of individuals studied were over the age of 40, and the archaeologists at this site suggest that sick or disabled people living in medieval central Russia were likely cared for by their community. 

The analysis of bones not only reveals information about past human health, but it can also provide insight into past environments.

In a study of medieval period cemetery sites across England, archaeologists described abnormal bone growth on multiple individuals’ skulls. The bone growths looked almost spongy with tiny pits and holes. 

The archaeologists determined that this damage to the skull was likely caused by sinusitis or the inflammation of the air cavities of the face, usually caused by exposure to smoke, air pollution, or allergens over a long period of time.

The archaeologists also found that people who lived earlier around the 11th century had lower rates of sinusitis than those living later around the 16th century. They correlated the increase of sinusitis to changes in house structure to have less ventilation, poor air quality in densely populated areas, and higher rates of diseases like Hansen’s disease and tuberculosis, which can make sinusitis worse.

Parasites

For millennia, humans and animals have also been plagued by parasitic infections. Parasites are organisms that live on or inside of a host and get its nutrition at the expense of its host. 

If you caught our video about archaeoentomology, you know that humans and ectoparasites like lice, fleas, and bedbugs go way back.

But paleopathologists are more focused on endoparasites. Those are those parasites that live inside our body.

Ancient physicians were very familiar with parasitic infections. Hippocrates, one of the most well-known medical writers in history, wrote color ful descriptions of worms causing headaches, gastrointestinal distress, and other unpleasant symptoms.

At a 4,000-year-old cemetery site on the island of Kea in Greece, archaeologists sampled the soil surrounding the pelvic bones of 25 individuals and found the eggs of several types of endoparasites, including whipworm and roundworm. Between the writings of Hippocrates and these scientific analyses, archaeologists and historians have pieced together a detailed picture of parasitic infections in ancient communities.

Coprolites

While soil analysis can provide important information about parasitic infections in the past, one of the best ways to study this is through coprolites, also known as archaeological feces or ancient poop.

Many parasites infect the gastrointestinal tract and their eggs are generally shed through poop, which provides a useful resource for archaeologists to learn about ancient health.

Disease spread is often facilitated by long-distance travel, which archaeologists can trace through the analysis of coprolites. 

 Near the Tarim Basin in northwestern China, archaeologists excavated a 2,000 year old latrine that was once used by travelers visiting a bustling Silk Road relay station. 

Coprolite analysis revealed the eggs of several parasites, including the Chinese liver fluke, which is a species of tapeworm, alongside roundworm and whipworm.

The Silk Road was a vast network of trade routes that connected Europe, Asia, and Africa over multiple centuries, from the 1st century BCE to the 1400s 

As this analysis demonstrates, Silk Road traders carried more than spices, silk, and precious metals. They also carried parasitic illnesses.

Molecular Analysis

 Shifting gears a bit, molecular analysis, including DNA extraction, is another important technique that we can use to learn about ancient diseases.  Archaeologists can extract the DNA or RNA of pathogens from samples of bones, mummified remains, coprolites, and teeth, and have sequenced genetic material from bacteria like tuberculosis, viruses like influenza and hepatitis B, and parasitic illnesses like Leishmaniasis and Chagas disease.

Sequencing genetic material can be especially helpful in understanding the transmission and evolution of pathogens over time.

Take Yersinia pestis, the bacterium responsible for the devastating bubonic plague.  Archaeologists extracted genetic material of this bacteria from the skeletal remains of three individuals from three sites. One buried in a 14th-century cemetery in the Volga region of Russia, one from a 14th-century mass grave near Barcelona, Spain, and one in a 16th-century cemetery in southwestern Germany.

 They found that the genetic sequence of the bacterium from each site was the same.

So that means each person died from the same strain of the bubonic plague, which was also the same as a previously extracted strain from a plague victim in London from the 1340s.  Archaeologists suggest that this strain of plague originated in Europe and subsequently spread eastward towards Asia and sparked epidemics there in the 14 hundreds.

Working Together

Bones, parasitic eggs, poop, and DNA are all useful individual methods. However, there are lucky times when you can use a combination of these methods on one individual. 

Ötzi, also known as the Iceman, is a 5,000 year old mummy who was found by hikers in the Tyrolean Alps in 1991.

He is one of the best preserved ancient humans ever recovered, and archaeologists have been able to reconstruct a detailed look into his health status.

 Based on Ötzi‘s bones, archaeologists have found that he suffered from a degenerative bone disease, especially in his right hip.

He also tested positive for whipworm eggs. And actually, these are some of the oldest whipworm eggs ever recovered. Scientists sequenced the DNA from several bacteria that Utsi carried, including one of the oldest complete bacteria genomes ever extracted of Heliobacter pylori, which caused stomach ulcers.

Ötzi was also one of the earliest known carriers of the bacterium that causes Lyme disease.

Outro

Well, we’ve been talking a lot about illnesses that have plagued ancient humans. There were actually many places where people were quite healthy.

For example, archaeologists working at Iron Age sites in Zambia found that only 35 percent of the individuals studied showed any signs of stress or malnutrition. There was very little evidence of joint disease, interpersonal violence, or infectious disease.

archaeologists found that the people in this area had a diet relying mostly on plants and little amounts of animal protein.

Now, if you’re curious about the relationship between plants and archaeology or just want to keep learning more about ancient diseases, check out these videos here.

Thanks for watching and we’ll see you in the next one. Bye!

Credits

Anya Gruber: Co-Producer, Researcher, Scriptwriter

Noor Hanania: Lead Video Editor

Smiti Nathan: Director, Co-Producer, Support Video Editor


If you enjoyed this post, check out my channel and other videos.

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Smiti Nathan

I’m an archaeologist that travels around the world for both work and pleasure. I have a penchant for exploring ancient and modern places and the people, plants, and foods entangled in them. I write about archaeology, travel, and productivity.

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