🌍 Abstract
Microbes are everywhere — in soil, rocks, oceans, and even inside your body! Your microbiome (the collection of microorganisms living on and inside you) affects your health.
🧬 Scientists studied the microbiome of mummified ancient Egyptians by analyzing their DNA (aDNA). They discovered:
Microbes that cause gum disease
Evidence of
leprosy, hepatitis, and other infectious diseases
📍 Location: Mummies came from Abusir el-Meleq, Middle Egypt (see map).
📘 Glossary of Key Terms
Ancient DNA (aDNA): DNA from long, long ago.
Bacteria: Single-celled organisms with cell walls but no nucleus.
BCE and CE: Before Common Era / Common Era (modern calendar terms).
DNA: Deoxyribonucleic acid – contains genetic code.
DNA sequence: The exact order of bits of DNA; sequencing finds this order.
Environmental microbiome: Microorganisms living in soil, air, and water.
Genetic: Related to genes.
Genome: Complete set of genetic information in an organism.
Hepatitis B virus (HBV): Infects the liver.
Microbiome: Microorganisms living in or on an organism.
Leprosy: Infectious disease affecting the skin.
Mummy: Preserved body of a dead organism.
Oral: Involving the mouth.
Pathogen: Any organism that causes disease.
Strain: A distinct variety within a species.
Tartar: Hard substance that builds up on teeth.
Virus: Small piece of DNA or RNA inside a protein coat that replicates inside cells.
🔍 Introduction
Your health depends on your microbiome — bacteria, fungi, and viruses living in and on your body. Some microbes:
Help digest food 🍎
Cause illness 🤒
Are still a mystery! ❓
Scientists wanted to understand how ancient pathogens evolved.
By studying ancient DNA (aDNA), they can learn what diseases affected people long ago.
💡 For the curious:
Pathogens are germs that cause diseases and are spread through infection. These usually don’t live on your body, but are spread through infection. Knowing what pathogens existed long ago also helps us know how they evolved.
🧫 Methods
It is hard to work with aDNA!
Heat, humidity, and age make DNA molecules fall apart. That’s why aDNA usually only exists in fragments (broken pieces). For a long time, the technology to read DNA wasn’t good for reading aDNA. Methods that work for modern, intact DNA don’t work well for ancient, fragmented DNA. But new methods and more powerful computers make it possible to reconstruct genomes from aDNA.
Other scientists used this method to study aDNA from humans and animals. But until now, no one had ever used this method to identify ancient microorganisms in mummified ancient Egyptian people!
We extracted DNA from tiny samples of the bones, soft tissue, teeth, and tartar of mummified people. We analyzed a total of 133 samples from 119 mummies. The archaeologist Otto Rubensohn excavated these people’s mummified remains between 1902 and 1905. These people lived in Abusir el-Meleq, Middle Egypt, which was inhabited at least from 3,250 BCE to 700 CE.
Can you imagine shredding a whole bookshelf and trying to put the books back together again? Reconstructing the full DNA sequence from an ancient bacterium is a bit like that.
We used a new technology designed to reconstruct DNA from mixed-up pieces. It reads the genetic code in each fragment, starting at each end. The two ends of the sequence are merged together. The computer compares the merged pieces to a library of known genetic sequences. With enough matches (and a powerful enough computer), we can identify the species. We can also reconstruct the majority of its genome!
Method Sumary:
Studying aDNA is difficult because:
Heat and humidity break DNA apart over time 🌡️
DNA exists only in tiny fragments
🧩 Researchers used new computer technology to piece together these fragments — like assembling shredded paper back into readable pages.
They:
Extracted DNA from bones, soft tissue, teeth, and tartar of 119 mummified people.
Compared this DNA to soil samples to make sure it wasn’t modern contamination.
Verified the DNA’s age by checking for damage patterns typical of ancient DNA.
📚 The process is like finding matching words in a shredded document to confirm what sentences were originally written.
🧠 Results
We successfully reconstructed the genomes of Mycobacterium leprae, the bacterium which causes leprosy. The leprosy bacterium that we found is 2,200 years old. As far as we know, that makes it the oldest ever found! We compared it to other strains of the bacterium. The leprosy bacterium strain we found is related to modern strains found in West Africa and Brazil.
We also reconstructed the genome for the hepatitis B virus (HBV). By our estimate, the HBV we found is 2,000 years old.
We found three other bacteria in the samples of bone and soft tissues:
-
Proteus mirabilis – causes urinary tract and wound infections.
-
Enterococcus faecalis and Enterococcus faecium – live in the intestines of healthy people but can cause serious illness elsewhere.
In the tooth and tartar samples, we identified many oral bacteria and found evidence of three bacteria that cause gum disease.
📊 Figure 1 shows pie charts comparing sources of bacterial DNA:
🟧 Modern tartar bacteria
🟪 Oral bacteria
🟩 Soil bacteria
⚪ Unknown sources
Tartar samples had the most identifiable DNA.
🦠 Mycobacterium leprae (causes leprosy) — 2,200 years old, oldest known strain!
→ Related to modern strains in West Africa and Brazil.🧫 Hepatitis B virus (HBV) — about 2,000 years old.
They also found:
Proteus mirabilis – causes wound and urinary infections
Enterococcus faecalis & E. faecium – usually harmless gut bacteria but dangerous if they spread elsewhere
Oral bacteria causing gum disease 🦷
💬 Discussion
We showed that it is possible to sequence DNA from mummified ancient Egyptian people. We reconstructed the genome of two ancient pathogens. We found signs of other bacteria as well, including some common species that live in the mouth.
Much of the DNA we found didn’t match anything in the library of known DNA sequences. This is because no one has studied the vast majority of microorganisms in the environmental microbiome yet.
We found other microorganisms that help with decomposition. They would not have been on the people we studied while they were still alive. Some of the unknown DNA could be from microorganisms that were common 2,000 years ago in Egypt but are less common now.
We hope that our success in finding ancient pathogens helps other scientists find out about the germs of the past.
✅ IN SHORT: This research proved it’s possible to read DNA from mummified remains.
They reconstructed ancient pathogens and discovered:
- Many unknown DNA sequences (possibly extinct microbes)
- Some DNA linked to microbes that existed 2,000 years ago but are rare today
- 🧫 Environmental microbes (from decomposition) were also found but weren’t part of the ancient microbiome.
🧾 Conclusion
When you see Egyptian mummies in books and museums, it’s important to remember that they are mummified people who lived long ago. Like us, they lived in a world of microbes. They struggled with many of the same diseases that people today suffer from.
We are lucky to live in a world where vaccines and antibiotics exist! For example, the vaccine against Hepatitis B is available to almost all children in the world, and leprosy is now curable by antibiotics.
You can help make sure you and your family stay healthy by getting all recommended shots and taking antibiotics only the way your doctor prescribes.
IN SHORT:
Mummies were once real people who lived among countless microbes — just like us! They faced many of the same diseases humans face today.
💉 Thanks to modern medicine, we now have:
- Vaccines (e.g., Hepatitis B)
- Antibiotics (e.g., to cure leprosy)
👨⚕️ Stay healthy:
- Get vaccinated
- Use antibiotics only when prescribed
🧩 Check Your Understanding
Why do scientists study ancient microbiomes?
What makes ancient DNA hard to analyze?
How did researchers confirm the DNA was ancient?
Where else could scientists search for ancient germs?
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