Ele in Paris

 

One of the archaeogenetics goals for the RATTUS project is to investigate how and when brown rats arrived in Europe. Genetic studies on living rats today suggest that the brown rat (Rattus norvegicus) arrived in Southeast Asia by the 13th century, but from there, it’s not clear how they moved into Europe. Perhaps they spread from Northeast Asia using existing trade networks, such as the silk road, before entering Eastern Europe via Caucasia and spread across the continent by the 18th century. Or maybe their spread was maritime-driven and the rats were transported all the way from Asia to Western Europe via colonial shipping networks. To investigate the route(s) the brown rats took, we will generate ancient DNA data for brown rats dating from 1750 to the early 1900s.

Earlier this year, David and I were in touch with Professor Violaine Nicolas-Colin about several historic brown rats held in the rodent collection at the Muséum National d'Histoire Naturelle - the French National Museum of Natural History (Photo 1). Our sampling request was approved and back in May, I took my first trip on the Eurostar to visit the collection. 

Photo 1: A sign at the garden entrance to the Muséum National d'Histoire Naturelle.

 

At the museum, I worked with Violaine to take samples of 7 brown rats caught between 1900 - 1910. These rats mainly came from France, but I also sampled one from Switzerland and one from Russia. The specimens were either cranial samples (the skull) or the skull with the preserved skin (Photo 2). 

 

Photo 2: A preserved brown rat skin with the skull (cranium and mandible) in a plastic bag.

 

It is possible to extract DNA from bone, teeth, skin or dried soft tissue so depending on the condition of each sample. I worked with Violaine to take the most minimally destructive sample possible from each specimen. One specimen from Melun, France, was in such good condition that we didn’t want to break the bone. Instead, I used a scalpel to remove the very small traces of dried soft tissue still on the mandible (Photo 3). The total weight of the tissue was just 10 mg, I usually extract from ~ 50 mg of material so it will be exciting if we get a good DNA yield from this small amount of material (to put this into context, a biro pen weighs 5.8 g or 5800 mg!). 

Photo 3: A mandible with dried soft tissue still attached to the bone surface.

 

After taking a sample for DNA analysis, I left a yellow tag with the specimen detailing the sampling (Photo 4). It’s quite a nice thought that my handwriting will be preserved in such an important national archive for years to come!  

Photo 4: For each specimen I sampled I left a little yellow tag briefly describing the material that was sampled, the date, the project and my name.

 

I took advantage of being in France and booked some holiday after the sampling trip as this was my first time in Paris. I packed loads into those 5 (holi)days, highlights included a cruise on the River Seine and seeing the Eiffel Tower light up. The atmosphere in the Jardins du Trocadéro was like New Years Eve! It was very busy as the Champ de Mars was closed because a stadium was being built there for the 2024 Olympics. 

Photo 5: The Eiffel Tower light show

 

I also visited lots of public parks in Paris and from this sign (Photo 6) it seems like rats are still present in the city - although I didn’t see any whilst I was there.

Photo 6: A sign in Square René Viviani just across the road from the Notre-Dame cathedral warning people to “Stop aux rats!”. In English: "Stop the rats! Waste left on the ground attracts rodents. Please throw your waste into the nearest bin."

Bonus: 

In Violaine’s office she had this brilliant poster - we need to get an English translation for our office door here in York!