Big cities like New York are riddled with millions of brown rats. They are considered a nuisance by the many as the rats spread disease, damage property, and basically just make a big mess of things. However, a recent study conducted by Dr. Munshi-South and his colleagues may have discovered an upside to having these undesired pests around. It all started when Dr. Munshi-South wanted to answer the simple question of “what is a New York City rat, and where did it come from?” so he asked researchers around the world if they could send him DNA samples in order to could compare the DNA of rats from different areas to the DNA of rats he had captured in New York. Many samples come in from all over inspiring him to discover not just where the New York brown rat came from, but where the world’s brown rat came from.
After analyzing all the samples it was discovered that the brown rat originally came from China. They started off wild but as farms began to form they moved to these farms as it was a more reliable food source. Eventually they began expanding further, inhabiting places all around the world. They either traveled on land or stowed away on ships, which carried them overseas. The brown rats that made it to Europe managed to spread across the world the most because when Europeans began to colonize the West the rats colonized with them. This is still happening today, as rats from different countries continue to arrive in New York. Surprisingly enough though, there is very little sign of any genetic mixing in rats from New York. It is theorized that the New York brown rats are keeping migrants out. This can be attributed to the fact that brown rats are very territorial, which means they are stopping any foreign rats from getting in. This is where the possible bright side of having rats around comes in. Thanks to them, other brown rats that might be carrying foreign diseases are unable to get into cities.
The results of this genetic research puts a positive spin on brown rats that are normally regarded with great animosity. It makes me think that brown rats might be worth keeping around instead of exterminating them. They might not be clean, they might cause damage, but if the theories here are correct then they are also the reason that diseases far worst aren’t spreading through our major cities.