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No Cats or Dogs

11/28/2022 5 minute read

Where Did Rats Originate?

Rats (also known as Muridae) are a large family of rodents which can be found in every part of the world except for Antarctica. They’re considered pests by many people because they spread diseases, destroy property, and generally, make a pest and nuisance of themselves.

There are many rat species that can be found all over the world – so many in fact, that people have started asking questions like, “Where did rats come from?” Rats are very much a part of history and had a significant influence on the course of world events and, as such, it’s important to understand where they came from.

So where did they come from, and how did they come to live in every part of the world? This article will try to shed some light on those questions, as well as describe some of the wildest and most interesting facts about rats.

Where Did Rats Come From?

Rats are believed to have originated from Southeast Asia. Around 200,000 years ago they started spreading to Northeast Asia and then to the Middle East about 3600 years ago. Later on, they spread to Africa, and once there, they conquered the world, the first major outbreaks occurred through transportation and trading routes.

Rats can be found all over Africa, Europe, Asia, North America, and South America. They’re even found on some of the smaller islands near these continents such as Fiji where they were introduced by humans.

Evolutionary Origins of Rats

In Asia and North America, the ancestors of rats first appear in fossil records about 54 million years ago, at the end of the Paleocene and the beginning of the Eocene period. They’re believed to have evolved from anagalids, a small family of rodent-like mammals that also direct descendants of Lagomorpha or rabbits and hares.

The Murids or Muridae family (Rattus, musculus, and relatives) first appeared in the fossil record about 34 million years ago in the late Eocene period. They have evolved to become their modern versions in the Miocene era about 25 million years ago.

The Rattus genus, native to southeast Asia, Mediterranean countries, and the Middle East, first emerged from within Murids around 5 million years ago. After which it gave rise to many new and distinct species.

Ancestors of brown rats (Norway rat) and black rats (Roof rat) diverged approximately 2 million years ago and both groups have since evolved to become their modern-day versions. To this day, the genus Rattus has 51 known species.

Old World Rats

The old world rats, black rat (ship rat), and the brown rat (Norway rat) (also known as Rattus rattus and Rattus norvegicus) are the most common type of rat you’re likely to find. Trading and transportation routes very likely have played a big part in the spread of these rats and they are considered one of the most successful invasive species in history.

Black Rats or Roof rats (Rattus rattus)

Black rats (Rattus rattus) otherwise known as ship rats or roof rats are very adaptable and can survive in almost any environment. Infamous for their role as a major carrier of the bubonic plague, came from Asia and spread throughout the world, killing 200 million people in Europe alone.

They’re strong swimmers too which means they don’t have to rely on humans for transport, although that certainly helps speed up the process of spreading them across continents.

Black rats are the most common in cities and urban areas where they thrive in sewers, drains, and old buildings. These city rats are often found in homes and shops, feeding on food waste. They’re also excellent climbers which means they can easily access the upper levels of buildings through windows, pipes, drainpipes, etc.

Black rats have been living with humans for over 4000 years and their adaptability has allowed them to thrive in almost any environment.

Brown Rats or Norway rat (Rattus Norvegicus)

The brown rat (Rattus norvegicus) is slightly bigger than the black rat with a body length of around 15 inches. They’re found in sewers, basements, cellars, and underground systems. They are also called sewer rats or Norway rats; yet, despite the name, these rats actually originated in China!

Brown rats thrive in urban areas and sewers but can live just about anywhere. They often find their way into homes where they cause damage to buildings and property, as well as spread diseases through droppings and urine which is why humans try so hard to control brown rat numbers in urban areas.

Origin of the Brown Rat

Brown rats are believed to have originated from the plains of Asia, probably from what is now north China or Mongolia where the rodents lived in burrows, feeding mainly on plant material.

As a result of trading and transportation routes, they were brought to Europe from Asia sometime around 1775 where their numbers increased dramatically. In North America, the brown rat was introduced in the early 1800s via ships that sailed into port cities along both coasts.

Origin of Black Rats

Black rats originated in the Indo-Malayan region and started spreading from there. These wild rats quickly found their way to the Middle East, Africa, Europe, and then finally North America where they were a cause of many problems for settlers trying to make a new life in this strange land.

How Did Rats Spread Across the World?

There are several different theories as to how rats managed to spread across the globe. How they spread so easily is still a topic of debate among researchers but it is widely believed that they made the journey by hitching a ride on boats. Trade is booming in the world so it’s very easy for boats to pick up a rat or two without knowing.

As the old world traders expanded their trade routes, rats were able to spread like wildfire. Most likely, it was a combination of all these things and more which led to the spread of black and brown rats across the world in such a short period of time.

Some ships would have dozens of rats on them and once they reached their destination, the rat population exploded exponentially until every continent had a thriving rat community within its borders.

Arrival in Europe

Rats have reached Europe around 1300 and quickly spread across the continent. They have traveled with humans and quickly became a part of their ecosystem. Black rats arrived first and then later brown rats as well.

It was first thought that the Rattus rattus arrived in Europe during the crusades but more recent evidence suggests that they arrived much earlier. Brown rats arrived a few centuries later. The two species thrived in the urban atmosphere of European cities – over-populated, and full of food scraps and garbage, an ideal environment for rats to make their home.

The brown rat especially thrived in the sewers beneath these cities, feeding off the human food scraps and waste. They were able to breed in huge numbers and they have spread like wildfire.

The silk road trade route also played a huge part in the spread of rats because trading ships from China brought rat-infested cargoes to Europe.

The Black Death is believed to have spread due to the movement of these rats throughout the continent. The bubonic plague was carried by fleas that lived on black rats and once it entered a city, millions were infected before anyone realized what had happened.

How Did Rats Come to America?

It is believed that rats first arrived in the United States around 1776, The brown rats, specifically, first came in boxes of grain and other food supplies brought in by Hessian troops that are hired by the British during their war against America.

Since then, they have been introduced to new areas by way of cargo boats, and ships, and then later on by cars, trucks, and trains. These animals are able to adapt to new climates easily so they were able to survive in the wild with relative ease across the world once humans made it part of their territory.

Commensalism with Humans

Rats have lived with humans for thousands of years. They’ve hitched rides on boats, live in human houses, and have even made their homes in the sewers of big cities. They are able to adapt to almost any environment.

They have been a part of human society for so long that they’ve become a natural part of the ecosystem in most places and their numbers have swelled to an impossible number – outnumbering humans in some cities, especially densely populated ones like New York City where there is food waste everywhere you look.

Other Means of Migrating

Besides using ships, trains and trucks, there are some other ways that rats have been able to reach new destinations. They can travel on foot through sewers and drainage pipes, and they swim!

Rats are great swimmers and many have crossed rivers to get into new territories. In fact, rats can swim half a mile and thread in water for 3 days straight without stopping! It is thought that swarms of rats have crossed the Volga river into Russia in this way.


As we’ve seen, rats have come a long way from their origins. They’ve traveled along with humans for thousands of years and if not for their penchant for spreading diseases and destroying stuff, they would have been one of the greatest traveling companions. Unfortunately, that’s not how they’ve made their mark on history!

They do have some uses though. For example, all laboratory rats are domesticated brown rats. A brown lab rat is a very common pet and is even used in scientific research. Rats are also used for their fur which is turned into clothing, and they’ve even eaten in some countries around the world!

Rats have been in this country a long time, but AAAC Wildlife Removal is here to help with all of your rat trapper needs!

Rat FAQs

Do rats burrow underground?

Rats do burrow, but not all rats live in burrows. Some rat den is in trees, in abandoned buildings, or even in people’s attics!

Can rats swim underwater?

Do rats like to swim? The answer’s yes! They are great swimmers and can tread water for up to three days!

Do all rats carry diseases?

Rats do carry diseases, the common rat diseases include salmonella, leptospirosis, and rat-bite fever. These diseases can be passed on to humans, so it’s important to be careful when handling them!

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