Changes to Rat DNA Reflects Adaptation to Modern Human Life and Consumption of Bagels, Beer, Croissants and Butter

Scientists have discovered that rats have adapted to modern human life, even adapting their diets to the cities they live in.

The scientists behind the study, first published on bioRxiv, claim that it could be possible that humans and rats have had parallel shifts in their genetic make-up, due to modern city life. The changes in the DNA could make rats susceptible to the same health problems as humans, such as pollutants and sugary foods.

The study showed that rats' diets have also adapted to their environment. Arbel Harpak, a population geneticist at New York's Columbia University who led the study, told The Guardian, "We know rats have changed in incredible ways in their behavior and in their diet, just as human communities have changed.

"In New York, you can see them eat bagels and beer; in Paris, they like croissants and butter. They adapt in amazing ways."

A rat eats on the platform at the Herald Square subway station in New York City on July 4, 2017. Gary Hershorn/Getty

The team of scientists analyzed the genomes of 29 New York rats and compared them with those of nine brown rats from Heilongjiang province, north-east China, which is the original home of Rattus norvegicus.

The finding showed that dozens of rat genes had been through major DNA changes over the centuries, as the rats spread from Asia to Europe and America, and from the countryside and into cities.

The changed genes were associated with diet, behavior, and movement, which added pressures and challenges for the rat to overcome, such as an increased danger of disease and changes in diets.

Harpak explained to The Guardian that "This could reflect the fact that urban rats have to move through highly artificial environments that are very different from natural habitats. So you could argue these gene changes might have evolved to help them move more easily through sewers and pipes."

As the rats are closely associated with city-living humans, the scientists believe that it is possible that similar shifts have happened in both species.

In November 2019, scientists revealed that they had taught rats how to drive as part of a behavioral research project that aimed to highlight the importance of enriched environments in lab-based animal studies and to benefit the field of neurodevelopmental and neurodegenerative diseases, such as like ADHD and Alzheimer's.

Additionally, in October 2019, scientists used rats to successfully test an enzyme that could be used to help people quit smoking. Two groups of rats were trained to self-administer nicotine, and over two weeks their nicotine intakes escalated, suggesting addiction. Then, one group of rats was given the enzyme, which led to a decreased nicotine intake. The scientists behind the study say that the enzyme could be developed for human use in the future.

Newsweek has contacted the researchers for comment and will update this story.