When ecologist Jason Munshi-South started studying rodents in New York City, more than a decade ago, he was mainly interested in native animals— specifically white-footed mice. He’d visit the city’s parks and try to see how they were moving around and adapting to one of the most urbanized environments on Earth. But he found many New Yorkers he encountered during his fieldwork were more interested in hearing about another rodent.
“Everybody kept asking about rats,” he said.
So Munshi-South set out to answer what seemed like a pretty basic question: “What is a New York City rat? Where did they come from?”
The answer, he found, was complicated.
Rats are one of the most prolific mammals on the planet. Their close, often-fraught relationship with humans have allowed them to spread to pantries, sewers and garbage piles around the world. Domesticated brown rats are a commonly used mammal in laboratories making advancements in medicine and health.
But the history, evolution and ecology of rats – particularly the brown rat – isn’t well understood.
In a new paper published in the journal Science, Friday, Munshi-South and other researchers wrote that with advances in genomics and paleoarchaeology – the study of ancient humans – that’s about to change.
“I think we’re kind of at this cusp of a deluge of information about rats coming from these two fields,” he said.
Information could help scientists understand the first time humans and rats started commingling in East Asia, beginning – for the rats, at least – what would become one of the most successful partnerships in the world. Information could also further illuminate parts of human history like ancient trade corridors and human migrations. Rats have been traveling with and beside humans for thousands of years.
“What is so fun about brown rats and black rats is because they were moved by humans, they are this fun proxy to think about how humans connected as well,” said Emily Puckett, an associate professor at the University of Memphis, who did her postdoctoral research in Munshi-South’s lab and was not involved in the new paper. “If we’re connecting through trade and we’re also moving animals through trade, helping them do range expansion, then that’s saying something about us as well.”
The paper is one of three rat-focused reviews published in a special issue of Science aimed at better understanding what it calls, “our perennial rodent companions.”
The other reviews address emerging patterns in diseases that are able to jump from rodents to humans and a growing understanding, in the scientific community, of how intelligent and empathetic rats are. Studies have shown that rats in laboratory settings will help each other when they’re in distress, raising ethical concerns about their treatment in research.
“We have treated rats and the problems associated with them as a really simple issue. We see a rat, we don’t like it, we kill a rat,” said Kaylee Byers, an assistant professor at Simon Fraser University. “But rats and issues associated with them are incredibly complex.”
To manage them, she said, “We need to not only understand the rat, but we actually also have to understand ourselves and our relationship to rats in order to move towards a healthier coexistence.”
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