It was assumed that mice didn’t really begin hanging out with humans until the dawn of agriculture, some 10,000 to 12,000 years ago—lured to our homes and towns by kitchens full of crumbs and granaries full of wheat. But new research indicates that the house mouse, Mus musculus domesticus, has been with us much longer, living among hunter-gatherers up to 15,000 years ago.
The study, published in the journal Proceedings of the National Academy of Sciences, details mice populations living among the Natufians, a prehistoric hunter-gather culture in Israel’s Jordan Valley. The results of this study suggest that wild mice began hanging out in human homes some 3,000 years earlier than expected—a period when the Natufians began settling into a more sedentary life.
Researchers began studying mouse populations at Natufians archaeological sites when they noticed large swings between two mouse species: what's now known as the house mouse (Mus musculus domesticus) and the short-tailed wild mouse (Mus macedonicus). They identified these species by using advanced methods to study the minute differences of their teeth and used radiocarbon dating to determine the creatures' age.
The results suggest that, though both species were likely attracted to the comforts of a permanent dwelling, the house mouse muscled out its native cousin, the short-tailed wild mouse, to become our number one pest, reports George Dvorsky for Gizmodo. The researchers found that the longer the Natufians stayed in one spot, the better the house mice thrived. However, during periods of drought or food scarcity, or when the tribe moved more often, the population of house mice in their camps dropped and the wild mice began to flourish instead.
"The beginning of sedentary living marked a turning point in human and environmental history when permanent settlement began to exert lasting impacts and ecological legacies on ancient landscapes," the researchers write in the paper.
The team also examined mouse populations living near a contemporary hunter gatherer society. They trapped two species of mice in a semi-mobile Maasai community in southern Kenya, reports Jason Bittel for National Geographic. Under natural conditions, the mice occupy similar habitats, but in the Maasai camp 87 percent of the rodents were Acomys ignitus while only 13 percent were Acomys wilsoni—ratios similar to those found in the late Natufian camps.
But why did one species beat out its closely related cousin? “We can speculate that with longer tails house mice were more agile and able to escape or navigate within a high-traffic human environment," Lior Weissbrod, researcher from the University of Haifa and co-author of the study, tells Dvorsky. "Also, behaviorally, we can speculate that house mice were better able to cope physiologically with increased levels of stress in the human environment. Probably, their dietary habits were more flexible, allowing them to adapt to whichever types of food were unintentionally made available by humans."
Knowing the ratios of domestic mice to wild mice in early human villages can help researchers understand whether archeological sites come from nomadic or sedentary populations and how those lifestyles changed over time. And it can help scientists tell the tale of how the long-tailed house mouse spread around the world.