How the house mouse tamed itself

Author: Bethany Brookshire / Source: Science News

tiny mouse skull — The tiny molars in this skull help tell a tale of mice and men, and how humans transitioned from nomadic to sedentary lifestyles.

Got a mouse in the house? Blame yourself. Not your housekeeping, but your species. Humans never intended to live a mouse-friendly life.

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But as we moved into a settled life, some animals — including a few unassuming mice — settled in, too. In the process, their species prospered — and took over the world.

The rise and fall of the house mouse’s fortunes followed the stability and instability of the earliest human settlements, a new study shows. By analyzing teeth from ancient mice and comparing the results to modern rodents hanging out near partially settled groups, scientists show that when humans began to settle down, one mouse species seemed to follow. When those people moved on, another species moved in. The findings reveal that human settlement took place long before agriculture began, and that vermin didn’t require a big storehouse of grain to thrive off of us.

Between 15,000 and 11,000 years ago (a time called the Natufian period), people began to form small stone settlements in what is now Israel and Jordan. They were not yet farming or storing grain, but they were living in a single place for a season or two, and coming back to that place relatively often. Those early settlers changed the ecosystem of the world around them — presenting new opportunities for local flora and fauna.

Lior Weissbrod, an archaeologist at the University of Haifa in Israel, started his career wanting to search for clues to the history of animal-human relationships. He was especially interested in animal remains. But, he admits, mouse teeth weren’t exactly his first choice. “[At] the site I was going to work on, the remains of larger animals were already studied,” he says. “I was left with the small mammals.”

Small mammals have even smaller teeth. The largest mouse molars are only about 1 millimeter long. This meant a lot of time sifting dirt through very fine mesh for Weissbrod. He collected 372 mouse teeth from the dirt of five different archaeological sites in modern-day Israel and Jordan, with remains dating from 11,000 to 200,000 years ago. He gave the teeth to his colleague Thomas Cucchi of the National Museum of Natural History in Paris, who developed a technique to classify the mouse teeth by species based on tiny differences in their shape.