They are six-legged, hairy home invaders that will not die, no matter how hard you try.

Cockroaches are experts at surviving indoors. But they did not start out that way.

A recent study uses genetics to examine cockroaches’ spread across the world, from beginnings in southeast Asia to Europe and beyond. The findings cover thousands of years of cockroach history and suggest the pests may have spread across the world by getting a ride with another species : people.

“It’s not just an insect story...It’s an insect and humanity story,” said Stephen Richards of Baylor College of Medicine. Richards was not involved with the study.

Researchers studied the genes of over 280 cockroaches from 17 countries and six continents. They confirmed that the German cockroach — a species found worldwide — has its beginnings in southeast Asia. The creature likely evolved from the Asian cockroach around 2,100 years ago. Scientists have long suspected the German cockroach’s Asian beginnings since similar species still live there.

The research appeared recently in the publication Proceedings of the National Academy of Sciences.

The cockroaches then spread around the world on two major paths. They traveled west to the Middle East about 1,200 years ago, perhaps living in soldiers’ food storage containers. And they may have gotten on Dutch and British East India Company trade ships to get to Europe about 270 years ago, the scientists’ findings suggest.

Once the creatures arrived in Europe, inventions like the steam engine and indoor plumbing likely helped the insects travel further and get used to living indoors, where they are most commonly found today.

Researchers said exploring how cockroaches conquered past environments may lead to better pest control.

Modern-day cockroaches are tough to keep away because they evolve quickly to resist pesticides , said the study’s writer Qian Tang of Harvard University.

I’m John Russell.

Adithi Ramakrishnan reported on this story for the Associated Press. John Russell adapted it for VOA Learning English.

Words in This Story

species – n. group of animals or plants that are similar

evolve – v. to develop by a process of evolution

plumbing -- n. the system of pipes and fixtures that distribute and use water in a building

pesticide -- n. an agent used to destroy insects or pests