(DALLAS) — They’re six-legged, hairy home invaders who won’t die no matter how hard you try.
Cockroaches are good at surviving indoors, hiding in kitchen pipes and musty drawers. But they weren’t like that from the beginning.
A new study uses genetics to chart the spread of cockroaches around the world, from their humble beginnings in Southeast Asia to Europe and beyond. The discovery spans thousands of years of cockroach history and suggests that cockroaches may have traveled the world riding on another species: humans.
“This is not just an insect story,” said Stephen Richards, an assistant professor at Baylor College of Medicine who studies insect genetics but was not involved in the study. “This is a story of insects and humans.”
Researchers analyzed the genes of more than 280 cockroaches from 17 countries on six continents. They confirmed that the German cockroach, found around the world, actually originated in Southeast Asia, where it likely evolved from the Asian cockroach about 2,100 years ago. Scientists have long suspected that the German cockroach originated in Asia, where it still lives.
The study was published Monday in the Proceedings of the National Academy of Sciences.
Cockroaches then flew around the world via two major routes. They traveled from the West to the Middle East about 1,200 years ago, probably hitchhiking in the granaries of soldiers. And scientists’ reconstructions and historical records suggest they may have stowed away on the Dutch-British East India Company’s trade routes to reach Europe some 270 years ago.
Once insects arrived, inventions such as the steam engine and indoor plumbing likely allowed them to travel further and further afield, allowing them to live comfortably indoors, the places we most commonly see them today.
Researchers said studying how cockroaches conquered past environments could lead to improved pest control.
Modern cockroaches are difficult to keep out because they have rapidly evolved to resist insecticides, said study author Qiantang, a postdoctoral fellow who studies insects at Harvard University.