Going Global

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German cockroaches are master travelers: These days, despite their name, they are literally everywhere – on every continent but Antarctica.

But because they lack a natural habitat, scientists have not been able to figure out where they actually came from.

Recently, however, researchers began tracking how the ubiquitous insect went global over a few millennia.

“The German cockroach can’t even fly,” evolutionary biologist Qian Tang, who led a new study on the bug, told National Geographic. “They hitchhike in human vessels around the world.”

First described by Swedish biologist Carl Linnaeus in 1767, the German cockroach, or Blattella germanica, is the most prevalent of roughly 4,600 cockroach species around the world.

Qian Tang and his colleagues probed the insect’s DNA, analyzing genome-wide markers for more than 280 cockroaches from 17 countries on six different continents.

Their findings showed that B. germanica evolved from the Asian cockroach (B. asahinai) some 2,100 years ago in what is now India and Myanmar.

At some point, the German cockroaches moved in with humans, which later triggered their dispersal: They arrived in the Middle East more than a millennium ago via traders and military movements during the Islamic Ummayad and Abbasid caliphates.

They later hitchhiked their way to other parts of the world thanks to the exploration and trade routes that took place nearly 400 years ago.

The researchers explained that their dispersal wasn’t just a coincidence, but related to the bug’s uncanny ability to survive and adapt to any environment, which stems from their rapid reproductive rate that also allows them to produce new offspring with new traits, such as resistance to pesticides.

Co-author Chow-Yang Lee said that it’s doubtful that humans will get rid of them anytime soon, while expressing awe for the tough bugs: “If you ask me to name one species or organism that I respect the most, it’s probably the German cockroach.”

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