(Roughly) Daily

As Rodrigo Pérez Ortega reports, that admonition has a very long history…

Long before rats roamed sewers and cockroaches lurked in kitchen corners, another unwelcome guest plagued early civilizations. A new genomic study published today in Biology Letters suggests that bedbugs—the blood-feeding insects that haunt our hotel stays—were the first urban pests, proving an itchy menace for tens of thousands of years.

“This is really amazing,” says Klaus Reinhardt, an evolutionary biologist at the Dresden University of Technology who was not involved in the new study. “I think the hypothesis is quite solid.” Still, other researchers quibble over whether bedbugs can indisputably claim that title.

Many species of bedbugs depend on us—and our blood—to survive, but long ago, their prey of choice was probably exclusively bats. Genetic evidence suggests that about 245,000 years ago, some bedbugs made the jump to early humans.

This split led to two genetically distinct bedbug lineages. One kept feeding on bats and today remains largely confined to caves and natural habitats in Europe and the Middle East. The other followed humans into modern dwellings. Exactly how that scenario played out remained a mystery, however. That’s why Warren Booth, an evolutionary biologist at the Virginia Polytechnic Institute and State University, and his team set out to study the genome of the common bedbug (Cimex lectularius) in depth…

… [Their findings make] bedbugs strong contenders for the title of the world’s first true urban pest that relies solely on humans, the researchers claim. Unlike more recent urban interlopers that feast on our stored food and enjoy our cozy homes—like the German cockroach (Blattella germanica), which formed a close association with humans just 2000 years ago, or the black rat (Rattus rattus), whose commensal relationship began about 5000 years ago—bedbugs may have started parasitizing humans just as our ancestors started building permanent settlements…

… the new findings underscore how humans have shaped the evolution of urban insects. Compared with their bat-feeding cousins, human-feeding bedbugs are smaller, less hairy, and have larger limbs—adaptations likely suited to navigating smooth walls and synthetic bedding. Today’s bedbugs also carry many DNA mutations linked to insecticide resistance, a relatively recent trait that reflects the pressures of modern pest control. “They’re a remarkable yet horrible species,” Booth says.

Understanding how these pests evolved together with us could help improve strategies for controlling them, especially as cities continue to grow—and as bedbugs now feed on the poultry we raise. Further research could also help us understand how our own immune system evolved, since some people develop allergies for bedbug bites. As a start, Booth and his team are analyzing centuries-old bedbug specimens in museums, to track how the insects’ genomes—and populations—have evolved over the past century alongside us.

“There’s a pretty intimate association, whether we like it or not,” Booth says. “That’s not going away anytime soon.”…

“Bedbugs may be the first urban pest,” from @rpocisv.bsky.social‬ in @science.org‬.

* common children’s rhyme

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As we contemplate the chronicle of a co-evolved curse, we might recall that it was on thus date in 1789 that Richard Kirwan published his essay in support of the phlogiston theory (the belief, that dates to alchemical times, in the existence of a fire-like element (dubbed “phlogiston”) contained within combustible bodies and released during burning. Kirwan was among the last of its advocates.

A well-regarded scientist in the late 18th and early 19th centuries, Kirwan met and corresponded with Black, Lavoisier, Priestley, and Cavendish. Indeed, while scientific history remembers him as a defender of an incorrect theory, his work probably spurred Priestley and Lavoisier, who respectively discovered and named the actual elemental agent of combustion, oxygen.

But Kirwan is also remembered for a personal eccentricity (one of many) relevant to this post: he hated bugs (especially flies). He paid his servant a bounty for each one they killed.

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