New genetic research shows that bedbugs were likely to become the first urban pest of humans when they abandoned bats and followed early humans from caves about 60,000 years ago.
These aggressive insects then flourished with human civilization, with their population explosions as they emerged about 13,000 years ago, according to groundbreaking genomic analysis published in biology letters, making them possible the world’s oldest urban pest species.
The study, led by researchers at Virginia Tech, compared the complete genetic sequences of two different bed bug lineages: one loyal to the genetic sequences of bats and the other loyal to bats, converting loyalty to humans. The results depict a fascinating picture of evolutionary opportunism reflecting population history.
The two paths differ in ancient caves
About 245,000 years ago, bed bugs were divided into two genetically distinct lineages. Both groups initially flourished in caves, feeding on bats and early human inhabitants. However, when modern humans began to leave their caves about 60,000 years ago, their evolutionary paths were significantly different.
“Living in caves with these humans, they took up a portion of the population when they moved out, so there is less genetic diversity in this human-related bloodline.”
Bat-related bed bugs remain behind, which is an expensive evolutionary error. Their population has been steadily declining since the last glacier peak, and continued to shrink today about 20,000 years ago.
The rise of urban opportunists
At the same time, the human-companion bed bug hits the evolutionary gold. Initially, both lineages experienced a decline in population during the Ice Age, but only those insects associated with humans recovered, and it was true.
“In both populations, the overall decline we saw was consistent with the final glacier maximum; the lineage associated with BAT never rebounds, and its size is still decreasing,” said Lindsay Miles, lead author and postdoctoral researcher of the study. “The real exciting part is that lineage associated with humans does recover, and its effective population increases.”
The turning point was about 13,000 years ago, when the first major human settlement was established with places like Mesopotamia. As population grows and cities expand, bedbug numbers explode exponentially.
Tracking human extensions with error DNA
The researchers analyzed that effective population size (the number of reproductive individuals that contribute to the next generation) is a genetic record of population history. Their findings suggest similarities between bedbugs and demographic patterns.
“We want to study changes in the size of the effective population, which is the number of reproductive individuals that contribute to the next generation, because that can tell you what happened to them in the past,” Miles explained.
Genetic data suggest that bed bugs may have beaten other well-known urban pests, known as “the first city dweller.” Although German cockroaches and black rats have established relationships with humans over the past 5,000 years, the urban partnership of Bud Bugs extends to prehistoric.
Key evolutionary insights
This study reveals several fascinating patterns in bed bug evolution:
- Ancient Schisels: Bed bug bloodlines diverged in shared cave environments 245,000 years ago
- Exodus of Humanity: 60,000 years ago
- Urban prosperity: Human-related bed bugs experienced population explosion 13,000 years ago
- Continue to decline: Bat-related bed bugs have declined steadily since the Ice Age
- Genetic bottlenecks: Auxiliary bed bugs show reduced genetic diversity of cave-out exodus
Impact of modern pest management
Understanding this ancient relationship has practical implications for modern pest control. This study provides key insights into how urban pests spread and develop, and as cities continue to expand globally, it can improve predictive models of pest and disease transmission.
Today, the evolutionary weapons race between humans and bed bugs continues. After DDT nearly eradicated bed bug populations in the mid-20th century, they rebounded within five years, creating resistance to pesticides.
“Bed bugs are common in the old world, but once DDT [dichloro-diphenyl-trichloroethane] “It was introduced for pest control, and the population collapsed. They were believed to have been eliminated at all, but within five years they started reappearing and resisting pesticides.”
Future research directions
The team plans to investigate recent evolutionary changes, especially the genetic mechanisms behind pesticide resistance. They have identified gene mutations that may cause pesticide resistance and are examining specimens collected over the past 120 years to track the evolution of these adaptations.
“What’s interesting is looking at what’s going on in the past 100 to 120 years,” Booth noted.
The study also opens doors to identify characteristics that have developed together in humans and pests during urban expansion, potentially revealing how other species adapt to urban life.
Larger pictures
This study illustrates how evolutionary research illuminates the unexpected connection between human history and the natural world. By tracking genetic changes, scientists can rebuild ancient relationships to continue shaping our daily lives.
As urban populations continue to grow globally, it is becoming increasingly important to understand how pests adapt to urban environments. As humanity’s longest urban companion, bed bugs provide unique insights into the process.
Research shows that some of our most persistent pest problems have surprisingly ancient ancestry. While we may never completely escape our evolutionary free riders, knowing their history helps us better predict and manage their future spread.
Perhaps most strikingly, this study shows that bed bugs are not only passive passengers of human expansion—they have been active participants, evolving with us for tens of thousands of years. In the ongoing battle between humans and pests, understanding of this deep evolutionary history may prove our most valuable weapon.
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