New genomic research reveals that bed bugs have been evolving alongside humans for over 60,000 years—making them perhaps the earliest true urban pest and a mirror to our species’ global expansion.
Key Points at a Glance
- Bed bugs split from their bat-associated relatives around 245,000 years ago
- Human-linked lineage shows population growth mirroring urban development
- Bat-associated lineage has declined since the Last Glacial Maximum
- Modern genome data reveal early signs of insecticide resistance
- Study offers insights into co-evolution of humans and pests
Long before rats roamed subways or cockroaches scuttled through city apartments, one parasite made the leap from the animal kingdom into human life—and stayed. According to new genomic research from Virginia Tech, bed bugs may be the first true urban pest, having followed humans out of caves and into cities for more than 60,000 years.
Published in Biology Letters, the study traces the evolutionary history of two genetically distinct bed bug lineages: one that still clings to bats, and another that’s been riding the human wave since the Ice Age. The findings provide remarkable evidence that as humans left caves, founded settlements, and built cities, a subset of bed bugs came along for the ride—and flourished.
“It’s a story of two very different evolutionary paths,” said Lindsay Miles, lead author and postdoctoral fellow at Virginia Tech. “The bat-associated bed bugs declined after the Last Glacial Maximum about 20,000 years ago. But the human-associated lineage recovered and exploded in population, mirroring human civilization.”
In other words, as humans congregated and built cities like ancient Mesopotamia some 12,000 years ago, our uninvited companions were expanding too, finding warmth, blood, and shelter in increasingly dense urban settings.
Warren Booth, associate professor and co-author of the study, explains that bed bugs likely migrated with early modern humans as they moved out of caves. “These humans took a small population of bed bugs with them. That led to less genetic diversity in the human-associated lineage—but clearly not less success,” he said.
Using whole-genome sequencing, the researchers were able to estimate effective population sizes and reconstruct demographic trends. The data reveal that while the bat-linked bugs have continued to decline, the human-associated bed bugs saw significant growth—especially as urbanization ramped up.
Even more intriguingly, the team is exploring recent evolutionary changes, especially over the last century. Bed bugs were thought to be nearly eradicated by mid-20th-century pesticide campaigns, particularly using DDT. But their comeback in recent decades—fueled by global travel and resistance to modern insecticides—has made them once again a formidable urban pest.
Booth, Miles, and graduate student Camille Block previously identified a gene mutation that could underlie this insecticide resistance. That discovery is part of their ongoing work tracking the bed bug’s genetic shifts using both modern and 120-year-old museum specimens.
What makes this research stand out is its blend of deep evolutionary context and pressing modern relevance. It’s not just a tale of prehistoric hitchhikers—it’s a real-time look at how organisms adapt to, exploit, and evolve within human-made environments.
As cities grow and climate change reshapes habitats, understanding the co-evolution of pests and humans becomes more than just a matter of curiosity—it’s essential for public health. Bed bugs, once thought to be relics of the past, have proven disturbingly adept at survival.
“It’s really a question of co-dependence, even if it’s unwanted,” Miles said. “These insects adapted to us, our behavior, our habitats. Their story is, in a strange way, part of our story.”
By mapping their genomic evolution, researchers are uncovering a hidden narrative of human expansion, urban development, and the unintended consequences of our changing world. And in doing so, they’re arming scientists and policymakers with the knowledge needed to stay one step ahead of our most ancient, unwanted roommates.
Source: Virginia Tech News
