Millipedes, those unassuming creatures with their countless legs, have been quietly shaping Earth's ecosystems for hundreds of millions of years. While vertebrates were just a twinkle in the cosmos, millipedes were already thriving on the planet's surface, playing a crucial role in the earliest terrestrial ecosystems. Despite their remarkable history, many questions about their evolution remained unanswered until now.
An international team of researchers, led by Virginia Tech scientists, has finally filled in one of the last gaps in the millipede family tree. By combining DNA data from modern species with physical evidence preserved in fossils, they traced the origins of millipedes back nearly 460 million years, suggesting they existed long before the oldest millipede fossils discovered so far. This groundbreaking study, published in Current Biology, reveals that millipedes beat vertebrates onto land by more than 80 million years, setting the stage for later life on land, including humans and vertebrates.
The research team, led by Paul Marek, an associate professor in the College of Agriculture and Life Sciences' Department of Entomology, embarked on a quest to find two rare millipede groups, Siphoniulida and Siphonocryptida. These groups had been recognized for over 100 years but were elusive due to the unavailability of fresh specimens for DNA analysis. The researchers traveled to Mexico and the Canary Islands, collecting species whose DNA had never been included in an evolutionary study. It was a challenging task, as finding these tiny millipedes required a dedicated team and advanced microscopy techniques.
The team sequenced DNA from the two groups and compared hundreds of genes across 82 millipede species. They also incorporated evidence from 29 fossils, resulting in terabytes of genetic data. With the help of Virginia Tech's Advanced Research Computing resources, they reconstructed evolutionary relationships stretching back hundreds of millions of years. The results were astonishing.
Siphonocryptida is not a separate millipede order but belongs within an existing lineage, while Siphoniulida was finally placed alongside its closest evolutionary relatives. This discovery suggests that millipedes may have originated nearly 460 million years ago, significantly earlier than previous estimates. At that time, Earth looked very different, with no vertebrates, trees, leaves, or flowering plants. Millipedes were among the early pioneers of life on land, helping recycle nutrients by feeding on decaying organic material in some of the first terrestrial ecosystems.
The study also sheds light on the origins of millipede chemical defenses, which evolved about 260 million years ago, offering the clearest evidence yet for when millipedes first developed this capability. Today, millipedes remain essential detritivores, breaking down dead plant material and supporting healthy ecosystems. However, their importance is often overlooked, as they are still poorly known, with tens of thousands of species potentially undiscovered.
For scientists like Luisa "Fernanda" Vasquez-Valverde, the sense of exploration and discovery is a driving force. As she continues her research, she remains curious about the potential for further discoveries, emphasizing the importance of exploration in understanding the natural world.
