An international research team has completed the first comprehensive evolutionary history of all living millipede lineages, revealing they are much older than expected

By successfully tracking down and sequencing the DNA of the last two unmapped groups, scientists have pushed the evolutionary origins of Earth’s first land animals back tens of millions of years.

Solving a century-old evolutionary mystery

Millipedes were the true pioneers of terrestrial life, establishing Earth’s early land ecosystems more than 80 million years before vertebrates left the oceans. Despite their ecological importance, full mapping of their evolutionary tree remained incomplete for over a hundred years due to two missing lineages: Siphoniulida and Siphonocryptida.

These missing links proved exceptionally difficult to study. One group consists of tiny creatures measuring barely 10 millimetres long that spend their entire lives deep underground, while the other survives in only a few remote geographic locations.

Without fresh tissue samples from these elusive animals, geneticists could not use DNA sequencing to accurately anchor them to the broader millipede family tree.

Microscopic fieldwork and advanced genomics

To resolve these missing branches, researchers from Virginia Tech led expeditions to Los Tuxtlas, Mexico, and Spain’s Canary Islands. The field teams successfully isolated specimens of Siphoniulus neotropicus and Hirudicryptus canariensis, capturing rare genetic material that had never before undergone evolutionary analysis.

Back in the laboratory, the researchers sequenced the DNA of these two elusive groups and compared hundreds of genes across 82 distinct living millipede species. They then processed terabytes of this genetic data alongside morphological evidence from 29 distinct fossil specimens.

The supercomputing analysis, published in Current Biology, successfully reclassified both groups. Siphonocryptida was revealed to be a component of an already existing millipede lineage rather than its own unique order, while Siphoniulida was definitively placed alongside its closest evolutionary relatives.

Redefining the timeline of land colonisation

The completed evolutionary timeline reveals that millipedes likely originated roughly 460 million years ago. This discovery pushes their true lineage back by 35 million years, making them significantly older than the oldest physical millipede fossils ever recovered.

During this primordial era, Earth lacked trees, leaves, seeds, and flowering plants. Millipedes pioneered terrestrial survival by consuming decaying mosses, decomposed slime, and early surface organic material, serving as the planet’s first active nutrient recyclers.

Additionally, the revised timeline allowed scientists to map the origin of the millipede’s signature survival trait: defensive chemical secretions. The data show that these organisms developed their complex internal chemical defences approximately 260 million years ago.

Cataloguing undiscovered species

While this study resolves the foundational backbone of millipede evolution, an immense amount of biodiversity remains uncataloged. Taxonomists have officially described roughly 14,000 millipede species globally, but estimate that tens of thousands of species have yet to be found.

Establishing this unified genetic framework provides future researchers with a reliable baseline to identify, classify, and protect these critical ecosystem decomposers as new species continue to be discovered worldwide.