Ancient Capybara Tooth Reveals Hidden Wet Phase in Atacama’s Past

A single fossilized capybara tooth unearthed in Chile’s Atacama Desert is reshaping scientists' view of the region’s climatic history, indicating that the world‑renowned arid basin experienced significantly wetter conditions in the distant past.

Capybaras are the largest living rodents and are closely tied to water‑rich habitats such as riverbanks, marshes and floodplains. Finding a tooth from this semi‑aquatic mammal deep within a landscape now famed for its extreme dryness suggests that the desert once supported ecosystems capable of sustaining such species.

The Atacama, long held as the planet’s oldest non‑polar desert, has been a benchmark for hyper‑arid research. Conventional reconstructions have portrayed the basin as perpetually barren for tens of thousands of years, with only occasional, brief humid pulses. The new fossil evidence challenges that narrative by providing a tangible, biological marker of sustained moisture.

Researchers identified the tooth within sedimentary layers that, according to stratigraphic analysis, belong to the late Pleistocene epoch. The surrounding matrix contains mineral signatures and pollen assemblages consistent with periodic lake formation and riparian vegetation, reinforcing the idea of a more humid environment than previously assumed.

While the discovery does not rewrite the entire climate record of the Atacama, it adds a crucial data point that may prompt a re‑examination of regional paleo‑environmental models. If larger, water‑dependent mammals could thrive there, it implies that precipitation levels, groundwater availability, or surface water bodies were substantially higher during that interval.

Future fieldwork will aim to locate additional faunal remains and to refine the dating of the deposit using radiometric techniques. Integrating these findings with existing ice core, lake sediment, and speleothem records could help clarify the timing, duration, and drivers of the desert’s wet phases, offering broader insights into how extreme environments respond to global climate fluctuations.