Amoeba Thrives Above 60°C in Californian Hot Spring

A newly studied amoeba species discovered in a hot spring in California has been found to thrive at temperatures above 60 °C, a threshold once considered lethal for complex organisms. The organism, isolated from the geothermal waters of the Geysers region, shows robust growth and cellular activity at temperatures that exceed the upper limits previously documented for eukaryotes.

Scientists from the University of California, Berkeley, conducted temperature tolerance assays that revealed the amoeba’s metabolic machinery remains functional even at 65 °C, with optimal growth observed around 62 °C. This finding challenges the long‑held assumption that complex life cannot survive beyond 60 °C and suggests that the thermal limits of eukaryotic life may be broader than previously thought. The discovery may prompt a reevaluation of the environmental constraints used to model early life on Earth and on potentially habitable exoplanets.

The study, published in the journal Nature Communications, underscores the adaptability of microbial eukaryotes to extreme environments. While the organism’s resilience does not overturn the general rule that most complex life is constrained to milder temperatures, it expands the known range of conditions under which such life can persist, offering new insights into the evolution of thermal tolerance in eukaryotes.