Lab tests across 17 temperatures showed no growth below 40°C or above 63°C, with peak growth at 55°C to 57°C; above 64°C it forms protective cysts, and exposure past 70°C inactivates them.
The finding overturns the long-held view that 60°C was the practical upper limit for eukaryotes, a group that includes animals and plants, and suggests complex life can tolerate more heat than scientists thought.
Worldwide e-DNA searches already found related RNA signatures in New Zealand’s Taupō Volcanic Zone and three matches in Yellowstone, hinting that other heat-tolerant relatives may still be undiscovered.