A new study from Yale University, published in the journal Current Biology, has uncovered that thirteen-lined ground squirrels can sense touch even in temperatures as low as 4°C (39°F). This discovery challenges previous beliefs about how mammals perceive touch, which were thought to be limited to warmer conditions. The research, led by scientists Elena Gracheva and Slav Bagriantsev from the Yale School of Medicine, focuses on mechanosensory neurons—specialized nerve cells that convert physical touch into electrical signals. These neurons remain active in cold conditions in the squirrels, unlike in most mammals, including humans, where cold exposure can lead to nerve damage. This study follows earlier research from 2017, which found that thirteen-lined ground squirrels and other hibernating animals have nerve cells less affected by low temperatures. The latest research zoomed in on mechanoreceptors—structures that detect physical contact. The scientists tested these receptors by incubating the neurons at 10°C and then stimulating them. They observed a strong response, indicating that the squirrels' nerve cells can function effectively even in cold environments. To confirm their findings, the researchers used a paintbrush to gently touch hibernating squirrels at 4°C. Each squirrel responded by awakening, suggesting they can detect physical contact while in a state of hibernation. The researchers believe this ability might help the squirrels sense potential threats, such as predators, while in their deep-sleep state. The study emphasizes the remarkable adaptability of the mammalian sensory system, showing that touch perception can occur outside the previously assumed temperature range. The findings could have important applications in medicine, particularly in procedures where patients are cooled to induce temporary cardiac arrest, such as during heart surgery. Understanding how hibernating animals naturally handle cold environments could lead to safer and more effective medical cooling techniques. The study, titled "Cold-gated potentiation of mechanotransduction supports touch sensation below 5°C in a mammalian hibernator," was published in Current Biology in 2026.