Researchers discovered that after previously being exposed to mustard oil, those with so-called Neanderthal variations in the sensory neuron-related gene SCN9A are more susceptible to pain from skin pricking. Three mutations in the SCN9A gene, referred to as M932L, V991L, and D1908G, have been found in sequenced Neanderthal genomes and there have been reports of increased pain sensitivity in people who possess all three variants. The precise sensory responses impacted by these variations were unknown, though, until this study.