Abstract. Less than 20 years ago it was discovered that thermal noise affects processes inside living cells to a remarkable extent. For example, it causes substantial non-genetic variation in the amount of proteins, as well as in the amino acid sequence of proteins. The latter kind of variation is caused by errors that ribosomes make when translating RNA information into proteins. We know very little about how noise and especially mistranslation affects evolution. Here I describe experiments that mitigate our ignorance. In these experiments, we asked, first, how evolving proteins cope with the damage that mistranslation causes, and showed that they adapt by increasing their robustness to noise. Second, we asked whether noise can also facilitate or accelerate adaptive protein evolution, and showed that it can do so in more than one way. For example, it can help diversify evolving populations by rendering new peaks in a fitness landscape accessible. The same DNA mutations that increase protein robustness are also involved in this diversification, and thus provide a link between protein robustness and evolvability.