Instead of resembling immutable proprietary software, a species’ genetic information is more like open-source code that is constantly tweaked and optimized to meet the users’ specific needs. So, which parts of the code have withstood the test of time, and which parts have undergone rapid evolutionary change? Joseph Ecker and his collaborators developed a simple method to comb whole genomes for all the software fixes and security patches accumulated over time. As a part of an international consortium, these scientists recently catalogued the genetic variations in over 1,001 strains of the mustard weed Arabidopsis thaliana that had been collected from the wild all over the world. As a general rule, genes that don’t change over time perform important housekeeping functions, while genes that vary widely are likely to mediate interactions with the environment. Identifying the genes that can help plants withstand challenging conditions such as heat, drought, high acidity, or salinity will give plant geneticists the tools to create tougher breeds that can easily adjust to new ecological niches arising due to climate change.