Charting this landscape is usually done through manual research. But now a computer has been taught to reconstruct lost languages using the sounds uttered by those who speak their modern successors.
Alexandre Bouchard-Côté at the University of British Columbia in Vancouver, Canada, and colleagues have developed a machine-learning algorithm that uses rules about how the sounds of words can vary to infer the most likely phonetic changes behind a language's divergence.
For example, in a recent change known as the Canadian Shift, many Canadians now say "aboot" instead of "about". "It happens in all words with a similar sound," says Bouchard-Côté.