Yet this figure represents only a fraction of the linguistic diversity that once existed, AzerNEWS reports. The study estimates that the total number of languages at its peak may have ranged from 30,000 to more than 75,000. Since then, linguistic diversity has declined significantly. For researchers, languages can also provide valuable clues about the past, including where populations lived, what they ate and how they understood the world. Instead, they developed simulation models based on known relationships between languages, populations and social structures.