The accounts the researchers analysed go as far back as to the 1800s. And that included for instance documentation on the type of toolkits found or notes from anthropologists visiting the sites those communities occupied. So no, the study didn’t only consider the past 100 years or so. Just whatever has been discovered and written down in that time period.

There obviously were many more hunter-gatherer communities in the past, and they went through the records of over 1,400 of them, but only 63 had explicit data on hunting.