The Paleolithic diet is a trendy food craze based on the premise that our digestive systems are best designed to consume the kinds of foods our Paleolithic ancestors ate, in a time before agriculture. That has been presumed to mean a diet rich in meat, nuts and berries.

But a new study suggests that this model may be too simplistic, and that our Paleolithic ancestors ate a far starchier and familiar diet than previously believed, reports New Scientist. It turns out that porridge, and possibly even flatbread, may have been a staple menu item for Stone Age people.

The research found traces of starchy oats on ancient stone grinding tools found in Italy, Russia and the Czech Republic, which means the oat-processing culture was rather widespread. The samples could be dated back at least 32,000 years, in a time long before the advent of agriculture, which only began some 12,000 years ago.

There was also evidence of what was likely done to the oats. The grains were starchy, gelatinous and swollen, indicating they had been heated in liquid after grinding, which would have transformed them into a porridge not unlike the food we eat today.

The wild oats were also heated up before grinding, which is a method for drying them out to better prepare them for the grinding process. The ground grains could also have been baked into a simple flatbread, something that's definitely supposed to be off-limits to modern-day Paleo dieters.

All the evidence points to a time-consuming and sophisticated process of transforming these grains into food. This was not done for the occasional snack. These grains were likely a central part of the Stone Age diet. Furthermore, the findings corroborate previous studies that found evidence in Paleolithic sites of ground up roots and other plants. So it would appear our Stone Age ancestors ate a much richer, plant-based diet than previously believed, which would have made meat far less of a necessity.

“We’ve had evidence of the processing of roots and cattails, but here we’ve got a grain, and a grain that we’re very familiar with,” Matt Pope, an archeologist from University College London, told New Scientist. “If we were to look more systematically for ground stone technology we would find this is a more widespread phenomenon.”