Paleolithic hominins — human ancestors — didn’t brush twice a day, which probably helped when archaeologists used the remains of dental plaque to learn which foods were popular back in the Middle Pleistocene era. It turns out the paleo diet wasn’t all meat: The plaque included nutritional plants, probably nuts and seeds.

In a study published this month in the journal Quaternary International, researchers extracted samples of plaque from the teeth of three hominins that lived 300,000 to 400,000 years ago in Qesem Cave, in what is now Israel. Dental plaque stores remnants of ingested food, and an analysis of the stuff found substantial amounts of starch granules and other plant-related chemical compounds.

The research presents “a stark contrast to the notion that an early Paleolithic diet was based largely on meat,” according to a summary published by the University of York, which partnered with the University of Barcelona and Tel Aviv University on the research. “Making deliberate use of local, nutritional plant resources ensured that their diet fulfilled their physiological requirements and suggests a detailed knowledge of the local ecology.”

In a statement provided by the University of York, Ran Barkai, an archaeology professor at Tel Aviv University, said: “Dental calculus from human teeth of this age has never been studied before, so we had very low expectations because of the age of the plaque. However, because the cave was sealed for 200,000 years, the teeth we analyzed were exceedingly well preserved. These findings are rare — there is no other similar discovery from this time period.”

Incidentally, our Paleo ancestors may not have brushed regularly, but they seem to have foreseen flossing: The university statement notes that “plant fibres and microwear patterns on the teeth point to chewing of raw materials and possibly oral hygiene activities such as tooth picking.”