If you're trying to follow a diet similar to what a caveman ate roughly 1.2 million years ago, you may want to add uncooked grass and meat to your routine.

A new study published in The Science of Nature journal looked at the hardened tartar buildup found in one of the oldest hominin remains discovered in Europe.

The teeth were from a jawbone discovered in 2007 at the Sima Del Elefante excavation site in Spain's Atapuerca Mountains. Archeologists believe the jawbone is between 1.1 and 1.2 million years old.

From the tartar samples, archeologists found various fibres including plants, animal tissues, a scale from a butterfly's wing and a fragment of an insect leg. Archeologists also found fibres from non-edible wood.

The wood is believed to have been from regular tooth picking, an early form of dental hygiene.

The other fibres found in the tartar offered a glimpse into the caveman's diet. Starch granules were found, suggesting early hominins may have eaten grass seeds.

Raw-food diet 

"Grasses produce abundant seeds in a compact head, which may be conveniently chewed especially before the seeds mature fully, dry out and scatter," lead researcher Karen Hardy said.

Hardy also said that because the granules were largely intact and uncharred, it's believed food was consumed uncooked. Other evidence of a raw-food diet was that the teeth showed signs of heavy use from gripping and chewing raw materials.

"Our evidence for the consumption of at least two different starchy plants, in addition to the direct evidence for consumption of meat and plant-based raw materials, suggests that this very early European hominin population had a detailed understanding of its surroundings and a broad diet," Hardy said.