When did people start eating grains?

Wheat and other grains were not part of our ancestor's diet from around two-and-one-half million years ago until the Agricultural Revolution around ten thousand years ago. Then people began eating wheat.

Many of us have a problem with wheat and grain because our bodies are still extremely similar to the bodies of our ancestors. Less than 1/10th of 1% of our genes have changed in the last 10,000 years. In terms of the evolution of our genes, it's not that long ago.