As an introduction, he writes…
The canonical Paleolithic diet approach excludes legumes because they were supposedly not part of our ancestral dietary pattern. I’m going to argue here that there is good evidence of widespread legume consumption by hunter-gatherers and archaic humans, and that beans and lentils are therefore an “ancestral” food that falls within the Paleo diet rubric. Many species of edible legumes are common around the globe, including in Africa, and the high calorie and protein content of legume seeds would have made them prime targets for exploitation by ancestral humans after the development of cooking.
Richard Wrangham thinks hominins started cooking with fire as long as 1.8 million years ago. There’s no expert consensus yet.