My impression is that some versions of the paleo diet don’t include tubers.
Here’s part of an abstract at the Proceedings of the National Academy of Sciences:
Three grinding stones from Shizitan Locality 14 (ca. 23,000-19,500 calendar years before present) in the middle Yellow River region [north China] were subjected to usewear and residue analyses to investigate human adaptation during the last glacial maximum (LGM) period, when resources were generally scarce and plant foods may have become increasingly important in the human diet. The results show that these tools were used to process various plants, including Triticeae and Paniceae grasses, Vigna beans, Dioscorea opposita yam, and Trichosanthes kirilowii snakegourd roots. Tubers were important food resources for Paleolithic hunter-gatherers, and Paniceae grasses were exploited about 12,000 y before their domestication.
Did you catch “grasses” and “beans”? Could these be the verboten grains and legumes?
I know the tubers/roots above are not the white and sweet potatoes I include on my paleo diet. The latter are a New World phenomenon, and domesticated to boot.