.....
While it's true that foods like acorns and beech nuts can provide a really important source of fat and protein, you've got to remember that not every year is a mast year. This would have been extremely important to our ancestors - for example, it's said of Cormac mac Airt (a legendary high-king of Ireland) that one of the reasons his reign was particularly auspicious was because every year he ruled was a mast year.
and the reality of MacBeth's long reign was that, "In his time there were fertile seasons"
The fertility of the King is transferred to the fertility of the Land.
On balance, I think it could be done, but it'd need a h3lluva lot of work and working knowledge of the plant seasons and environments and lots of land to forage over. I also think that like bears there'd be a real need to lay down fat reserves for our cold, dark and wet Winters and early Spring.
cheers,
Toddy