Worth pointing out as well that many h-g tribes indulged in limited forms of agriculture as a way of ensuring food supplies, both vegetable and animal (planting crops attracts certain insects & plants, which in turn attracts larger animals such as predators, grazers or scavengers, which in turn gives hom sap both meat and two veg in his little patch.
Lots didn't - one of the most magnificent things about our h-g ancestors was that they were able to adapt enough, in enough places (most of the planet - no other basic level species is able to exist in as many separate environments as humans), to breed and most importantly keep the kids alive.
BTW, cheers for the Guns, Germs and Steel stuff...I'm gonna look that up as a torrent...