Two recent episodes of 'The Food Chain' (World Service, episodes are available on BBC iPlayer) cover this story about the Hadza and the gut biome - absolutely fascinating!
Recently I also listened to a (much older) episode of the programme about survival - a guy who was marooned at sea and living off desalinated water and fish he caught, for 9 weeks. The diet expert interviewed said that a lack of carbs is definitely survivable and explained gluconeogenesis (although not by name).
Really interesting stuff. I love iPlayer radio, and that programme in particular.