Something I'm genuinely curious. What is the minimum number of people put together in a trade network sufficient to establish a particular technological framework? A hunter gather knows just as many things about the world as I do but will generally know the same things that everybody else in their tribe of the same gender knows. And of course there's access to specialized materials too to consider, starting with getting both copper and tin or arsenic in the same place during the Bronze Age. If we were trying to establish a settlement on Mars what would be the minimum number of people needed to make it self sustaining and able to build things like computers?