Cheap energy had very little to do with our massive changes. We are talking about consistent trend of people getting more adapted to civilization from the Neolithic through the Iron age and up until the 19th century. Freeze technology in any point between, humans would keep adapting to that level. And as long as populations continued to rise and new long distance trade links where being established, according to the 10k explosion hypothesis, faster. But I see your point, eventually as humans reached a new equilibrium and became decently adpated to life in static civilization and since there wouldn't be a lot of change, intelligence may no longer be needed for stuff like farming, human evolution would start slowing down and veering into odd directions. I'm just not sure this [stagnant civ] would actually happen given the absence of say fossil fuels. Arguably genes for high IQ became maladaptive basically at the same time when we got cheap energy and launched the industrial revolution. Sure there is the possibility that evolution goes ahead and changes us into something like farming, herding mammalian ants in the absence of cheap energy, but why is this so much more likley than say the idiocracy scenario of Azatoth doing horrible things to us in the presence of cheap energy? (depending on how one interprets history we may have evidence in favour of both btw) [...] On a time-scale of what, a century? In the absence of oil and coal I can't imagine say 18th century European civilization stagnating on a time scale of millennia. These are cosmic eye blinks. Canals, wind-power and watermills had already basically created a mini industrial revolution in some places. I also can't imagine say Aztec civilization stagnating in the absence of easily obtainable gold or copper. On the grand scale, over time carrying capacities will generally rise as the crops and animals used are improved, people will get better at living in cities, merchant and priestly casts will keep getting