Yes - but the humans that lived for those "millenia" were much smaller in number than today. They were much poorer, often "dirt poor", despite constant manual l

Yes - but the humans that lived for those "millenia" were much smaller in number than today. They were much poorer, often "dirt poor", despite constant manual labor that barely left time for literacy – much less HN-like discussions. They died comparatively young, often of diseases we can now avoid/cure, or in violent battles for meager resources. And, those were no great stewards for the environment either. They used slash-and-burn famring. They hunted species to extinction. The Sahara desert (& lots of other desertification) might be the result of primitve land misuse. And of course they rarely met a slightly-different tribe of humans on the next hillside, competing for limited resources, that they didn't eventually try to massacre (often succeeding). Unless you are over 100 years old – I'm not – there's no "we" that could have magically decided, with what they knew 100 years ago, to magically prioritize "solar refrigerators" or whatever other fairytale innovation you think could've replaced today's fossil-fuel usage. (Solar refrigerator usage wouldn't have delivered your computer, your meals, your education, or your entertainment.) There's only the people who existed then, doing the best they could with what they then knew, and now us, doing the best we can with what we now know. "We" now are only recently rich enough & smart enough to even care about far-away oil spills, & long-term sustainability. And we owe those riches & smarts to the flawed best efforts of prior generations. As we unwind those arrangements & path-dependencies that, with hindsight, are hurting us or likely to hurt our offspring in the future, we have to be realistic about how to feed, educate, & give meaning to 8 billion fellow humans. I don't want to go back to a tiny population of humans eking by – when lucky! – on hunter-gathering or subsistence farming, until the sun burns out. (And any defections to a more ambitious developmental path would be held down by what new religion or government, exactly?) If that's the 'sustainable' future, we might as well just end it all now – homo sapiens already lived that cycle of mundane misery, for hundreds-of-thousands-of-years. I'd rather see how the 'progress' path, with potential happy & ever-varying lives for billions or trillions more humans, might work out – instead of just retreat back to the 'safe stagnation' path.