Hacker News
- Could an Industrial Prehuman Civilization Have Existed on Earth Before Ours? https://www.scientificamerican.com/article/could-an-industrial-prehuman-civilization-have-existed-on-earth-before-ours/ 12 comments
- Could an Industrial Prehuman Civilization Have Existed on Earth Before Ours? https://www.scientificamerican.com/article/could-an-industrial-prehuman-civilization-have-existed-on-earth-before-ours/ 3 comments