Almost a perfect list. Although I'd replace metallurgy with medicine. Seems more important to prevent a pandemic, especially with the current level of global travel. Metallurgy (namely steel and aluminum alloys) are being replaced in many cases with composites, ceramics, etc.SakSak said:1. Writing
2. Wheel
3. Metallurgy
4. Semi-conductors (think transistor, people)
5. Mathematics
Almost made it to the list: Gunpowder, Fire, Compass.