What are the three most important scientific and technological discoveries that have shaped human history?

Three is definitely too few... IMHO, it's impossible to fit the entire development path into them. But here's a rough and very brief outline: 1. Tools; 2. The wheel; 3. Technology (this is a general concept, of course). And also...

Fire, electricity, language.

Agilist, you shouldn't write this with commas... it's funny :)