Well, we discovered that we needed to upgrade security so that potential criminals weren't coming into our country, and so potentially harmful substances weren't being brought onto our planes. That meant literally anything that could become a bomb, start a fire, stab someone etc. As for Pearl Harbour, I think that had more of an affect on how we thought our military and defence system was working.
Population growth, agricultural policy, land ownership policy, and illegal logging.
Answer:
The Step Pyramid of Djoser! Hope this helps :)
Wait, who lived in that time? The answer could be 'war' but I need more information...
