I have about two or three happiness more than unhappiness, with four small cities in the early game. When I get a new tech, be it trade, calendar, or military theory, my unhappiness suddenly jumps to 5 or so more than my happiness and sends all my cities into instant famine. When I reloaded and changed my tech from trade to calendar just one turn before I was to get trade, I had no such unhappiness leap. That is, until about 25 turns later when I got calendar and my unhappiness suddenly shot up again. Yet when I reloaded and changed my tech from calendar to military theory just one turn before I was to get calendar, there was no unhappiness leap once again. That is, until about 25 turns later I got military theory, then the leap again. It seems that whenever I get a new tech, I get a huge jump in unhappiness. Can someone please explain?