I am nearing the end game of a Monarch game done on a large map. I had a bit of trouble in the beginning trying to broker techs because I could not get in contact with some other civs for quite a while. Without the Lighthouse and with continents being so distant, I just could not get a galley out to them and the Lighthouse civ did not send a ship out until much later. I was forced to just deal with my own continent for a while - and of course I ALWAYS seem to get stuck with the continent that has FOUR civs on it. I had to kill off the Indians to give myself a better foothold, so I only had the Japanese and the Russians to trade with. The other civs turned out to be the Persians, Babylonians, Zulus and Germans. Of course, the Persians and Babylonians kept building wonders before I could get the techs in ancient times, so I knew I was going to have to work from behind.
Well, when I finally met the Persians, I was indeed behind. After some initial trading, I found that there was only one thing that I could do to get myself even and give myself a shot at climbing into a tech lead: be a jerk.
I lowered my science to 0% and my luxuries to minimum (giving myself maximum per-turn income) and called on the Persians (the most advanced). I bought all of their techs for large per-turn payouts. If I couldn't buy one, I sold to other civs what I just bought for per-turn to increase MY per-turn income to buy more from the Persians. Then, I up and declared war. With all of my per-turn income back, I put it back into tech and even began to take a lead. And the Persians were so far away that I really didn't care what went on. I was even able to bribe their Babylonian neighbors to go to war with them. So while I sat at home and built infrastructure and traded for luxuries and the like, war was raging far away. I kept trying to get peace every turn as I feared war weariness, and I was able to have peace with the Persians before it set in.
The most important thing that this allowed was getting to Theory of Evolution the quickest. As the Chinese, I was able to produce some leaders, and I kept one at the ready in case I needed it for this wonder. Thankfully I didn't, and as I was building it, I found it was a great strategy to boost science to the max before it was finished. I was taking a loss of about 150-180 per turn, but I got some timely techs and when the Theory was built, the extra two gave me a nice lead that I've kept throughout. Then I put science to normal levels and forged ahead.
A note about the Theory of Evolution: It would seem that once it's built it will NOT give you the tech that you are currently working on as one of the two (I guess unless it HAS to due to prerequisites). This is good if you are close to finishing a tech that you've been researching for 5 turns, but could be bad if you just started a very important tech that you would like to have had sooner rather than later. Also could be bad if it gives you something like flight before you'd like it and cancels your Colossus.
OK, so the moral of the story:
1. Even without good contact in the beginning it is still possible to climb into and above the science rate with diplomacy - even if it's EVIL diplomacy. At least at Monarch level - I have a feeling that the same game on Deity would have dusted me.
2. Theory of Evolution holds a greater importance than ever in the higher level tech races.