If you have met other civilizations that have discovered some technology you do not have, your cost to research that technology is discounted.

The formulas are

discount = floor(30*civRatio) civRatio = civs that are both met and have the tech / total civs on map

Here are the discounts for some civRatio values:

CivRatio : Discount 25% : 7% 50% : 15% 75% : 22% 100% : 30% (not attainable, as you would have the tech)

Given this information... one potential use is to push hard for civil service (food good for science), then catch up on other research.