Environmental Research. One of three "environmental" options in the "planetary improvement" line that will increase adjacency bonuses. As mentioned above, events can also increase adjacency. Like the motivational speaker who tells everyone to get along.
It works like this: If the building gets an adjacency bonus from one or more neighboring tiles, that bonus is increased by the amount of your total additional bonuses from tech/events. For example, if you've got Environmental research and nothing else, you'll end up with what you've got - +3 instead of +2. These do not stack with more neighbors, so whether you've got 1 neighbor or 6, you'll get the same amount bonus added on. So +2 becomes +3, +6 becomes +7, etc.
If you're playing Yor, they get more techs that increase the bonus. Since their production buildings do less than other race's, this is particularly important for them.
