Smarter groups tend to be more cooperative. This finding, which shows up both in lab experiments and in free-form negotiation studies, means that intelligent groups have more social intelligence. That helps explain why countries with high average test scores usually have stronger economies and more effective governments.
Good literature review on the positive relationship between intelligence and cooperation in economic games, from a new book from Stanford University Press: Hive Mind: How Your Nation’s IQ Matters So Much More Than Your Own by Garett Jones.