Toni Antonucci, a professor of psychology at the University of Michigan, has conducted research into friendship and says; "Relationships help people feel that they're worthy, that they are capable, that they can set goals and accomplish them, and that they can control their life," Harvard relationship expert Lisa Berkman says that people who have a lot of friends often don't need as many close family ties. Meanwhile Ryan Howell, assistant professor of psychology at San Francisco State University has undertaken research which concludes that, in the long run, relationships make us happier than possessions.
This is a very brief summary of research that you can find in a search fairly easily if you want to delve deeper. In summary friendships make you happy and experiences are more rewarding than possessions. Most of us will know that to be true intuitively, without the need for supporting research but it is there if you need it.
The key thing is that the experiences which build friendships can be positive or negative. Surviving a hostile situation together can create significant bonds. Many people who have fought in wars describe the relationships that they had with their comrades as something that could not be matched by peacetime friendships.
When you consider your own friendships often you will have survived traumas together but there will also be countless days out, shopping trips and meals which are the building blocks of friendship.
It's much the same with working relationships and team building. There are some overly pious team building specialists who put fun events down as not useful and suggest that only theory based programmes are capable of building teams. They couldn't be more wrong. High performing teams will have a long history of positive experiences, as well as some traumas that they have survived. These positive experiences will include meals out and also more structured activity based team building days. It will also include more theory based work to develop their strategies and personality profiling so they can get to know each other better.
There is no great science to team building, any more than friendship is something than can only be understood by analysis and study. We are a social species. There are studies, and there is some science ... and a lot of pseudo-science, but most of the conclusions are those that we know, intuitively to be right. Having fun with your colleagues makes for better teamwork in the office.