The document discusses a behavioral hypothesis for team formation based on three critical conditions: 1) a shared, voluntary goal that is embraced by all team members; 2) a goal that is not achievable by any individual alone and requires teamwork; and 3) an appropriate level of challenge that is not too easy or too difficult. It proposes that if these conditions exist, team formation will naturally begin through a process similar to Tuckman's stages of forming, storming, norming, and performing. Several practices are described that can help foster an environment where these three critical conditions exist, such as collaborative user story writing, team-written acceptance criteria, and emphasizing shared rather than individual goals.