A paleoanthropologist conducts research at a remote fossil site in eastern Africa. The anthropologist is a researcher based at a major university in the United States, and he spends 6 weeks every summer excavating and cataloging fossil materials at the site. The anthropologist has been working in this area for over 15 years, and he has formed close partnerships with local scholars and residents. His current field team is made up of students from the United States and from Kenya, as well as professional colleagues from both countries. He also hires residents from the local village to help with the excavations and to act as field staff, including drivers, cooks, and guides. In this situation, the anthropologist is studying fossil materials that are over 2 million years old. From whom should he obtain informed consent for his work?