Graduate, University Oslo, 1972. Doctor of Philosophy, University Oslo, 1978. Doctor honoris causa (honorary), University Antwerp, Belgium, 2001.
Research associate Norwegian International Biological Progressive, 1972—1975, University Oslo, 1975—1978, associate professor population dynamics, 1980—1985, professor, 1985—1989, professor zoology, 1990—2003, research professor, chair ecology and evolution, since 2004. Associate professor ecology University Lund, Sweden, 1979—1982. Visiting Fulbright scholar Museum Vertebrate Zoology University California, Berkeley, 1984.
Visiting professor department biology University Kansas, Lawrence, 1989, honorary curator Museum Natural History, 1989—1997. Science advisory Norwegian Institute Nature Research, 1989—1992. Director Center Development and the Environment University Oslo, 1990—1992.
Visiting professor conservation ecology University Kent, 1994—2001. Senior/chief scientist II Institute Marine Research, since 2000. Member Species Survival Commission World Conservation Union (International Union for Conservation of Nature), since 2002.
Professor II Hedmark University College, since 2003. Chair EcoClim-NCoE, since 2003. Research associate department statistics and actuarial science University Iowa, since 2005.
Fellow: French Academy of Sciences (foreign fellow), Academia Europaea, Royal Norwegian Science Society and Letters, Norwegian Academy of Sciences and the Letters, Internatcia Scienca Akademio Comencus. Member: Norwegian Association Non-fiction Writers.