Epigenetics and the Lamarckian Temptation

David Haig
Department of Organismic and Evolutionary Biology; Harvard University

Systems of epigenetic inheritance and the fetal origins of adult disease have sometimes been claimed to re-open the question of the inheritance of acquired characteristics. I will argue that these claims represent a misunderstanding of historical debates over 'Lamarckian' forms of inheritance. Epigenetic inheritance does however challenge some interpretations of the 'central dogma' of molecular biology that information flows from nucleic acids to protein and the phenotype, but not in the reverse direction. Many environmental effects in utero that have consequences for later health are conceptually little different from environmental effects on gene expression in adult life, although more interesting. The implications of these effects for evolutionary theory will be discussed.