• development;
  • epigenesis;
  • epigenetics;
  • gene-centrism;
  • genomic context;
  • genotype;
  • phenotype;
  • preformationism;
  • Waddington

Abstract: One continuous thread in this volume is the name of Conrad H. Waddington (1905-1975), the developmental biologist known as the inventor of the term epigenetics. After some biographical notes on his life, this article explores the meaning of the Waddingtonian equation and the context wherein it was developed. This equation holds that epigenesis+genetics=epigenetics, and refers in retrospect to the debate on epigenesis versus preformationism in neoclassical embryology. Whereas Waddington actualized this debate by linking epigenesis to developmental biology and preformation to genetics, thereby stressing the importance of genetic action in causal embryology, today's epigenetics more and more offers the possibility to enfeeble biological thinking in terms of genes only, as it expands the gene-centric view in biology by introducing a flexible and pragmatically oriented hierarchy of crucial genomic contexts that go beyond the organism.