Genes, embryos and evolution

Abstract

When Mendel’s work was rediscovered, around the year 1900, and with the subsequent progress in genetics, one could expect that the science of heredity would eventually foster a fruitful dialogue between evolutionary biology and developmental biology, but history went otherwise until the emergence of evolutionary developmental biology or evo-devo. Within evo-devo, we can eventu- ally explain both the fact that phenotypes very similar to existing ones and in all likelihood functional, nevertheless do not occur in nature and also that na- ture often generates hardly functional ‘monsters’. Both classes of facts suggest that variation, irrespective of the selective value of the different phenotypes that are produced, has an intrinsic structure with both preferred and possibly prohibited alternatives. In the long history of evolutionary change of develop- mental change, even the rules of evolution have been evolving through time, and the same can be said of the units, and the processes, to which these rules apply and even of the categories themselves – categories like individual and species.