Population epigenetics: Historical notes and applications in human health

A key factor contributing to the success of Darwin and Wallace's theory of biological evolution by natural selection was its population-level perspective. This conceptual framework was not immediately adopted, largely due to the enduring intuitive appeal of Lamarckian ideas. The development of genetics during the twentieth century provided compelling evidence that effectively excluded Lamarckian mechanisms from the mainstream understanding of evolutionary processes. Some naturalists, however, proposed mechanisms by which environmental factors could influence genotypes in shaping phenotypes, later attributed to chemical modifications of DNA or chromosomal proteins, among others. The field of population epigenetics emerged with the aim of extending the well-established discipline of population genetics by incorporating such phenomena. This review seeks to provide a historical background on this subject and to examine how advances in both contemporary epigenetics and population epigenetics have been achieved, as well as their implications for the study of human diseases, particularly regarding their contribution to the phenomenon of missing heritability. Because there are major taxonomic differences in the transgenerational inheritance of epigenetic modifications, the potential effects of epigenetic architecture on phenotypes of interest also differ, as in the case of mammals and, in particular, humans.