a1 Cohn Institute for the History and Philosophy of Science and Ideas, Tel Aviv University, Tel Aviv 69978, Israel [email protected]
a2 11 Fernwood, Clarence Road, London N22 8QE, United Kingdom [email protected]
In his theory of evolution, Darwin recognized that the conditions of life play a role in the generation of hereditary variations, as well as in their selection. However, as evolutionary theory was developed further, heredity became identified with genetics, and variation was seen in terms of combinations of randomly generated gene mutations. We argue that this view is now changing, because it is clear that a notion of hereditary variation that is based solely on randomly varying genes that are unaffected by developmental conditions is an inadequate basis for evolutionary theories. Such a view not only fails to provide satisfying explanations of many evolutionary phenomena, it also makes assumptions that are not consistent with the data that are emerging from disciplines ranging from molecular biology to cultural studies. These data show that the genome is far more responsive to the environment than previously thought, and that not all transmissible variation is underlain by genetic differences. In Evolution in Four Dimensions (2005) we identify four types of inheritance (genetic, epigenetic, behavioral, and symbol-based), each of which can provide variations on which natural selection will act. Some of these variations arise in response to developmental conditions, so there are Lamarckian aspects to evolution. We argue that a better insight into evolutionary processes will result from recognizing that transmitted variations that are not based on DNA differences have played a role. This is particularly true for understanding the evolution of human behavior, where all four dimensions of heredity have been important.
Eva Jablonka is a Professor in the Cohn Institute for the History and Philosophy of Science at Tel Aviv University, Israel. Her doctoral studies in molecular genetics were carried out in the Hebrew University, Jerusalem, and she has published papers in microbiology and cytogenetics. More recently, her work has been in epigenetics, evolution, and the philosophy of biology, and she is the author or coauthor of many articles in these fields. Jablonka has written a textbook on evolutionary biology for the Open University of Israel and a short book on the history of heredity (both in Hebrew), and is coauthor of Epigenetic Inheritance and Evolution (1995) and Evolution in Four Dimensions (2005) with Marion Lamb, and of Animal Traditions (2000) with Eytan Avital.
Before her retirement, Marion Lamb was a Senior Lecturer in the Biology Department of Birkbeck College, University of London. Her laboratory research and publications were in radiation biology, mutagenesis and ageing. For the past 20 years she has been working on theoretical aspects of epigenetics and evolutionary biology. She is author of the book Biology of Ageing (1977), and coauthor (with Eva Jablonka) of Epigenetic Inheritance and Evolution (1995) and Evolution in Four Dimensions (2005).