Contributions from Mendel, Darwin, and Watson and Crick  among others have led to the heuristic model we teach in school which describes how genetic information is passed from generation to generation, and how it is used by the cell to produce functioning protein. The model describes how small changes in the genetic material happen, and how advantages from those small changes over time can result in some organisms being more competitive leading to change of species over time.  Just when we think that all the pieces of the puzzle start coming together, we find some alternate evidence which may require a different model, or certainly a modification of the current one.

The popular press likes to show things as controversial. In a recent example, you may have read about in newspapers or in popular science magazines, it was reported that some inheritance appeared more related to the older theory of Lamark rather than the model of Darwin. What seems to be happening is that in some cases, changes are brought on by the environment which last for several generations. For example, it was found that some mice when fed certain diets produced offspring very much different than the same genetic variants fed a different diet. Furthermore, these changes in the offspring were passed on for many generations yet there was no change in the genetic code. In other words, phenotypic changes in offspring were expressed even though there were no mutations.

The current understanding of the phenomena is explained not by getting rid of over 100 years of the model, but by supplementing the long standing model with what is called epigenetics. The prefix epi means on top of. Epigenetics refers to something imposed on top of genetics. The something may be as simple as a change to the regulation of a gene which may be simply an on – off switch. A lot of research in going into this topic and we can expect to read a lot more about epigenetics in the future.