Norrbotten, a province in northern Sweden, was an area prone to a wide variations of famine and abundance in the early to mid 19th century. Data was meticulously collected during that time, looking at what years famine and abundance took place, and the overall health of the population. What the scientists at the Karolinska Institute discovered was that children who suffered from famine early in their lives turned on and off certain genes in their genetic code – which would later influence the health of their offspring in negative ways. In times of abundance the same was true but in reverse – children born from this group generally grew up healthier and bigger. This observed phenomenon was a shocking conclusion that flew in the face of Darwinian evolution – significant genetic changes weren’t happening over millions of years, but rather over the course of just a single generation. Environmental factors seem to not just be integral to an organism’s survival, but can also influence the genetic markers of their offspring. It was from this that the foundation for modern epigenetics was laid.
Conrad Waddington and the Epigenetic Landscape
The precursor to the contemporary field of epigenetics was a biologist named Conrad Waddington. In the late 1930s Waddington observed that the Drosophila, a genus of fly, had activated a gene in response to an application of heat. This gene specifically targeted the formation of the wing and seemed to be heritable. The next couple generations of Drosophila then inherited this trait despite not undergoing any heat stressors. After more observations, Waddington was able to assert that gene regulation is not only influenced by the environment, but also heritable. This theory of genetic assimilation led to Waddington using the epigenetic landscape metaphor. In this metaphor he used the imagery of a marble going down a hill. The final stopping points of this marble represent the type of tissue that it would ultimately become – with the resting point being influenced by the path of the hill. Here, epigenetics is the study of the changes that can occur on that path, leading to a new stopping point for the marble.
Lamarckianism
This theory of genetic assimilation brought a lot of rebuke from his colleagues – the primary criticism that Waddington was supporting a modern version of Lamarckian inheritance. Lamarckian inheritance, a hypothesis put forward by French biologist Jean-Baptiste Lamarck, asserted that used characteristics during an organism’s lifetime where heritable by their offspring. Also called soft inheritance, this idea was largely considered debunk after a host of experiments largely disproved it. Other scientists came to Waddington’s defense, putting forward that while Waddington was critical of pure Darwinism, he still considered himself a Darwinian scientist. Nonetheless, there are still some who support the idea that epigenetics is a form of neo-Lamarckianism.
Epigenetics in the Modern Era
While term has been around since the 17th century and has historically meant simply ‘extra growth’, the modern usage of epigenetics didn’t start to develop until the 1990s. Even then, as the burgeoning science started to grow, epigenetics could have a fluid meaning. It wasn’t until a Cold Spring Harbor meeting of scientists in a December 2008 concluded that epigenetic traits are merely phenotypes that heritable and change without any alterations to the DNA. Today the field has grown leaps and bounds with small studies on epigenetic inheritance in mice, to data collected from large scale modern famines such as in during the Great Leap Forward in China. This data has influenced the pharmaceutical, medical, and psychology fields in dramatic ways. Using inhibitors like 5-azacytidine can help turn off genes that lead to diabetic retinopathy – which is damage to the eye as a result of diabetes. Exposure therapy in treating anxiety and trauma is also heavily influenced by epigenetics – individuals exposed to stimuli that makes them fearful in a controlled environment has led to increased receptors in the brain that are crucial to activating genes to downregulate this anxiety. Other studies have found how pollutants can modify our genetic code to make use more susceptible to different types of cancers and other diseases.
The Future of Epigenetics
The field of epigenetics has come far, but still has a long way to go. since Ever since the completion of the Human Genome Project (HGP) there has been a push to properly map all the different epigenetic traits. This would be a considerable process that would be even larger in scope than the massive HGP was. This Human Epigenome Project (HEM), if completed, could cause massive breakthroughs in how scientists treat diseases and mental disorders. Genetic modification, once the realm of fiction, now has a possibility to become a reality.
Also check out my E-Book – Epigenetics: How to Modify Your Gene Expression For Optimal Health
Citations:
http://genesdev.cshlp.org/content/23/7/781.full
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3857581/