Archive for May, 2011

The battle between our genes and the environment: our DNA isn’t our destiny

Sunday, May 15th, 2011

DNA does not make who we are, this is a fact now. Forget everything you know or think you know about genes. Recent years have accumulated scientific evidence suggesting a completely new paradigm based in the influence of the environment in changing our fate and destiny. The environment includes the diet, smoking, lifestyle, etc. Of course the genetic background is very important, but recent studies have been showing a different side of the history which is basically linked to an exciting field named epigenetics. This field studies the relationship between the environment and our genes at the organismal level. At the molecular level, it represents changes in our genetic material, especially the DNA, which modifies the structure of it without changing the blueprint of the sequence. Epigenetics has a major impact in changing gene expression and is affected directly and indirectly by the exposures we have before and after our birth. The findings in the field of epigenetics represent perhaps the most important discovery in the science of hereditary since the discovery of the gene. One classical example of the impact of the environment is the effect that the mother’s milk has for newborns (see the article “Mother’s milk: A rich opportunity” in Nature, 2010 by Anna Petherick). It is clear that breast milk feeding can affect brain development of the infants mainly as a consequence of changes in gene expression. These changes are mostly associated to compounds in the mother’s milk that affect the epigenetic mechanisms in the babies’ DNA. Lack of breast-feeding is also associated to increased risks of diseases such as diabetis and auto-immune disordes. In addition, a large study named ALSPAC (Avon Longitudinal Study of Parents and Children) has offered important insights on how the environmental pressures can influence health and development: baby lotions with peanut oil may be partly responsible for the rise in peanut allergies, high maternal anxiety during pregnancy is associated with later development of asthma by the kids and little kids who are too “clean” or living in a clean environment can have increased risks for eczema. Interestingly, epigenetics also pose a challenge for evolutionists since it brings back some of Lamarck’s theories and give us cards to play (if we are playing poker in the game of evolution…) against Darwin and his hypothesis. Lamarckism proposes that the environment directly affects the organisms and that the acquired changes can pass through generations. On the other hand, Darwin argued that evolution works indirectly through impartial selection – the more adapted would live and procreate. For a classical example, Lamarck believed that giraffes acquired long necks because recent ancestors had to get food in high trees that were rich in nutrients. For Darwin, long necks of giraffes evolved during millennia because genes for long neck had slowly gained advantage to these animals against their “competitors” with shorter necks. The conclusion is that our destinies are a product of a complex interplay between our genes and the environmental stimuli dynamics, such as the influence of our parents lifestyle, our lifestyle, diet and places we had lived. It will take geneticists several years to work out all these new implications, but we can be assured that the age of epigenetics has arrived to stay!