The relatively new field of epigenetics is smashing holes through the traditional theory of evolution, proving that natural selection isn’t as straightforward as we once might have thought:
One study, again from Sweden, looked at lifespans in Norrbotten, the country's northernmost province, where harvests are usually sparse but occasionally overflowing, meaning that, historically, children sometimes grew up with wildly varying food intake from one year to the next. A single period of extreme overeating in the midst of the usual short supply, researchers found, could cause a man's grandsons to die an average of 32 years earlier than if his childhood food intake had been steadier. Your own eating patterns, this implies, may affect your grandchildren's lifespans, years before your grandchildren – or even your children – are a twinkle in anybody's eye.
This new way of understanding how genes are passed on doesn’t in anyway disprove the general theory of evolution (that those best adapted to a particular environment will flourish, while others will fail), but it does go to show that our environments play a far greater role than first believed, and that an individuals lifestyle may be able to influence his or hers DNA.
The implications of this discovery are stunning. Take for example the study of neuroplasticity. The field is forever altering the way we look at intelligence with evidence conclusively pointing to the fact that the brain has the ability to change up until very late in life, and that it can re-wire itself to take over functions should a particular system (say the part that controls reading) die off or get damaged. The fact that the brain is ‘plastic’ means we can change it, and epigenetics suggests those changes could possibly be passed on to our children or grandchildren.