I imagine there will be many posts in this blog in the future regarding the nature-nurture debate. It’s a question that has intrigued, perplexed, and frustrated many people for centuries past. Why are we the way that we are? Is the answer written in our DNA or in our upbringing? Are we biologically predetermined in the womb to be a certain way or is that path full of choices?
In this post, I want to begin that discussion by introducing a concept that is brand-new to me (and, I would imagine, to most other people as well)… and that is epigenetics.
Epigenetics is the topic of the cover story of the most recent edition of Time magazine. In that article, John Cloud (the author) delves into the unexpected and rather significant implications of epigenetics- including its relevance in the nature-nurture debate.
So, what is epigenetics? In short, it represents the changes to an individual’s phenotype (what we see or what is expressed) that last over multiple generations but are separate from the individual’s DNA. This means that certain qualities or traits are passed from parents to offspring- and the transmission is neither fully genetic nor fully environmental.
Let’s take a look at a couple of examples from the article…
A little over a year ago, an experiment was done by biochemist Larry Feig using several generations of rats with genetic predispositions to poor memory. The first generation of rats was placed in an environment that promoted learning- full of things to play with, things to do, and attention from researchers. These rats, who were prone to poor memory, displayed significant improvement in their ability to remember things. There is nothing strange about this- it is well established that a positive environment can make up for genetic shortcomings (and vice versa). The odd thing was what happened when this generation of rats had children.
For those who aren’t too familiar with genetics, it takes a huge number of generations for significant changes in DNA to develop- and by that, I mean, non-random changes. Thus, if two rats with poor memory mate, the overwhelming majority of their offspring will also have poor memory. So, when Feig’s second generation (and subsequent ones) displayed greater capacity for memory- even without the positive environment of their parents- it came as quite a shock.
Here’s one more example, this time dealing with people.
During the early 19th century, a small geographic area of northern Sweden was plagued by alternating years of extreme famine and extreme feast. Preventative-health specialist Dr. Lars Olov Bygren studied a sample of families whose male ancestors had grown up during these feast and famine years. The results were startling.
People who went from normal seasons to seasons of extreme feast ended up producing children and grandchildren who were prone to a plethora of diseases and to shortened life spans. In fact, the difference in lifespan for their children compared to that of the opposite category was an astounding 32 years.
Remember, the 2nd and 3rd generations experienced no strange nutritional environments, yet their bodies were somehow “told” that they should prepare for harsh (or plentiful, in the opposite case) conditions. Thus, information was passed biologically from one generation to the next and it did this without changing any of the genetic code- something otherwise thought to be impossible.
I’m sure much will be written and said about epigenetics in the next couple of decades. From the little I know, it is a field with a huge amount of potential that could significantly impact our lives. For me, it’s just another great addition to the highly intriguing subject of nature-nurture.