I talk to myself, and not just a little. Drives my girlfriend crazy sometimes, not to mention my co-workers. I also talk to my environment – the television (especially during Habs games), my computer, lab equipment, particularly annoying nails, the refrigerator, whatever. Like I said, I talk to myself a lot. I’m told that I only need to worry when things start talking back.
But they do. Not so much in a disembodied voice kind of way, which would indeed be cause for worry, but our environment is always telling us things. It tells us when it’s cold, when we might be damaged by something, when there’s something big and heavy coming our way. This is no mistake, all organisms from lowly bacteria to humans have evolved over millions of years to be able to hear the things our environments say so that we can survive.
Our environments talk to us by biological mechanisms. It’s easy to understand this in terms of moment-to-moment changes registered by our eyes, ears and noses. It’s less obvious that these signals all go into the brain and start off their own chains of signals inside brain cells at the levels of proteins and genes. Accepting this as true, it makes sense that more complicated things about our environments – a loving family, proper exercise, a good education, eating right – also affect these basic biological processes.
Dr. Michael Meaney‘s research here at the Douglas Institute has done a great deal to advance these ideas and our understanding of the biology that underlies these changes. Through studying maternal behaviour in rats, we have learned that babies who receive a lot of attention from their mothers grow up to have less anxiety-like behaviours than babies who receive very little attention. We have also shown that a rat taken from a mother who doesn’t much care for her pups and given to a more attentive mother also grows up to be less anxious.
This is an amazing finding for two main reasons. Firstly, it confirms in a scientific manner something we have all suspected, namely that your parents are to blame for all the terrible things you’ve done in your life. Secondly, because the differences are based on the mother’s care, we know that it’s parenting and not genetic information passed down from the mother and father. Because we have done some pretty complicated and elaborate experiments, we have a good idea why the high maternal care pups are less anxious and have gained some insight into the mechanism by which this happens.
In my last post, I mentioned that a gene is a piece of DNA that “codes” for a protein, which go on to do the work inside cells. The elements of your DNA – the millions of A, C, T and G molecules – are inherited from your parents and you’re stuck with them for the rest of your life. Unless you dose yourself with a huge amount of radiation, which I don’t recommend. Unlike in the comic books, you will almost certainly not be gifted with superpowers.
The DNA inside every one of your cells is the same, but there is an incredibly wide variety of different kinds of cells in your body – brain cells, skin cells, liver cells. They are specialized to perform specific functions, and they can do this because they produce the proteins that allow them to do their jobs, and other genes that aren’t needed are shut off. The actual content of your DNA is the same between cells, but the way that the DNA is organized is vastly different. Proteins are capable of restructuring your DNA to control genes in a process we call epigenetics.
The DNA gets organized by signals that come from outside the cell. During development, specific biochemical signals force stem cells to make brain cells or spleen cells, and proteins inside the cell organize its DNA accordingly. What you might find surprising is that researchers are finding out that even very routine events in the brain, like forming new memories, seem to involve precise epigenetic DNA reorganization events in certain brain cells.
Should it be any more surprising that maternal care can produce epigenetic changes? Dr. Meaney’s research shows that rats that received high amounts of maternal care organize their DNA differently than their low-maternal care cousins. The DNA coding for a protein called glucocorticoid receptor is more easily accessible for the proteins that sort of “turn on” the gene in a specific area of the brain. This increased amount of glucocorticoid receptor can help the high-maternal care offspring inhibit some of their stress response, which in turn makes them have less anxious behaviours.
Which brings me back to my initial point: our environments speak to us. Even if we haven’t been listening, the various environments of our lives have been chatting with our DNA in secret, deciding things about our fates in backroom deals like crooked politicians. It’s not easy to decode what the DNA has agreed to do in response to the environment whispering in its ear, however. It’s even more difficult trying to understand how exactly the message got through in the first place.
Listening in on and understanding these messages is a large challenge in biology, but it’s very important. Psychology has had a notion of “nature vs. nurture” for a great many years, where some traits are solely genetic and some are environmental in nature. This is becoming a largely meaningless debate, as we are beginning to understand that there is an ongoing discussion between genes and environment that impact who we are, the things we do, and even our mental health.
Which in turn, is why I don’t think I’m crazy for talking so much to my environment. I look at it more as just trying to get my two cents’ worth into the conversation…
Posted in Molecular biology.Posted on 12 Mar 2009