Making babies: how human behavior and chemistry craft the future

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Yesterday I was listening to an Radiolab podcast on inheritance. The program was a sequence of three dives into the topic, with the second one describing the rub between nature versus nurture at a level one might not think exists.

Apparently mother rats tend to do a lot of licking of their children, but not always. The licking behavior is considered a motherly instinct. When investigated scientists discovered the rats that lick more have an larger amount of a protein than their lick-less counterparts. And here is where the story gets interesting!

Proteins are created by DNA, something that everyone knows is not alterable in nature. So why do some rats produce more than others? The theory is that when mom’s lick their pups they are aroused releasing adrenaline and noradrenaline which then kick off the production of serotonin, the mood chemical, into the chemistry of the cells of the brain. Serotonin kicks off a bunch of changes, one of which are transcription factor proteins which preserve the expression of DNA.

At the center of cells is DNA surrounded by a turbulent mix of chemicals – who knew? The activity can be so high that some of the chemicals actually collide with the DNA and stick (methyl groups) covering part of the DNA. So back to our rats. Imagine a mother rat that has methyl groups covering the part of the DNA that hold the motherly licking trait. The trait is not expressed and not passed. They do not lick their babies and their young pass it forward. For the rats that are licking the transcription factors are removing the methyl groups allowing the expression of the trait. Based on a New York Times article from September of 2012, Why Fathers Really Matter, this is called epigentic (above or beyond genetic).

So beyond this being intellectually cool, what this explores is the chemical reaction of nature and nurture. If baby rats are not licked their DNA expression is altered, so while the blueprints are not altered directly, they are not necessarily expressed. The expression is dependent on the environment – the mother rat stimulating.

My daughter is now almost 16 months old and her personality has been intensifying as she ventures through each day’s experiences. She has a key set of care givers each stimulating in their own way. It is amazing to think we are chemists setting off different reactions that fundamentally alter who she is and will become. Parenting is not just having the patience and presence to guide but the reactions set off that release deeper expression.

The same New York Times article mentioned earlier referenced similar research to the RadioLab production discussing how a man’s life experience is genetically passed to his offspring and their offspring. Again, environmental conditions that alter the male sperm and transmit the “learning” forward.

If environment plays such a critical role in the expression of genes – chemical based obfuscation – what might this say about the contexts we exist in as adults? What chemical changes are induced by the environment we operate in? How might these changes alter the learned aspects of those around us? What impact do our life decisions, given that many of us have control of where and how we live, have on our children and grandchildren? We may not be faced with a seasonal famine, instead the opposite deluge of information, virtualization, genetically modified, chemically enhanced and medicated flow. What are we helping humanity evolve to?

I always thought it was simply the mix of DNA, random mutations and learned behavior that made us unique. Assuming the theories are true, this introduces a new factor to consider in the crafting of the individual.

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