The Epigenetics of Cuddling

How Personal Contact Could Alter the Genome

A study by the McGill Program for the Study of Behavior looked at the effects of grooming on gene acetylation, and subsequent behavioral differences in offspring.  They wanted to know if grooming, or the habitual cleaning and petting of baby female mice could change their lives forever.

The results were quite striking: mothers who received high levels of grooming from their mothers gave birth to offspring were much more relaxed, and less prone to stress. Increased grooming in the first generation causes higher levels of glucocorticoid receptors in the hippocampus- caused by increased acetylation around the promoter for the glucocorticoid receptor gene. The authors also noted changes in methylation in the regions of interest. Grooming behaviors are a common way mice show affection and are a good indicator of proper maternal care.

In English, this means that the simple action of grooming offspring causes epigenetic changes that persist into subsequent generations, suggesting that a nurturing touch can actually change someone’s genes. Mice are social animals, so this might be extrapolated to humans: being loving with one generation might help propogate a whole family of loving individuals, and alleviate anxiety and stress reactivity.

We already know epigenetic modifications can regulate depression, so it should come as no surprise that anxiety can be controlled by similar mechanisms. For a more detailed explanation of this phenomenon, click here. Sadly, that means the opposite could also be true. Children raised under an abusive environment could gain epigenetic modifications that persist for generations and cause them to be abusive themselves. It’s also possible that a lack of social contact could result in improper development. While grooming is one of the most endearing events in mouse behavior, humans are extremely social beings and thrive with ample social contact. With TV babysitters on the rise, it’s no surprising that anxiety and autism disorder victims are too.

With Great Power…

If you take anything from this, know that your actions have the potential to change not only the day, but the genome of others. What you do today can ripple to cause effects years and years down the line. Not every single action will be life changing, but why not choose to be a net positive force in the world?  Increasing compassion can go a long way in restoring a good emotional balance, and obtaining state control. While the authors of the study failed to propose a mechanism of grooming’s effect on the epigenome, oxytocin is a good bet. Oxytocin is a neuropeptide hormone involved in countless human and animal social interactions. The epigenetics of social behavior continue to be researched, and show great promise towards our future understanding of humanity.

Some Caveats

These studies were conducted in rodents, not humans.  While rats, like other mammals, are highly social, the depth and diversity of their social contact is nowhere near that of humans.   While humans do sometimes reflect the same “grooming” behaviors—don’t we all love a good back scratch?—these actions may not have the same effect on our epigenome.  As always, more research is needed to fully understand these mechanisms.