The effort to focus more on positive psychology has been a struggling trend for a while now. Most studies focus on negative emotions and treating psychopathology. Still, since the 1990s more have been studying happiness and contentment and how to promote such positive experiences, e.g., exercise, making enough money for economic security, meditation, maintaining social supports. Most of this effort has focused on humans. We have known at least since Darwin’s 1872 book, The Expression of Emotions in Man and Animals, that our human feelings have deep biological roots.
So I find a small, admirable study on PLOS looking at the expression of positive emotions in rats. How did they stimulate this to study it? By tickling in contrast to placing in an unknown environment with intermittent white noise (trust me, you would not like it either). They found that when rats are happy from friendly handling and tickling, their ears relax to the sides and grow pinker. Other measures of facial expression such as eye widening, eyebrow shifting, and grimacing showed no difference between the two conditions. So we now know how rats show their happiness, albeit a somewhat limited means of expression. Maybe rats are not biologically primed for enjoyment as humans and other primates are (or dogs, don’t forget dogs). Maybe other expressions would be seen in parenting behaviors, e.g., nursing, the young leaving the nest, or in social play as juveniles, but these are harder to study.
In addition to their findings, like all good researchers, they also reported refinements in procedures. One is the technique for photographing and analyzing facial expressions, certainly an important advance. Another, and here comes the humor, is “the refinement of the tickling procedure”. I love it. I also appreciate that they are studying “heterospecific play treatment” (play between us and them) to promote animal welfare (more on that later maybe, but consider Yuval Noah Harari’s contention in his book, Sapiens: A Brief History of Humanind, that our domestication of animals and subsequent treatment of them is one of our crueler innovations). Anyway, here is the link to the PLOS study: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0166446
And now travel on.