The act of "Tree Hugging" has taken a bad rap over the years, particularly in the political arena, where conservative partisans on the right use the descriptor as a derogatory term for those on the left. Liberals are chided as tree huggers primarily because of their environmentally-friendly leanings towards a desire to preserve the world's natural resources.
However, in the animal kingdom, the term appears to take on a whole new meaning. As somewhat of an oxymoron, "global warming" among certain species of wildlife has more to do with 'cooling off' than warming up. For some animals, it actually has more to do with how trees affect their personal being versus the planet.
For instance, tree-hugging helps koalas beat the heat in Australia according to some recent research. By spreading their bodies around trunks and branches, these marsupials are able to absorb the cooler temperatures that emanate from inside the trees. This action not only makes them more comfortable, it reduces their core temperatures and increases their chances of surviving the intense heat-waves that occur during the summer months in Australia.
The full research which can be found in Biology Letters was headed up by Dr. Michael Kearney from the University of Melbourne's zoology department. His team fitted radio collars around the koalas' necks so they could track them during the day in both winter (June–August 2009) and summer (December–March 2010 and 2011). They then used thermal imaging technology to confirm and further analyze their observations.
Here you can see a thermal image of a koala hugging a cool lower limb of a tree, illustrating a posture typically observed during hot versus cooler weather periods. The purple tones are the coldest, with the lightest (yellow) colors indicating warmth. The orange hues show temperatures in between the two extremes.
These bears have evolved bodies that are perfectly suited for the task. "Koalas have thinner fur in their bellies, which we suspect is to aid close contact with the tree trunk," Kearney noted.
He also postulated that as a koala hugs the tree, "the blood flowing through the body would continually replenish cooled blood near the parts of the koala in contact with the tree with warm blood from other parts of the body, with the ultimate effect of cooling the whole body down."
Other animals who seek out trees for coolness include the tiny tarsier and the green tree monitor lizard. The study found that Acacia trees were the most preferred during extremely hot days by all of these species.
Being primates ourselves, our human ancestors most likely spent a lot of their time hugging trees as well (even before it became a contentious political issue). After all, trees are the perfect shape for hugging, given that we and many other animals can wrap two or more of our limbs around them at the same time. And if anyone objects the next time you hug a tree, just let them know it's the coolest thing to do!