Written by Cliff Hamrick, LPC, McCallum Place Austin In his book, Biophilia (1984), biologist E. O. Wilson suggested the biophilia hypothesis, which states that humans have a natural affinity towards other living systems. These living systems include large systems such as forests, oceans, and fields, but can also include smaller systems such as leaves, feathers, and spider webs. But, considering that living systems exist alongside non-living systems, this affinity can be extended to include mountains, rocks, streams, and weather. In his books, Last Child in the Woods: Saving Our Children from Nature-Deficit Disorder (2008) and The Nature Principle: Reconnecting with Life in a Virtual Age (2012), journalist Richard Louv suggested nature-deficit disorder to explain a variety of mental and physical health