I believe that an evolutionary perspective is the single most important idea for anyone who is interested in human behavior. To paraphrase Theodosius Dobzhansky, when seen in the light of evolution, the study of human behavior is, perhaps, intellectually the most satisfying and inspiring science. Without that light it becomes a pile of sundry facts -- some of them interesting or curious but making no meaningful picture as a whole.For example, people make New Year’s resolutions and, every year, losing weight and living a healthier lifestyle are among the most popular areas for self-improvement. Why?We could simply add this to our growing list of sundry facts -- people want to be thinner and more active. The alternative, however, is to try to understand why people in some societies perceive themselves to be overweight and too sedentary.The evolutionary perspective suggests that many of us struggle to eat less and move around more because our ancestors were more successful if they ate more and moved around less (or, at least, no more than necessary).We tend to be overweight couch potatoes because our human nature was shaped in a very different environment. The cartoon version is of hungry cavemen and cavewomen working to survive in a world without cars, restaurants, grocery stores, fridges, or even houses. In such an environment, eating as much as possible and never frivolously wasting calories led to survival and reproduction.The evolutionary perspective argues we are not built to derive the most pleasure from low calorie foods. Furthermore, most of us are not going to instantaneously want to jump off the couch and hit the trail for 5 miles or more.In the areas of diet and exercise, our toughest battles are often with ourselves or, more precisely, with our evolved ancestral mechanisms.To stake out a clear and controversial stance, I believe that understanding the evolutionary nature of our battle for healthier lifestyles is more important than weighing our food, monitoring our miles on our new iWatch, or any of the myriad helpful steps to better diet and lifestyle.I believe the evolutionary perspective holds the key to many other human struggles including substance abuse, financial difficulties, violence, and even friendship. (By way of disclosure I have co-written a book with Jay Phelan, Mean Genes, that makes this argument; indeed the line above, “our toughest battles are with ourselves,” is taken from that work.)Do we owe this insight to Evolutionary Psychology. No and yes.There are precursors to evolutionary psychology going all the way back to Plato, who wrote, man “is a tame or civilized animal”. More than two thousand years later Darwin wrote, “He who understands baboons would do more toward metaphysics than Locke.”More recently, John Bowlby noted that most modern humans live in an environment that is very different from that of our ancestors. Bowlby wrote: the Environment of Evolutionary Adaptedness (The EEA) is “the one that man inhabited for two million years until change of the past few thousand years led to the extraordinary variety of habitats he occupies today.”Evolutionary psychology deserves credit, then, not for inventing the idea of a biological and evolutionary perspective, but for transforming the idea into a scientific field.I consider four works to be among those that constitute the foundation of evolutionary psychology (there are many other great works); On Human Nature by EO Wilson, The Adapted Mind by Barkow, Tooby, & Cosmides, The Psychological Foundations of Culture by Tooby & Cosmides, and Cognitive Adaptations for Social Exchange by Cosmides & Tooby.Collectively, these four works have more than 10,000 Google citations. Thus, there is now an entire field devoted to understanding the human mind as an evolved organ, shaped by cultural and genetic selection. (To be sure, many of these 10,000 works criticizes the original view.)Furthermore, even though I write the there is nothing wrong with evolutionary psychology, there are many works that claim this label that are very wrong. At the worst extreme, people who claim to be evolutionary psychologists have been naive, misogynistic, foolish, misguided, and even racist. Of course, we all should condemn bigotry wrapped in bad science, and I do. However, an active debate including criticism is part of the scientific process.Most importantly, none of the flaws, or even sins, committed in the name of evolutionary psychology alters the facts. Humans evolved by natural selection, and we can better predict and understand our world today using an evolutionary psychology perspective.