Why do we act the way that we do, so typically human? Without applying evolutionary theory there is no scientific way to say whether a behavior is adaptive (serves a purpose) or not (see Intentional Design.) Ordinary psychology is to evolutionary psychology as geography is to geology. Geography describes the shape of the land, while geology is concerned with the processes that shaped the land—how it got the way that it is. Evolutionary psychology attempts to explain human motivations and behavior as being the consequence of evolution. Behaviors and capacities are assumed to be adaptive: to enhance survival and reproductive success.

Evolutionary psychology is a large and rapidly growing field, and we won't attempt to summarize it here. See Evolutionary psychology and books such as The Happiness Hypothesis and The Tangled Wing that apply the perspective of evolutionary psychology to understanding the human condition. What we will try to do is provide some high level context for understanding evolutionary psychology, especially concerning criticisms from outside the field, controversies within the field, and the scientific reasons for the apparent preoccupation with sensitive issues such as sex differences in behavior or unpleasant behaviors such as selfishness and deception.

Some sort of evolutionary psychology is required to understand the subjective human experience, but we believe that aspects of the evolutionary psychology first proposed in the 1990's (see History of evolutionary psychology) are incomplete or have misplaced emphasis:

• The assumption that human evolution effectively stopped 10,000 or more years ago, and the associated idea of mismatch, that puzzling and non-adaptive current behaviors may have once been adaptive in that ancient environment. The emergence of genetic/cultural coevolution theory, in combination with genetic evidence and the surprising effectiveness of animal breeding experiments strongly suggest some degree of recent human evolution. At the same time, coevolution theories have found that some behaviors make a great deal more sense when people are viewed in their context as cultural animals.
• A general neglect of culture and the importance of Cultural Evolution, resulting in a strong tendency toward genetic determinism. Evolutionary psychology does propose that our psychological commonalities are a consequence of our genetic heritage. There is no blank slate, but this doesn't create as tight a “leash” on human behavior as some evolutionary psychologists suppose. This strong position on the Nature Versus Nurture debate has burdened evolutionary psychology with heartfelt opposition.

Evolutionary psychology has also been hampered by an interpretive gap. Some proponents (such as Richard Dawkins) have undermined acceptance by coming across as arrogant iconoclasts (see Smarty-Pants Critique.) The sort of mechanistic evolutionary explanations offered by evolutionary psychology seem to demean and deny the Reality of fundamental human motivations and feelings. We believe that a more nuanced story can help by explaining the relationship between Mind and the brain through concepts such as Emergence (see Level Map).

Why are evolutionary psychologists so obsessed with sex? Isn't that rather juvenile? And why have they put forward those politically awkward arguments about the innateness of behavior differences between men and women? The answer is that evolutionary theory tells us that if there is anywhere that we would expect to find a strong selective influence on behavior it will be in behavior related to reproduction itself, and sex is a crucial part of human reproductive behavior. Humans have quite a few peculiarities in their reproductive strategies which evolutionary psychologists have connected to differences in male and female behavior (see Sex Differences).

To many it seems nonsensical to propose that having lots of grandchildren is the intention underlying all human behavior because:

• Especially in the modern world, most of our daily activities don't advance our supposed reproductive goal in any obvious way (reading People magazine), and in many cases clearly reduce the prospects for our continued survival (binge drinking, running for president.)
• When you ask people what their intention is they will hardly ever mention reproductive success. If you press someone for the ultimate top-level goal it will usually be either emotional (because I love her), moral (it was the right thing to do) or spiritual (it gives meaning to my life.)

Evolutionary psychologists reply that:

• Many apparently unproductive activities either do advance our reproductive success (in ways that are either subtle or politically incorrect), or were adaptive up until recently, or can be regarded as an incidental side-effect of important adaptive behaviors, and
• That we behave as though reproductive success were our intention even though this is not an intention that we are conscious of (see Intentional Opacity). Evolutionary psychologists are particularly interested in explaining why we have the emotions and motivations that we do.

Another objection to evolutionary psychology is that it paints such a bleak picture of the human condition. Why are evolutionary psychologists so interested in unpleasant behaviors such as competitiveness, selfishness, deception, self-promotion, cheating and violence? Most people are kind, decent, peaceful and law-abiding, yet evolutionary psychologists explain self-serving and violent behavior as just another strategy for reproductive success. Furthermore, evolutionary psychology has had big problems with altruism, and at time seems to say that everything we do either has some hidden selfish motive (such as favoring relatives) or is basically a mistake.

The convergence of evolutionary psychology with anthropology and social psychology has resulted a tentative solution to the “problem of altruism”, but only by pushing the violence and competition up a level, so that it is now between social groups. Paradoxically, one of the clearest examples of altruistic behavior is risking death in battle to defend the community. Furthermore, evolutionary social psychology argues that humans are not only innately selfish, but also innately groupish, tending to favor whatever group we find ourselves part of. This is unpleasantly like racism and other forms of prejudice.

The question of morality and whether humans are basically good or evil is big enough that it must be discussed elsewhere (see Good Or Evil?). Here we ask why evolutionary psychology is so obsessed with the unsavory side of human behavior. Some degree of selfishness is necessary to sustain human life; with no selfishness there is no life, and the moral discussion is cut short. Given selfish motivation, there is no need to suppose that lying, cheating and stealing are innate—the advantages are so obvious that they could be rediscovered by each generation. The truly interesting question is why beneficial cooperation is the norm and selfish abusive behavior is so rare; this is a major question that evolutionary psychology seeks to answer. If people are basically good, then that demands an evolutionary explanation.

The most fundamental weakness of evolutionary psychology is that it often relies on speculations about what might have happened in the distant past. It is at risk of incorrect explanations of the status quo, and these can be misinterpreted as justifications for the status quo (see Just-So Stories). Even within evolutionary psychology there is considerable dispute about whether behaviors such as music and religion are adaptive or not, and to what degree they are hard-wired. This distinction is in fact somewhat ill-founded, because as Daniel Dennett points out in Darwin's Dangerous Idea, all adaptation is exaptation. This means every feature or behavior of an organism must have its origin in a feature that was purely accidental, or served a different purpose. While it is clearly true that many of an organism's structures and behaviors serve purposes, there are also many traits with no clear purpose. It may serve no purpose at all, or might have multiple minor benefits.