We hear often that our cognitive limitations and our social and psychological flaws are due to our evolutionary heritage. Supposedly, the characteristics of minds and our psyches reflect the conditions in the primordial savannah or caves and therefore are not a good fit to the very different conditions of the 21st century.
Psychological characteristics that have been explained this way in recent articles include:
Finding math difficult. Brian Greene says, in an article in the New Yorker, "[Math] is not what our brains evolved to do. Our brains evolved to survive in the wilderness. You didn't have to take exponentials or use imaginary numbers in order to avoid that lion or that tiger or to catch that bison for dinner. So the brain is not wired, literally, to do the kinds of things that we now want it to do."
Political conservatism. John Hibbing, Kevin Smith, and John Alford claim that political conservatives are marked by a "strong negativity bias"; that is, conservatives are much more prone than liberals to view the world as threatening or dangerous. They speculate that the reason for this personality flaw, clearly inappropriate in our day and age, may be that "a strong negativity bias was extremely useful in the Pleistocene. Compared with the modern era, existence then was much more likely to be terminated prematurely at the hands of other human beings or by accidents involving wild animals or natural disasters. ... In such an environment, a heightened negativity bias would be advantageous." (This article was taken up gleefully in the popular left-wing press.)
Religious belief. Satoshi Kanazawa, in an article entitled Why Liberals and Atheists are More Intelligent, scores a two-fer. He states that "All our ancestors had to do to solve their everyday adaptive problems was to follow the dictates of such evolved psychological mechanisms and behave according to how they felt, following their emotions and feelings. Conscious and deliberate reasoning was seldom necessary for our ancestors because most of their adaptive problems were recurrent and familiar, and they had innate solutions in their brains." He goes on to make up fables in which the proto-liberals among our caveman ancestors (marked by their friendliness to outsiders) and the proto-atheists (marked by their willingness to attribute misfortunes to chance rather to hostile gods) came to bad ends, whereas the proto-conservatives and the proto-religious flourished and had many descendants. Thus in our day atheism and political liberalism is found only among smart people who have somehow gotten past this inheritance from the Stone Age; stupid people who cannot escape it are the conservatives and religious. (This is not a caricature; read the article. I have discussed the quite explicit contempt for conservatism and religion built into much work of this kind in social psychology here.)
Revenge. "Vengeful acts were what kept our prehistoric ancestors alive. Back then letting a slap go unpunished marked you as prey," writes Kate Murphy.
Gender differences, particularly in sexual fidelity. Since the subject is so fraught and so enjoyable, there is a large literature, pro and con, as to whether it is real among contemporary Americans; if so, whether it is culturally specific or a near cultural universal; and if universal, whether the evolutionary explanations are plausible. There is a fine review by Dan Slater and another, on the con side, by Erin Anderson.
So what's the problem? First, as has often been pointed out, most notably by Stephen Jay Gould, these explanations tend toward just-so stories, a.k.a. post-hoc rationalizations. You find a feature of the human mind that you dislike, or one that you think is an ineradicable part of human nature, and you make up a story about why it was good for the cavemen. You find a desirable feature that isn't there, and you explain its absence by noting that it was unnecessary for our ancestors on the savannah. You find a feature that some people have and others don't and you explain that the bad guys have inherited it from the cavemen, but that the good guys have overcome it.
This objection doesn't, of course, apply to traits that are obviously strongly adaptive; there is no problem in saying that the language facility, the ability to do complex planning, and so on, evolved in humans because they were adaptive. But almost all of those are equally adaptive now. Likewise, traits that are obviously maladaptive didn't evolve because they were maladaptive.
Second, one should not underestimate our distant ancestors. Some of the above, such as the quotations from Greene and Murphy, seem to reflect Hobbes' view that primitive life was "poor, nasty, brutish, and short". These are, after all, the people from whom we inherit number systems, art, and language. They did not spend all their time escaping from lions and hunting bison.
Finally, and most importantly, these explanations don't explain. Until we have a much better understanding of how the mind works, no explanation of why it works that way can be very convincing.* Our cognitive apparatus has all kinds of characteristics that, one has to suppose, were unhelpful for primitive people: our working memory is limited in size, our long-term memory is error-prone, we are susceptible to all manner of cognitive illusions and psychological illnesses, we are easily distracted and misled, we are lousy at three-dimensional mental rotation and not great at three-dimensional geometry of any kind, our languages have any number of bizarre features. We find it harder to communicate distance and direction than bees; we find it harder to navigate long distances than migratory birds. On the other hand, there are all kinds of mental activities that people do without difficulty and enjoy that, as far as one can tell, had no value in avoiding lions or catching bison: reading novels, singing songs, looking at pictures, pretending, telling jokes, talking nonsense, dreaming.
Our ancestors on the savannah saw parabolic motion whenever they threw a stone; they experienced spherical geometry whenever they looked up at the starry sky. They never encountered a magic wand or a magic ring. Nonetheless, most people find it easier and much more enjoyable to read and remember four volumes of intricate tales about magic rings or seven about magic wands than to read a few dozen pages with basic information about parabolas; and even most mathematicians find spherical geometry unappealing and difficult. Why? We have absolutely no idea.
* "I well remember something that Francis Crick said to me many years ago, ... 'Why do you evolutionists always try to identify the value of something before you know how it's made?' At the time I dismissed this comment ... Now, having wrestled with the question of adaptation for many years, I understand the wisdom of Crick's remark. If all structures had a `why' framed in terms of adaptation, then my original dismissal would be justified for we would know that "whys" exist whether or not we had elucidated the "how". But I am now convinced that many structures ... have no direct adaptational 'why'. And we discover this by studying pathways of genetics and development --- or, as Crick so rightly said to me, by first understanding how a structure is built. In other words, we must first establish 'how' in order to know whether or now we should be asking 'why' at all." --- Steven Jay Gould, "Male Nipples and Clitoral Ripples", in Bully for Brontosaurus 1991.