December 3, 2005
Evolutionary Psychology: Science or Pseudoscience?The field of evolutionary psychology is now decades old and some people believe it's here to stay. We don't think so. In fact, we think the general method constitutes a pseudoscience.
A typical "proof" paradigm in evolutionary psychology might be as follows (constructed by us for this text):
Because hoarding food would have increased chances for survival in lean times, our Pleistocene ancestors should have developed by natural selection an adaptive tendency to hoard food. Since the modern era is too close to the Pleistocene for any substantial biological evolution to have occurred, modern behavior should have strong Pleistocene adaptive components. One assumption is that universality of a behavior constitutes evidence of a biologically evolved adaptation. A current survey of 10,000 households in 50 states shows that on average, when economically possible, people tend to store excess food in quantity in kitchen cupboards. The hypothesis of evolution of this adaptive behavior by natural selection is thus considered to be confirmed.
Problems: Do we know enough about Pleistocene behavior to say that a survey of current behavior confirms anything about any Pleistocene evolutionary scheme? Are the conclusions here already implicit in the premises? Is universality of a behavior pattern evidence of biological evolutionary adaptation? Is this science or rhetoric?
Aside from questions about "confirmation", how is this game played? Apparently, the first thing is to do a small pilot survey of maybe 100 households. If one obtains results that contradict the hypothesis, one either puts the hypothesis in a drawer for "future study" and moves on to another proposed evolved Pleistocene adaptive behavior, or one looks for "faults" in the details of the survey sample or data gathering and repeats the study. The probability is high that eventually some behavioral survey will be made that "confirms" some Pleistocene evolutionary adaptation scheme. A much larger study is then designed and hopefully funded, and the general outcome is that advocates of the theoretical approach of evolutionary psychology will tend to publish research papers supporting their formulated hypotheses, and tend not to publish research papers that contradict biological determinism of particular behavior patterns.
The larger the survey that's published, the more likely, because of time and expense, that it will not be repeated or redesigned by others. Certainly at least not for a few years, often not for a decade or more. Meanwhile, the large study is touted in college courses and in the media as "evidence" for biological determinism of such things as human mating behavior, marriage relations, altruism, parenting, homicidal tendencies, gender-based social inequalities, and so on.
Another approach, even more egregious, is to first do a pilot survey, get a small-sample determination of universality of some current behavior, call it an evolutionary "adaptation", concoct a Pleistocene story that explains why the behavior would evolve by natural selection, then do a larger sample study to "confirm" the evolutionary hypothesis.
As expected, at a number of campuses in the US, platoons of evolutionary psychology doctoral students are busy constructing evolutionary adaptation stories of human behavior as a prelude to designing their pilot thesis surveys. Or maybe in some cases some pilot thesis survey to identify the presence of a universal behavior pattern comes first and the evolutionary adaptation story follows.
A usual commentary is to emphasize the heuristic value of the general scientific approach, i.e., the approach at least produces new research. But is that enough? During the 50-year period 1920-1970, a similar research paradigm produced thousands of studies "derived" from psychoanalytic theory in psychology, the number of such studies dwindling to a trickle only after psychoanalytic theory went out of fashion. Yes, such heuristic approaches do produce new research and keep people busy and on salary. The question is, after the fashion passes and the sand is sifted, are we left with any substantive and enduring new knowledge?
Various proponents of evolutionary psychology talk of hypotheses "derived" from Darwinian theory. But there are really no derivations in any rigorous sense, merely speculations suggested by what are often simplistic Darwinian ideas.
The scientific problem here is that our ability to concoct a speculation about the behavior of Pleistocene humans that can be argued as consistent with biological determinism is not evidence of either Pleistocene behavior or biological determinism, but evidence only of our imaginative abilities to concoct such speculations, and studies of current human behaviors that are supposedly extensions of Pleistocene behavior add no substance to the mix of speculation, since the idea that any current behavior is an extension of Pleistocene behavior is also a speculation. In sum, evolutionary psychology is not even a "soft" science, it's a pseudoscience that endures as a fashion.
The main offering of evolutionary psychology consists merely of arguments that are plausibly consistent with elementary Darwinism coupled with simplistic speculations about Pleistocene adaptations. It's not enough. And the bleat that human behavior is complex provides no remedy for a pseudoscience of human psychology.
The idea that the social sciences can potentially benefit from more attention to human biology is valuable and should definitely be encouraged, especially in the training of social scientists. Whether or not some or all aspects of human behavior are the result of evolution by natural selection (as opposed to cultural consequences or some combination of the two sources of variables) is still an open question not yet handled adequately by any rigorous scientific approach. Certainly, applications of any current "results" of evolutionary psychology to public policy-making are at present not justified and potentially dangerous to society.
In addition to generating technological and public progress, science has always been a source of public confusions. From one academic enclave or another, gas-filled balloons are sent out to be caught by the media, who in turn do a wonderful job of confusing the public. It's unfortunate that currently in the social sciences evolutionary psychology is a prime source of confusions about the links between biological evolution and human behavior.
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Addendum (12.04.05):
Evolutionary psychology has been vigorously criticized by others over the years, and the ideas above are nothing new. What prompted this editorial were some queries from readers concerning the origins of human behavior, and a desire to clarify our views.
Dan Agin
ScienceWeek
dpa@scienceweek.com
http://scienceweek.com/editorials.htm#051203