@PsychToday descended to new lows of #badscience and #titillation this week when it published Satoshi Kanazawa's latest blogpost on the physical attractiveness of black women, complete with some pseudoscientific tosh about evolutionary psychology and testosterone. Following a storm of protest, Psychology Today has removed the offending blogpost (although it is still available elsewhere, for example on Quora); its other bloggers (Daniel Hawes, Nathan Heflick, Scott Barry Kaufman, Robert Kurzban, Mikhail Lyubansky, Melody T McCloud, Michael Mills, Stanton Peele, Steven Reiss, Gad Saad, Sam Sommers, and others) have felt the need to gang up on Dr Kanazawa, as if that somehow redeemed the reputation of the website. Commentary and criticism elsewhere includes BBC News, Nanjala Nyabola (Guardian). PZ Myers names Kanazawa "among the many reasons that I detest evolutionary psychology".
This is not the first time that Dr Kanazawa's pseudoscientific musings have provoked criticism from his fellow bloggers at Psychology Today. In November 2008, Christopher Ryan argued that Sloppy methodology is the Achilles Heel of evolutionary psychology. I myself took issue with Dr Kanazawa in my piece on Footballers Wives and Evolutionary Psychology.
But is it just Dr Kanazawa who is at fault here, as some of his more cautious critics suggest, or is there a fundamental methodological flaw at the core of evolutionary psychology? Dr Ryan has also recently criticized Stephen Pinker, suggesting that he may have used misleading data in his TED talk on the origins of war (Stephen Pinker's Stinker). For his part, Stanton Peele believes that "Satoshi Kanazawa's racism perfectly embodies evolutionary psychology".
Dr Ryan's generously illustrated blog features posts on human sexual behaviour and the female form, which he compares with other species - notably the bonobo. What he seems to be claiming is that the similarities between human and bonobo are explained not by their common genetic heritage, but by the existence of some evolutionary advantage of these characteristics.
Sounds plausible enough, but then pseudoscience can make all kinds of speculative explanation sound plausible. For example, someone might try to construct an argument to the effect that large breasts change shape more with age and maternity, therefore breast size makes the visual effects of ageing more obvious and helps men to choose younger and more fertile partners with fewer previous offspring. (That might sound ridiculous, but the logical structure is not very different from other arguments I've seen. See my post on the Purpose of Baldness.) But how on earth do we ever choose between conflicting theories, how do research bodies decide whether to fund this kind of research, and what kind of evidence is deemed relevant?
There is a simplistic POSIWID argument behind a lot of evolutionary biology and psychology, which goes like this. Here is an interesting and perhaps puzzling characteristic; therefore it must have some evolutionary purpose (expressed in terms of selective advantage); so the researchers just need to work out what it is. They then corroborate our hypothesis by carrying out a quick study, often using American psychology students as the subjects.
There are several methodological problems with this approach: firstly, in the way the characteristic is framed in the first place, secondly in the presumption that each characteristic must have a clearly identifiable purpose in its own right, thirdly in demonstrating purpose by identifying outcomes that can be correlated with the characteristic in question, and fourthly in inferring evolutionary processes from present-day observations alone. Kanazawa might just as well argue that Michael Phelps does everything he does in order to get laid. Beyond parody.