Miles Jackson Well, I for one think it's sloppy biology when biologists do it, just as it's sloppy psychology when psychologists do it. C'mon guys, this is Philosophy of Science 101: speculation is fine, it generates potentially useful theories. However, if there is no meaningful way to empirically test the speculation, we're not doing science. Thus making up a story about how X must have led to reproductive success in the past--whether X is a physical body part or a psychological trait--is interesting, but it's not really science.
^^^^^ CB: Well, yea you are right. Strike the word "speculation". Darwin argued based on evidence, but the evidence was not like what you have for many experiments in medicine or psychology today. And I think the point here is that the evidence for arguments regarding ancient selection for behavioral traits in humans is roughly the same as the evidence for ancient selection of body part traits,isn't it ? Arguments about ancient evolutionary processes, both physical traits and behaviors are based on scant evidence relative to the evidence on living people's psychologies.
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Now, if an ethologist carefully observes multiple generations of a particular bird species and discovers that monogamous mating pairs tend to have better reproductive success, the speculation is at least to some degree empirically grounded, and it doesn't bug me as much as some goofball like Dawkins. Granted, contemporary studies don't directly demonstrate that evolutionary pressures on a trait existed in species history, but it's better than making up just-so stories and calling it a scientific theory.
Miles