“Evolutionary psychology hypotheses are testable and falsifiable.”

Eric Charnov points to this recent article by William Costello et al., which begins:

The field of evolutionary psychology has often been the target of allegations that its hypotheses are unfalsifiable. . . . We . . . present evidence of several evolutionary psychological hypotheses that have generated specific, falsifiable predictions; undergone multiple empirical tests; and been refuted. Specifically, we discuss the evidentiary status of (a) the ovulatory shift in mate preferences (dual-mating) hypothesis, (b) the mate deprivation hypothesis of rape, and (c) the kin altruism hypothesis for the evolution of male homosexuality. We contrast these with the wide range of evolutionary psychology hypotheses whose specific predictions have been robustly supported by empirical data. . . . many academics continue to perceive evolutionary psychology as unfalsifiable, despite evidence to the contrary, a misconception that has also permeated mainstream culture. . . . By illustrating that hypotheses generated by evolutionary psychology can be directly tested with appropriate scientific rigor, we dispel these pervasive misconceptions and highlight the field’s heuristic potential for generating valuable insights into human behavior.

It’s interesting to see this article. I have to admit I have a generally negative view of evolutionary psychology, a view that probably isn’t so fair. The problem is that I’ve been exposed to a lot of bad evolutionary psychology . . . David Weakliem and I wrote a whole article about it.

Also some blog posts. Let’s search on “evolutionary psychology” and see what comes up:

2025: I have a horrible feeling sometimes that heavily promoted crap research on space aliens, cold showers, mind-body healing, schoolyard evolutionary psychology, extra-sensory perception, magic golf balls, air rage, himmicanes, subliminal smiley faces, etc etc etc, has softened the ground so that the seeds of more evil trees could then be planted and take root. 2023: Hey—here’s some ridiculous evolutionary psychology for you, along with some really bad data analysis. 2022: Evolutionary psychology in economics: Mo papers, mo problems

And some things I’ve written:

2025: I don’t mean this in a sinister way, necessarily, the idea that crafty researchers are using their networking powers to insert bad work into the literature—even though, yes, I think this happens all the time—but rather in more general terms, that it takes a lot of active effort to keep these bad ideas in embodied cognition, evolutionary psychology, subliminal effects, etc., continuing in the scientific literature. In the same way that the Loch Ness monster, UFOs as space aliens, and various political conspiracy theories require constant refreshing to stay in the news. Yes, people hold all sorts of silly beliefs—a third of Americans say they believe in ghosts!—but passive belief is not enough. Well-connected people need to be actively promoting them, or they drift to the back of the collective consciousness. 2025: The [erroneous] belief that if a general phenomenon (e.g., “nudge,” or “evolutionary psychology,” or “social priming”) is real, that it will show up in the same direction no matter how it is studied (for nudging this could be investment decisions or food choice or risky behaviors; for evolutionary psychology this could be the sex of babies or religious behavior or voting behavior; for social priming this could be walking speed or hormone levels or political attitudes; etc.). 2025: I also don’t see any substantive theory behind the claims, other than that it seems very intuitive to people that (1) the sex of a baby should be predictable and (2) sex ratios should vary a lot. I think the basis for that first intuition is gender essentialism: men and women are so clearly different that it just stands to reason that they should somehow be externally distinguishable (in the pre-ultrasound era) even in the womb, and that the sex of the baby should be influenced by various ways as might be explained by gender essentialism. I think the basis for the second intuition is what Tversky and Kahneman called “the law of small numbers”: everybody knows someone with several siblings, all of the same sex. People don’t have a sense of the huge sample size that would be needed to learn anything useful from such data, even setting aside selection and recall issues. Also, gender essentialism: it just stands to reason that parents of boys should be more masculine, in some way, than parents of girls. This bit of intuition can be backed up by endless speculation of the sort that is called evolutionary psychology and which plays well in Freakonomicsland. 2024: In some settings, I fear that “replication” is serving a shiny object to distract people from the central issues of measurement, and I think that’s what’s going on here. The authors of this study were working with some vague ideas of evolutionary psychology, and they seem to be working under the assumption that, if you’re interested in theory X, that the way to science is to gather some data that have some indirect connection to X and then compute some statistical analysis in order to make an up-or-down decision (“statistically significant / not significant” or “replicated / not replicated”). Again, that’s not enuf! Science isn’t just about theory, data, analysis, and conclusions. It’s also about measurement. It’s quantitative. And some measurements and designs are just too noisy to be useful. 2012: Schoolyard Evolutionary Biology: The idea that, because of evolution, all people are equivalent to all other people, except that all boys are different from all girls.

OK, so that’s some attitude.

That said, I don’t recall ever characterizing the hypotheses coming from evolutionary psychology as unfalsifiable.

Let me put it this way: I think that evolutionary psychology can produce falsifiable predictions (there I agree with Costello et al.); I also think it is often employed in an unfalsifiable way, either by motivating flexible stories that can explain any possible data pattern, or though flexible data analysis (“forking paths”) that can fit any theory.

Stepping back, I don’t think evolutionary psychology, as a whole, is falsifiable. But that’s ok. I don’t think that any science is falsifiable as a whole. I don’t think chemistry or physics are falsifiable either. Evolutionary psychology, like chemistry and physics, is a framework under which falsifiable theories can be developed. Which is fine; indeed, Costello et al. carefully write, “Evolutionary psychology hypotheses are testable and falsifiable,” not that evolutionary psychology as a whole is testable and falsifiable. I would just amend their statement to, “Some evolutionary psychology hypotheses are testable and falsifiable.”

But then you get to the specific cases in the paper, the several evolutionary psychological hypotheses that they say were “refuted,” and . . . I don’t know!

What they describe as “refutations” look to me more like unsuccessful replications. Or, more specifically, results that are not statistically significant. But a not-statistically-significant finding is, at most, a refutation of the hypothesis that the average effect is large (relative to the standard error of estimation); it does not refute the hypothesis that there is a nonzero effect, or that there is an effect in a specified direction.

This is not to say that data can’t inform theorizing in this area. I just think that the framework of “falsification” isn’t so useful here, as it doesn’t address three key factors in the experimental human sciences:

1. The uncertainty involved in learning from statistical evidence in the presence of variation or noisy measurements;

2. The often shaky connection between underlying scientific theories and the particular statistical models being tested;

3. Variation in effects, which can be positive in some settings and negative in others, making it difficult to pin down exactly what is the hypothesis being tested.

For better or worse, I think we need to give up on strict falsificationism and move to a more Lakatosian perspective in which theories are informed by data. And all this presupposes that we’re doing serious science and not screwing around with experiments that are essentially pure noise.

Again, these are issues with the human sciences in general, nothing special about evolutionary psychology here.