Evolutionary psychology is unfalsifiable? New scientific paper aims to kill this “zombie idea”

Evolutionary psychology hypotheses can be rigorously tested, and sometimes decisively overturned, challenging the long-standing claim that the field is inherently unfalsifiable, according to a conceptual review published in American Psychologist.

Since the 1970s, critics have contended that evolutionary explanations of human behavior amount to “just-so stories,” plausible but empirically untestable narratives flexible enough to accommodate virtually any outcome.

Drawing on Popper’s philosophy of science, these critiques claim that evolutionary psychology fails the criterion of falsifiability and therefore lacks scientific rigor, a perception that has persisted both within academia and public discourse.

William Costello, a doctoral researcher at the University of Texas at Austin explains, “As a graduate student preparing to go on the job market I am passionate about correcting the many misconceptions about evolutionary psychology that pervade academia and cultural consciousness. Evolutionary psychology is enormously explanatorily powerful for a wide range of domains, so it is frustrating to constantly have to contend with the decades old ‘zombie idea’ that its hypotheses are unfalsifiable. This false perception may also prevent younger scholars from embracing the framework in their own work, so hopefully our paper can empower them to push back against uncharged criticisms when they face them.”

The article takes up that challenge by clarifying what falsifiability requires and by examining how evolutionary psychology constructs and evaluates its hypotheses.

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The authors begin by specifying formal criteria for falsifiability: a hypothesis must generate explicit, prohibitive predictions that could, in principle, be contradicted by observable evidence. Vague or underspecified claims can evade disconfirmation, but the authors argue that this is a problem of imprecision, not a defining feature of evolutionary psychology.

They then situate evolutionary psychology within a Lakatosian research program structure. At the top sits evolutionary theory as a metatheoretical foundation; below it are middle-level theories (such as parental investment theory); and at the lowest level are specific hypotheses that generate concrete predictions. It is at this level that falsification operates. By distinguishing among these tiers, the authors argue that critics often mistake broad theoretical commitments for unfalsifiable claims, when in fact it is the lower-level predictions that are directly tested and, at times, rejected.

To demonstrate falsifiability in action, the authors review three prominent hypotheses that have been substantially weakened or refuted. First, the ovulatory shift (dual-mating) hypothesis predicted that women’s mate preferences would reliably shift toward traits signaling “good genes” during ovulation. Although early studies appeared supportive, larger and more rigorous replication efforts largely failed to confirm consistent fertility-linked preference shifts. The core prediction has not proven robust.

Second, the mate deprivation hypothesis of rape proposed that men lacking mating opportunities would be more likely to commit sexual violence. Empirical tests found the opposite pattern: men with greater mating success and higher status were more likely to report coercive behavior. These findings directly contradict the hypothesis’ central prediction.

Third, the kin altruism hypothesis for male homosexuality suggested that same-sex-attracted men would offset reduced direct reproduction by investing heavily in genetic relatives. Cross-cultural research has yielded mixed or negative evidence, and the level of kin investment observed does not appear sufficient to satisfy inclusive fitness requirements. As a result, the hypothesis lacks strong empirical support.

Alongside these refuted cases, the authors emphasize that many other evolutionary psychological hypotheses, such as those concerning parental investment, jealousy, disgust, and kin-directed altruism, have generated precise predictions that have received substantial empirical backing. The coexistence of confirmed and disconfirmed hypotheses, they argue, is exactly what one would expect in a progressive scientific field.

Reflecting on broader lessons, Costello noted: “There are many other leaders in the field (e.g., Ed Hagen) who have already tackled this problem well in other work. It would be nice to think that our article would be the final word and resolve the matter once and for all, but I think that because there are so many who are ideologically motivated to dismiss evolutionary psychology, scholars will need to defend against this misconception in each generation. We need to be prepared to do so and not allow misconceptions to flourish. There are those who think that we should not bother defensively correcting misconceptions and instead just focus on improving our field. I think we can and should do both.”

He added, “I think it’s good for scholars to have contemporary theoretical work in a leading psychology journal to now point to when they hear the myth espoused in academic or public discourse.”

“Evolutionary psychology is by no means immune to poor hypothesizing and we should always reflect on helping scholars to formulate their hypotheses with sufficient precision that they garner evidence for or against the hypothesized design features of a psychological mechanism,” explained Costello.

“Previous generations of our lab, led by David Lewis (who has been an amazing mentor to me) have taken a very proactive approach on this front. They published a terrific paper in American Psychologist called Evolutionary Psychology: A How to Guide. I encourage readers to read that article too.”

By documenting hypotheses that have been directly contradicted by empirical findings, the article argues that evolutionary psychology is not immune to disconfirmation but instead operates as a research program capable of generating testable (and falsifiable) claims.

The researcher shared that future work could examine whether academic and public perceptions of unfalsifiability have shifted since earlier surveys, and whether interventions such as reading the present article or taking an evolutionary psychology course change minds.

“I was pleased that the article was chosen as the APA Editor’s choice, which means it will be available to read ‘open access’ for 30 days since publication so please go and read it,” Costello told PsyPost. “Or reach out to me to get your hands on a PDF if you can’t gain access to it.” 

“Also, the article was published alongside two commentaries, who both agreed with our core argument that evolutionary psychology hypotheses are indeed falsifiable. Our reply gave us the opportunity to speak to some of evolutionary psychology’s other theoretical strengths (e.g., its heuristic value). That’s titled Beyond Falsifiability: Evolutionary Psychology’s Many Theoretical Strengths: Reply to Geary (2026) and Moore (2026) and I encourage people to read those also.”

William Costello is a doctoral researcher of Evolutionary Psychology at the University of Texas at Austin working under the supervision of Dr. David Buss. You can follow his work on ResearchGate, Google Scholar or on social media at X: @CostelloWilliam or BlueSky: @williamcostello.bsky.social

The research, “Evolutionary Psychology Hypotheses Are Testable and Falsifiable,” was authored by William Costello, Anna G. B. Sedlacek, Patrick K. Durkee, Courtney L. Crosby, Rebecka K. Hahnel-Peeters, and David M. Buss.