No More Sneaking Around: The Changing Terminology of Orangutan Male Reproductive Strategies

Orangutans exhibit male bimaturism, characterized by pronounced variation among adult males. Early research framed this variation as age-based morphs with two alternative reproductive tactics (ARTs), contrasting "sneak and rape" subadults with "consort and combat" adults. Subsequent research demonstrated that males previously labeled as subadults can remain unflanged well into adulthood, and both types of males mate with and without force, leading to a revised ART framework: flanged males "sit, call, and wait" while unflanged males "go, search, and find." This study examines how these frameworks have been taken up and represented over time in the scholarly literature.

A bibliometric analysis of 810 publications which use orangutan and morph- and strategy-based keywords identified 124 relevant publications which were coded by morph and strategy classification and analyzed for temporal trends.

The "subadult" and "sneak and rape" terminology is no longer dominant in peer-reviewed primatology; yet, these imprecise frameworks persist, particularly outside of primatology in the secondary literature regarding the evolution of human male aggression.

The persistence of the "sneak and rape" framework does not reflect empirical evidence, as primatology now distinguishes male morphs without defining them by sexual aggression. Nor can it be explained by disciplinary lag alone, as some studies update the term from subadult to unflanged male while retaining outdated behavioral framing. Instead, selective uptake aligns with broader narratives in human evolution that naturalize male aggression and female vulnerability, underscoring the need to clarify primatological frameworks that inform interpretations of human evolution.