# Revisiting Infanticide in Non‐Human Primates Reveals a Similar Likelihood of Male and Female Perpetrators

## TL;DR

A review of 54 years of data shows that female infanticide in non-human primates is underreported due to biased terminology, leading to an inaccurate perception of male dominance in such behaviors.

## Contribution

The study reveals a terminology bias in primate infanticide literature, showing that female and male infanticide rates are comparable when using consistent definitions.

## Key findings

- Female-inflicted lethal behaviors are often misclassified, leading to underreporting of female infanticide.
- Using classical definitions shows no significant difference in infanticide rates between male and female primates.
- Consistent terminology improves understanding of primate infanticide and reduces sex-based bias in reporting.

## Abstract

Infanticide is understood as any direct or indirect behavior that fatally harms an infant, regardless of whether the perpetrator gains benefits. In non‐human primates, males are frequently identified as the perpetrators. Classical studies categorized behaviors like “abuse”, “fatal neglect”, “kidnapping”, and “aunting to death” as forms of infanticide when they resulted in infant death. However, in more recent literature, some of these behaviors are excluded from classifications of infanticide without clear justification, particularly those involving female‐related lethal actions. Therefore, we conducted a systematic review spanning 54 years to investigate potential sex biases in primate infanticide literature. Our findings show that female actions leading to infant death are often labeled with terms like “abuse” and “fatal neglect”. In contrast, similar male behaviors are consistently classified as infanticide. As a result, infanticide by non‐human primate females has been systematically underreported. Classifying all lethal behaviors by females toward infants as infanticide eliminates the sex difference in the frequency of such acts. Our study shows that being consistent with the original definition of infanticide for non‐human primates provides a more accurate understanding of infanticide in these animals. Thus, we strongly recommend adhering to the infanticide definition, which integrates the recorded behaviors into established theoretical frameworks, enabling more comprehensive discussions of primate infanticidal behavior.

Infanticide by non‐human females has been underreported as lethal behaviors are often not classified as infanticide. In contrast, this does not occur when males are the perpetrators, revealing a bias in how these behaviors are categorized.Our analyses, drawing on the classical understanding of infanticide, which incorporates abuse, fatal neglect, kidnapping, and aunting to death, reveal no statistically significant differences in infanticide levels committed by males and females.By using infant death as the definitive outcome measure, following classical studies on the subject, we provide a more comprehensive basis for evaluating infanticide across primate species.

Infanticide by non‐human females has been underreported as lethal behaviors are often not classified as infanticide. In contrast, this does not occur when males are the perpetrators, revealing a bias in how these behaviors are categorized.

Our analyses, drawing on the classical understanding of infanticide, which incorporates abuse, fatal neglect, kidnapping, and aunting to death, reveal no statistically significant differences in infanticide levels committed by males and females.

By using infant death as the definitive outcome measure, following classical studies on the subject, we provide a more comprehensive basis for evaluating infanticide across primate species.

This review synthesizes 54 years of data on infanticide in non‐human primates, revealing a sex bias in terminology rather than in behavior. Applying Hrdy's (1979) and Hausfater & Hrdy's (1984) definitions reduces potential sex‐based bias and clarifies that both males and females engage comparably in lethal infant‐directed acts.