Skip to main content
Kent Academic Repository

Countering infanticide: Chimpanzee mothers are sensitive to the relative risks posed by males on differing rank trajectories

Lowe, Adriana, Hobaiter, Catherine, Newton-Fisher, Nicholas E. (2019) Countering infanticide: Chimpanzee mothers are sensitive to the relative risks posed by males on differing rank trajectories. American Journal of Physical Anthropology, 168 (1). pp. 3-9. ISSN 0002-9483. E-ISSN 1096-8644. (doi:10.1002/ajpa.23723) (KAR id:69499)


Objectives: Infanticide by males is common in mammals. According to the sexual selection hypothesis, the risk is inversely related to infant age because the older the infant, the less infan- ticide can shorten lactational amenorrhea; risk is also predicted to increase when an infanticidal male's chance of siring the replacement infant is high. Infanticide occurs in chimpanzees (Pan troglodytes), a species in which male dominance rank predicts paternity skew. Infanticidal male chimpanzees (if low-ranking) are unlikely to kill their own offspring, whereas those who are cur- rently rising in rank, particularly when this rise is dramatic, have an increased likelihood of fathering potential future infants relative to any existing ones. Given that mothers should behave in ways that reduce infanticide risk, we predicted that female chimpanzees, and specifi- cally those with younger, more vulnerable infants, would attempt to adjust the exposure of their infants to potentially infanticidal males. Specifically, mothers of young infants should reduce their association with adult males in general, and to a greater extent, with both low-ranking males and those rising in rank from a position where paternity of current infants was unlikely, to a rank where the probability of siring the next infant is significantly higher. We also investigated the alternative possibility that rather than avoiding all adult males, mothers would increase association with males of stable high rank on the basis that such males could offer protection against infanticide.

Materials and methods: We examined data on female association patterns collected from the Budongo Forest, Uganda, during a period encompassing both relative stability in the male hierar- chy and a period of instability with a mid-ranking male rising rapidly in rank.

Results: Using linear mixed models, we found that mothers reduced their association with the rank-rising male, contingent on infant age, during the period of instability. We also found evi- dence that females preferentially associated with a potential protector male during the high-risk period.

Discussion: Our results support the sexually selected hypothesis for infanticide and demon- strate that female chimpanzees are sensitive to the relative risks posed by adult males.

Item Type: Article
DOI/Identification number: 10.1002/ajpa.23723
Uncontrolled keywords: aggression, association, Budongo, counter-strategy, Pan troglodytes
Subjects: G Geography. Anthropology. Recreation > GN Anthropology
Q Science > QH Natural history > QH301 Biology
Q Science > QL Zoology
Divisions: Divisions > Division of Human and Social Sciences > School of Anthropology and Conservation
Depositing User: Nicholas Newton-Fisher
Date Deposited: 10 Oct 2018 17:05 UTC
Last Modified: 25 Mar 2022 15:52 UTC
Resource URI: (The current URI for this page, for reference purposes)

University of Kent Author Information

  • Depositors only (login required):

Total unique views for this document in KAR since July 2020. For more details click on the image.