Intra-community infanticide in wild, eastern chimpanzees: a 24-year review

Area of Science:

• Primatology
• Behavioral Ecology
• Evolutionary Biology

Background:

• Infanticide is observed in chimpanzees, but its rarity has hindered hypothesis testing.
• Existing hypotheses include sexual selection, male mating competition, resource competition, and meat acquisition.

Purpose of the Study:

• To analyze the largest dataset of infanticides in a single chimpanzee community.
• To test four major hypotheses explaining chimpanzee infanticide using 24 years of data.

Main Methods:

• Analysis of 33 attacks (infanticides and attempted infanticides) over 24 years in the Sonso chimpanzee community, Uganda.
• Identification of perpetrators and victims, with a focus on victim age and perpetrator sex.

Main Results:

• Data best support the sexual selection hypothesis for infanticide.
• Male attackers were predominant, and victims were disproportionately very young (under one week old).
• Cannibalism was infrequent, suggesting meat acquisition is a byproduct, not a primary driver.

Conclusions:

• Sexual selection is the most supported explanation for chimpanzee infanticide.
• Female infanticide, though rare, may also be driven by sexual selection via intra-sexual competition.