Kin recognition: evidence that humans can perceive both positive and negative relatedness

Area of Science:

• Evolutionary Biology
• Social Psychology
• Behavioral Genetics

Background:

• Spiteful behavior evolves when actors incur costs to harm negative relatives, who are genetically dissimilar.
• While kin recognition of positive relatives is well-documented, recognizing negative relatives remains under-researched.
• Previous research explored human phenotype matching for kin recognition.

Purpose of the Study:

• To investigate if humans can detect negative relatedness cues.
• To extend phenotype matching research by introducing a novel cue for negative relatedness.
• To examine the impact of negative self-resembling faces on social judgments.

Main Methods:

• Participants evaluated trustworthiness and attractiveness of opposite-sex faces.
• Faces were manipulated to either positively or negatively resemble the participant's own facial phenotype.
• Negative self-resembling faces were designed to differ from an average face in the opposite direction of the participant's own facial differences.

Main Results:

• Positive and negative self-resembling faces had opposing effects on trustworthiness and attractiveness ratings.
• Participants' judgments were significantly influenced by the degree of negative facial resemblance.
• This study provides the first empirical evidence for human sensitivity to negative relatedness cues.

Conclusions:

• Humans demonstrate sensitivity to cues indicating negative relatedness.
• Negative facial resemblance can influence social judgments, potentially facilitating spiteful behavior.
• Findings suggest the adaptive potential for spiteful behavior allocation based on relatedness detection.