Science Magazine

Fear Contagion

The video explains a new study on fear contagion – the rapid spread of fear among animals – and its neurochemical basis. Researchers asked whether oxytocin, a hormone linked to love and empathy in mammals, also governs this phenomenon in zebrafish, a distant evolutionary branch. Using CRISPR‑edited zebrafish that cannot produce or regulate oxytocin, scientists paired a “subject” fish with a tank of demonstrator fish injected with the fear‑inducing chemical Shrektoff. Normal fish watched the demonstrators zig‑zag and freeze, then mirrored the freezing response, confirming social transmission of fear. Mutant fish, however, remained indifferent, showing no freezing despite the alarmed neighbors. When the oxytocin‑deficient fish received a brief oxytocin boost, they instantly adopted the freezing behavior, a moment the lead researcher described as an “Eureka” realization. The experiment demonstrates that oxytocin is both necessary and sufficient for social fear contagion in fish, mirroring findings in rodents and suggesting a deep evolutionary root. These results imply that the oxytocin system is a conserved mechanism for detecting and responding to social threats across vertebrates. Understanding this pathway could inform treatments for anxiety, PTSD, and empathy‑related disorders, and highlights the hormone’s broader role beyond bonding and affection.