Parasites Control Host Behavior

The natural world is filled with astonishing examples of mind control, and the single-celled parasite (Review) *Toxoplasma gondii* is a master manipulator. Its ultimate goal is to sexually reproduce, which can only happen inside the digestive tract of a feline. To get there, it often infects an intermediate host, such as a rat. The parasite then hijacks the rodent's neural circuits, fundamentally altering its survival instincts. It specifically targets the brain's fear center, the amygdala, transforming the rat's innate, healthy fear of cat predators into a dangerous, even rewarding, sense of curiosity.

This "fatal feline attraction" is a remarkable evolutionary strategy. By making the scent of cat urine seem appealing, the parasite dramatically increases the likelihood that its rodent host will venture into a cat's territory and be eaten. Once consumed, *T. gondii* can complete its life cycle. Interestingly, humans can also be infected, typically through undercooked meat or contact with cat feces. While most infections are harmless, ongoing research explores potential subtle links between