Answer:
According to the author, the biological link between love and anger is found in the Prefrontal Cortex. This part of the brains neural system, which is responsible for rage, shares proximity with the cranial centers that anticipate rewards. The author also posits that winning a beloved one is interpreted as a type of reward by the brain.
The brain, as posited, responds with frustration when love as a stimulus is withdrawn from it. This observation is called the "Frustration-Aggression Hypothesis".
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