People who can endure hardship are less friendly. Research findings suggest a stable association between a general liking for bitter foods and beverages and stronger "dark" personality traits. Specifically, those who particularly enjoy bitter foods such as black coffee and quinine water are more likely to exhibit narcissistic, Machiavellian, and psychopathic traits, including selfishness, indifference, lack of empathy, and even manipulative and aggressive tendencies(. This does not mean that liking bitterness directly causes antisocial behavior, but rather reveals a shared biological basis. Researchers propose a "toxicity" hypothesis to explain this phenomenon, suggesting that a preference for bitterness may be an evolutionary signal, symbolizing a more resilient or even more confrontational survival strategy developed by individuals in response to external threats or challenges. This behavioral strategy manifests in personality as antisocial tendencies. Therefore, a preference for bitterness may not only be a taste issue but also a potential clue reflecting an individual's deep-seated personality traits.