Department of Psychology, University of California, Los Angeles, CA 90095, USA.
Psychol Sci. 2011 Oct;22(10):1288-95. doi: 10.1177/0956797611420729. Epub 2011 Aug 26.
Mothers in numerous species exhibit heightened aggression in defense of their young. This shift typically coincides with the duration of lactation in nonhuman mammals, which suggests that human mothers may display similarly accentuated aggressiveness while breast feeding. Here we report the first behavioral evidence for heightened aggression in lactating humans. Breast-feeding mothers inflicted louder and longer punitive sound bursts on unduly aggressive confederates than did formula-feeding mothers or women who had never been pregnant. Maternal aggression in other mammals is thought to be facilitated by the buffering effect of lactation on stress responses. Consistent with the animal literature, our results showed that while lactating women were aggressing, they exhibited lower systolic blood pressure than did formula-feeding or never-pregnant women while they were aggressing. Mediation analyses indicated that reduced arousal during lactation may disinhibit female aggression. Together, our results highlight the contributions of breast feeding to both protecting infants and buffering maternal stress.
许多物种的母亲在保护幼崽时表现出更强的攻击性。这种转变通常与非人类哺乳动物的哺乳期持续时间一致，这表明人类母亲在哺乳时可能表现出类似的攻击性增强。在这里，我们报告了第一个关于哺乳期人类攻击性增强的行为证据。与配方奶喂养的母亲或从未怀孕的女性相比，母乳喂养的母亲对过度攻击的同谋者发出的惩罚性声音更大、更长。其他哺乳动物的母性攻击被认为是由哺乳期对应激反应的缓冲作用所促进的。与动物文献一致，我们的结果表明，当哺乳期女性表现出攻击性时，她们的收缩压低于配方奶喂养或从未怀孕的女性，而当她们表现出攻击性时，她们的收缩压低于配方奶喂养或从未怀孕的女性。中介分析表明，哺乳期的唤醒减少可能会抑制女性的攻击性。总之，我们的研究结果强调了母乳喂养对保护婴儿和缓冲母亲压力的贡献。
