Human studies consistently report a 60%–80% maternal left cradling preference. The dominant explanation points to an engagement of the emotionally more-attuned right brain. In contrast, we found equal incidences of left (31.3%), right (34.3%) and no-preference (34.3%) cradling in an impoverished South African population living under adverse conditions characterized by extreme dangers. We found striking differences on the Parenting Stress Index (PSI) between mothers with no cradling laterality preference and mothers with either a left or right preference. In several mammals a homologous left preference becomes stronger when acute threats prevail, rendering the rightwards shift we observed under dangerous conditions seemingly paradoxical. We propose this paradox can be resolved in terms of life-history strategy theory which predicts reduced parental investment in chronically dangerous environments. We interpret our high PSI score findings in no-preference cradlers as indicative of poorer, or at least ambivalent, maternal coping which many studies show is typically associated with reduced emotional sensitivity and responsiveness. We suggest that the latter may be a psychological mechanism mediating a partial withdrawal of parental investment in response to an enduringly adverse environment. To the best of our knowledge, this is the first study investigating cradling laterality preferences in an adverse socioeconomic environment.

人体研究一致报告说，有60％–80％的母亲对左侧育儿偏爱。占主导地位的解释指出了情感上更协调的右脑的参与。相比之下，我们发现生活在不利条件下，极端危险的南非贫困人口中，左（31.3％），右（34.3％）和无偏爱（34.3％）的婴儿发生率相等。我们发现无偏侧偏爱的母亲与偏左偏爱或偏右偏爱的母亲在育儿压力指数（PSI）上存在显着差异。在几种哺乳动物中，当急性威胁盛行时，同源的左偏偏会更强，这使我们在危险条件下观察到的向右移位似乎是矛盾的。我们建议可以根据生活史策略理论解决这一悖论，该理论预测了在慢性危险环境中父母的投资减少了。我们将无偏爱的婴儿中较高的PSI分数解释为母亲的应对能力较差或至少矛盾的一种指示，许多研究表明，这种应对通常与情绪敏感性和反应性降低有关。我们建议后者可能是一种心理机制，可以调解父母对长期不利环境的投资的部分撤出。据我们所知，这是第一项研究不利社会经济环境中的偏侧性偏好的研究。许多研究表明，或者至少是矛盾的，孕产妇的应对通常与情绪敏感性和反应能力降低有关。我们建议后者可能是一种心理机制，可以调解父母对长期不利环境的投资的部分撤出。据我们所知，这是第一项研究不利社会经济环境中的偏侧性偏好的研究。许多研究表明，或者至少是矛盾的，孕产妇的应对通常与情绪敏感性和反应能力降低有关。我们建议后者可能是一种心理机制，可以调解父母对长期不利环境的投资的部分撤出。据我们所知，这是第一项研究不利社会经济环境中的偏侧性偏好的研究。