<!-- bryant-content-generator:start --> # The one thing the field refuses to say out loud is... > The one thing the field refuses to say out loud is that the ape mother rarely kills her own infant with her hands because she rarely needs to; her instruments are quieter and they run earlier. Among wild geladas in the Simien Mountains, a new male's takeover of a unit sends infant mortality up more than thirtyfold as he kills what his predecessor sired, and the females answer before he can reach the next one: roughly eighty percent of pregnant females terminate their pregnancies within weeks of his arrival, and the ones who do so return to fertility faster and breed sooner with the male who would have killed the child anyway. The primatologists call it the Bruce effect, after the woman who found it in mice, and what it describes is a female organism deciding, at the level of the endocrine system and without a single conscious thought, that the offspring of the departed male is a bad investment under the new administration. Where the calculation runs past birth, it runs on helpers. In the Peruvian forest a moustached tamarin mother who had raised three sets of twins when four or five adult males were present in her group bit through the skull of her newborn and ate the head when the helper count fell to two or three and another female was pregnant, and the same arithmetic appears in the only other wild case in her genus. {{The primate mother does not ask whether she loves the infant. She asks who will carry it, who will feed her while she carries it, and whether the male who fathered it is still standing.}} {{A mother's tenderness is a budget line, and nature audits it.}} **Source:** [[books/Chimping Out|Chimping Out]] ## Share on Social Media ``` “The one thing the field refuses to say out loud is that the ape mother rarely kills her own infant with her hands because she rarely needs to; her instruments are quieter and they run earlier. Among wild geladas in the Simien Mountains, a new male's takeover of a unit sends infant mortality up more than thirtyfold as he kills what his predecessor sired, and the females answer before he can reach the next one: roughly eighty percent of pregnant females terminate their pregnancies within weeks of his arrival, and the ones who do so return to fertility faster and breed sooner with the male who would have killed the child anyway. The primatologists call it the Bruce effect, after the woman who found it in mice, and what it describes is a female organism deciding, at the level of the endocrine system and without a single conscious thought, that the offspring of the departed male is a bad investment under the new administration. Where the calculation runs past birth, it runs on helpers. In the Peruvian forest a moustached tamarin mother who had raised three sets of twins when four or five adult males were present in her group bit through the skull of her newborn and ate the head when the helper count fell to two or three and another female was pregnant, and the same arithmetic appears in the only other wild case in her genus. The primate mother does not ask whether she loves the infant. She asks who will carry it, who will feed her while she carries it, and whether the male who fathered it is still standing. A mother's tenderness is a budget line, and nature audits it.” — Bryant McGill https://bryantmcgill.com/passages/passages-thing-field-refuses-line-nature-audits ``` <!-- bryant-content-generator:end -->