 Further revising our understanding of adaptation is the observation that maternal antibodies may be passed on to descendants, allowing progeny to inherit some of the acquired immune characteristics of their parents. An example of such vertical immune transfer has been found in studies of the composition of the microbiota mothers pass on to the infant through vaginal and breastfeeding routes that program the newborn’s immune system and metabolism (Mueller et al. 2015; Gomez de Agüero et al. 2016). By molding the composition of its microbiota during pregnancy, the mother’s immune system engineers its environment by constructing a microbial model for her offspring (Chiu and S. Gilbert 2015; Mueller et al. 2015). When dysbiotic microbial populations are transmitted by obese mothers, their metabolic abnormalities and associated pro-inflammatory phenotype are imprinted upon their children (Soderborg et al. 2018; Ley et al. 2005). Due to the reliance on microbial niche construction, the acquisition of an infant’s immune characteristics is an instance of ecological inheritance, where transmission of selective pressures from one generation to another pre-sets the process of the progeny’s adaptation to the environment (Odling-Smee, Laland, and Feldman 2003; Odling-Smee et al. 2013; Chiu and S. Gilbert 2015). Alterations in this ecological mode of immune transmission in humans by C-section or administration of antibiotics may compromise the health of the child and thus predispose them to a variety of immune-related disorders (e.g., allergy and autoimmunity) (Bokulich et al. 2016). Thus, adaptive immunity exhibits various modalities in which variation may be generated and transferred from one generation to another. These findings challenge traditional Darwinian and Lamarckian categories, with wide-ranging ramifications.