Carrying human infants – An evolutionary heritage

We propose that infant carrying is a biological norm for human caregiving, given that human infants have evolved a capacity to cling onto an upright caregiver whose body co-evolved to enable offspring carrying. The origins of this mutual adaptation may date back 4 million years, with the emergence of bipedalism, which precluded the infant horizontal and gravity-supported position on the back of a quadrupedal caregiver. We describe infant cooperative reflexes and behaviors, including the carrying-induced calming response and discuss hypotheses for the invention of infant carrier tools.Carrying involves several physiological and behavioral parent-infant co-adaptations that imply it is an evolutionarily conserved strategy. Epigenetic transmission of reproductive behavior through generations affects the development of the offspring, as well as the mental health of the parent. Carrying might have contributed to the evolution of Hominidae, potentially aiding dexterity, handedness, language acquisition, and social interactions.We review the evolutionary milestones and time points where the infant-caregiver interactions might have changed, exploring infant carrying as it intersects with biological and cultural evolution. We briefly summarize the effects of infant carrying on physiological, epigenetic, and socio-emotional outcomes.     

Theories of Attachment: The Long and Winding Road to an Integrative Developmental Science

Although traditional accounts of attachment theory attempted to partition the organism’s attachment and separation responses into those that were instinctive and those that were the result of the developmental environment, recent findings from epigenetics are indicating that no such partitioning is possible, even in principle. Rather than assuming the expression of a given behavioral trait is based on some set of instincts (as Bowlby and many of his colleagues did for attachment and separation responses), behavioral development is now seen as a self-organizing, probabilistic process in which pattern and order emerge and change as a result of ongoing co-actions among developmentally relevant components both internal (e.g., genes, hormones, neural networks) and external (e.g., temperature, diet, social interaction) to the organism. Exploring the specific prenatal and postnatal features of the mother–infant interaction system is providing a new appreciation of the complexity of the origins and maintenance of early attachment and its long-term consequences.