Every animal has a nest, including humans. At full-term birth, a human baby looks like the fetus of other animals for nine more months. The newborn emerges with only 25% of adult brain capacity, which grows especially rapidly in the first year with 90% in place by age 5 (Wenda Trevathan, 2011). Thus an intensive, supportive nest is needed for proper development of human capacities.

Studying the evolved nest is necessarily an interdisciplinary area of study because we have to know our history as social mammals, what optimizes our development in our sensitive early years and what undermines the development of a cooperative human nature.

What does interdisciplinary scholarship tell us about the evolved nest? For humans, who are part of the social mammalian line, the evolved nest includes:

  1. Soothing perinatal experience. Wenda Trevathan studies the evolution of human birth and why human infants have to be so much more immature than other animals. She discusses perinatal experience and, for example, why adults hate to hear babies cry.
  2. Nearly constant touch in the first year and extensive affection thereafter. C. Sue Carter established the importance of oxytocin in social bonding. The development of the oxytocin system relies on affectionate touch. James Prescott, formerly of the National Institutes of Health, pointed out the relationship between early experience—particularly affection and breastfeeding—in producing peaceful people and societies.
  3. On-request breastfeeding for several years. James McKenna’s (University of Notre Dame, Anthropology) research on mother-baby co-coordination during sleep has led more recently to the notion of breastsleeping, the natural state of human infants’ early life.
  4. Warm responsiveness to needs by mother and then a small community of caregivers. Allan Schore (UCLA), the “American Bowlby,” continues to review the neurobiological studies of early life experience and its effects, showing that responsive mother care supports optimal brain development and secure attachment.
  5. Self-directed play in the natural world with multi-aged playmates. Douglas Fry, anthropologist at the University of Alabama, reviewed data on societies, pointing out how small-band hunter-gatherers, representative 99% of human genus history, are a unique type of society that live largely without war (and hierarchy and possessions). Play is one way we learn self-restraint.
  6. Positive social support. Vincent Felitti (MD at Kaiser Permanente), was one of the authors of the Adverse Childhood Experiences Studies (ACES), showing that emotional, physical abuse in the family, among other traumas, are related to greater illness and shorter lifespan.

All these components foster well-functioning physiological systems in social mammals and humans. Systems developed during the early years include the stress response, vagus nerve, endocrine systems, neurotransmitters, immune system, and sociality. These are all influenced by the quality of the nest. But emotion systems are also shaped by these components. The late Jaak Panksepp was a pioneer in showing the similarities between humans and other social mammals in terms of emotion systems and their development.

References

Narvaez, D., Panksepp, J., Schore, A., & Gleason, T. (Eds.) (2013). Evolution, Early Experience and Human Development: From Research to Practice and Policy. New York, NY: Oxford University Press.

Trevathan, W.R. (2011). Human birth: An evolutionary perspective, 2nd ed.. New York: Aldine de Gruyter.

2010 symposium with talks by anthropologists, clinical, developmental and neuro-scientists.

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