*See note on basic assumptions below.

Letting babies "cry it out" is an idea that has been around since at least the 1880s when the field of medicine was in a hullaballoo about germs and transmitting infection and so took to the notion that babies should rarely be touched (see Blum, 2002, for a great review of this time period and attitudes towards childrearing).

In the 20th century, John Watson (1928), interested in making psychology a hard science, took up the crusade against affection as president of the American Psychological Association. He applied the mechanistic paradigm of behaviorism to child rearing, warning about the dangers of too much mother love. The 20th century was the time when "men of science" were assumed to know better than mothers, grandmothers and families about how to raise a child. Too much kindness to a baby would result in a whiney, dependent, failed human being. Funny how "the experts" got away with this with no evidence to back it up! Instead, there is evidence all around (then and now) showing the opposite to be true!

A government pamphlet from the time recommended that "mothering meant holding the baby quietly, in tranquility-inducing positions" and that "the mother should stop immediately if her arms feel tired" because "the baby is never to inconvenience the adult." A baby older than six months "should be taught to sit silently in the crib; otherwise, he might need to be constantly watched and entertained by the mother, a serious waste of time." (See Blum, 2002.)

Don't these attitudes sound familiar? A parent reported to me recently that he was encouraged to let his baby cry herself to sleep so he "could get his life back."

[Note: In other posts on infant sleep, my co-authors and I point out flaws in studies of sleep training. Here is another example. Check out this article and its table that lists the studies reviewed. The table shows that every study is flawed—either the intervention was not followed (fidelity) and/or only parent reports were used, not observation. Moreover, the age range of the children varied. Most importantly, note that most studies did not measure child wellbeing. So there is no responsible way to draw generalizable conclusions from this set of flawed studies. The standards for publishing such studies appear to be very low. In a forthcoming post, we note how many studies use an "Intent to Treat" criterion for distinguishing conditions, not bothering about what actually happened.]

With , we can confirm what our ancestors took for granted—that letting babies get distressed is a practice that can harm children and their relational capacities in the long term.

The discredited behaviorist view sees the baby as an interloper in the life of the parents, an intrusion who must be controlled by various means so the adults can live their lives without too much bother. Perhaps we can excuse this attitude and ignorance because at the time, extended families were being broken up and new parents had to figure out how to deal with babies on their own, an unnatural condition for humanity—we have heretofore raised children in extended families. The parents always shared care with multiple adult relatives.

According to a behaviorist view, the child 'has to be taught to be independent.' But forcing "independence" on a baby could lead to greater dependence. Instead, giving babies what they need leads to greater independence later. In anthropological reports of small-band hunter-gatherers, parents took care of every need of babies and young children. Toddlers felt confident enough (and so did their parents) to walk into the bush on their own (see Hunter-Gatherer Childhoods, edited by Hewlett & Lamb, 2005).

Behaviorists then and now encourage parents to condition the baby to expect needs not to be met on demand, whether feeding or comforting. It's assumed that the adults should 'be in charge' of the relationship. Certainly this might foster a child that doesn't ask for as much help and , but it is more likely to foster a whiney, unhappy, aggressive and/or demanding child, one who has learned that one must scream to get needs met.

Caregivers who habitually respond to the needs of the baby before the baby gets distressed, preventing crying, are more likely to have children who are independent than the opposite (e.g., Stein & Newcomb, 1994). Soothing care is best from the outset. Once patterns of distress get established, it's much harder to change them.

Rats are often used to study how mammalian brains work and many effects are similar in human brains. In studies of rats with high or low nurturing mothers, there is a critical period for turning on that control anxiety for the rest of life. If in the first 10 days of life you have a low nurturing rat mother, the gene never gets turned on and the rat is towards new situations for the rest of its life, unless drugs are administered to alleviate the anxiety. These researchers say that there are hundreds of genes affected by nurturance.

Similar mechanisms are found in human brains—caregiver behavior matters for turning genes on and off. (See work of Michael Meaney and colleagues; e. g., Meaney, 2001).

We should understand the mother and child as a mutually responsive dyad. They are a symbiotic unit that make each other healthier and happier in mutual responsiveness. This expands to other caregivers too.

One strangely popular notion still around today is to let babies 'cry it out' (aka total extinction or unmodified extinction) when they are left alone, isolated in cribs or in other devices. This comes from a misunderstanding of child brain development.

Babies grow from being held. Their bodies get dysregulated when they are physically separated from caregivers. (See here for more.)

Babies indicate a need through gesture and eventually, if necessary, through crying. Just as adults reach for liquid when thirsty, children search for what they need in the moment. Just as adults become calm once the need is met, so do babies.

There are many long-term effects of undercare or need-neglect in babies (e.g., Bremmer et al, 1998; Blunt Bugental et al., 2003; Dawson et al., 2000; Heim et al 2003).

Secure is related to responsive parenting, such as comforting babies when they wake up and cry at night.

Why should we avoid 'crying it out'?

The brain is developing quickly. When the baby is greatly distressed, it creates conditions for damage to synapses, the network construction which is ongoing in the infant brain. The cortisol is released. In excess, it's a neuron killer but its consequences may not be apparent immediately (Thomas et al. 2007). A full-term baby (40-42 weeks), with only 25% of its brain developed, is undergoing rapid brain growth. The brain grows on average three times as large by the end of the first year (and head size growth in the first year is a sign of , e.g., Gale et al., 2006). Who knows what neurons are not being connected or being wiped out during times of extreme ? What deficits might show up years later from such regular distressful experience? (See my addendum below.)

Disordered stress reactivity may be established not only in the brain with the stress response system (Bremmer et al, 1998), but also in the body through the , a nerve that affects functioning in multiple systems (e.g., digestion). For example, prolonged distress in early life can result in a poorly functioning vagus nerve, which is related to various disorders as irritable bowel syndrome (Stam et al, 1997). See more about how early stress is toxic for lifelong health from the recent Harvard report, The Foundations of Lifelong Health are Built in Early Childhood).

may be undermined. The baby is dependent on caregivers for learning how to self-regulate. Responsive care—meeting the baby's needs before he gets distressed—tunes the body and brain up for calmness. When a baby gets scared and a parent holds and comforts him, the baby builds expectations for soothing, which get integrated into the ability to self-comfort. Babies don't self-comfort in isolation. If they are left to cry alone, they learn to shut down in face of extensive distress—stop growing, stop feeling, stop trusting (Henry & Wang, 1998).

Trust may be undermined. As Erik Erikson pointed out, the first year of life is a sensitive period for establishing a sense of trust in the world, the world of caregiver and the world of self. When a baby's needs are met without distress, the child learns that the world is a trustworthy place, that relationships are supportive, and that the self is a positive entity that can get its needs met. When a baby's needs are dismissed or ignored, the child develops a sense of mistrust of relationships and the world. And is undermined. The child may spend a lifetime trying to fill the resulting inner emptiness.

Caregiver sensitivity may be harmed. A caregiver who learns to ignore baby crying might learn to ignore the more subtle signaling of the child's needs. Second-guessing intuitions that guide one to want to stop child distress, the adult who learns to ignore baby needs learns to "harden the heart." The reciprocity between caregiver and baby is broken by the adult but cannot be repaired by the young child. The baby is helpless.

Caregiver responsiveness to the needs of the baby is related to most many positive child outcomes. In our work, caregiver responsiveness is related to intelligence, , lack of or , self-regulation, social competence. Because responsiveness is so powerful, we have to control for it in our studies of other practices and child outcomes. The importance of caregiver responsiveness is common knowledge in developmental psychology.

The 'cry it out' approach seems to have arisen as a solution to the dissolution of extended family life in the 20th century. The vast knowledge of (now great great) grandmothers was lost in the distance between households with children and those with the experience and expertise about how to raise them well. The of keeping babies happy was lost between generations.

But isn't it normal for babies to cry?

A crying baby in our ancestral environment could have alerted predators to tasty morsels. So our evolved parenting practices likely served to alleviate baby distress and preclude crying except in emergencies. Babies are built to expect the equivalent of an "external womb" after birth (see Allan Schore, specific references below). What is the external womb? Being held constantly, breastfed on demand, having needs met quickly (I have numerous posts on these things). These practices are known to facilitate good brain and body development (discussed with references in other posts). When babies display discomfort, it signals that a need is not getting met, a need of their rapidly growing systems.

Below is a good set of articles about all the things that a baby's cry can signal. We can all educate ourselves about what babies need and the practices that alleviate baby crying. We can help one another to keep crying from happening as much as possible.

Check these out:

How to soothe babies: http://www.babycenter.com/0_12-reasons-babies-cry-and-how-to-soothe-them_9790.bc?page=2

Soothing babies crying "for no reason": http://www.babycenter.com/0_what-to-do-when-your-baby-cries-for-no-reason_10320516.bc

Soothing babies who have "colic": http://www.babycenter.com/0_colic-how-to-cope_1369745.bc

Science of Parenting, an inexpensive, photo-filled, easy-to-read book for parents by Margot Sunderland, has much more detail and references on these matters. I keep copies on hand to give to new parents.

Here is a terrific post on co-sleeping (the abandoned practice that is behind notions of leaving babies to cry it out) by my esteemed colleague, Peter Gray. Much more about co-sleeping research is here at the website of my colleague, James McKenna.

More on babies' and children's needs here, here, here.

Giving babies what they need is really a basic right of babies. See here for more rights I think babies should expect. And see here for a new book by Eileen Johnson on the emotional rights of babies.

ADDENDUM: I was raised in a middle-class family with a depressed mother, harsh father and overall emotionally unsupportive environment—not unlike others raised in the USA. I have only recently realized from extensive reading about the effects of early parenting on body and brain development that I show the signs of undercare—poor (cortisol released during distress harms hippocampus development), irritable bowel and other poor vagal tone issues, and high . The USA has epidemics of poor physical and mental health (e.g., UNICEF, 2007; USDHSS, 1999; WHO/WONCA, 2008). The connection between the lack of ancestral parenting practices and poor health outcomes has been documented for touch, responsiveness, breastfeeding, and more (Narvaez et al., in press). If we want a strong country and people, we've got to pay attention to what children need for optimal development.

NOTE on BASIC ASSUMPTIONS:

When I write about human nature, I use the 99% of human genus history as a baseline. That is the context of small-band hunter-gatherers. These are “immediate-return” societies with few possessions who migrate and forage. They have no hierarchy or coercion and value and sharing. They exhibit both high autonomy and high commitment to the group. They have high social wellbeing. See a comparison between dominant Western culture and this evolved heritage in my article (you can download from my website):

Narvaez, D. (2013). The 99 Percent—Development and socialization within an evolutionary context: Growing up to become “A good and useful human being.” In D. Fry (Ed.), War, Peace and Human Nature: The convergence of Evolutionary and Cultural Views (pp. 643-672). New York: Oxford University Press.

When I write about parenting, I assume the importance of the evolved developmental niche (EDN) for raising human infants (which initially arose over 30 million years ago with the emergence of the social mammals and has been slightly altered among human groups based on anthropological research).

The EDN is the baseline I use for determining what fosters optimal human health, wellbeing and compassionate . The niche includes at least the following: infant-initiated breastfeeding for several years, nearly constant touch early, responsiveness to needs so the young child does not get distressed, playful companionship with multi-aged playmates, multiple adult caregivers, positive social support, and soothing perinatal experiences.

All EDN characteristics are linked to health in mammalian and human studies (for reviews, see Narvaez, Panksepp, Schore & Gleason, 2013; Narvaez, Valentino, Fuentes, McKenna & Gray, 2014; Narvaez, 2014) Thus, shifts away from the EDN baseline are risky and must be supported with longitudinal data looking at wellbeing in children and adults. My comments and posts stem from these basic assumptions.

My research laboratory has documented the importance of the EDN for child wellbeing and moral development with more papers in the works see (my Website to download papers):

Narvaez, D., Gleason, T., Wang, L., Brooks, J., Lefever, J., Cheng, A., & Centers for the Prevention of (2013). The Evolved Development Niche: Longitudinal Effects of Practices on Early Psychosocial Development. Early Childhood Research Quarterly, 28 (4), 759–773. Doi: 10.1016/j.ecresq.2013.07.003

Narvaez, D., Wang, L., Gleason, T., Cheng, A., Lefever, J., & Deng, L. (2013). The Evolved Developmental Niche and sociomoral outcomes in Chinese three-year-olds. European Journal of Developmental Psychology, 10(2), 106-127.

Also see these books for selected reviews:

Evolution, Early Experience and Human Development (Oxford University Press)

Ancestral Landscapes in Human Evolution (Oxford University Press)

Neurobiology and the Development of Human Morality (W.W. Norton)