Busting myths about evolutionary biology and infant sleep, cry-fuss problems, and sensory motor development

Evolutionary biology and infant sleep: key myths

#	Myth	Updated evolutionary science
1	Teaching baby to self-settle makes life easier for parents and allows women to return to paid work.	Attempts to teach infants to self-settle often result in elevated stress and distress for families; do not decrease frequency of night waking over time; and may result in excessive night waking some weeks down the track.
2	Bedsharing is inherently dangerous for infants	Bedsharing is the evolutionary norm, and the most common sleeping arrangement across human cultures. Risks associated with bedsharing are socioculturally determined and are minimised with appropriate parent education.
3	Mothers have to cosleep in a C-shaped posture around their baby when bedsharing, to keep baby safe.	Although researchers have found that breastfeeding mothers are more likely to adopt this posture when bedsharing with their baby compared to formula feeding parents, there is no evidence to suggest that breastfeeding women have to adopt this posture to improve infant safety. There are likely to be unintended consequences of adopting a research observation as an education or clinical principle which should be taught to women.
4	Babies need to be taught to sleep.	Sleep is a biological state change which is under the control of two sleep regulators, not a behaviour which can be taught.
5	Sleep breeds sleep.	The physiology of sleep tells us that sleep does not bring on more sleep - rather, sleep drops the sleep pressure. However, calm does breed more calm.
6	Go with the flow and let sleep be natural or intuitive.	Evolutionary biology teaches us that infant care is an interaction between biology and parenting behaviour, which is profoundly shaped by sociocultural influences. Labelling certain behaviours as natural or intuitive is unkind of parents, because when these behaviours don't seem to work the parents feel that they are unnatural or lacking in intuition. Excessive night waking is very common in societies in which sleep training or graduated extinction methods are dominant within health systems, and creates severe and unsustainable sleep deprivation.

Evolutionary biology and infant sensory motor development: key myths

#	Myth	Updated evolutionary science
1	Avoid overstimulation.	Rich and diverse sensory motor experience optimises infant developmental outcomes. Infants cry in contexts of inadequate sensory motor nourishment.
2	Carrying baby uses up too much parent energy.	Carrying an infant makes the days easiest.
3	Newborns and young babies shouldn't be put into carriers due to safety risks.	From an evolutionary and developmental perspective, there are multiple advantages to appropriate carrier use from birth. Parents require education about how to use carriers safely.
4	Lying in for six weeks is best for the mother (using traditional customs).	Women need to adapt to the culture in which they currently live, taking into account an infant's evolutionary needs. There are profound differences between the sensory motor experiences available to the infant inside homes in traditional contexts and also historically, compared to contemporary interior environments. Lying in through the first six weeks can make life much harder for that mother and baby, rather than easier, because unmet sensory motor needs results in a dialled up baby.

Evolutionary biology and infant cry-fuss problems: key myths

#	Myth	Updated evolutionary science
1	Crying for 2 hours a day is developmentally normal.	Infants do not cry for long durations in many cultures, and durations of infant crying are shaped by culturally-determined infant care approaches.
2	Developmental outcomes are normal for babies who cry and fuss a lot in the first months of life	Unsettled infant behaviour in the first months of life is linked with a range of suboptimal outcomes for families and infants. This is a correlative, not causative link, and relevant to a small subgroup of crying infants who are genetically or psychosocially vulnerable. But NDC proposes that this link demonstrates why the evidence-based, multidomain approach to infant cry-fuss problems (the Possums 5-domain approach) is so important for outcomes when families present with this problem.

Recommended resources

Evolutionary biology basics for health professionals who work with parents and infants

Busting myths about evolutionary biology and infant care generally

Breastfeeding durations in ancestral environments. A little extra something - part 3

Busting myths about evolutionary biology and breastfeeding

A timeline of relevant evolutionary events for health professionals who care for parents and infants