The mother and baby (or carer and baby, or parent and baby) are a single biological system

Evolutionary biologists tell us that a mother and her baby, or a parent and baby, are most helpfully understood as a single biological ecosystem - really for at least the first nine months of baby's life.

Thinking of yourself and your baby as a single biological ecosystem doesn't make life with your little one harder though! The Possums programs don't require any kind of 'extreme' parenting. Once we cut through the myths, thinking of yourself, your baby's other parent or carers, and your baby holistically, as a dynamic biological system, usually makes life easiest for the whole family. The Possums programs use evolutionary biology and scientific knowledge to make caring for your baby as workable and enjoyable as possible, in the midst of our complicated 21st century lives.

In depth knowledge about the multiple physiological systems involved in breastfeeding reveals how you and your baby form a single biological ecosystem. Cognitive, emotional, physiological and motor development go best for our infants if we behave towards them as if we are, together, a complex adaptive system (another way of referrring to a biological system). Here's some research-based examples of how a loving parent and baby form a single biological system.

• Kangaroo care improves the outcomes for infants who are born preterm.

• Skin-to-skin contact regulates newborn temperature, dials down the newborn's sympathetic nervous system, and improves breastfeeding outcomes.

• The microbiome of the mother's nipple and breast skin, her breast milk, and her gut interact with the baby's oral and gut microbiomes, shaping and protecting each other.

• Lots of physical contact, sensory motor stimulation, carrying, and social interaction protect babies' motor outcomes.

• Babies are most settled in the first few months of life when they are fed frequently and flexibly, and receive ample physical contact with a loving carer.

You can trust in the flexibility and resilience of your mother-baby or parent-baby ecosystem!

Another important thing to know about a biological system is that it's self-organising. In Possums Breastfeeding & Lactation, this means that you experiment a lot, looking for what feels good and right for you and your own unique baby.

It also means that a lot of the problems which arise can be helped, once we know how to treat a breastfeeding mother and her baby as a single system. That's not to say that the Possums programs will always help, but there is often a lot that can be done.

In any complex system, there is great deal of buffering and resilience. Things don't need to go perfectly for your baby to grow and flourish! It's not that a woman can always breastfeed or even wants to breastfeed, for instance. It's just about working with your and your baby's biological system as a whole when problems arise, instead of treating the baby as a separate system.

Recommended resources

• You can find out more about resilience, the butterfly effect, and being a biological system as you breastfeed your baby here.

• You can find out why breastfeeding is a symphony of biological systems here.

• You can find out why the breastfeeding mother-baby pair are a complex adaptive system or CAS (not a dyad) here

• You can find out about the highly mouldable baby brain here.

Selected references

Alawadi AQH. Exclusive breastfeeding as a complex adaptive system: a qualitative study. Scientific Journal of Medical Research. 2020;4(15):70-86.

Braithwaite J, Churruca K, Long JC, Louise EA, Herkes J. When complexity science meets implementation science: a theoretical and empirical analysis of systems change. BMC Medicine. 2018;16:63.

Christian P, Smith ER, Lee SE. The need to study human milk as a biological system. American Journal of Clinical Nutrition. 2021;113:1063-1072.

Douglas PS, Hill PS, Brodribb W. The unsettled baby: how complexity science helps. Arch Dis Child. 2011;96:793-797.

Guillen-Morales DdJ, Cruz-Cortes I, Sosa-Velazco TA, Aquino-Dominguez AS. The mother-infant symbiosis: a novel perspective on the newborn's role in protecting maternal breast health. Hygiene. 2025;5(46):https://doi.org/10.3390/hygiene5040046.

Sturmberg J, Topolski S. For every complex problem, there is an answer that is clear, simple and wrong. Journal of Evaluation in Clinical Practice. 2014;6:1017-1025.