Mothering and Recovery Six
Interbirth Intervals, Allomothers and the Great Mismatch
Science writer Elena Bridgers and biological anthropologist Dr. Molly M. Fox suggest in their 2024 paper that the ways in which we mother today in our global industrial world are not well aligned to our enduring biological framework as social primates. Not only do they suggest that this gap underlies the “stressed out mom” of today, but that it may even suggest that perinatal mood disorders are not disorders but rather an evolutionary mismatch in how we are biologically designed to mother compared to how we are forced to mother in our current societies.[1]
Unsurprisingly, these researchers reference Dr. Sarah Blaffer Hrdy and her book Mothers and Others: the evolutionary origins of mutual understanding, as many of their investigations on current hunter-gatherer societies compared to both agrarian and modern industrial (or post-industrial) life, build upon Dr. Hrdy’s body of work on the topic.
Interbirth Intervals
Interbirth interval refers to the time between each pregnancy and birth. For modern day hunter-gatherers it’s 4 years. In agrarian societies it was approximately 2 years, in the US today it’s 3 years.
“Although there is increasing evidence that spacing births closely increases certain risks (specifically, birth spacing closer than 18 months appears to be associated with a higher risk for premature rupture of membranes and placenta previa), less research is available on the potential mental and emotional impact of spacing births closely [41, 42]. A 2007 study by Mayberry et al. of American women indicates that higher parity is positively correlated with depression symptom severity [4]. Another study of Norwegian parents found that closely spaced births were more often associated with mothers’ mortality and medication use in mid-life or early old age [43]. Finally, there is ample research to show that high levels of parenting stress and childcare stress, defined as the imbalance between the demands of caring for young children and available resources, are risk factors for postpartum depression [17].”
Reduced interbirth intervals today, when compared to hunter-gatherer societies, has happened for a variety of reasons: women begin having children at a later age; women plan on staying home for a few years before the children start school, benefit from having the children closer in age when it comes to returning to waged labour; and breast feeding occurs for much shorter duration (breast feeding acts as a clamp on the fertility of the mother). The interbirth interval has increased from early agrarian times thanks to birth control. Hunter-gatherer societies have the greatest interbirth intervals due to breast feeding for much longer than agrarian or modern industrial mothers.
Allomothering
“Studies of hunter-gatherer societies have repeatedly shown that caring for babies is a collaborative effort. A study of !Kung mothers and infants showed that for nearly half of the recorded incidences of infant crying, someone other than the mother responded, either together with the mother or alone and in one-third of instances the mother was not present [33].”
Allmomothering means the child is receiving care from someone in the group other than the mother. Allomothering is not the use of older children to parent younger children, as was common for extremely large families in agrarian societies. Allomothering is the involvement of other men and women in the tribe. While it may involve older children as well, there is not a nuclear family where those children are the only other form of support for parenting in the vicinity.
Receiving care from multiple adults in our modern world is often achieved through daycare and studies show higher sociability (a willingness to be surrounded by people and to be attached to them) in adulthood if a child is in daycare from ages 3 or 6 compared to those raised with home-based care with a primary caregiver.[4]
And it appears boys benefit most from daycare settings, whereas girls do equally well on the following measures whether raised exclusively in the home, or with daycare attendance: boys had greater odds of graduating from school and they had reduced odds of low income as adults as well.[5]
However, the overall body of research provides conflicting results for daycare attendance and the adult outcomes for those children. It appears as though higher socio-economic status and resistance of parents to having their children in daycare, results in worse outcomes.[6],[7] This likely reflects bias and stigma in our culture that the mother acting as the primary caregiver is superior to multiple unrelated adults supporting the care in a daycare setting. Given that higher socio-economic status seems to correlate to worse outcomes, it may reflect the pressure on a mother to stay-at-home for the good of the child’s development when the absolute financial need to have a paid job is unnecessary due to the partner’s comfortable income.
Completely as an aside, there is a reduced risk of Type 1 diabetes for children when they attend daycare. It’s surmised that this occurs because there is earlier exposure to microbes (no data to support that guess just yet).[8]
The takeaway is that daycare is not equivalent to alloparenting in hunter-gatherer societies, but it may provide some reasonable simulation of the benefits to children, and it alleviates the stress of lone mothering.
Learning to Mother
As we do not tend to live in social environments where we are connected to individuals at different stages of their lives, we don’t begin parenting until all of our social circle is busy parenting as well. Our own parents might be present, but that may or may not alleviate the stress of being a new parent. Even if we are involved in social activities across several generations, we only tend to witness other parents parenting in very structured and time-limited settings, as opposed to a hunter-gatherer tribe living and working together.
Very few us also get to attempt mothering duties in a completely non-responsible way—meaning we learn a bit by doing as an allomother/mother-in-training but with oversight from numerous adult tribespeople nearby who ensure we are not over faced or overwhelmed at any given moment. There are definitely women just a bit older than me in francophone Canada who played the role of substitute parent, not really alloparent, for their young siblings, but it involved tremendous responsibility and little to no oversight. Many of them as adults choose not to have children because they feel they’re done with raising children by the time they turn 18.
Part Seven coming April 25.
Bridgers E, Fox MM. Lonely, stressed-out moms: Does the postindustrial social experience put women at risk for perinatal mood disorders?. Evolution, Medicine, and Public Health. 2024;12(1):204-13.
ibid.
Bridgers E, Fox MM. Lonely, stressed-out moms: Does the postindustrial social experience put women at risk for perinatal mood disorders?. Evolution, Medicine, and Public Health. 2024;12(1):204-13.
Oksman E, Rosenström T, Gluschkoff K, Saarinen A, Hintsanen M, Pulkki-Råback L, Viikari J, Raitakari OT, Keltikangas-Järvinen L. Associations between early childcare environment and different aspects of adulthood sociability: The 32-year prospective Young Finns Study. Frontiers in psychology. 2019 Sep 10;10:2060.
Domond P, Orri M, Algan Y, Findlay L, Kohen D, Vitaro F, Tremblay RE, Côté SM. Child care attendance and educational and economic outcomes in adulthood. Pediatrics. 2020 Jul 1;146(1).
Fort M, Ichino A, Zanella G. Cognitive and noncognitive costs of day care at age 0–2 for children in advantaged families. Journal of Political Economy. 2020 Jan 1;128(1):158-205.
Kuehnle D, Oberfichtner M. Does starting universal childcare earlier influence children’s skill development?. Demography. 2020 Feb;57(1):61-98.
Tall S, Virtanen SM, Knip M. Day Care Attendance and Risk of Type 1 Diabetes: A Meta-Analysis and Systematic Review. JAMA pediatrics. 2024 Dec 1.
Image in synopsis: Flickr.com: Aenea Studio
