The sacrifices a primate mother must make to bear her young are literally profound. A new study in macaques has revealed that pregnancy can leave a permanent mark on the skeleton.
After the birth of a child, female macaques have significantly lower concentrations of calcium, phosphorus and magnesium in their bones compared to those who have not experienced pregnancy.
Although this particular study did not focus on humans, the findings help explain how major life events can leave a signature in the skeletal tissues of primates in general.
Although they may look like concrete pillars on which fleshy bodies grow, primate bones are surprisingly dynamic. Bones gradually widen throughout life, with annual fluctuations in growth often influenced by lifestyle factors.
Most of us know that bone density can be lost with age, especially after menopause, but throughout life illness, diet, climate and pregnancy can leave a permanent record. in the calcified tissues which can be “read” in the afterlife.
During human pregnancy, evidence suggests the mother’s body can actually extract calcium from her bones where insufficient amounts of the nutrient are consumed, which decreases the mass, composition and density of her skeleton for a period of time.
When breastfeeding, a mother’s bones are actually “resorbed” into her bloodstream to produce enough calcium-rich milk. Lost minerals are easily restored once lactation is over, but even then there might be a way for scientists to notice the momentary lapse.
In forensics and archaeology, identifying whether someone was pregnant using only their bones is controversial work. Signs on the pelvis of childbirth have been called unreliable, and today the methods and interpretations of this work vary widely. Maybe it’s time we looked deeper inside the bones instead.
“Our research shows that even before fertility stops, the skeleton responds dynamically to changes in reproductive status,” says anthropologist Paola Cerrito of New York University.
“Furthermore, these findings reaffirm the significant impact of childbirth on a female organism – quite simply, the evidence of reproduction is ‘inscribed in the bones’ for life.”
The study is based on only seven naturally deceased rhesus macaques, including four females, but even among this limited group, femur (thigh) bones showed relative changes that could only be explained by pregnancy and pregnancy. ‘feeding with milk.
Compared to males and females that were not born young, the two macaques that bred during their lifetime had relatively different bone composition, including lower calcium, phosphorus and magnesium content.
The observed changes in calcium and phosphate density were related to childbirth, while the decline in magnesium content coincided with lactation.
The authors suspect their results to be a sign of bone resorption during reproduction, but more studies are needed to say this for sure.
“The findings regarding elemental changes associated with reproduction are relevant because detecting parturition from mineralized tissue is still a largely unexplored area of research with significant implications for evolutionary, conservation, and archaeological studies,” the authors write.
Further research is needed, preferably using representatives of wild primate populations, to see if the same can be said for other animals.
It is possible, according to the authors, “that the signal of reproductive and weaning events that we detected could be masked, in wild populations, by physiological responses to changing diets and environments.”
The study was published in PLOS ONE.