Having children linked to reduced aging: study
VANCOUVER, Canada, January 26, 2016 (LifeSiteNews) – A unique Canadian study of 95 Mayan tribeswomen over 13 years shows that the more children they had, the slower their cells had aged, contradicting earlier research.
However, the team says news stories suggesting a causal connection between women having children and the rate their bodies age are completely false. "We found an association, a correlation, but we haven't found causation. It would be terrible if women went out and had more children in order to live longer," the team's statistician, Rachel Altman, told LifeSiteNews. "What those headlines are saying is just crazy."
Dr. Patrick Fagan, director of the Marriage and Religion Research Institute, a division of the Washington, D.C.-based Family Research Institute, called the correlations between number of children and longevity "very good, very strong" but agreed that they fell far short of causation. "The next step," he recommended, would be to duplicate the study in very different cultures such as the United Kingdom and the Philippines. "This is relatively easy and cheap to do. Longitudinal data … there are lots of longitudinal studies out there that could be tapped into," he said.
Nonetheless, said Fagan, "This rather interesting study in biology illustrates yet again that love (having more children) is great, not only for the children, but for the mother too. Humans thrive on love – both the receiver (the child) and the giver (the parent)."
The study was conducted by a team from Simon Fraser University comparing genetic data taken from 75 Guatemalan women for a previous and unrelated study in 2000 with new information collected in 2013. It is the first such study of humans, and it contradicts many studies already conducted on other life forms and mammals, all of which show that having more children is associated with shorter cell life.
The researchers don't know why, but they speculate that their contrary finding could be due either to the benefits of the extra estrogen produced during human pregnancy, or the added parenting support women receive in the two Guatemalan villages from their extended families, husbands, and other women when they have more children.
"This apparently protective effect of having more children may lay [sic] with humans' cooperative-breeding strategy," their study offers. "In a number of socio-economic and cultural contexts, having more children appears to be linked to an increase in social support for mothers (e.g., allomaternal care)." That is, more support means less stress and longer cell life.
The researchers apparently expected the opposite result, which would be consistent with Life History Theory. According to LHT and the evidence of studies on birds, fish, and mice, "energy invested in reproduction is not available for tissue maintenance, thus having more offspring is expected to lead to accelerated senescence." Here the study appears to be linking cell life with biological life.
What the study measured to draw its conclusions was the length of telomeres taken from the survey groups' cell tissue. Telomeres are protective tips that grow on the end of chromosome strands. They are worn away by stress and by oxidants in the environment. When the telomeres are worn down past a certain point, the cell stops growing.
The researchers note that during pregnancy, women produce more estrogen, which contains a steroid, estradiol, which both protects cells from oxidants and encourages production of telomerase, a substance that sustains the telomeres.
Nonetheless, researcher Altman said researchers would have to track the full lifespan of the Guatemalan women to correlate childbearing with longevity.
Even a correlation does not establish a causal link between children and longer cell life, let alone longer biological life, warned Altman. "We've found no causation, and the association we found applies only to the tiny population in these two villages."
In her apparent effort to reduce the significance of the study, or at least to avoid saying anything positive about having children, Altman claims there is no link between the SFU's finding about cell longevity and how long people live. Yet several times the study itself links maternity with biological aging – in a negative way – when summarizing Life History Theory, most tellingly in the opening sentence of the study: "Life history theory (LHT) predicts a trade-off between reproductive effort and the pace of biological aging."
Dr. Fagan commented that the researchers "seem to be shying away from the hard data, telomeres, and going for soft data, cultural community support." He said he would be adding the report to MARRI's impressive databank of research supporting the benefits of marriage and family.