The study was published in Nature. Using high-tech methods pioneered at Mount Sinai, the scientists analyzed teeth from Australopithecus africanus (A. africanus), an early human ancestor that lived about two to three million years ago in South Africa and had both human and apelike features. Scientists reconstructed diet histories using the teeth, measuring preserved chemical biomarkers. The growth patterns of teeth, which resemble tree rings, allow investigators to determine concentrations of barium, an element found in milk, in teeth over time, which yields information about their nursing and dietary patterns.
Researchers found the species breastfed for up to one year and then had six monthly cycles of food scarcity, which could have caused them to fall back to increased breastfeeding or find other food sources. “Seeing how breastfeeding has evolved over time can inform best practices for modern humans by bringing in evolutionary medicine,” says Christine Austin, Ph.D., one of the study’s first authors and Assistant Professor of Environmental Medicine and Public Health at the Icahn School of Medicine at Mount Sinai and member of Mount Sinai’s Institute for Exposomic Research.
“Our results show this species is a little closer to humans than the other great apes which have such different nursing behaviors,” Austin continued. “These are important findings from an evolutionary perspective, because humans have long childhoods and short breastfeeding periods while apes have longer breastfeeding periods than humans do. We’re still in the dark about why or when we made that change and what the effect of more recent major changes in breastfeeding, with agriculture and industrialization, could have on mothers’ and babies’ health.”
Mount Sinai’s Institute for Exposomic Research looks into how to develop biomarkers of exposure, and a prime one is measuring chemicals in teeth. “For the first time, we’ve gained new insight into the way our ancestors raised their young, and how mothers may have adapted to seasonal food shortages with breastfeeding,” added the study’s lead first author, Renaud Joannes-Boyau, Ph.D., head of the Geoarchaeology and Archaeometry Research Group (GARG) at Southern Cross University in Australia.
What More Accurate Aging Of Teeth Can Identify
Anatomical science and community dentistry researchers at Wits University believe that more accurate aging of teeth could hold the key to identifying health-compromised children on the African continent. The researchers are investigating dental development as a more reliable gauge for assessing the age of children and juveniles in forensic and anthropological contexts.
They also published a systematic review of dental development assessment methods to determine the best and most accurate means to estimate chronological age in different populations. "It is important to accurately estimate chronological age from a sample of living children in the population of interest, because this information can then be used as a benchmark for evaluating the growth of health-compromised children,” says Professor Lynne A Schepartz, Associate Professor and Head of the Biological Anthropology Division at Wits and co-author of the paper. “Our review illustrates that there is significant population-level variation in the tempo of dental development."
Their review focused on studies investigating the predominant dental development assessment methods - the Demirjian and the Willems methods - in different populations with the aim of determining the more accurate method. The findings conclude that the Willems method of dental age estimation provides a better and more accurate estimation of chronological age in different populations than the Demirjian method. Still, the ages of children in most populations are over-estimated using that method.
Population-based data on human biological growth and development processes are fundamental for assessing the health status of a community. For many populations in rural Africa, birth registry and eliciting date of birth are still challenges. Data on uncompromised development and growth variation in most developing populations are surprisingly lacking, and researchers typically compare growth in the population of interest to standards that are formulated for European or U.S. children.
The findings have implications for growth assessment in general, and the use of global standards that are largely untested in African populations. The research highlights the need for population-specific standards for age estimation, as their use extends beyond basic biological anthropology and health research. The Wits researchers say the information from dental development may play a major role in determining many clinical decisions, including choices about treatment options and sequence of treatment in the future.
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With over 30 years of writing and editing experience for newspapers, magazines and corporate communications, Kevin Kerfoot writes about natural health, nutrition, skincare and oral hygiene for Trusted Health Products’ natural health blog and newsletters.
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