Nav: Home

Early human species' teeth provide insight into evolution of breastfeeding

July 15, 2019

(New York, NY - July 15, 2019) -- Mount Sinai researchers working as part of an international team have discovered previously unknown breastfeeding patterns of an extinct early human species by studying their 2-million-year-old teeth, providing insights into the evolution of human breastfeeding practices, according to a study published in Nature in July.

Breastfeeding is a critical aspect of human development, and the duration of exclusive nursing and the timing of introducing solid food to the diet are also important determinants of health in human and other primate populations. Many aspects of nursing, however, remain poorly understood.

Using high-tech methods pioneered at Mount Sinai, the scientists analyzed teeth from Australopithecus africanus (A. africanus), an early human ancestor that lived about 2 to 3 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. Our results show this species is a little closer to humans than the other great apes which have such different nursing behaviors," said one of the study's first authors, Christine Austin, PhD, 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. "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. Diet is a big part of the exposome--someone's environmental exposure history--and nutritional stress is an exposure that is important to measure to understand overall health after exposures, Dr. Austin said.

"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," said the study's lead first author, Renaud Joannes-Boyau, PhD, head of the Geoarchaeology and Archaeometry Research Group (GARG) at Southern Cross University in Australia.
-end-
Dr. Joannes-Boyau conducted part of the experiments with Dr. Austin in 2017 while he was a visiting Associate Professor at Mount Sinai's Institute for Exposomic Research. This study was funded by grants from the National Institutes of Health Eunice Kennedy Shriver National Institute of Child Health and Human Development (R00HD087523) and the National Institute of Environmental Health Sciences (U2CES026561 and DP2ES025453).

About The Institute for Exposomic Research

The Institute for Exposomic Research at the Icahn School of Medicine at Mount Sinai is the world's first research institute devoted to the intensive study of the exposome, or the totality of environmental influences on human health. The mission of the Institute is to understand how the complex mix of nutritional, chemical, and social environments affect health, disease, and development later in life and to translate those findings into new strategies for prevention and treatment. For more information, visit http://icahn.mssm.edu/exposomics.

About the Mount Sinai Health System

The Mount Sinai Health System is New York City's largest integrated delivery system, encompassing eight hospitals, a leading medical school, and a vast network of ambulatory practices throughout the greater New York region. Mount Sinai's vision is to produce the safest care, the highest quality, the highest satisfaction, the best access and the best value of any health system in the nation. The Health System includes approximately 7,480 primary and specialty care physicians; 11 joint-venture ambulatory surgery centers; more than 410 ambulatory practices throughout the five boroughs of New York City, Westchester, Long Island, and Florida; and 31 affiliated community health centers. The Icahn School of Medicine is one of three medical schools that have earned distinction by multiple indicators: ranked in the top 20 by U.S. News & World Report's "Best Medical Schools", aligned with a U.S. News & World Report's "Honor Roll" Hospital, No. 12 in the nation for National Institutes of Health funding, and among the top 10 most innovative research institutions as ranked by the journal Nature in its Nature Innovation Index. This reflects a special level of excellence in education, clinical practice, and research. The Mount Sinai Hospital is ranked No. 18 on U.S. News & World Report's "Honor Roll" of top U.S. hospitals; it is one of the nation's top 20 hospitals in Cardiology/Heart Surgery, Gastroenterology/GI Surgery, Geriatrics, Nephrology, and Neurology/Neurosurgery, and in the top 50 in six other specialties in the 2018-2019 "Best Hospitals" issue. Mount Sinai's Kravis Children's Hospital also is ranked nationally in five out of ten pediatric specialties by U.S. News & World Report. The New York Eye and Ear Infirmary of Mount Sinai is ranked 11th nationally for Ophthalmology and 44th for Ear, Nose, and Throat. Mount Sinai Beth Israel, Mount Sinai St. Luke's, Mount Sinai West, and South Nassau Communities Hospital are ranked regionally.

For more information, visit http://www.mountsinai.org/, or find Mount Sinai on Facebook, Twitter and YouTube.

The Mount Sinai Hospital / Mount Sinai School of Medicine

Related Evolution Articles:

Chemical evolution -- One-pot wonder
Before life, there was RNA: Scientists at Ludwig-Maximilians-Universitaet (LMU) in Munich show how the four different letters of this genetic alphabet could be created from simple precursor molecules on early Earth -- under the same environmental conditions.
Catching evolution in the act
Researchers have produced some of the first evidence that shows that artificial selection and natural selection act on the same genes, a hypothesis predicted by Charles Darwin in 1859.
Guppies teach us why evolution happens
New study on guppies shows that animals evolve in response the the environment they create in the absence of predators, rather than in response to the risk of being eaten.
Undercover evolution
Our individuality is encrypted in our DNA, but it is deeper than expected.
Evolution designed by parasites
In 'Invisible Designers: Brain Evolution Through the Lens of Parasite Manipulation,' published in the September 2019 issue of The Quarterly Review of Biology, Marco Del Giudice explores an overlooked aspect of the relationship between parasites and their hosts by systematically discussing the ways in which parasitic behavior manipulation may encourage the evolution of mechanisms in the host's nervous and endocrine systems.
More Evolution News and Evolution Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...