Teeth analysis reveals breastfeeding behaviours of Neanderthals

New cutting edge technology located at Southern Cross University has helped unlock the mystery of how long pre-historic women breastfed their children.

The international study, Barium distributions in teeth reveal early life dietary transitions in primates published today (May 23) in the journal Nature, tracked diet transitions during infancy using the isotopic distribution of barium in modern and fossil teeth.

“For the first time scientists have been able to identify the breastfeeding behaviours of Neanderthals,” said geochronologist Dr Renaud Joannes-Boyau, from the University’s Special Research Centre Southern Cross GeoScience.

“We are able to confirm that Neanderthals breastfed their children for approximately seven months, then weaned them for another seven months before shifting their offspring to an entirely solid food diet. This clearly indicates an abrupt cessation of breastfeeding at 1.2 years of age.

“Interestingly, this replicates what we see in modern humans today.”

Dr Joannes-Boyau was part of the international research team led by Dr Christine Austin from the Icahn School of Medicine at Mount Sinai in the US and Associate Professor Tanya Smith from Harvard University.

The barium study documented dietary transitions in a Middle Palaeolithic juvenile Neanderthal to show large dietary shifts in early life manifest as compositional variations in dental tissues.

Dr Joannes-Boyau said high levels of barium were present in breast milk and those levels of barium, along with other major dietary shifts during infancy, childhood and adulthood, are accurately recorded in mineralised dental tissues.

“Barium levels in dental tissues formed during nursing are higher than in tissues that mineralise before birth, during solid food supplementation or after nursing ceases.

“These growth lines in the teeth are similar to the growth rings in trees,” Dr Joannes-Boyau said.

Dr Joannes-Boyau analysed and interpreted THE dental tissues using a high-resolution laser-ablation unit coupled to an inductively coupled plasma mass spectrometer (LA-ICPMS) which allows researchers to quantify the elemental and isotopic composition of samples.

“Using laser-ablation to obtain isotopic spatial distributions with histological mapping of tooth formation enables novel studies and new understandings of human evolution. For example, we can track changes in the diets of migrating humans,” he said.

“One of my roles in the study was the assessment of potential diagenetic effects during burial that could have modified the biomarkers distribution, and therefore hampered the readability of early-life dietary history.”

A dedicated laboratory has been established for the unit, known as the Southern Cross Laser-Ablation Research Instrument or SOLARIS for short. The main advantage of the LA-ICPMS is, unlike other elemental and isotopic analyses, it minimises the destruction or significant alteration of the original sample; a major consideration when sampling archaeological material. The SOLARIS laboratory will be useful in a range of fields including archaeological sciences, ecology and environmental sciences and has the potential to analyse the composition of a wide range of materials including soils, rocks, corals, shells, artefacts and fossil remains. Funded through a successful ARC LIEF project, submitted by Professor Richard Bush, Associate Professor Ed Burton, Associate Professor Andrew Rose, Associate Professor Anja Scheffers and Dr Sanders Scheffers in 2011, the SOLARIS laboratory is a major investment costing around $450,000.

The SOLARIS laboratory is headed and managed by Dr Joannes-Boyau.

BIO
Dr Renaud Joannes-Boyau’s research interests are (i) the development of geochronology techniques; enhancing methodology, protocols and accuracy of ESR and U-series dating methods applied to human fossils; (ii) the application of geochemistry and geochronology techniques to archaeological and paleoenvironmental sciences, such as the effect of past, present and future climate changes on landscape evolution and populations; and (iii) Investigating the mobilisation, incorporation and migration of isotopes and radionuclide into animal and human remains to understand migration and dietary history.
Photo: Dr Renaud Joannes-Boyau in the SOLARIS laboratory with a replica of the Kabwe skull from South Africa.