Press Release for Smith et al. Science Advances Study
** Embargoed: Not for Release Until 2:00 pm U.S. Eastern Time Wednesday, 31 October.**
The Geoarchaeology and Archaeometry Research Group (GARG) at Southern Cross University was once again in the spot light with a new study on the interaction between our Ancestors and their environment. The study new study published today in Science Advances (http://advances.sciencemag.org/content/4/10/eaau9483.full) reports a major breakthrough in the reconstruction of ancient climates ¾ a significant factor in human evolution, as temperature and precipitation cycles influenced the landscapes and food resources our ancestors relied on.
Associate Professor Tanya Smith of Griffith’s Australian Research Centre for Human Evolution led an international team of biological anthropologists, archaeologists, earth scientists, and public health specialists from Australia, North America, and Europe.
Smith prepared delicate thin sections of the teeth of two Neanderthals and one modern human from a French archaeological site, which she then imaged with polarized light microscopy to document each day of their childhood growth. Teeth have biological rhythms akin to tree rings, but on a much finer scale, leading to numerous applications detailed in Smith’s new popular science book from MIT Press, The Tales Teeth Tell.
The team then used the sensitive high-resolution ion microprobe (SHRIMP) at ANU to collect information on oxygen variation during three years of tooth growth in each youngster. “This allowed us to relate their development to ancient seasons, revealing that one Neanderthal was born in the spring, and that both Neanderthal children were more likely to be sick during colder periods. At the time they grew up, 250,000 years ago, this region of southeast France was much more seasonal than it is today,” reports Smith.
Dr Renaud Joannes-Boyau, leading researcher at GARG, and equal contributor to the paper, had been working on the teeth for the past 7 years, mapping the concentrations of metal in the sections. He discovered the intriguing signal in particular the Pb recurring signal while measuring the teeth at SCU and again with his colleagues Prof Manish Arora and Dr Christine Austin a year later at the Icahn School of Medicine at Mount Sinai, New York. The team was quite surprised to discover that the two Neanderthal children either ingested or inhaled lead during their childhood, representing the oldest documented lead exposure in any hominin (humans and their close ancestors and relatives). This occurred multiple times during the cooler seasons, potentially happening in caves as underground lead sources have been found within 25 km of the archaeological site.
Tiny amount of barium also showed that one Neanderthal appears to have breastfed for 2.5 years, weaning in the fall. This individual survived infancy, but was unlikely to have reached adulthood. Smith and her team are keen to explore the childhoods of other hominins using this novel paleobiological approach, as many questions remain about why humans survived while our many evolutionary cousins, including the Neanderthals, were not so lucky.
Smith, T.M.,* Austin, C.*, Green, D.R.* Joannes-Boyau, R.* Bailey, S., Dumitriu, D., Fallon, S., Grün, R., James, H.F., Moncel, M-H., Williams, I.S., Wood, R., Arora, M. (2018) Wintertime stress, nursing, and lead exposure in Neanderthal children. Science Advances 4: eaau9483
* These authors contributed equally to this work.