LIFE HiSTORY of our ancestors
EVOLUTION OF NURSING
Elemental mapping by LA-ICPMS protocol: (A) Sketch of a fossil tooth dentine and enamel section with indication of biogenic accentuated lines (green) (B) crystal structure and (C) Elemental mapping
Dietary transitions in a Neanderthal permanent first molar: (Top) developmental time (in days from birth), (Bottom) barium distribution shows marked variations in enamel.
A remarkable aspect of human evolution is that human infants are weaned much earlier but have much longer childhoods than our closest ape relatives. For example, while a chimpanzee is dependent upon its mother for its first few years of life, it gains independence at around six years of age. There is much debate about when early weaning occurred in the hominin lineage. Reliable markers of early diet transitions in ancient hominins and non-human primates have been largely unavailable - until now.
Early life dietary transitions are recorded in teeth and remain stable in fossil remains from thousands of years ago. Teeth grow following a regular pattern that creates permanent daily lines, like the rings found in trees. Teeth also carry a “birth certificate” in the form of an accentuated line visible in baby teeth and first permanent molars. As the teeth grow within the gum they incorporate elements that circulate the body after uptake from food, water and environmental sources. Using special analytical chemistry and microscopy techniques we are able to trace changes in the element content of teeth with precision timing. Barium a naturally occurring element, is found in very small amounts in newborns as the placenta restricts crossing of barium from the mother to the foetus. It is, however, present in breast milk, and as a baby starts to breastfeed, the “rings” laid down in their milk teeth contain larger amounts of barium.
In this study, we applied the technique to an approximately 100,000-year-old Middle Palaeolithic Neanderthal tooth from Belgium and extrapolate the nursing behaviour. The pattern indicated that this individual was breastfed for about seven months before supplementation with non-milk foods, and followed by an abrupt, complete switch to non-milk foods at 14 months. The period of exclusive breastfeeding is similar compared to modern humans , but weaning occurred remarkably early in this individual. The transition from maternal milk to non-milk foods is a fundamental aspect of primate evolution and an important determinant of health in contemporary human populations.
We are applying this methods to other hominid fossils to understand the history and evolution of nursing in the human evolution journey.
DIET, TROPHIC LEVEL & MIGRATION
Our work explores geochemical proxies to reconstruct accurately the diet, trophic level and migration pattern of fauna and Hominin species. From the understanding of the extinction of ancient apes, the expansion of Homo erectus and Homo sapiens, to the complex diet of early modern humans our research investigates fossil teeth using state-of-the-art Laser Ablation Inductively Coupled Plasma Mass Spectrometer (LA-ICPMS).
Wintertime stress and lead exposure in Neanderthal children
In our new research, we have investigated the relationship between human evolution and climate change. Neanderthals, who survived extreme Eurasian environmental variation and glaciations, mysteriously went extinct during a cool interglacial stage. Our work integrates weekly records of climate, tooth growth, and metal exposure in two Neanderthals and one modern human from southeastern France. Both Neanderthals were exposed to lead at least twice during the deep winter and/or early spring. This multidisciplinary approach elucidates direct relationships between ancient environments and hominin paleobiology.
Seasonal migration of megafauna in Pleistocene Sahul
Australia was once home to a giant prehistoric Ice Age marsupial related to wombats and koalas, and that followed an annual seasonal migration. The three-tonne beast, up to 1.8 metres tall and 3.5 metres long, was the only known marsupial to follow a migration pattern, according to our research published in the journal Proceedings of the Royal Society of London B. For many years, palaeontologists have marvelled at the fossil deposits of southeast Queensland’s Darling Downs, describing it as a “vast graveyard” of the enormous herbivorous and carnivorous animals of the Pleistocene(from about 1.6 million to 10,000 years ago).