teeth provides insight into breastfeeding

Analysis of ancient fossil teeth provides insight into breastfeeding habits

On the left is a tooth of an Australopithecus africanus and on the right that of an early Homo. Through microscopic analysis, researchers were able to determine calcium stable isotope compositions that revealed group-specific nursing behaviours. (Photograph: Vincent Balter)

Dental Tribune International

Thu. 5. September 2019

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BRISTOL, UK: The importance of mother’s milk to an infant’s development is now well established. In a recent study, researchers analysed the fossilised teeth of some of our earliest ancestors and discovered that the first humans breastfed their infants for significantly longer periods than did their contemporary relatives. This may have played a part in areas such as brain development and thus the evolution of the human species.

The data collected from analysing a collection of almost 40 fossilised teeth from South African hominins, early Homo, Paranthropus robustus and Australopithecus africanus, provide the first glimpse into the practice of weaning and the role it likely played in an evolutionary context.

In the study, the researchers measured the proportions of stable calcium isotopes in the tooth enamel, an indicator of mother’s milk intake by infants. According to the results, by reconstructing the age and tooth enamel development, the scientists were able to show that early Homooffspring were breastfed until the age of approximately 3 or 4 years. The significance of this is highlighted in the length of time infants of P. robustusand A. africanus were breastfed. Analysis of their teeth showed that breastfeeding stopped in the first months of life. “The development of such behavioural differences likely played major roles in the evolution of the members of human lineage, being associated for instance with size and structure of social groups, brain development or demography,” said one of the study’s lead authors, Dr Theo Tacail from the University of Bristol’s School of Earth Sciences.

“The findings stress the need for further exploration of calcium stable isotope compositions in the fossil record in order to understand the co-evolution of weaning practices with other traits such as brain size or social behaviours,” he continued.

The study, titled “Calcium isotopic patterns in enamel reflect different nursing behaviors among South African early hominins”, was published on 28 August 2019 in Science Advances.