Can boron isotopes be used as a palaeodietary proxy?

Past Life and Environments

BBK

UCL

The stable isotope and trace element biogeochemistry of fossil tooth enamel has provided many insights into the dietary and behavioural ecology of extinct mammals, including early hominins, especially carbon isotopes as a proxy for C4 (savannah) grasses (Lee-Thorp et al., 2012). Boron isotopes in marine microfossils reflect the pH of the ocean environment, but little work on δ11B has been applied to the terrestrial realm.
Boron is an essential micronutrient in plants (O’Neill et al., 2004), and is digested and incorporated into the tissues of mammals. Measurements of δ11B can be obtained from tooth enamel (He et al., 2015), which is resistant to alteration during fossilisation.
Given the large mass difference in boron isotopes, δ11B fractionation may occur during the preparation or consumption of food. A broader understanding of the transfer and isotopic fractionation of boron within an ecosystem could facilitate the development of boron as a new and informative dietary proxy, with implications for our understanding of the dietary habits of primate and human ancestors.

• Tim Newling Fieldwork Fund – Birkbeck, University of London

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