Analysis of zinc isotopes in fossil teeth from Tam Hay Marklot cave shows that animals with mixed diets had the widest variation in zinc isotope levels, allowing scientists to identify which ancient...
Mechanism
Synthesis from 1 study
Animals that eat only plants end up with teeth that have a lot of a heavier form of zinc, while meat-eaters have teeth with less of it. Animals that eat both end up with teeth showing a wide mix of both signals, because their diet switches between the two. This mix gets locked into their teeth as...
Most probable mechanism
When animals eat plants, their bodies absorb zinc that has more of a heavier isotope, making their teeth record a higher value. When animals eat meat, they get zinc that has less of that heavy isotope, making their teeth record a lower value. Animals that eat both plants and meat end up with teeth that show a wide range of values because their diet switches between these two sources. This variation gets locked into their tooth enamel as it forms, and stays there for millions of years, letting scientists tell if an ancient animal ate both plants and animals.
Plants absorb zinc from soil and preferentially take up heavier zinc isotopes in their roots, while lighter isotopes move more readily to leaves and other edible parts.
Herbivores consuming plant material incorporate the elevated heavy isotope signature into their body tissues with minimal change, resulting in high zinc isotope values in their enamel.
Carnivores consuming herbivore muscle tissue receive zinc that has been depleted in heavy isotopes due to metabolic processes that favor retention of heavier isotopes in bone and excretion of lighter ones, resulting in lower zinc isotope values in their enamel.
Omnivores consuming both plant and animal resources integrate zinc isotopes from both sources, leading to a broader range of isotopic values in their body tissues.
During tooth formation, zinc is incorporated into enamel bioapatite in a stable, non-replaceable form that preserves the isotopic signature of the diet at the time of mineralization.
Evidence from Studies
Supporting (1)
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Zinc isotopes in Late Pleistocene fossil teeth from a Southeast Asian cave setting preserve paleodietary information
Contradicting (0)
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