Australia: The Land Where Time Began

A biography of the Australian continent 

Fossilised Teeth Used to Reveal Dietary Shifts in Ancient Herbivores and Hominins

A new study that was published in the journal Proceedings of the National Academy of Sciences documents dietary shift in herbivores that lived in the Lower Omo Valley, Ethiopia, between 1 and 3 Ma. The researchers examined stable isotopes in fossilised teeth in herbivores such as antelopes and pigs and found a shift away from C3-derived foods, which are characteristic of woody vegetation, to C4-derived foods, which are representative of grasses and sedges. There are 2 distinct times periods, approximately 2.7 Ma and 2.0 Ma, when the environment of the Lower Omo Valley was transitioning to open savanna.

The study, “Dietary Trends in herbivores from the Shungura Formation, southwestern Ethiopia,” served as a comparative framework to an associated dietary study that was published in the same week, of which Negash was a co-author. “Isotopic evidence for the timing of the dietary shift to C4 foods in eastern Africa Paranthropus,” examined carbon isotope data from the fossilised tooth enamel of Paranthropus boisei, which is a non-ancestral hominin relative.

The research team behind this paper found a profound shift towards foods that were C4-derived about 2.37 Ma, which preceded the morphological shift of the skull and jaw of P. boisei. It is suggested by the new findings that there were behavioural dietary changes that can precede apparent morphological adaptations to new foods.

According to Negash the major shifts that were observed in their study reflect the response of the herbivores to major ecological and environmental changes during this time. This allowed a better understanding of the environmental context of similar dietary changes in hominins.

According to Wynn it is very important to consider these hominins as a small part of an ecosystem that included other species of plants and animals that responded to changing environments      in an interconnected way, though they are interested in how the diets of our distant and immediate ancestors evolved to produce our modern human diet.

Wynn, J. G., et al. (2020). "Isotopic evidence for the timing of the dietary shift toward C₄ foods in eastern African <em>Paranthropus</em>." Proceedings of the National Academy of Sciences 117(36): 21978-21984.