Famously, humans will have a go at eating anything, which is why they’re considered to be omnivores, and they are therefore omnivorous *. However, information concerning how such dietary preferences came to be, and when – and where – in the course of human evolution is not complete. One source of evidence that’s been exploited by Emanuela Cristiani et al. is ‘dental calculus’ . Alternatively known as tartar (“the mineralised biofilm of dental plaque adhering to the tooth enamel”), this material can give an indication of materials – such as food – taken into the mouth. The particular plaque examined was adhering to a tooth ** from one of our ancestors from the Mesolithic (or “towards the end of the 8th millennium BC” in the language of the article) whose remains were found on an island in the sea off modern-day Croatia. Christiani et al’s analysis identified presence of microscopic ‘fish’ *** material and plant remains [such as starch grains from cereal grasses (e.g. oats, Avena sp.), fibres of nettle (Urtica sp.)], “wood fragments with characteristic conifer tracheid fibres”, and conifer pollen in the dental plaque. Apparently, this is a first-time discovery for the period and region, and emphasizes the role played by marine resources in what had previously been assumed to be a terrestrial-based foraging lifestyle for these Mediterranean peoples. This interpretation also underlines how some organisms can feed in two quite different habitats – land and sea – and therefore impact upon many diverse ecosystems.
* Somewhat predictably, Michel Lotito, a Frenchman famed for eating ‘everything’, including glass and metal objects – and consequently known as Monsieur Mangetout – comes to my mind at this point. Now, since his intake of material is pretty much any- and every-thing, he really can be described as omnivorous (a term derived from the Latin word omnivorous, literally meaning eating all or everything). But, since most other organisms have a much more restricted dietary intake, the term ‘omnivore’ – in the true meaning of the word – seems overly-optimistic and actually inaccurate. Or, in the words of Silvia Pineda-Munoz and John Alroy, “the term ‘omnivore’ should be avoided because it does not communicate all the complexity inherent to food choice”. We already have a whole taxonomy of ‘-vories’, such as frugivory, granivory, insectivory, exudativory, molluscivory, etc., underlining the point that, unless an organism truly is omnivorous, it really should be described more aptly, mixovorous maybe..? Or mixotrophic Food for thought?
** And teeth can themselves give important clues to an animal’s diet, e.g. plant-eating herbivores have strong and flat molars and small or non-existent canine teeth; meat-consuming carnivores have very defined canine teeth, combined with a sometimes limited number of molars.
Cristiani, E., Radini, A., Borić, D., Robson, H. K., Caricola, I., Carra, M., … Vujević, D. (2018). Dental calculus and isotopes provide direct evidence of fish and plant consumption in Mesolithic Mediterranean. Scientific Reports, 8(1). https://doi.org/10.1038/s41598-018-26045-9
Pineda-Munoz, S., & Alroy, J. (2014). Dietary characterization of terrestrial mammals. Proceedings of the Royal Society B: Biological Sciences, 281(1789), 20141173. https://doi.org/10.1098/rspb.2014.1173
Lallemand, F., Figura, T., Damesin, C., Fresneau, C., Griveau, C., Fontaine, N., … Selosse, M.-A. (2018). Mixotrophic orchids do not use photosynthates for perennial underground organs. New Phytologist, 221(1), 12–17. https://doi.org/10.1111/nph.15443