A research analyses the behaviour of primates from teeth remains

The international research team discovered that the vegetable remains recovered from the register of dental calculus of chimpanzees from the Taï Forest (Ivory Coast) coincide, in general terms, with the collected diet data from the last 20 years in the project Chimpanzee Taï, made by the Max Planck Institute for Evolutionary Anthropology (Leipzig, Germany). From this contrasting correlation, the key point is that these remains give very precise information on behaviours that cannot be observed directly in these primates -the genetically closest to human-, how they are, at what age they wean or when they start to master the ability to cruck nuts.

Thus, the dental calculus or plaque, has become a source of multiple data on the history of the life of these individuals, dead or alive, and it is gaining ground to be considered as a priceless material for the objective reconstruction of history of life.

Researchers increasingly use the particles of plants which are trapped in the dental calculus in order to reconstruct the alimentary choice of population from the past. For example, vegetable microremains fro dental calculus have been used to identify the use of plants in hominids, like Neanderthals and ‘Australopithecus sediba’.

However, deducing the use of plants from dental calculus is still a challenge to refine and improve, because until now, very few studies have tried to correlate the data that the dietary registers provide. In this sense, chimpanzees, as well as other from alive relatives closer to humans, constitute one of the best analogies to test this method and discover others of older human behaviours as specie.

“In our study we compare the information of the composition of the dental calculus from animals, with the long-term observed data of the behaviour of chimpanzees from Taï National Park in Ivory Coast”, explains the PhD student Rober Poder, from Max Planck Institute for Evolutionary Anthropology, and whose thesis is directed by the researcher Domingo C. Salazar Garcia from Universitat de València. With this objective, researchers carried out a high resolution analysis of the microremains of dental calculus from 24 dead chimpanzees (‘Pan troglodytes verus’) from Taï and , on the basis of the mixture of microremains (phytoliths and starch) from the vegetable remains, they reconstructed the diet of the animals. On the other hand, researchers identified proof of important events occurred in the life of individuals, like weaning and the acquisition of tool using abilities, like cracking nuts.

The understanding of the diet ecology is fundamental to recognise which evolutionary pressures gave rise to great apes and humans. It is known from a long time ago that factors like diet specialisation, the acquisition of feeding tools and the weaning age of breastfed are of great importance in great apes and in human, and also that they significantly differ between species. Nonetheless, until now many of the perspectives used to reconstruct the diet have left unanswered the specific questions about its composition and about the events occurred in the life of individuals, especially for fossilized specimen. Therefore, there is a need for using new methods to recover data about the diet of different population which avoid some deficiencies that other techniques present, like direct observation or the analysis of stable isotopes. It is clear that in some contexts direct observation, like in the case of great apes and extinguished human groups population.

This study is one of the first to confirm that the register of dental calculus can provide an essential image of the diet, and it stresses the importance of the method used in the study of populations for which it is not possible to directly observe the eating behaviour, like in isolated primate groups, and even in human ancestors group. “These results clarify how we can use dental calculus to reconstruct diet ecology in archaeology, primatology and human evolution”, affirms researcher Domingo C. Salazar-García, from Department of Prehistory and Archaeology of the Universitat de València. This discovery shows that dental calculus is, probably, a very useful reservoir of the diet, but at the same time more complicated than what it was expected.

Robert C. Power, Domingo C. Salazar-García, Roman M. Wittig, Martin Freiberg, Amanda G. Henry

‘Dental calculus evidence of Taï Forest Chimpanzee plant consumption and life history transitions one foods African breadfruit important shared food’

Scientific Reports, 19 October 2015, DOI: 10.1038/srep15161