Microparticles from dental calculus disclose paleoenvironmental and palaeoecological records

Abstract

Plants have always represented a key element in landscape delineation. Indeed, plant diversity, whose distribution is influenced by geographic/climatic variability, has affected both environmental and human ecology. The present contribution represents a multi-proxy study focused on the detection of starch, pollen and non-pollen palynomorphs in ancient dental calculus collected from pre-historical individuals buried at La Sassa and Pila archaeological sites (Central Italy). The collected record suggested the potential use of plant taxa by the people living in Central Italy during the Copper-Middle Bronze Age and expanded the body of evidence reported by previous palynological and palaeoecological studies. The application of a microscopic approach provided information about domesticated crops and/or gathered wild plants and inferred considerations on ancient environments, water sources, and past health and diseases. Moreover, the research supplied data to define the natural resources (e.g., C₄-plant intake) and the social use of the space during that period. Another important aspect was the finding of plant clues referable to woody habitats, characterised by broad-leaved deciduous taxa and generally indicative of a warm-temperate climate and grassy vegetation. Other unusual records (e.g., diatoms, brachysclereids) participated in defining the prehistoric ecological framework. Thus, this work provides an overview on the potential of the human dental calculus analysis to delineate some features of the ancient plant ecology and biodiversity.

Keywords: ancient landscape; paleoenvironment; plant ecology; prehistoric times; tartar; water sources.

FIGURE 1

Archaeological sites. Geographical localisation of the studied archaeological sites (Latium, Central Italy) (red dots; panel a). For La Sassa cave (coordinates of the entrance WGS84, 41°25′30″ N, 13°14′11″ E; Sonnino, LT; panel b) and Pila cave (coordinates of the entrance 42°10′26″ N; 12°55′46″ E; Pozzaglia Sabina, RT; panel c), pictures of the current entrance (taken from the internal rooms), a representative human skeletal remain, and the relative planimetry were shown. Photos by A. Ferracci and A. D'Agostino.

FIGURE 2

Mosaic of selected plant microparticles recovered in dental calculus samples from La Sassa cave. Some of the images captured by optic microscopy were shown. Triticeae starch (a); aggregate of Triticeae starch granules (b); Panicoideae starch granules, still adhering to calculus flecks, and relative polarised images (c and d); Asteroideae pollen (e); Brassicaceae/Oleaceae pollen grain emerging from undissolved dental calculus (f); Betulaceae pollen grain (g); Alnus spp. pollen (h); Tilia sp. pollen (i); Poaceae spontaneous group pollen (j); sporangium (k); fragment of plant epidermis with visible trichomes (the arrow indicates a polyhedral starch) (l); brachysclereid aggregate (m); brachysclereid aggregate at different magnifications (n and o). The scale bar indicates 25 μm (except for panel n: 55 μm).

FIGURE 3

Plant microparticles retrieved from human calculi of Pila cave. Representative images obtained by optic microscopy analysis were shown. Triticeae starch (Morphotype I, indicated by the arrow) with three starch granules belonging to Morphotype II (a); aggregate of Panicoideae starch granules, still adhering to calculus flecks, and relative polarised image (b); Panicoideae starches and relative polarised image (c); Betulaceae pollen (the arrow indicates two polyhedral granules) (d); Fagaceae pollen (e); Cupressaceae pollen grain (indicated by the arrow), emerging from undissolved dental calculus (f); Tilia sp. pollen (g) Asteraceae pollen type (h and i); Trifolium‐type pollen aggregate at different focus (j and k); fern spore (l). The scale bar indicates 25 μm.

FIGURE 4

Mosaic selection of microdebris recovered from dental calculus samples of Pila cave. Examples of microremains captured by optic microscopy are shown. Fragments of plant vascular tissue (a and b); tracheid fragment in radial section from conifer wood, with uniseriate torus‐margo pits (c); microdebris consisting in tracheid pitting more seriate and alternate arrangement in radial walls (d and e); fragments of plant tissue containing articulate phytoliths (f–i); acute bulbous phytolith (j); globular echinate phytolith (k); parasite eggs indicated with arrows (l–n); magnification of a section of Lepidoptera wing (o), in the subpanel the whole microparticle. The scale bar indicates 30 μm.

FIGURE 5

Siliceous microdebris retrieved from human calculi of Pila cave. Some of the images obtained by light microscopy analysis were shown. Microremains attributable to: Spumellaria order, putative Actinommidae family (a); Spumellaria order, putative Coccodiscidae family (b); putative Nassellaria radiolarians or diatoms (c–j); dissolved diatom frustules (k–n); putative amoeba shell at different focuses (o). Arrows localise the debris in panels (i and j). The scale bar measures 30 μm.