Abstract:

This study extracted and analysis of micro-residues preserved on ancient human teeth excavated from two terminal Paleolithic sites, Maludong and Tangzigou, in Yunnan Province. Through comparative analysis of starch granule types within the residues, this research investigates plant resource utilization strategies adopted by ancient populations in Southwest China during the late Pleistocene-Holocene transition. Dental surfaces yielded five morphologically distinct starch granule categories: A) Disc-shaped; B) Spheroidal; C) Elliptical or rounded triangular; D) Polyhedral and irregular; E) damaged forms. These starch types correspond to botanical sources including Poaceae seeds, subterranean storage organs, and acorns from the Quercus of Fagaceae.

Category A (2 granules): Granule diameters range from 12.33-23.57 μm. The planar structure exhibits disc-shaped or elliptical morphology. Under polarized light, extinction crosses appear vertical or X-shaped, with broad and indistinct extinction areas and faint lamellae. These characteristics suggest a likely origin from Poaceae seeds.

Category B (2 granules): Granule diameters range from 11.34-11.55 μm. Spherical in shape with slightly eccentric and open hila. Polarized microscopy reveals X-shaped extinction crosses and absent lamellae. These granules are tentatively attributed to Amorphophallus species.

Category C (2 granules): Granule diameters range from 12.4-12.91 μm. Morphologies include smooth elliptical (Fig: 2d) and rounded triangular (Fig: 2e) forms with eccentric hila. Brightfield microscopy highlights distinct hila and faint lamellae, while polarized light shows broad vertical and narrow curved extinction crosses. These are likely derived from Quercus species.

Category D (4 granules): Granule diameters range from 11.95-24.5 μm. Polyhedral and irregular shapes with slightly eccentric hila, fissures, and uneven surfaces. Polarized microscopy displays X-shaped and narrow curved extinction crosses. These are provisionally classified as originating from root/tuber plants or Fagaceae plants.

Category E (3 granules): Damaged and unidentifiable due to structural degradation.

Analytical results indicate three identifiable starch types in Maludong specimens: Poaceae-type (likely wild cereals), Quercus-type (acorns), and Amorphophallus-type (konjac tubers). Notably, gelatinized starch aggregates observed on the surface of specimen MLDG1902 (deciduous first molar) from Maludong suggest plant-based dietary practices involving food processing techniques such as cooking or roasting. In contrast, Tangzigou samples yielded Quercus-type starch alongside unclassified root/tuber varieties. These findings indicate prolonged reliance on subterranean plant resources and Fagaceae nuts. Integrating regional Holocene climate data, this dietary pattern may correlate with the high biomass production of nut-bearing trees (e.g.,Quercus) and geophytes under warm, humid conditions characteristic of evergreen broad-leaved forests. Such environments provided a sustainable resource base for human exploitation. The persistent utilization of acorns and underground storage organs reflects adaptive strategies to ecological constraints, balancing caloric returns with seasonal availability.

Future research should systematically expand sampling to include ancient human dental remains from other terminal Paleolithic sites in Yunnan, such as the Yiliang Zhangkou Cave site, Fuyuan Dahe site, Chenggong Longtanshan site, and Jinghong Naminnan Cave site—locations with both regional representativeness and chronological continuity. This approach aims to trace the evolution of plant resource utilization by prehistoric humans during critical periods of environmental change, explore how dietary adaptations responded to ecological shifts, and provide key evidence for understanding human adaptive strategies in Southwest China’s mountainous regions since the late Pleistocene.

Key words: Late Pleistocene, southwest China, ancient humans, plant microremains