Medicinal Properties in the Diet of Tibetan Macaques at Mt. Huangshan: A Case for Self-Medication

Maintaining health homeostasis is a central activity of all living organisms. To this end, diet selection is important to assure the proper balance of nutrients for energy, growth, maintenance, and reproduction. While the initial innate response of an animal is to avoid eating plants with toxic, digestion-disruptive secondary metabolites, these properties can be medicinal when ingested in appropriate amounts. It is suggested that when faced with conditions that require more direct intervention (health maintenance or self-medication), animals ingest even toxic plants for their medicinal benefits to regain health homeostasis. Previous studies on primate diet, from the perspective of “medicinal foods” (plants with bioactive, physiology-modifying properties) selection, have found that 15–25% of the plant items in their diet could be classified as medicinal food. Here we focused on identifying prospective medicinal foods in the diet, in order to investigate the potential properties and possible roles of such items for the YA1 troop of Tibetan macaques (Macaca thibetana) at Mt. Huangshan, Anhui Province, China. Using a previously published 50 species (61 item) food list of this troop, we conducted a pharmacological literature database search. We identified 12 species (24%) in total with significant pharmacological potential. Across the year of this study, the contribution of medicinal foods ranged from 18 to 23% of YA1 troop’s total diet in any one season. The reported activities in these items included antiparasitic, antibacterial, anticancer, febrifugal, antirheumatic, antidiabetic, neuroprotective, osteoprotective, reproductive stimulant, wound healing, and several other health-promoting activities. While the actual medicinal benefits to macaques gained from ingesting these plants are yet unknown, based on the available evidence for their parasite infection ecology, reproductive behavior, and possible stress reduction, we hypothesize on the possible scope of self-medication in Tibetan macaques and suggest future avenues for research.