Trees as brokers in social networks: Cascades of rights and benefits from a Cultural Keystone Species.

Indigenous trees play key roles in West African landscapes, such as the néré tree (Parkia biglobosa (Jacq.) R.Br. ex G.Don). We applied social-ecological network analysis to understand the social-ecological interactions around néré. We documented the benefits néré provides and the multiple social interactions it creates amongst a large range of actors. The flows of rights over the trees and benefits from them formed two hierarchical networks, or cascades, with different actors at the top. The two forms of power revealed by the two cascades of rights and benefits suggest possible powers and counter-powers across gender, ethnicity, and age. We documented how the tree catalyses social interactions across diverse groups to sustain vital social connections, and co-constitute places, culture, and relationships. We argue that a paradigm shift is urgently needed to leverage the remarkable untapped potential of indigenous trees and Cultural Keystone Species in current global restoration and climate change agendas.

Seasonal variability of women's dietary diversity and food supply: a cohort study in rural Burkina Faso.

OBJECTIVE: To investigate the seasonal variations of women's dietary diversity (WDD) (items consumed and food supply) and its linkages with agriculture, market and wild resources. DESIGN: A cohort of 300 women was followed-up over a year to investigate WDD and food sources (production, purchase or foraging). Monthly qualitative 24 h recalls allowed computing WDD Scores from a standard 10-food groups (FG) classification (WDDS-10). Associations between farm/women's characteristics and WDDS-10 were investigated using multivariate mixed models including interaction terms factor*months. SETTING: Tuy province, Burkina Faso. PARTICIPANTS: 300 women of reproductive age. RESULTS: Both dietary diversity and food sources were seasonal. The mean WDDS-10 was relatively stable from August to January (ranging from 3·1 to 3·5 FG) when farm production predominated. The WDDS-10 gradually increased from February, concomitantly with an increase in food purchases (onions, tomatoes, mangoes) and reached its highest levels (>4 FG) from March to June, when food purchases were still relatively high and when more women consumed foraged fruits (shea plums and wild grapes). Women living on farms owning > 3 plough oxen and different animal species had significantly higher WDDS-10 than others (+0·28 and +0·35 FG, respectively). Women who practiced off-farm activities also had higher WDDS-10 than those who did not (+0·21 FG, P < 0·05). Other factors, for example, the number of foraged edible species, provided advantages in terms of dietary diversity only during certain seasons (October - January, P for interaction < 0·01). CONCLUSIONS: Diversifying women's diets throughout the year requires complementary interventions aimed at diversifying production, promoting foraging and increasing income-generating activities to enable food purchasing.

Untangling the environmental from the dietary: dust does not matter.

Both dust and silica phytoliths have been shown to contribute to reducing tooth volume during chewing. However, the way and the extent to which they individually contribute to tooth wear in natural conditions is unknown. There is still debate as to whether dental microwear represents a dietary or an environmental signal, with far-reaching implications on evolutionary mechanisms that promote dental phenotypes, such as molar hypsodonty in ruminants, molar lengthening in suids or enamel thickening in human ancestors. By combining controlled-food trials simulating natural conditions and dental microwear textural analysis on sheep, we show that the presence of dust on food items does not overwhelm the dietary signal. Our dataset explores variations in dental microwear textures between ewes fed on dust-free and dust-laden grass or browse fodders. Browsing diets with a dust supplement simulating Harmattan windswept environments contain more silica than dust-free grazing diets. Yet browsers given a dust supplement differ from dust-free grazers. Regardless of the presence or the absence of dust, sheep with different diets yield significantly different dental microwear textures. Dust appears a less significant determinant of dental microwear signatures than the intrinsic properties of ingested foods, implying that diet plays a critical role in driving the natural selection of dental innovations.

Seeds, browse, and tooth wear: a sheep perspective.

While grazing as a selective factor towards hypsodont dentition on mammals has gained a lot of attention, the importance of fruits and seeds as fallback resources for many browsing ungulates has caught much less attention. Controlled-food experiments, by reducing the dietary range, allow for a direct quantification of the effect of each type of items separately on enamel abrasion. We present the results of a dental microwear texture analysis on 40 ewes clustered into four different controlled diets: clover alone, and then three diets composed of clover together with either barley, corn, or chestnuts. Among the seed-eating groups, only the barley one shows higher complexity than the seed-free group. Canonical discriminant analysis is successful at correctly classifying the majority of clover- and seed-fed ewes. Although this study focuses on diets which all fall within a single dietary category (browse), the groups show variations in dental microwear textures in relation with the presence and the type of seeds. More than a matter of seed size and hardness, a high amount of kernels ingested per day is found to be correlated with high complexity on enamel molar facets. This highlights the high variability of the physical properties of the foods falling under the browsing umbrella.