27 research outputs found
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Foraging strategies and diet composition of Hadza children
Among the Hazda hunter-gatherers of Tanzania, children are active foragers and collect various types of wild plant foods and hunt small sized prey animals. The collection effort of Hazda children is reported to have a positive effect on a mother’s foraging yield (Bulurton-Jones et at. 1994, Journal of Anthropological Research 50(3): 217; Hawkes et al. 1995, Current Anthropology 36(4): 688), yet few quantitative data are available on the caloric values of children’s foods and the ways in which children distribute their own foraging yield. Here, we report on foraging return rates, consumption data, and the compositional values for several of the plant foods collected by children. Due to predator pressure, it is not safe for children to wander far from camp without adult supervision, therefore they typically focus on foods that are close to camp and easy to collect and process. We calculated the caloric content for the following foods: baobab fruit (346 kcal/100g dry matter (DM)), berries (320 kcal/100g DM), legumes (311 kcal/100g DM), drupes (325 kcal/100g DM), and figs (365 kcal/100g DM). Legumes, drupes, and figs have not been previously analyzed; our values for baobab and berries agree with previous analyses (Murray et al. 2001, Journal of Food Consumption and Analysis 14: 3). In addition, we calculated foraging return rates and daily consumption values for children. Our results suggest that they collect a significant portion of their daily caloric intake and act as allomothers providing caloric contributions to other children.
Support: National Science Foundation, Regents of the University of California San Diego, Friends of the International Center at the University of California San Diego, and Harvard University.AnthropologyHuman Evolutionary Biolog
Do Fruit Nutrients Affect Subgrouping Patterns in Wild Spider Monkeys (Ateles geoffroyi)?
One of the main costs of group living is feeding competition. Fission–fusion dynamics are thought to be a strategy to avoid overt competition for food resources. We tested whether food abundance and quality affected such dynamics in a species characterized by a high degree of fission–fusion dynamics. We collected data on 22 adult and subadult spider monkeys (Ateles geoffroyi) living in a large community in the protected area of Otoch Ma’ax Yetel Kooh, Yucatan, Mexico. We recorded subgroup size and fission events as well as fruit abundance during 12 mo and conducted nutritional analyses on the fruit species that the study subjects consumed most. We found no effect of fruit abundance or nutritional quality of recently visited food patches on individual fission decisions, but the amount of protein in the food patches visited over the course of the day was a good predictor of subgroup size. While the absence of support for a relationship between fruit characteristics and fission decisions may be due to the short temporal scale of the analysis, our findings relating subgroup size to the amount of protein in the visited food patches over the course of the day may be explained by individual spider monkeys attempting to obtain sufficient protein intake from their fruit-based diet. © 2016 Springer Science+Business Media New Yor
Strategies for the Use of Fallback Foods in Apes
Researchers have suggested that fallback foods (FBFs) shape primate food processing adaptations, whereas preferred foods drive harvesting adaptations, and that the dietary importance of FBFs is central in determining the expression of a variety of traits. We examine these hypotheses in extant apes. First, we compare the nature and dietary importance of FBFs used by each taxon. FBF importance appears greatest in gorillas, followed by chimpanzees and siamangs, and least in orangutans and gibbons (bonobos are difficult to place). Next, we compare 20 traits among taxa to assess whether the relative expression of traits expected for consumption of FBFs matches their observed dietary importance. Trait manifestation generally conforms to predictions based on dietary importance of FBFs. However, some departures from predictions exist, particularly for orang-utans, which express relatively more food harvesting and processing traits predicted for consuming large amounts of FBFs than expected based on observed dietary importance. This is probably due to the chemical, mechanical, and phenological properties of the apes’ main FBFs, in particular high importance of figs for chimpanzees and hylobatids, compared to use of bark and leaves—plus figs in at least some Sumatran populations—by orang-utans. This may have permitted more specialized harvesting adaptations in chimpanzees and hylobatids, and required enhanced processing adaptations in orang-utans. Possible intercontinental differences in the availability and quality of preferred and FBFs may also be important. Our analysis supports previous hypotheses suggesting a critical influence of the dietary importance and quality of FBFs on ape ecology and, consequently, evolution