Among hunter-gatherers, the sharing of male and female foods is often assumed to result in virtually the same diet for males and females. Although food sharing is widespread among the hunting and gathering Hadza of Tanzania, women were observed eating significantly more tubers than men. This study investigates the relationship between patterns of dental wear, diet, and extramasticatory use of teeth among the Hadza. Casts of the upper dentitions were made from molds taken from 126 adults and scored according to (...) the Murphy dental attrition scoring system. Females had significantly greater anterior occlusal wear than males when we controlled for age. Males exhibited greater asymmetry in wear, with greater wear on the left side in canines, first premolars, and first molars. We suggest that these sex differences in wear patterns reflect the differences seen in the diet, as well as in the use of teeth as tools. (shrink)

Folk stories featuring prosocial content are ubiquitous across cultures. One explanation for the ubiquity of such stories is that stories teach people about the local socioecology, including norms of prosociality, and stories featuring prosocial content may increase generosity in listeners. We tested this hypothesis in a sample of 185 Hadza hunter-gatherers. We read participants a story in which the main character either swims with another person (control story) or rescues him from drowning (prosocial story). After hearing the story, participants played (...) a dictator game with dried meat sticks and then were given a recall test of facts presented in the story. There was moderate evidence for a small effect of the prosocial story: participants who heard the prosocial story gave an estimated 0.22 [90% HDI: −0.12–0.57] more meat sticks than those who heard the control story. However, the association between generosity and sex, marital status, and region of residence was stronger; men gave more than women, unmarried participants gave more than married participants, and participants living in a region with more exposure to markets gave more than participants living further from markets. There was no evidence that the prosocial story was more easily recalled than the control story. These results provide some support for the hypothesis that prosocial stories can increase prosociality in listeners, though the effect of hearing a single story is small. (shrink)

The Hadza foragers of Tanzania are currently experiencing a nutritional shift that includes the intensification of domesticated cultigens in the diet. Despite these changes, no study, to date, has examined the possible effects of this transition on the food collection behavior of young foragers. Here we present a cross-sectional study on foraging behavior taken from two time points, 2005 and 2017. We compare the number of days foraged and the type and amount of food collected for young foragers, aged 5–14 (...) years, in age- and season-matched samples. Compared with 2005, in 2017 fewer subadults left camp to forage, and overall, they targeted a smaller variety of wild foods, with the noticeable absence of wild honey, figs, and tubers. In addition, participants in 2017 were significantly more likely to have attended school. Despite the increased presence of domesticated plant foods in the diet and increased attendance at school, some young foragers continue to be highly productive in collecting wild, undomesticated foods. Despite the preliminary nature of our results, our findings suggest that the range of wild foods targeted by subadults is decreasing as the amount of domesticated cultigens in the diet increases. These data underscore the importance of studying diet composition and foraging decisions across temporal, nutritional, and ecological landscapes. (shrink)

Aspects of human life history and cognition, such as our long childhoods and extensive use of teaching, theoretically evolved to facilitate the acquisition of complex tasks. The present paper empirically examines the relationship between subsistence task difficulty and age of acquisition, rates of teaching, and rates of oblique transmission among Hadza and BaYaka foragers from Tanzania and the Republic of Congo. We further examine cross-cultural variation in how and from whom learning occurred. Learning patterns and community perceptions of task difficulty (...) were assessed through interviews. We found no relationship between task difficulty, age of acquisition, and oblique transmission, and a weak but positive relationship between task difficulty and rates of teaching. While same-sex transmission was normative in both societies, tasks ranked as more difficult were more likely to be transmitted by men among the BaYaka, but not among the Hadza, potentially reflecting cross-cultural differences in the sexual division of subsistence and teaching labor. Further, the BaYaka were more likely to report learning via teaching, and less likely to report learning via observation, than the Hadza, possibly owing to differences in socialization practices. (shrink)

Cross-cultural sex differences in mobility and harm avoidance have been widely reported, often emphasizing fitness benefits of long-distance travel for males and high costs for females. Data emerging from adults in small-scale societies, however, are challenging the assumption that female mobility is restricted during reproduction. Such findings warrant further exploration of the ontogeny of mobility. Here, using a combination of machine-learning, mixed-effects linear regression, and GIS mapping, we analyze range size, daily distance traveled, and harm avoidance among Hadza foragers during (...) middle childhood and adolescence. Distance traveled increased with age and, while male adolescents had the longest daily ranges, average daily distance traveled by each sex was similar. We found few age- or sex-related patterns in harm-avoidant responses and a high degree of individual variation. When queried on the same issues, children and their parents were often in alignment as to expectations pertaining to harm avoidance, and siblings tended to behave in similar ways. To the extent that sex differences in mobility did emerge, they were associated with ecological differences in physical threats associated with sex-specific foraging behaviors. Further, we found no strong association between harm avoidance and mobility. Young Hadza foragers of both sexes are highly mobile, regardless of how harm avoidant they are. Taken together, our findings indicate that the causal arrows between harm avoidance and mobility must be evaluated in ecologically specific frameworks where cultural expectations of juvenile mobility can be contextualized. (shrink)

A correction to this paper has been published: https://doi.org/10.1007/s12110-021-09403-x.

© 2016 Elsevier LtdJumping spiders are famous for their visually driven behaviors [1]. Here, however, we present behavioral and neurophysiological evidence that these animals also perceive and respond to airborne acoustic stimuli, even when the distance between the animal and the sound source is relatively large and with stimulus amplitudes at the position of the spider of ∼65 dB sound pressure level. Behavioral experiments with the jumping spider Phidippus audax reveal that these animals respond to low-frequency sounds by freezing—a (...) common anti-predatory behavior characteristic of an acoustic startle response. Neurophysiological recordings from auditory-sensitive neural units in the brains of these jumping spiders showed responses to low-frequency tones —recordings that also represent the first record of acoustically responsive neural units in the jumping spider brain. Responses persisted even when the distances between spider and stimulus source exceeded 3 m and under anechoic conditions. Thus, these spiders appear able to detect airborne sound at distances in the acoustic far-field region, beyond the near-field range often thought to bound acoustic perception in arthropods that lack tympanic ears [2]. Furthermore, direct mechanical stimulation of hairs on the patella of the foreleg was sufficient to generate responses in neural units that also responded to airborne acoustic stimuli—evidence that these hairs likely play a role in the detection of acoustic cues. We suggest that these auditory responses enable the detection of predators and facilitate an acoustic startle response. Video. (shrink)

In the passage about the flax plant, lini natura et miracula at the beginning of Book 19 of his Naturalis historia, Pliny launches into a moralizing diatribe on man's assault against Nature, fulminating against the evils which man brings upon himself by taking to the high seas in ships with sails. The passage culminates in the rhetorical outburst audax uita, scelerumque plena, which serves as something of a moral aphorism for the jeremiad as a whole. Although it has been (...) the subject of much discussion in Plinian scholarship, the text still remains in need of attention : audax uita, scelerumque plena! aliquid seri, ut uentos procellasque capiat, 5. et parum esse fluctibus solis uehi, iam uero nec uela satis esse maiora nauigiis, sed, cum uix amplitudini antemnarum singulae arbores sufficiant, super eas tamen addi alia uela, praeterque alia in proris et alia in puppibus pandi, ac tot modis prouocari mortem, denique tam paruo semine nasci quod orbem terrarum ultro citro portet, tam gracili auena, tam non alte a tellure tolli, neque id uiribus suis necti, sed fractum tunsumque et in mollitiem lanae coactum iniuria ad summam audaciam peruenire! (shrink)

Augustine’s commentary on Alypius’ curiositas at the gladiatorial show (6, 8, 13) recounts one of the most well-known stories in Augustine’s Confessiones. Despite the various interpretations or explications of the story in Augustinian scholarship, this paper argues that the story centres around Alypius’ curiositas as a function of Alypius’ preceding, morally deficient character. The author provides a fourfold, cumulative and philological case for this thesis. He develops this case by means of four evidences. First, Augustine uses the phraseology of animus (...) forti temperantia (6, 7, 12), the virtuous character describing Alypius when he had overcome his love of the gladiatorial games. Second, Augustine distinguishes between “supreme” and “a surface level” virtue, the existence of which is best explained by its application in Augustine’s remark that Alypius had been audax rather than fortis. Third, Augustine uses the language of talis in reference to Alypius, a term describing sorts or kinds of things or persons; in this context, this is the language of character. Finally, Augustine’s use of adhuc implies that there is a type of character Alypius had been, the remedy of which was to acquire an animus forti temperantia. The author then argues that Augustine envisions that the healing of curiositas (as a vice) is from God, especially when a virtuous character – the means by which one is able to overcome curiositas – itself is articulated as a gift of God’s grace. The response to such healing, then, is gratitude. The author concludes that this paper contributes both to a more comprehensive interpretation of the Alypius narrative (6, 8, 13) as well as contemporary scholarship on Augustine’s relation to (psychotherapeutic) healing. (shrink)