In some small-scale societies, a sexual division of labor is common. For subadult hunter-gatherers, the onset of this division dates to middle childhood and the start of puberty; however, there is apparently no physiological explanation for this timing. The present study uses an experimental approach to evaluate possible energetic differences by sex in gathering-related activities. The energetic cost of gathering-related activities was measured in a sample of 42 subjects of both sexes aged between 8 and 14 years. Body mass and (...) other anthropometric variables were also recorded. Our results show that the energetic differences in the simulated gathering activities depend only on body mass. Both sexes expend a similar amount of energy during locomotion activities related to gathering. Discarding the energetic factor, the sexual division of tasks may be explained as an adaptation to acquire the skills needed to undertake the complex activities required during adulthood as early as possible. Carrying out gathering activities during childhood and adolescence could be favored by the growth and development cycles of Homo sapiens. Moreover, if most of the energetic costs of gathering activities depend on body mass, the delayed growth in humans relative to other primates allows subadults to practice these tasks for longer periods, and to become better at performing them. In fact, this strategy could enable them to acquire adults’ complex skills at a low energetic cost that can be easily subsidized by other members of the group. (shrink)

En este trabajo exponemos algunas categorías modales orientadas al estudio y comprensión de los sistemas autoorganizados que muestran complejidad. Para ello centramos nuestra investigación en el área de la ecología y, más en particular, en el ámbito de la ecología aural, es decir, en el estudio de los sonidos que componen los ecosistemas. Las categorías modales aquí desarrolladas son, por un lado, la «repertorialidad», referida a la coherencia y estabilidad interna de todo sistema autoorganizado; la «disposicionalidad» o experimentación y variación (...) inherente a estos sistemas y, finalmente, el «paisaje», que tiene en consideración lo realmente efectivo, lo dado. Este conjunto de categorías nos lleva a explorar el sistema modal de necesidad-contingencia-posibilidad-imposibilidad, el cual, aplicado a los estudios sonoros se convierte en el juego de señales-redundancia-ruido-silencio. Estas categorías, aplicadas a ejemplos en la naturaleza, nos ayudan a comprender el devenir inherente a todo ecosistema. Finalmente, descubrimos cómo la investigación categorial de los paisajes sonoros aporta información sobre el comportamiento evolutivo y el estado de conservación de estos sistemas. (shrink)

Extractive foraging tasks, such as digging, are broadly practiced among hunter-gatherer populations in different ecological conditions. Despite tuber-gathering tasks being widely practiced by children and adolescents, little research has focused on the physical traits associated with digging ability. Here, we assess how age and energetic expenditure affect the performance of this extractive task. Using an experimental approach, the energetic cost of digging to extract simulated tubers is evaluated in a sample of 40 urban children and adolescents of both sexes to (...) measure the intensity of the physical effort and the influence of several anatomical variables. Digging is a moderately vigorous activity for inexperienced girls and boys from 8 to 14 years old, and it requires significant physical effort depending on strength and body size. However, extracting subterranean resources is a task that may be performed effectively without previous training. Sex-specific and age-specific differences in the net energy expenditure of digging were detected, even though both sexes exhibited similar proficiency levels when performing the task. Our results highlight that both boys and girls spend considerable energy while digging, with differences largely driven by body size and age. Other factors beyond ability and experience, such as strength and body size, may influence the proficiency of juveniles in performing certain physically intensive foraging tasks, such as gathering tubers. (shrink)