Evolutionary demography of agricultural expansion in preindustrial northern Finland

A shift from nomadic foraging to sedentary agriculture was a major turning point in human evolutionary history, increasing our population size and eventually leading to the development of modern societies. We however lack understanding of the changes in life histories that contributed to the increased population growth rate of agriculturalists, because comparable individual-based reproductive records of sympatric populations of agriculturalists and foragers are rarely found. Here, we compared key life-history traits and population growth rate using comprehensive data from the seventieth to nineteenth century Northern Finland: indigenous Sami were nomadic hunter-fishers and reindeer herders, whereas sympatric agricultural Finns relied predominantly on animal husbandry. We found that agriculture-based families had higher lifetime fecundity, faster birth spacing and lower maternal mortality. Furthermore, agricultural Finns had 6.2% higher annual population growth rate than traditional Sami, which was accounted by differences between the subsistence modes in age-specific fecundity but not in mortality. Our results provide, to our knowledge, the most detailed demonstration yet of the demographic changes and evolutionary benefits that resulted from agricultural revolution.     

Robustness and management adaptability in tropical rangelands: a viability-based assessment under the non-equilibrium paradigm

Rangelands provide the main forage resource for livestock in many parts of the world, but maintaining long-term productivity and providing sufficient income for the rancher remains a challenge. One key issue is to maintain the rangeland in conditions where the rancher has the greatest possibility to adapt his/her management choices to a highly fluctuating and uncertain environment. In this study, we address management robustness and adaptability, which increase the resilience of a rangeland. After reviewing how the concept of resilience evolved in parallel to modelling views on rangelands, we present a dynamic model of rangelands to which we applied the mathematical framework of viability theory to quantify the management adaptability of the system in a stochastic environment. This quantification is based on an index that combines the robustness of the system to rainfall variability and the ability of the rancher to adjust his/her management through time. We evaluated the adaptability for four possible scenarios combining two rainfall regimes (high or low) with two herding strategies (grazers only or mixed herd). Results show that pure grazing is viable only for high-rainfall regimes, and that the use of mixed-feeder herds increases the adaptability of the management. The management is the most adaptive with mixed herds and in rangelands composed of an intermediate density of trees and grasses. In such situations, grass provides high quantities of biomass and woody plants ensure robustness to droughts. Beyond the implications for management, our results illustrate the relevance of viability theory for addressing the issue of robustness and adaptability in non-equilibrium environments.     

Cattle and pastoralism: Survival and production in arid lands

Traditional subsistence pastoralists in East Africa tend to keep large herds, milk cattle in preference to eating them, and subject them to long foraging treks. Such practices are widely considered ill-suited to arid lands and are believed to arise because cattle are raised more for social prestige than food production. Whether this is true can only be judged by considering the responses of cattle to arid zones and, given the herder's goals and options, his management practices. In considering these factors, we show that indigenous East African cattle demonstrate energy-sparing capabilities during drought. Pastoralists can therefore herd cattle at great distances from water at little more cost than animals on the normal maintenance diet and watered more frequently. The physiological response of cattle to drought, the ecological constraints imposed by livestock and wildlife competition, and the energetic efficiency of mixed milk and meat pastoralism explain why herders traditionally select their characteristic management practices.     

藏香猪翻拱型放牧对不同类型高寒草甸植物特征的影响及土壤环境驱动力

生态系统脆弱的高寒草甸是生态学研究的热点。藏香猪翻拱土壤并取食地下草根层,是藏族自治区一种特有的放牧类型,关于该放牧类型对藏区高寒草甸的影响尚缺乏研究。以滇西北高原国际重要湿地——纳帕海流域的典型高寒草甸为对象,研究了不同高寒草甸类型(陆生草甸与沼泽化草甸)中的植物群落结构特征对藏香猪翻拱型放牧的响应。结果表明,翻拱型放牧显著降低了植被盖度(63.5%)、地上生物量(84.6%)与地下生物量(97.4%),并促进植物生物量向地上部分的再分配。翻拱型放牧下随着植被盖度与生物量降低,植物竞争强度减小,植株高度与空间利用率提高。然而,不同草甸类型中的植物群落结构对翻拱型放牧表现出差异响应。陆生草甸上的群落组成基本未变,而沼泽化草甸上的优势植物华扁穗草(Blysmus sinocompyessus)向1年生水生植物水蓼(Polygonum hydropiper)演替。土壤含水率是导致植物响应差异的关键驱动力。综上,藏香猪翻拱型放牧对植物生物量及盖度等特征均产生不利影响,导致高寒草甸生物量积累锐减,而植物群落结构的变化是放牧干扰与土壤水分、空间竞争协同作用的结果,反映出植物在不同环境中对放牧干扰的差异化响应。研究区域环境特征与放牧干扰的耦合关系,可以为藏香猪放牧作用下的高寒草地植物多样性保护及恢复提供理论依据。     

Nutritional Consequences of Wealth Differentials in East African Pastoralists: The Case of the Datoga of Northern Tanzania

Among African pastoralists evidence that wealth is associated with other measures of household success is scant and the significance of wealth differentials for family welfare remains poorly understood. Predictions that wealth in livestock is associated with increased adequacy of household food supply and with improved child nutrition are tested with longitudinal data on herd size, household composition, food supply, and anthropometric status collected in 1992 for a sample of traditional Datoga households (n = 20) living in the Eyasi basin in northern Tanzania. Although a majority subsisted below poverty cutoffs estimated for east African pastoral populations, there was large variation among households in measures of wealth and resource availability. Individuals in relatively wealthy households did not appear to benefit either in terms of adequacy of household food supply or in terms of average growth performance of young children. Theoretical and methodological challenges in the study of the relationship between wealth and health in nomadic pastoralists are discussed.     

Inter-group encounters and female transfer in mountain gorillas: Influence of group composition on male behavior

This paper examines the behaviors used by male gorillas (G. gorilla beringei) to influence female choice during inter-group encounters. Encounters are related to the acquisition of females rather than to the defense of a group's range. Data on 58 independent encounters confirms that encounters are generally aggressive, but that contact aggression is less frequent than previously reported. A high number of potential migrants in one of the groups involved, rather than the newness of either group, predicts the likelihood of contact aggression between males. Encounters with a newly formed unit last longer than encounters involving established groups. Male herding serves to prevent female transfer. Females without dependent offspring are more likely than others to be herded. Proceptive females are the target of herding more often than non-proceptive cycling females. Groups where herding has been observed are more likely to be newly formed, and they include significantly more males. This last result confirms that there are advantages to male cooperation in gorillas. It also raises the question of why such cooperation does not occur more often. © 1993 Wiley-Liss, Inc.     

Herding Strategies of the Datoga Pastoralists of Tanzania: Is Household Labor a Limiting Factor

Datoga herding follows a cyclical pattern depending on the availability of grazing and water. This analysis focuses on two questions: (a) Is the herding strategy followed by individual households limited by the amount of labor available to that household? and (b) does the herding strategy followed by individual households influence the dynamics of cattle herds? The results show that the availability of labor on a household level does not influence either the herding strategies used by individual households, or the dynamics of cattle herds. This suggests that once minimum labor requirements are met, livestock productivity is insensitive to additional labor inputs.     

Isotopic reconstruction of human diet and animal husbandry practices during the Classical-Hellenistic, imperial, and Byzantine periods at Sagalassos, Turkey

An isotopic reconstruction of human dietary patterns and livestock management practices (herding, grazing, foddering, etc.) is presented here from the sites of Düzen Tepe and Sagalassos in southwestern Turkey. Carbon and nitrogen stable isotope ratios were determined from bone collagen extracted from humans (n = 49) and animals (n = 454) from five distinct time periods: Classical‐Hellenistic (400–200 BC), Early to Middle Imperial (25 BC–300 AD), Late Imperial (300–450 AD), Early Byzantine (450–600 AD), and Middle Byzantine (800–1200 AD). The humans had protein sources that were based on C₃ plants and terrestrial animals. During the Classical‐Hellenistic period, all of the domestic animals had δ¹³C and δ¹⁵N signatures that clustered together; evidence that the animals were herded in the same area or kept in enclosures and fed on similar foods. The diachronic analysis of the isotopic trends in the dogs, cattle, pigs, sheep, and goats highlighted subtle but distinct variations in these animals. The δ¹³C values of the dogs and cattle increased (reflecting C₄ plant consumption) during the Imperial and Byzantine periods, but the pigs and the goats displayed little change and a constant C₃ plant‐based diet. The sheep had a variable δ¹³C pattern reflecting periods of greater and lesser consumption of C₄ plants in the diet. In addition, the δ¹⁵N values of the dogs, pigs, cattle, and sheep increase substantially from the Classical‐Hellenistic to the Imperial periods reflecting a possible increase in protein consumption, but the goats showed a decrease. Finally, these isotopic results are discussed in the context of zooarcheological, archeobotanical, and trace element evidence. Am J Phys Anthropol 149:157–171, 2012. © Wiley Periodicals, Inc.