Testosterone levels in dominant sociable males are lower than in solitary roamers: Physiological differences between three male reproductive tactics in a sociably flexible mammal

The relative plasticity hypothesis predicts that alternative tactics are associated with changes in steroid hormone levels. In species with alternative male reproductive tactics, the highest androgen levels have usually been reported in dominant males. However, in sociable species, dominant males show amicable behaviors to gain access to females, which might conflict with high testosterone levels. We compared testosterone, corticosterone, and resting metabolic rate in male striped mice (Rhabdomys pumilio) following a conditional strategy with three different reproductive tactics: (i) philopatric group-living males, (ii) solitary-living roamers, (iii) dominant but sociable group-living territorial breeders. Philopatrics had the lowest testosterone but highest corticosterone levels, suggesting that they make the best of a bad job. Dominant territorial breeders had lower testosterone levels than roamers, which have a lower competitive status. Roamers had the highest testosterone levels, which might promote risky behavior, such as invading territories defended by territorial males. Roamers also had lower resting metabolic rates than either type of group-living males. Our results suggest that dominant males' testosterone levels reflect a trade-off between low testosterone amicable behavior and high testosterone dominance behavior.

Alternative reproductive tactics in male Cape ground squirrels Xerus inauris

In some animal societies, males vary in the strategies and tactics that they use for reproduction. Explanations for the evolution of alternative tactics have usually focussed on extrinsic factors such as social status, the environment or population density and have rarely examined proximate differences between individuals. Anecdotal evidence suggests that two alternative reproductive tactics occur in cooperatively breeding male Cape ground squirrels. Here we show that there is strong empirical support for physiological and behavioural differences to uphold this claim. `Dispersed' males have higher resting metabolic rates and a heightened pituitary activity, compared with philopatric 'natal' males that have higher circulating cortisol levels. Dispersed males also spend more time moving and less time feeding than natal males. Additionally, lone males spend a greater proportion of their time vigilant and less of their time foraging than those that were in groups. The choice of whether to stay natal or become a disperser may depend on a number of factors such as age, natal group kin structure and reproductive suppression, and the likelihood of successful reproduction whilst remaining natal. Measuring proximate factors, such as behavioural and endocrine function, may provide valuable insights into mechanisms that underlie the evolution of alternative reproductive tactics.

The anonymity of the hunt: A critique of hunting as sharing

Hunter-gatherers are often ascribed a “monistic” worldview at odds with the nature-society dichotomy. The centerpiece of this claim is that they view hunting as similar to sharing within the band and prey animals as part of a common sphere of sociality. This article challenges this thesis. An examination of the work of its main proponents shows that it conflates two different senses of “animal”—the flesh-and-blood animals of the hunt and the animal Spirit that is said to control the animals. The sharing motif in hunting makes sense with respect to the anthropomorphic Spirit but not to the animals hunted. The conditions of the hunt as a spatiotemporal event provide further grounds for skepticism toward the idea of hunting-as-sharing. Drawing on biologist Robert Hinde’s model of relationships, I argue that hunting represents an anonymous one-off interaction that cannot develop into a personal relationship, in stark contrast to the durable forms of personalized sociality associated with the hunter-gatherer band. This is not to deny the possibility of human-animal cosociality in the form of personal relationships but rather to redirect the search away from the hunt to the interface with domesticated animals.

Cheetahs, Acinonyx jubatus, balance turn capacity with pace when chasing prey

Predator–prey interactions are fundamental in the evolution and structure of ecological communities. Our understanding, however, of the strategies used in pursuit and evasion remains limited. Here, we report on the hunting dynamics of the world's fastest land animal, the cheetah, Acinonyx jubatus. Using miniaturized data loggers, we recorded fine-scale movement, speed and acceleration of free-ranging cheetahs to measure how hunting dynamics relate to chasing different sized prey. Cheetahs attained hunting speeds of up to 18.94 m s-1 and accelerated up to 7.5 m s-2 with greatest angular velocities achieved during the terminal phase of the hunt. The interplay between forward and lateral acceleration during chases showed that the total forces involved in speed changes and turning were approximately constant over time but varied with prey type. Thus, rather than a simple maximum speed chase, cheetahs first accelerate to decrease the distance to their prey, before reducing speed 5–8 s from the end of the hunt, so as to facilitate rapid turns to match prey escape tactics, varying the precise strategy according to prey species. Predator and prey thus pit a fine balance of speed against manoeuvring capability in a race for survival.

Consensus in organizations:Hunting for the social choice conundrum in APA elections

According to the axiomatic literature on consensus methods, the best collective choice by one method of preference aggregation can easily be the worst by another. Are award committees, electorates, managers, online retailers, and web-based recommender systems stuck with an impossibility of rational preference aggregation? We investigate this social choice conundrum for seven social choice methods: Condorcet, Borda, Plurality, Antiplurality, the Single Transferable Vote, Coombs, and Plurality Runoff. We rely on Monte Carlo simulations for theoretical results and on twelve ballot datasets from American Psychological Association (APA) presidential elections for empirical results. Each of these elections provides partial rankings of five candidates from about 13,000 to about 20,000 voters. APA preferences are neither domain-restricted nor generated by an Impartial Culture. We find virtually no trace of a Condorcet paradox. In direct contrast with the classical social choice conundrum, competing consensus methods agree remarkably well, especially on the overall best and worst options. The agreement is also robust under perturbations of the preference prole via resampling, even in relatively small pseudosamples. We also explore prescriptive implications of our findings.

Flexible energetics of cheetah hunting strategies provide resistance against kleptoparasitism

Population viability is driven by individual survival, which in turn depends on individuals balancing energy budgets. As carnivores may function close to maximum sustained power outputs, decreased food availability or increased activity may render some populations energetically vulnerable. Prey theft may compromise energetic budgets of mesopredators, such as cheetahs and wild dogs, which are susceptible to competition from larger carnivores. We show that daily energy expenditure (DEE) of cheetahs was similar to size-based predictions and positively related to distance traveled. Theft at 25% only requires cheetahs to hunt for an extra 1.1 hour per day, increasing DEE by just 12%. Therefore, not all mesopredators are energetically constrained by direct competition. Other factors that increase DEE, such as those that increase travel, may be more
important for population viability.

Composite hunting technologies from the Terminal Pleistocene and Early Holocene, Niah Cave, Borneo

Renewed archaeological investigation of the West Mouth of Niah Cave, Borneo has demonstrated that even within lowland equatorial environments depositional conditions do exist where organic remains of late glacial and early post-glacial age can be preserved. Excavations by the Niah Cave Research Project (NCP) (2000-2003) towards the rear of the archaeological reserve produced several bone points and worked stingray spines, which exhibit evidence of hafting mastic and fibrous binding still adhering to their shafts. The position of both gives strong indication of how these cartilaginous points were hafted and gives insight into their potential function. These artefacts were recovered from secure and (14)C dated stratigraphic horizons. The results of this study have implications for our understanding the function of the Terminal Pleistocene and Early Holocene bone tools recovered from other regions of Island Southeast Asia. They demonstrate that by the end the Pleistocene rainforest foragers in Borneo were producing composite technologies that probably included fishing leisters and potentially the bow and arrow. (C) 2009 Elsevier Ltd. All rights reserved.

Hunting in a Tropical Rainforest:Evidence from the Terminal Pleistocene at Lobang Hangus, Niah Caves, Sarawak

The Terminal Pleistocene zooarchaeological evidence from Lobang Hangus, an east-facing entrance to the Niah Cave complex, provides unique insights into the hunting habits of the human inhabitants of this cave. The composition and structure of the vertebrate accumulation indicates that a variety of locally available terrestrial, arboreal and aquatic taxa were being exploited, The age structure of the principal predated species, the presence of bone points and evidence from modern rainforest hunting combine to suggest that some form of projectile weaponry as well as trapping technologies were probably being employed by the hunters at Niah before the end of the Pleistocene. Copyright (C) 2009 John Wiley & Sons, Ltd.