Social Organization and Knowledge

This paper explores the relationship between different types of social organization, on the one hand, and different modes of knowing and types of knowledge, on the other. Some characteristic distinctions are suggested and supported with evidence, both from diverse areas of theory, and from the study of two contrasting Melanesian cultures: that of the Lavongai of New Hanover and the Tikana of New Ireland.     

Hunter-Gatherers and the Origins of Religion

Recent studies of the evolution of religion have revealed the cognitive underpinnings of belief in supernatural agents, the role of ritual in promoting cooperation, and the contribution of morally punishing high gods to the growth and stabilization of human society. The universality of religion across human society points to a deep evolutionary past. However, specific traits of nascent religiosity, and the sequence in which they emerged, have remained unknown. Here we reconstruct the evolution of religious beliefs and behaviors in early modern humans using a global sample of hunter-gatherers and seven traits describing hunter-gatherer religiosity: animism, belief in an afterlife, shamanism, ancestor worship, high gods, and worship of ancestors or high gods who are active in human affairs. We reconstruct ancestral character states using a time-calibrated supertree based on published phylogenetic trees and linguistic classification and then test for correlated evolution between the characters and for the direction of cultural change. Results indicate that the oldest trait of religion, present in the most recent common ancestor of present-day hunter-gatherers, was animism, in agreement with long-standing beliefs about the fundamental role of this trait. Belief in an afterlife emerged, followed by shamanism and ancestor worship. Ancestor spirits or high gods who are active in human affairs were absent in early humans, suggesting a deep history for the egalitarian nature of hunter-gatherer societies. There is a significant positive relationship between most characters investigated, but the trait “high gods” stands apart, suggesting that belief in a single creator deity can emerge in a society regardless of other aspects of its religion.     

Evolution of Multilevel Social Systems in Nonhuman Primates and Humans

Multilevel (or modular) societies are a distinct type of primate social system whose key features are single-male–multifemale, core units nested within larger social bands. They are not equivalent to fission–fusion societies, with the latter referring to routine variability in associations, either on an individual or subunit level. The purpose of this review is to characterize and operationalize multilevel societies and to outline their putative evolutionary origins. Multilevel societies are prevalent in three primate clades: papionins, Asian colobines, and hominins. For each clade, we portray the most parsimonious phylogenetic pathway leading to a modular system and then review and discuss likely socioecological conditions promoting the establishment and maintenance of these societies. The multilevel system in colobines (most notably Rhinopithecus and Nasalis) has likely evolved as single-male harem systems coalesced, whereas the multilevel system of papionins (Papio hamadryas, Theropithecus gelada) and hominins most likely arose as multimale–multifemale groups split into smaller units. We hypothesize that, although ecological conditions acted as preconditions for the origin of multilevel systems in all three clades, a potentially important catalyst was intraspecific social threat, predominantly bachelor threat in colobines and female coercion/infanticide in papionins and humans. We emphasize that female transfers within bands or genetic relationships among leader males help to maintain modular societies by facilitating interunit tolerance. We still lack a good or even basic understanding of many facets of multilevel sociality. Key remaining questions are how the genetic structure of a multilevel society matches the observed social effort of its members, to what degree cooperation of males of different units is manifest and contributes to band cohesion, and how group coordination, communication, and decision making are achieved. Affiliative and cooperative interunit relations are a hallmark of human societies, and studying the precursors of intergroup pacification in other multilevel primates may provide insights into the evolution of human uniqueness.     

Male Cheetah Social Organization and Territoriality

Patterns of territory ownership in male cheetahs inhabiting the Serengeti Plains are described, and factors affecting territorial behaviour are examined. Body size and age were factors influencing whether males became territorial, and single males usually had to join up with others in order to oust residents. Both size of male coalition and body size of its members were associated with length of tenure on territories. Limited data suggest that territory owners were probably no more likely to encounter females than were non-territorial males but there was a suggestion that they suffered lower survivorship costs than non-territorial males.     

Specific Functions of BIG1 and BIG2 in Endomembrane Organization

Background

Transport of molecules from one subcellular compartment to another involves the recruitment of cytosolic coat protein complexes to a donor membrane to concentrate cargo, deform the membrane and ultimately to form an independent carrier. Small-GTP-binding proteins of the Arf family are central to many membrane trafficking events. Arfs are activated by guanine nucleotide exchange factors (GEFs) which results in their recruitment to membranes and subsequent engagement with Arf-effectors, many of which are coat proteins. Among the human BFA-sensitive large Arf-GEFs, the function of the two closely related BIG1 and BIG2 is still not clear, and recent studies have raised the question of functional redundancy between the two proteins.

Methodology/Principal Findings

Here we have used small-interfering RNA on human cells and a combination of fixed and live-cell imaging to investigate the differential functions of BIG1 and BIG2 in endomembrane organization and function. Importantly, in this direct comparative study, we show discrete functions for BIG1 and BIG2. Our results show that depletion of BIG2 but not of BIG1 induces a tubulation of the recycling endosomal compartment, consistent with a specific role for BIG2 here. In contrast, suppression of BIG1 induces the formation of Golgi mini-stacks still polarized and functional in terms of cargo export.

Conclusions

A key finding from our work is that suppression of BIG1 expression results in a fragmentation of the Golgi apparatus. Our data indicate that the human BFA-sensitive large Arf-GEFs have non-redundant functions in cell organization and membrane trafficking. BIG1 is required to maintain the normal morphology of the Golgi; BIG2 is important for endosomal compartment integrity and cannot replace the function of BIG1 in Golgi organization.     

Ecology and Evolution of Social Organization in Arctic Sandpipers

A comparative analysis of sandpiper social systems on arcticand subarctic breeding grounds (24 species in the family Scolopacidae,subfamily Calidridinae) shows four major patterns. In a majorityof the species (15), populations are dispersed through a stronglydeveloped territorial system, with strong monogamous pair bondsand only minor yearly fluctuations in numbers. The second patternis seen in three species in which the female of a pair may laytwo sets of eggs in quick succession, one for each member ofthe pair to incubate. This opens opportunities for facultativepolygyny or polyandry (‘serial polygamy’) and forthe evolutionary weakening of the strong pair bond seen in thefirst pattern. The third and fourth patterns are those of polygyny(three species) and promiscuity (three species). These six speciesshow clumped dispersions; their year-to-year fluctuations tendto be strong; the males defend compressible, often small, territories;and high densities can occur locally. It is suggested that thepattern of overdispersion and monogamy represents a conservativemode of adapting to high-latitude environments, while the patternof clumped dispersion with polygyny or promiscuity representsan opportunistic mode in that the birds are concentrated intobreeding areas where and when weather, food, and/or some otherenvironmental factors are particularly favorable. Apparentlyfalling evolutionarily between these two basic patterns areseveral species conservative in their life-styles, but polygamousat least occasionally and showing some features of opportunism.There is thus a striking diversity of social systems in calidridinesandpipers, that is, in the styles of habitat exploitation theyhave evolved in the arctic and subarctic habitats to which theirbreeding is confined. A graphic model suggesting paths of evolutionarydevelopment and of interplay among factors considered criticalin the evolution of these systems is proposed.     

Task-Based Core-Periphery Organization of Human Brain Dynamics

As a person learns a new skill, distinct synapses, brain regions, and circuits are engaged and change over time. In this paper, we develop methods to examine patterns of correlated activity across a large set of brain regions. Our goal is to identify properties that enable robust learning of a motor skill. We measure brain activity during motor sequencing and characterize network properties based on coherent activity between brain regions. Using recently developed algorithms to detect time-evolving communities, we find that the complex reconfiguration patterns of the brain''s putative functional modules that control learning can be described parsimoniously by the combined presence of a relatively stiff temporal core that is composed primarily of sensorimotor and visual regions whose connectivity changes little in time and a flexible temporal periphery that is composed primarily of multimodal association regions whose connectivity changes frequently. The separation between temporal core and periphery changes over the course of training and, importantly, is a good predictor of individual differences in learning success. The core of dynamically stiff regions exhibits dense connectivity, which is consistent with notions of core-periphery organization established previously in social networks. Our results demonstrate that core-periphery organization provides an insightful way to understand how putative functional modules are linked. This, in turn, enables the prediction of fundamental human capacities, including the production of complex goal-directed behavior.     

The Structure and Organization of the Human NPAT Gene

Ataxia telangiectasia (AT) is an autosomal recessive gene disorder, andATM,a housekeeping gene, has been identified as the gene responsible for AT. Recently we found that another housekeeping gene,NPAT,is located upstream ofATMon human chromosome 11. The two housekeeping genes are transcribed in opposite directions and share a 0.5-kb 5′ flanking sequence. The structure and organization ofNPATwere determined by direct sequencing of cosmid clones carrying the gene and by application of the long and accurate (LA)-PCR method to amplify regions encompassing the exon/intron boundaries and all of the exons. The gene spans at least 44 kb and consists of 18 exons and 17 introns. It has been suggested that AT heterozygotes have an increased risk of developing cancer, especially breast cancer in women. Frequently, loss of heterozygosity at loci on 11q22–q24 has been observed in DNA isolated from tumors of the breast, uterine cervix, and colon, perhaps suggesting the location of a tumor suppressor gene in 11q22–q24. For investigation of the role ofNPATin AT and these tumors with allelic loss of 11q22–q24, appropriate primer sequences and PCR conditions for amplification of all theNPATexons from genomic DNA were determined. We previously reported that no recombinations are found amongAtm, Npat,andAcat1(acetoacetyl-CoA thiolase) loci as determined by fine genetic linkage mapping of the mouse AT region. The results of the LA-PCR analysis usingNPAT- andACAT-specific primers and human genomic DNA allowed us to mapACAT12 kb centromeric toNPAT.