Factors driving the variability in diving and movement behavior of migrating humpback whales (Megaptera novaeangliae): Implications for anthropogenic disturbance studies

Humpback whales (Megaptera novaeangliae) undertake one of the longest migrations of any animal and while on a broad‐scale this journey appears direct, on a fine‐scale, behaviors associated with socializing and breeding are regularly observed. However, little is known about which social and environmental factors influence behavior during this time. Here we examined the effect of multiple factors on the movement (speed and course) and diving behavior (dive and surfacing duration) of humpback whales during migration off the eastern coast of Australia. Focal data (202 h) were collected on 94 different whale groups with simultaneous social and environmental context data. The environmental factors water depth and wind speed were found to be important predictors of dive and movement behavior, whereas social factors were less influential at this site. Groups tended to dive for longer with increased water depth but traveled more slowly in increasing wind speeds. These baseline studies are crucial when examining the effect of anthropogenic disturbance. Determining which natural factors significantly affect behavior ensures any observed behavioral changes are correctly attributed to the disturbance and are not a result of other factors. In addition, any responses observed can be put into biological context and their relative magnitude determined.     

Contributions to the theory of imitative behavior: The number of political parties as determined by biological and social factors

The theory of imitative behavior as applied tow mutually exclusive behavior patterns (N. Rashevsky,Mathematical Biology of Social Behavior, Rev. Ed., 1959; The University of Chicago Press) leads to the possibility of any numberw of different behavior patterns existing in a social group. Mutually inhibitory effects suppress the effectiveness of behavior of groups that are very small numerically. The manner in which the different biological and social parameters that enter into the theory of imitative behavior determine the number of different effective behaviors is discussed. The results are applied to the problem of what determines the number of political parties in different countries. This number is expected to increase with increasing spread of the distribution curves for the tendencies towards different behaviors, with decreasing imitation factors, and with increasing instability of psychophysical judgments of the average individuals.     

The neurobiology of lipid metabolism in autism spectrum disorders

Autism is a neurodevelopmental disorder characterized by impairments in communication and reciprocal social interaction, coupled with repetitive behavior, which typically manifests by 3 years of age. Multiple genes and early exposure to environmental factors are the etiological determinants of the disorder that contribute to variable expression of autism-related traits. Increasing evidence indicates that altered fatty acid metabolic pathways may affect proper function of the nervous system and contribute to autism spectrum disorders. This review provides an overview of the reported abnormalities associated with the synthesis of membrane fatty acids in individuals with autism as a result of insufficient dietary supplementation or genetic defects. Moreover, we discuss deficits associated with the release of arachidonic acid from the membrane phospholipids and its subsequent metabolism to bioactive prostaglandins via phospholipase A(2)-cyclooxygenase biosynthetic pathway in autism spectrum disorders. The existing evidence for the involvement of lipid neurobiology in the pathology of neurodevelopmental disorders such as autism is compelling and opens up an interesting possibility for further investigation of this metabolic pathway.     

Cultural transmission can inhibit the evolution of altruistic helping

The study of culturally inherited traits has led to the suggestion that the evolution of helping behaviors is more likely with cultural transmission than without. Here we evaluate this idea through a comparative analysis of selection on helping under both genetic and cultural inheritance. We develop two simple models for the evolution of helping through cultural group selection: one in which selection on the trait depends solely on Darwinian fitness effects and one in which selection is driven by nonreproductive factors, specifically imitation of strategies achieving higher payoffs. We show that when cultural variants affect Darwinian fitness, the selection pressure on helping can be markedly increased relative to that under genetic transmission. By contrast, when variants are driven by nonreproductive factors, the selection pressure on helping may be reduced relative to that under genetic inheritance. This occurs because, unlike biological offspring, the spread of cultural variants from one group to another through imitation does not reduce the number of these variants in the source group. As a consequence, there is increased within-group competition associated with traits increasing group productivity, which reduces the benefits of helping. In these cases, selection for harming behavior (decreasing the payoff to neighbors) may occur rather than selection for helping.     

Modeling users' activity on twitter networks: validation of Dunbar's number

Microblogging and mobile devices appear to augment human social capabilities, which raises the question whether they remove cognitive or biological constraints on human communication. In this paper we analyze a dataset of Twitter conversations collected across six months involving 1.7 million individuals and test the theoretical cognitive limit on the number of stable social relationships known as Dunbar's number. We find that the data are in agreement with Dunbar's result; users can entertain a maximum of 100-200 stable relationships. Thus, the 'economy of attention' is limited in the online world by cognitive and biological constraints as predicted by Dunbar's theory. We propose a simple model for users' behavior that includes finite priority queuing and time resources that reproduces the observed social behavior.     

Modelling the role of social behavior in the persistence of the alpine marmot Marmota marmota

A general rule of thumb for biological conservation obtained from simple models of hypothetical species is that for populations with strong environmental noise moderate increases in habitat size or quality do not substantially reduce extinction risk. However, whether this rule also holds for real species with complex behavior, such as social species with breeding units and reproductive suppression, is uncertain. Here we present a population viability analysis of the alpine marmot Marmota marmota, which displays marked social behavior, i.e. it lives in social groups of up to twenty individuals. Our analysis is based on a long‐term field study carried out in the Bavarian Alps since 1982. During the first fifteen years of this study, 687 marmots were individually marked and the movements and fate of 98 dispersing marmots were recorded with radio‐telemetry. Thus, in contrast to most other viability analyses of spatially structured populations, good data about dispersal exist. A model was constructed which is individual‐based, spatially explicit at the scale of clusters of neighbouring territories, and spatially implicit at larger scales. The decisive aspect of marmot life history, winter mortality, is described by logistic regression where mortality is increased by age and the severity of winter, and decreased by the number of subdominant individuals present in a group. Model predictions of group size distribution are in good agreement with the results of the field study. The model shows that the effect of sociality on winter mortality is very effective in buffering environmental harshness and fluctuations. This underpins theoretical results stating that the appropriate measure of the strength of environmental noise is the ratio between the variance of population growth rate and the intrinsic rate of increase. The lessons from our study for biological conservation are that simple, unstructured models may not be sufficient to assess the viability of species with complex behavioral traits, and that even moderate increases in habitat capacity may substantially reduce extinction risk even if environmental fluctuations seem high.     

How copying affects the amount, evenness and persistence of cultural knowledge: insights from the social learning strategies tournament

Darwinian processes should favour those individuals that deploy the most effective strategies for acquiring information about their environment. We organized a computer-based tournament to investigate which learning strategies would perform well in a changing environment. The most successful strategies relied almost exclusively on social learning (here, learning a behaviour performed by another individual) rather than asocial learning, even when environments were changing rapidly; moreover, successful strategies focused learning effort on periods of environmental change. Here, we use data from tournament simulations to examine how these strategies might affect cultural evolution, as reflected in the amount of culture (i.e. number of cultural traits) in the population, the distribution of cultural traits across individuals, and their persistence through time. We found that high levels of social learning are associated with a larger amount of more persistent knowledge, but a smaller amount of less persistent expressed behaviour, as well as more uneven distributions of behaviour, as individuals concentrated on exploiting a smaller subset of behaviour patterns. Increased rates of environmental change generated increases in the amount and evenness of behaviour. These observations suggest that copying confers on cultural populations an adaptive plasticity, allowing them to respond to changing environments rapidly by drawing on a wider knowledge base.     

Demographic trends in the Cactaceae

Although our biological knowledge regarding cactus species is thorough in many areas, only in recent years have ecologists addressed their demographic behavior. Here we attempt a first review of the present knowledge on cactus demography, including an analysis of the published information on species with different growth forms and life-history traits. Our review shows that cactus distribution ranges are determined by environmental heterogeneity and by species-specific physiological requirements. Temperature extremes may pose latitudinal and altitudinal distribution limits. At a more local scale, soil properties dramatically affect cactus distribution. Most cacti show a clumped spatial distribution pattern, which may be the reflection of a patchy resource distribution within their heterogeneous environments. The association of cacti with nurse plants is another factor that may account for this aggregated distribution. Many cacti grow in association with these perennial nurse plants, particularly during early life-cycle phases. The shade provided by nurse plants results in reduced evapotranspiration and buffered temperatures, which enhance cactus germination and establishment. In some cases a certain degree of specificity has been detected between particular cactus species and certain nurse plants. Yet some globose cacti may establish in the absence of nurse plants. In these cases, rocks and other soil irregularities may facilitate germination and establishment. Cacti are slow-growing species. Several abiotic factors, such as water and nutrient availability, may affect their growth rate. Competition and positive associations (i.e., mycorrhizae and nurse-cacti association) may also affect growth rate. Age at first reproduction varies greatly in relation to plant longevity. In general, cactus reproductive capacity increases with plant size. Populations are often composed of an uneven number of individuals distributed in the different size categories. This type of population structure reflects massive but infrequent recruitment events, apparently associated with benign periods of abundant rainfall. A few cactus species have been analyzed through the use of population-projection matrices. A total of 17 matrices were compiled and compared. Most of them reflect populations that are close to the numerical equilibrium (λ = close to unity). Elasticity analyses revealed that the persistence of individuals in their current size category (“stasis”) is the demographic process that contributes the most to population growth rate. Also, adult categories (rather than juveniles or seedlings) show the largest contributions to λ. No differences were apparent regarding this matter between cacti with different life-forms. This review shows that our knowledge of cactus population ecology is still incipient and rather unevenly distributed: some topics are well developed; for others the available information is still very limited. Our ability to preserve the great number of cactus species that are now endangered depends on our capacity to deepen our ecological understanding of their population processes.     

Cumulative cultural dynamics and the coevolution of cultural innovation and transmission: an ESS model for panmictic and structured populations

When individuals in a population can acquire traits through learning, each individual may express a certain number of distinct cultural traits. These traits may have been either invented by the individual himself or acquired from others in the population. Here, we develop a game theoretic model for the accumulation of cultural traits through individual and social learning. We explore how the rates of innovation, decay, and transmission of cultural traits affect the evolutionary stable (ES) levels of individual and social learning and the number of cultural traits expressed by an individual when cultural dynamics are at a steady‐state. We explore the evolution of these phenotypes in both panmictic and structured population settings. Our results suggest that in panmictic populations, the ES level of learning and number of traits tend to be independent of the social transmission rate of cultural traits and is mainly affected by the innovation and decay rates. By contrast, in structured populations, where interactions occur between relatives, the ES level of learning and the number of traits per individual can be increased (relative to the panmictic case) and may then markedly depend on the transmission rate of cultural traits. This suggests that kin selection may be one additional solution to Rogers's paradox of nonadaptive culture.     

Neuroplasticity and temporal retardation of development (paedomorphic morphology) inhuman evolution: A consideration of biological requirements for the plasticity of human cognition and the potential acquisition of culturally dependent ethical world views

The fact thatHomo sapiens have one of the longest childhoods in the animal kingdom is a most significant factor when considering the biological requirements for cultural evolution. The so-called long childhood is necessary for the intergenerational transmission of learned skills and behaviors that defined culture. It is important to distinguish between behavior motivated byinstinct and behavior that islearned as a result of having been reared in a culturally dependent environment. Our neotenic development occasions an ability to learn a variety of culturally dependent behaviors. Since we are born, quite literally, as human embryos, we must recognize that our brain undergoes the bulk of its development post-natally. It is significant that at the same time the brain develops its distinctive axon-neuron network structure, persons are learning culturally dependent accepted patterns of behavior that are related to (amongst many other things) language, altruism, aggression, rites, filial, proprieties, etc. The old reductionistic nature-nurture issue is best understood as a complex array of developmental processes in which environmental stimuli (nurture) may affect the physiological development (nature) of the brain. The early plasticity of human cognition may be, to a significant degree, shaped and physiologically constrained by environmental factors (especially in the early years of development). The presence of a diversity of environmental influences the world over suggests the possibility that a person's intolerance of foreign ethical belief systems may stem from a genuine inability to conceive of ethical relationships in a manner far removed from one's daily life and native environment. After consideration of the effects of neuroplasticity and human neotenic development, it is argued that a viable sociobiological research agenda must study not only those ethical behaviors that seem to beshared across cultures, but also those behaviors that stem from culturally distinctive attitudes that arenot shared across cultural boundaries.     

Oxytocin and dendrite remodeling in the hypothalamus

For most people, their quality of life depends on their successful interdependence with others, which requires sophisticated social cognition, communication, and emotional bonds. Across the lifespan, new bonds must be forged and maintained, and conspecific menaces must be managed. The dynamic nature of the human social landscape suggests ongoing specific alterations in neural circuitry across several brain systems to subserve social behavior. To discover the biological mechanisms that contribute to normal social activities, animal models of social behavior have been developed. One valuable model system has been female rat sexual behavior, which is governed by cyclic variation of ovarian hormones. This behavior is modulated by the neuropeptide oxytocin (OT) through its actions in the hypothalamic ventromedial nucleus (VMH). The fluctuation of this behavior is associated with dendrite remodeling, like several other examples of behavioral plasticity. This review compares hormone-induced plasticity in the VMH with other examples of dendrite plasticity across the mammalian nervous system, namely the neurobehavioral paradigms of environmental enrichment, chronic stress, and incentive sensitization, which affect the neocortex, hippocampal formation, and ventral striatum, respectively. This comparison suggests that the effects of ovarian hormones on VMH neurons in rats, given the simple dendritic arbor and short time course for dendrite remodeling, provide a dual opportunity for mechanistic and functional studies that will shed light on i) the neural actions of OT that regulate social behavior and, ii) behaviorally relevant dendrite regulation in a variety of brain structures. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.     

Effects of caller activity and habitat visibility on contact call rate of wild Japanese macaques (Macaca fuscata)

A major function of contact calls in nonhuman primates is to maintain spatial cohesion among individuals in a group. The risks of spatial/visual separation from the group are likely to affect auditory contact behavior, in particular by increasing the call rate. We tested whether the risk of separation influences coo call emission by investigating the variation in call rate among behavioral contexts in two wild populations of Japanese macaques (Macaca fuscata). We focused on caller activity and the degree of visibility within the habitat as primary potential factors mediating call rate. We first estimated the habitat visibility of the two research sites at Yakushima Island (YK) and Kinkazan Island (KZ), Japan. The habitat visibility of YK was significantly more restricted than that of KZ. We then compared the call rate of 20 adult and 12 juvenile female macaques between the two wild populations to examine the potential effects of environmental differences. Both populations had a lower call rate during grooming than during feeding and moving, which are behaviors associated to higher interindividual distances. The call rate of YK adult females was significantly greater than that of both juveniles and KZ adult females, independently of activity. The call rate increased as macaques matured in the YK population, but not in the KZ population, suggesting that different developmental processes involved in contact calling of the two populations. Our findings suggest that separation risk influences call rate, and also imply a possibility of social influence that social structure change effects on the call rates.     

Effects of social group size on information transfer and task allocation

Summary Social animals exchange information during social interaction. The rate of interaction and, hence, the rate of information exchange, typically changes with density and density may be affected by the size of the social group. We investigate models in which each individual may be engaged in one of several tasks. For example, the different tasks could represent alternative foraging locations exploited by an ant colony. An individual's decision about which task to pursue depends both on environmental stimuli and on interactions among individuals. We examine how group size affects the allocation of individuals among the various tasks. Analysis of the models shows the following. (1) Simple interactions among individuals with limited ability to process information can lead to group behaviour that closely approximates the predictions of evolutionary optimality models, (2) Because per capita rates of social interaction may increase with group size, larger groups may be more efficient than smaller ones at tracking a changing environment, (3) Group behaviour is determined both by each individual's interaction with environmental stimuli and by social exchange of information. To keep these processes in balance across a range of group sizes, organisms are predicted to regulate per capita rates of social interaction and (4) Stochastic models show, at least in some cases, that the results described here occur even in small groups of approximately ten individuals.     

Behavioural responses to human‐induced environmental change

The initial response of individuals to human‐induced environmental change is often behavioural. This can improve the performance of individuals under sudden, large‐scale perturbations and maintain viable populations. The response can also give additional time for genetic changes to arise and, hence, facilitate adaptation to new conditions. On the other hand, maladaptive responses, which reduce individual fitness, may occur when individuals encounter conditions that the population has not experienced during its evolutionary history, which can decrease population viability. A growing number of studies find human disturbances to induce behavioural responses, both directly and by altering factors that influence fitness. Common causes of behavioural responses are changes in the transmission of information, the concentration of endocrine disrupters, the availability of resources, the possibility of dispersal, and the abundance of interacting species. Frequent responses are alterations in habitat choice, movements, foraging, social behaviour and reproductive behaviour. Behavioural responses depend on the genetically determined reaction norm of the individuals, which evolves over generations. Populations first respond with individual behavioural plasticity, whereafter changes may arise through innovations and the social transmission of behavioural patterns within and across generations, and, finally, by evolution of the behavioural response over generations. Only a restricted number of species show behavioural adaptations that make them thrive in severely disturbed environments. Hence, rapid human‐induced disturbances often decrease the diversity of native species, while facilitating the spread of invasive species with highly plastic behaviours. Consequently, behavioural responses to human‐induced environmental change can have profound effects on the distribution, adaptation, speciation and extinction of populations and, hence, on biodiversity. A better understanding of the mechanisms of behavioural responses and their causes and consequences could improve our ability to predict the effects of human‐induced environmental change on individual species and on biodiversity.     

The adaptive significance of cultural behavior

In this article, I argue that human social behavior is a product of the coevolution of human biology and culture. While critical of attempts by anthropologists to explain cultural practices as if they were independent of the ability of individual human beings to survive and reproduce, I am also leery of attempts by biologists to explain the consistencies between neo-Darwinian theory and cultural behavior as the result of natural selection for that behavior. Instead, I propose that both biological and cultural attributes of human beings result to a large degree from the selective retention of traits that enhance the inclusive fitnesses of individuals in their environments. Aspects of human biology and culture may be adaptive in the same sense despite differences between the mechanisms of selection and regardless of their relative importance in the evolution of a trait. The old idea that organic and cultural evolution are complementary can thus be used to provide new explanations for why people do what they do.This article was prepared from remarks I presented at the Smithsonian Conference on Human Biogeography in April 1974. Help with phenotypic costs came from an NSF Pre-doctoral Fellowship and the University of Michigan Society of Fellows.     

Culture as a stressor: A revised model of biocultural interaction

Contemporary urban societies display in high relief the action of social stratification on human biology. Recent studies of biological responses to urban environments and of socioeconomically disadvantaged people indicate that culture allocates risks disproportionately to some individuals and groups within society through its constituent values and related patterns of behavior. Although risk allocation is present in all societies, it is very clear in urban environments within stratified societies where high exposure to harmful materials is many times more likely for some segments of society. In urban environments, culture may be seen as adding stressors to the environment by concentrating naturally occurring materials to levels that are toxic to humans and through the creation of new toxic materials. In stratified societies the risk of exposure to these new stressors is focused on the socioeconomically disadvantaged. This exposure has consequences that increase the likelihood of more exposure and more socioeconomic disadvantage, thereby increasing social stratification. This suggests that models of biocultural interaction include a feedback relationship in which biological factors influence the sociocultural system in addition to the usual action of the sociocultural system on biological features and responses. This model strongly reinforces the view that stressors can originate from cultural arrangements. Am J Phys Anthropol 102:67–77, 1997 © 1997 Wiley-Liss, Inc.     

The Health Consequences of Cultural Consonance: Cultural Dimensions of Lifestyle, Social Support, and Arterial Blood Pressure in an African American Community

Cultural dimensions of health and behavior have been difficult to study because of limited theoretical and methodological models linking the cultural, the individual, and the biological. We employ a cognitive theory of culture to understand culture and health in an African American community in the southern United States. First, cultural consensus analysis is used to test for shared cultural models of lifestyles and social supports within the community. Then, the theoretical and operational construct of "cultural consonance" is used to assess the degree to which individuals behave in a way consistent with cultural models. Findings indicate that cultural consonance in lifestyle and social support combine synergistically in association with blood pressure. These associations of cultural consonance and health are not altered by taking into account a variety of other variables, indicating an independent association of cultural dimensions of behavior with health status. Implications of these results for culture theory are discussed, [culture theory, culture consensus analysis, cultural consonance, African American community, arterial blood pressure]     

Local dynamics of worker activity of the invasive Vespula germanica and V. vulgaris (Hymenoptera: Vespidae) wasps in Argentina

1. The abundance of insects depends essentially on the reproductive success of individuals. In social insects, however, the abundance of sterile workers outside a nest depends on colony size but is also determined by ontogeny, nest demands, and local environmental factors. For invasive social wasps, the drivers of worker abundance are important because they determine the impact that these species have on the native systems, people, and their goods. 2. The aim of the present study was to understand the relative importance of endogenous and exogenous factors on the abundance of workers of populations of Vespula spp., by analysing 12 years of trap captures in NW Patagonia. This is the first attempt to model the activity levels of invasive Vespula spp. wasps over time in Argentina. 3. It was shown that between years, the worker activity of both vespids presents fluctuations, and that of V. germanica is determined by the spring mean temperatures. Within the flight season, V. germanica worker activity is affected by the relative abundance of workers in that year, whereas for V. vulgaris, activity it is affected by the relative abundance of both species that year. We found no relationship between individual weather variables and activity within a flight season for both wasps. 4. The patterns observed for Argentina are similar to those observed in all invaded temperate areas where Vespula spp. are established. This study provides useful information to understand the driving factors that affect Vespula spp. worker activity in Argentina. This could be a necessary step to develop plans to manage these invasive social insects.     

How does social behavior differ among sperm whale clans?

When individuals primarily associate with and learn from those who behave similarly, society and culture become closely tied. Sperm whales (Physeter macrocephalus) exhibit multilevel social structure, the levels of which are differentiated in part by characteristic cultural behaviors. Sperm whales are organized into sympatric clans, with distinctive vocal repertoires that are socially learned. Other behaviors, such as movement patterns and foraging, also differ among clans. Here we ask whether the clan partition also includes divergences in social behavior. Off the Galápagos Islands, members of two clans differed consistently in diving synchrony, heterogeneity, and temporal stability of social relationships. While number of associates (indicated by social unit, group, and cluster sizes) were similar between clans, Regular clan members dived more synchronously and had more homogeneous relationships than the Plus‐One clan members. Plus‐One social units had generally longer associations than those of the Regular clan. Differences in surface‐time coordination and quality of social relationships are likely byproducts of the clan segregation, which could affect alloparental care giving, therefore scaling up to differential calf survival rates between clans. This new dimension of behavioral divergence between sperm whale clans indicates that sympatric, socio‐cultural entities of nonhumans can also display characteristic social behavior.     

Inclusive heritability: combining genetic and non‐genetic information to study animal behavior and culture

Phenotypic variance results from variation in biological information possessed by individuals. Quantitative geneticists often strive to partition out all environmental variance to measure heritability. Behavioral biologists and ecologists however, require methods to integrate genetic and environmental components of inherited phenotypic variance in order to estimate the evolutionary potential of traits, which encompasses any form of information that is inherited. To help develop this integration, we build on the tools of quantitative genetics and offer the concept of ‘inclusive heritability’ which identifies and unifies the various mechanisms of information transmission across generations. A controversial component of non‐genetic information is animal culture, which is the part of phenotypic variance inherited through social learning. Culture has the unique property of being transmitted horizontally and obliquely, as well as vertically. Accounting for cultural variation would allow us to examine a broader range of evolutionary mechanisms. Culture may, for instance, produce behavioral isolating mechanisms leading to speciation. To advance the study of animal culture, we offer a definition of culture that is rooted in quantitative genetics. We also offer four testable criteria to determine whether a trait is culturally inherited. These criteria may constitute a conceptual tool to study animal culture. We briefly discuss methods to partition out cultural variance. Several authors have recently called for ‘modernizing the modern synthesis’ by including non‐genetic factors such as epigenetics and phenotypic plasticity in order to more fully explain phenotypic evolution. Here, we further propose to broaden the concept of inheritance by incorporating the cultural component of behavior. Applying the concept of inclusive heritability may advance the integration of multiple forms of inheritance into the study of evolution.