Great Adaptive Value Research Articles

Генезис психологической суверенности: фактор порядка рождения

The ability to defend the boundaries of one’s empirical self — dispositional sovereignty — is a personality trait with a great adaptive value. It develops through the generalization of everyday actions aimed at protecting the boundaries in discrete situations with other people, first, with one’s family. This paper explores the role of sibling status (birth order) in the development of this trait. Two empirical studies were conducted. In the first of them, carried out with the participation of children aged from two to ten, it is shown that the most mature ways of protection are for only children in the family, the least mature are the first children, and the second children in the family demonstrate an intermediate level of development of boundary protection skills. In the second study conducted on the youth sample, it is shown that the relationship between sovereignty and the order of birth depends on gender: sovereignty hits its peak among younger girls and older boys.

Unlearned visual preferences for the head region in domestic chicks.

Unlearned tendencies to approach animate creatures are of great adaptive value, especially for nidifugous social birds that need to react to the presence of potential social companions shortly after hatching. Domestic chicks’ preferences for taxidermized hens provided the first evidence of social predispositions. However, the nature of the stimuli eliciting this predisposition is not completely understood. Here we explore the unlearned preferences of visually naïve domestic chicks for taxidermized animals. Visually naive chicks were tested for their approach preferences between a target stimulus (an intact stuffed animal whose head region was clearly visible) and a control stimulus. After confirming the predisposition for the intact stuffed fowl hen (Exp. 1), we found an analogous preference for a taxidermized, young domestic chick over a severely scrambled version of the same stimulus, whose body structure was completely disrupted, extending to same-age individuals the results that had been obtained with taxidermized hens (Exp. 2). We also directly tested preferences for specimens whose head region is visible compared to ones whose head region was occluded. To clarify whether chicks are sensitive to species-specific information, we employed specimens of female mallard ducks and of a mammalian predator, the polecat. Chicks showed a preference for the duck stimulus whose wings have been covered over a similar stimulus whose head region has been covered, providing direct evidence that the visibility of the head region of taxidermized models drive chicks’ behaviour in this test, and that the attraction for the head region indeed extends to females of other bird species (Exp. 3). However, no similar preference was obtained with the polecat stimuli (Exp. 4). We thus confirmed the presence of unlearned visual preferences for the head region in newly-hatched chicks, though other factors can limit the species-generality of the phenomenon.

Assessor teaching and the development of the capacity to innovate and to imitate

Human beings have generated a system of cumulative cultural learning with great adaptive value. The evolution of this system required an increase in the capacity to innovate and to imitate in hominin lineage. However that development is costly and, moreover, imitation may restrain the adaptive advantage of a greater investment on innovation. We suggest that a possible way to overcome this problem in hominin evolution was parental teaching by evaluative feedback - i.e. assessor teaching. To explore this hypothesis we developed a mathematical model of cumulative cultural learning. We consider two cognitive levels, one Basic, with less ability to imitate and innovate, and the other Smart, with more ability of both. We study the transition from Basic to Smart in the absence or in presence of teaching. We also study the transition from no teaching to teaching at each cognitive level. We show that the transition to a Smart is easier in a teaching context than in one of only imitation. We also show that the transition to teaching is easier the greater the cognitive level.

EXPRESSIVIDADE E REGULAÇÃO EMOCIONAL EM ESTUDANTES DO ENSINO SUPERIOR

Abstract.EXPRESSIVITY AND EMOTIONAL REGULATION IN COLLEGE STUDENTSEmotions have a great adaptive value for individuals, allowing them to challenges the opportunities offered by the environment (Plutnchik , 1990) . So this study is important the utmost importance in education contexts. By emotional expressiveness is meant changes in behavior (eg , facial and postural accompanying emotions such as crying, laughing , blushing ) ( Gross & John , 1998) . Despite this multidimensional view of emotional expressiveness not be the only (there is a great proliferation) this view and adds that greater agreement among authors. In turn, emotional regulation refers to all of the strategies used to reduce, maintain or increase an emotion (Gross, 2001) . The strategies of emotional regulation are implicated in personality, emotions on cognition in social development (including resilience ). The objective of this research is to understand what patterns of regulation and emotional expression can meet college students and which variables influence them. The sample comprises 182 subjects, 83.5 % female and 16.5 % male, aged 17 to 51 years (M=23.5 years ; SD 6.6 ), the to Higher Education in the 1st (17.3% ), 2 (37.9 %), 3 (46.2 %) and 4th year (2.2%), students of Psychology (30.8 %), Educational Sciences (19.8 %) and Nursing (49.5 %) . The instruments used are: a Emotional Expressiveness Questionnaire of Berkeley (Gross & John , 1997) that assesses three dimensions: negative expressivity, positive expressivity and impulse, and the Emotional Regulation Questionnaire (Gross & John, 2003) This study show that the dimensions of emotional expressiveness and regulation depend on gender, year, course and age.Keywords: Emotional expressivity, emotional regulation, College students, Higher Education.Resumo.As emoções têm um grande valor adaptativo para os indivíduos, permitindo enfrentar os desafios e aproveitar as oportunidades oferecidas pelo meio (Plutnchik, 1990). Pelo que o seu estudo se releva da maior importância na área da educação. Por expressividade emocional deve entender-se as mudanças de comportamento (por exemplo, facial e postural que acompanham as emoções, como sejam chorar, rir, corar) (Gross & John, 1998). Apesar desta visão multidimensional da expressividade emocional não ser a única (há uma grande proliferação) esta visão e a que agrega maior concordância entre os autores. Por sua vez, a regulação emocional refere-se a todas as estratégias usada para reduzir, manter ou aumentar uma emoção (Gross, 2001). As estratégias de regulação emocional estão implicadas na personalidade, nas emoções na cognição no desenvolvimento social (incluindo a resiliência). O objetivo desta investigação é o de compreender que padrões de regulação e expressão emocional podemos encontrar nos estudantes do Ensino Superior e quais as variáveis que os influenciam. A amostra deste estudo consta de 182 sujeitos, 83,5% do sexo feminino e 16,5% do sexo masculino, com idades compreendidas entre os 17 e os 51 anos (Média 23,5 anos e Desvio Padrão 6,6), a frequentar o Ensino Superior no 1º (17,3%), 2º (37,9%), 3º (46,2%) e 4º ano (2,2%), dos cursos de Psicologia (30,8%), Ciências da Educação (19,8%) e Enfermagem (49,5%). Os instrumentos utilizados foram o questionário de expressividade emocional de Berkeley (Gross & John, 1997) que avalia três dimensões: expressividade negativa, expressividade positiva e a força do impulso; e o questionário de regulação emocional (Gross & John, 2003). Os estudos mostram que as dimensões da expressividade e da regulação emocional dependem do género, ano de curso, curso e idade.Palavras chave: Expressividade emocional, regulação emocional, Estudantes ensino superior, Ensino Superior.

Stress and life history

In his book on behavioural endocrinology, Randy Nelson describes 'stress' as a 'notoriously ethereal concept'. Yet, despite this lack of clarity, studies of the consequences of stress across different time scales, life history stages, taxa and levels of biological enquiry form a large part of modern biology and biomedicine. Organisms need to recognise and respond to environmental challenges. Being able to do so appropriately, and with minimal costs, is an important physiological attribute, with great adaptive value. The costs and benefits of different mechanisms that enable organisms to cope with unpredictable environmental changes can be manifest to different degrees at different life stages. Accordingly, the level of stress experienced in the environment can act as a strong selective pressure that drives the evolution of life histories.

Integrating reinforcement learning, equilibrium points, and minimum variance to understand the development of reaching: a computational model.

Despite the huge literature on reaching behavior, a clear idea about the motor control processes underlying its development in infants is still lacking. This article contributes to overcoming this gap by proposing a computational model based on three key hypotheses: (a) trial-and-error learning processes drive the progressive development of reaching; (b) the control of the movements based on equilibrium points allows the model to quickly find the initial approximate solution to the problem of gaining contact with the target objects; (c) the request of precision of the end movement in the presence of muscular noise drives the progressive refinement of the reaching behavior. The tests of the model, based on a two degrees of freedom simulated dynamical arm, show that it is capable of reproducing a large number of empirical findings, most deriving from longitudinal studies with children: the developmental trajectory of several dynamical and kinematic variables of reaching movements, the time evolution of submovements composing reaching, the progressive development of a bell-shaped speed profile, and the evolution of the management of redundant degrees of freedom. The model also produces testable predictions on several of these phenomena. Most of these empirical data have never been investigated by previous computational models and, more important, have never been accounted for by a unique model. In this respect, the analysis of the model functioning reveals that all these results are ultimately explained, sometimes in unexpected ways, by the same developmental trajectory emerging from the interplay of the three mentioned hypotheses: The model first quickly learns to perform coarse movements that assure a contact of the hand with the target (an achievement with great adaptive value) and then slowly refines the detailed control of the dynamical aspects of movement to increase accuracy.

Common solutions to resolve different dietary challenges in the ruminant dentition: The functionality of bovid postcanine teeth as a masticatory unit

Plasticity of tooth shape in mammals is of great adaptive value for the efficient exploitation of specific feeding niches and is a crucial mechanism for ecological diversification. In this study, we aimed to infer chewing effectiveness from the functional shape of different postcanine teeth within bovids, the most diverse extant group of large herbivorous mammals. We consider the postcanine dentition as a masticatory unit and test for differences related to food biomechanical properties, dietary abrasiveness, and chewing dynamics. We compare functional properties of the postcanine tooth row among species with well-known dietary strategies by integrating digitalization of high-resolution occlusal surface 3D-models of upper postcanine dentitions and quantification of the indentation index (D), a structural parameter representing enamel complexity. We test for differences in the occlusal shape among tooth positions in the postcanine dentition using robust, heteroscedastic tests in a one-way analysis of variance. Our results show three distinct patterns of enamel complexity along the tooth row: (1) D is more homogeneously distributed among tooth positions; (2) D increases gradually in the mesiodistal axis along the tooth row; and (3) D increases abruptly only at the transition between premolars and molars. We interpreted these patterns as different adaptive configurations of the postcanine tooth row relating to diet. Grass- and fruit-eating bovids show the same abrupt increase in enamel complexity at the transition from premolars to molars. Intermediate feeding and leaf-browsing species show the same gradual, mesiodistal increase in complexity along the tooth row. The absolute physical dietary resistance (biomechanical properties plus abrasiveness) and its relation to mechanical constraints of the chewing stroke are the likely selective factors leading to convergence of enamel complexity patterns along the tooth row among taxa with different diets.

Adaptive strategies of desmids in two tropical monomictic lakes in southeast Brazil: do morphometric differences promote life strategies selection?

Adaptive strategies of desmids in two tropical monomictic lakes were studied in relation to morphometric differences. The study aimed at evaluating desmids' strategies during inter-annual succession patterns in two tropical lakes (Dom Helvecio and Carioca) in southeast Brazil. From monthly samples of freshwater algae collected during five consecutive years (2002–2006) from the two lakes, the desmids were classified according to size, life form, and life strategies (competitive, stress tolerant, and ruderal). Our results indicated that Lake Carioca (19o45′20″S, 42o37′12″W), a small, shallow, turbid, and mesotrophic system showed dominance of invasive/opportunistic taxa (C) and R-strategists (Staurastrum species 50 μm) and tolerant to stress (S) species (Staurastrum and Staurodesmus species >20 μm). A significant number of desmids from the lakes had low MLD (≤20 μm), low volume ( 1). Consequently, C-strategist species were abundant and formed a group having great adaptive value in the lakes, with higher resilience and capacity to change composition after the turnover period. Stratification stability and atelomixis were the main driving forces to sustain high desmid biomass in these two lakes, despite the greater macrophyte richness and great water column depth at Lake Dom Helvecio and the main factor influencing richness and contribution of complex forms.

Emergent phenomena belong only to biology

In this philosophical paper, I discuss and illustrate the necessary three ingredients that together could allow a collective phenomenon to be labelled as “emergent.” First, the phenomenon, as usual, requires a group of natural objects entering in a non-linear relationship and potentially entailing the existence of various semantic descriptions depending on the human scale of observation. Second, this phenomenon has to be observed by a mechanical observer instead of a human one, which has the natural capacity for temporal or spatial integration, or both. Finally, for this natural observer to detect and select the collective phenomenon, it needs to do so on account of the adaptive advantage this phenomenon is responsible for. The necessity for such a teleological characterization and the presence of natural selection drive us to defend, with many authors, the idea that emergent phenomena should belong only to biology. Following a brief philosophical plea, we present a simple and illustrative computer thought experiment in which a society of agents evolves a stigmergic collective behavior as an outcome of its greater adaptive value. The three ingredients are illustrated and discussed within this experimental context. Such an inclusion of the mechanical observer and the natural selection to which this phenomenon is submitted should underlie the necessary de-subjectivation that strengthens any scientific endeavor. I shall finally show why the short paths taken by ant colonies, the collective flying of birds and the maximum consumption of nutrients by a cellular metabolism are strongly emergent.

Leaf-level plasticity of Salix gordejevii in fixed dunes compared with lowlands in Hunshandake Sandland, North China

To cope with adverse environments, the majority of indigenous plants in arid regions possess adaptive plasticity after long-term evolution. Leaf-level morphology, anatomy, biochemical properties, diurnal water potential and gas exchange of Salix gordejevii distributed in fixed dunes and lowlands in Hunshandake Sandland, China, were compared. Compared to plants growing in lowlands, individuals of S. gordejevii in fixed dunes displayed much smaller leaf area (0.26 vs 0.70 cm(2)) and thicker leaves (leaf total thickness 148.59 vs 123.44 mum), together with heavier crust wax, denser hairs, and more compacted epidermal cells. Moreover, those growing in fixed dunes displayed stronger drought-resistance properties as evidenced by higher levels of proline (3.68 vs 0.20 mg g(-1) DW) and soluble sugar (17.24 vs 14.49%). Furthermore, S. gordejevii in fixed dunes demonstrated lower water potential and lower light compensation point (28.8 vs 51.9 micromol m(-2) s(-1)). Our findings suggest that morphological and/or anatomical plasticity in leaves has had great adaptive value for Salix in responding to deteriorating environments. The evidence provided here may facilitate the prediction of plant adaptation in community succession in sandy habitats.

Sperm‐duct gland secretion of the grass goby Zosterisessor ophiocephalus exhibits antimicrobial activity

The grass goby Zosterisessor ophiocephalus sperm‐duct gland extract displayed antimicrobial activity against gram‐positive and gram‐negative bacteria. This suggests that sperm‐duct gland mucins might be functional in protecting eggs and possibly parents from pathogens, an activity of great adaptive value for Z. ophiocephalus, which lays eggs in mud nests.

Thyroid–Adrenergic Interactions: Physiological and Clinical Implications

The sympathoadrenal system, including the sympathetic nervous system and the adrenal medulla, interacts with thyroid hormone (TH) at various levels. Both systems are evolutionary old and regulate independent functions, playing probably independent roles in poikilothermic species. With the advent of homeothermy, TH acquired a new role, which is to stimulate thermogenic mechanisms and synergize with the sympathoadrenal system to produce heat and maintain body temperature. An important part of this new function is mediated through coordinated and, most of the time, synergistic interactions with the sympathoadrenal system. Catecholamines can in turn activate TH in a tissue-specific manner, most notably in brown adipose tissue. Such interactions are of great adaptive value in cold adaptation and in states needing high-energy output. Conversely, in states of emergency where energy demand should be reduced, such as disease and starvation, both systems are turned down. In pathological states, where one of the systems is fixed at a high or a low level, coordination is lost with disruption of the physiology and development of symptoms. Exaggerated responses to catecholamines dominate the manifestations of thyrotoxicosis, while hypothyroidism is characterized by a narrowing of adaptive responses (e.g., thermogenic, cardiovascular, and lipolytic). Finally, emerging results suggest the possibility that disrupted interactions between the two systems contribute to explain metabolic variability, for example, fuel efficiency, energy expenditure, and lipolytic responses.

The Psychopharmacological Treatment of Primary and Secondary Disorders of Aggression

Free AccessThe Psychopharmacological Treatment of Primary and Secondary Disorders of AggressionHans Steiner, Kirti Saxena and Kiki ChangHans SteinerSearch for more papers by this author, Kirti SaxenaSearch for more papers by this author and Kiki ChangSearch for more papers by this authorPublished Online:July 2005https://doi.org/10.1521/capn.9.7.1.62278PDFPDF PLUS ShareShare onFacebookTwitterLinkedInRedditEmail ToolsAdd to favoritesDownload CitationsTrack Citations AboutReferencesAmerican Psychiatric Association (2000). Diagnostic and statistical manual of mental disorders, Text Revision (DSM–TR), American Psychiatric Association, Washington, DC Google ScholarBlair, J., Coccaro, E., Connor, D., Ferziger, R., Leibenluft, E., Post, R., Swann, A., Steiner, H. (Stanford/Howard/AACAP Workgroup on Juvenile Impulsivity and Aggression). Juvenile Maladaptive Aggression: The Neuroscience of Maladaptive Aggression, 2004 Google ScholarConnor, D.F. Aggression and Antisocial Behavior in Children and Adolescents: Research and Treatment. 2002. New York, Guilford, 2002. Google ScholarConnor, D., Carlson, G., Chang, K., Daniolos, P., Ferziger, R., Findling, R., Hutchinson, J., Malone, R., Halperin, J., Plattner, B., Post, R., Reynolds, D., Rogers, K., Saxena, K., Steiner, H. (Stanford/Howard/AACAP Workgroup on Juvenile Impulsivity and Aggression). Juvenile Maladaptive Aggression: A Brief Review Of Treatment, Prevention, Service Configuration, And A Proposed Research Agenda, 2004. Google ScholarPappadopulos , E., Macintyre, Ii JC, Crismon, M.L. et al. 2003 Treatment recommendations for the use of antipsychotics for aggressive youth (TRAAY). Part II. Journal of the American Academy of Child & Adolescent Psychiatry42, 145–61. Crossref, Google ScholarSaxena, K., Steiner, H., Chang, K. (2003). Divalproex Sodium Reduces Aggression in Bipolar Offspring with Psychopathology. Scientific Proceedings Of The Annual Meeting Of The American Academy Of Child And Adolescent Psychiatry, 19, 149. Google ScholarSchur , S.B., Sikich, L., Findling, R.L., Malone, R.P., Crismon, M.L., Derivan, A., Macintyre, J.C., Pappadopulos, E., Greenhill, L., Schooler, N., Van Orden, K., Jensen, P.S. (2003). Treatment recommendations for the use of antipsychoticsfor aggressive youth (TRAAY). Part 1: A review. Journal of the American Academy of Child & Adolescent Psychiatry; 42, 132–44. Crossref, Google ScholarSilverman , M., Carrion, V., Chang, K., Matthews, Z., Peterson, M., Steiner, H. : Divalproex Sodium and PTSD Treatment: A Randomized Controlled Clinical Trial, Scientific Proceedings Of The Annual Meeting Of The American Academy Of Child And Adolescent Psychiatry, 17: 115, 2001 Google ScholarSteiner , H. (2002). The Evaluation And Management Of Aggression In Juveniles. New Directions In Psychiatry, 22 (11), 355–369. Google ScholarSteiner, H.(Ed). Handbook Of Mental Health Interventions in Children And Adolescents: An Integrated Developmental Approach. San Francisco, Wiley/Jossey–Bass, 2004. Google ScholarSteiner, H., Blair, J., Coccaro, E., Connor, D., Dougherty, D., Ferziger, R., Karnik, N., Youngstrom, E., (Stanford/Howard/AACAP Workgroup on Juvenile Impulsivity and Aggression). Juvenile Maladaptive Aggression: Taxonomy and Measurement, 2004 Google ScholarSteiner, H., Karnik, N. (2004). Child or adolescent antisocial behavior. In Sadock, B.J., Sadock, V.A. (Eds.) Comprehensive textbook of psychiatry/VIII, Vol 2, NY: Williams & Wilkins. Google ScholarSteiner , H., Saxena, K., Chang, K. (2003). Psychopharmacological strategies for the treatment of aggression in Youth. CNS Spectrums, 8(4), 298–308. Crossref, Google ScholarWorld Health Organization, 1992. The ICD–10 Classification of Mental and Behavioural Disorders. Clinical Descriptions and Diagnostic Guidelines. World Health Organization (WHO), Geneva. Google Scholar Next article FiguresReferencesRelatedDetails Volume 9Issue 7Nov 2004 Information© Guilford Publications Inc.PDF download

Is each light-harvesting complex protein important for plant fitness?

Many of the photosynthetic genes are conserved among all higher plants, indicating that there is strong selective pressure to maintain the genes of each protein. However, mutants of these genes often lack visible growth phenotypes, suggesting that they are important only under certain conditions or have overlapping functions. To assess the importance of specific genes encoding the light-harvesting complex (LHC) proteins for the survival of the plant in the natural environment, we have combined two different scientific traditions by using an ecological fitness assay on a set of genetically modified Arabidopsis plants with differing LHC protein contents. The fitness of all of the LHC-deficient plants was reduced in some of the growth environments, supporting the hypothesis that each of the genes has been conserved because they provide ecological flexibility, which is of great adaptive value given the highly variable conditions encountered in nature.

Morphological synergism in root hair length, density, initiation and geometry for phosphorus acquisition in Arabidopsis thaliana: A modeling approach

Low phosphorus availability regulates root hair growth in Arabidopsis by (1) increasing root hair length, (2) increasing root hair density, (3) decreasing the distance between the root tip and the point at which root hairs begin to emerge, and (4) increasing the number of epidermal cell files that bear hairs (trichoblasts). The coordinated regulation of these traits by phosphorus availability prompted us to speculate that they are synergistic, that is, that they have greater adaptive value in combination than they do in isolation. In this study, we explored this concept using a geometric model to evaluate the effect of varying root hair length (short, medium, and long), density (0, 24, 48, 72, 96, and 120 root hairs per mm of root length), tip to first root hair distance (0.5, 1, 2, and 4 mm), and number of trichoblast files (8 vs. 12) on phosphorus acquisition efficiency (PAE) in Arabidopsis. SimRoot, a dynamic threedimensional geometric model of root growth and architecture, was used to simulate the growth of Arabidopsis roots with contrasting root hair parameters at three values of phosphorus diffusion coefficient (De=1×10 −7 ,1 ×10 −8 , and 1×10 −9 cm 2 s −1 ) over time (20, 40, and 60 h). Depzone, a program that dynamically models nutrient diffusion to roots, was employed to estimate PAE and competition among root hairs. As De decreased from 1×10 −7 to 1×10 −9 cm 2 s −1 , roots with longer root hairs and higher root hair densities had greater PAE than those with shorter and less dense root hairs. At De=1×10 −9 cm 2 s −1 , the PAE of root hairs at any given density was in the order of long hairs > medium length hairs > short hairs, and the maximum PAE occurred at density = 96 hairs mm −1 for both long and medium length hairs. This was due to greater competition among root hairs when they were short and dense. Competition over time decreased differences in PAE due to density, but the effect of length was maintained, as there was less competition among long hairs than short hairs. At high De(1×10 −7 cm 2 s −1 ), competition among root hairs was greatest among long hairs and lowest among short hairs, and competition increased with increasing root hair densities. This led to a decrease in PAE as root hair length and density increased. PAE was also affected by the tip to first root hair distance. At low De values, decreasing tip to first root hair distance increased PAE of long hairs more than that of short hairs, whereas at high De values, decreasing tip to first root hair distance increased PAE of root hairs at low density but decreased PAE of long hairs at very high density. Our models confirmed the benefits of increasing root hair density by increasing the number of trichoblast files rather than decreasing the trichoblast length. The combined effects of all four root hair traits on phosphorus acquisition was 371% greater than their additive effects, demonstrating substantial morphological synergy. In conclusion, our data support the hypothesis that the responses of root hairs to low phosphorus availability are synergistic, which may account for their coordinated regulation.

Temperament, Cognitive Ability, Emotion Knowledge, and Adaptive Social Behavior

Few studies have related emotion knowledge to positive behavioral outcomes in middle childhood, and none of these included both temperament and cognitive ability in the analysis. In the present study of 166 seven-year-old children from economically disadvantaged families, we show that temperamental inhibition, cognitive ability, a traditionally studied index of emotion knowledge (emotion recognition), and emotion memories contribute to the concurrent prediction of adaptive social behavior. We also found that temperament and cognitive ability relate significantly to emotion recognition which, in turn, partially mediates the relations of inhibition and cognitive ability to adaptive social behavior. Emotion memories relate significantly to the behavioral outcome after removing the variance due to inhibition, cognitive ability, and emotion recognition. We argue that compared to memories tagged simply as good (pleasant) or bad (unpleasant) events, discrete emotion memories have greater adaptive value because they provide more useful information and have the capacity to facilitate the anticipation and management of emotion arousal.

An adaptationist view of apoptosis.

A cell's decision whether to undergo apoptosis (cell suicide) is examined here from an adaptationist perspective, rather than a mechanistic one. External and internal inputs to the cell's protein-based information processing network are used in making this decision, with the cell factoring in its replaceability. A system in which each cell takes primary responsibility for deciding its own fate has great adaptive value because it harnesses each cell's self-knowledge rather than waiting for external cues to be recognized by other cells. Cell self-destruction can be an important selective mechanism, potentially leading to better performance of tissues over time. However, reliance on cells to monitor themselves has a flaw, since cells may incur selfish mutations that impair their apoptotic responsibility. The tight control exerted over somatic cells serves to check selfish genes involved in neoplasia and viral infections. Germ cells appear to be similarly monitored, both by other germ cells and by supporting follicular or Sertoli cells, thus maintaining the advantages offered by an apoptotic system. The adaptationist approach views the limited replacement of neurons and cardiac myocytes as likely to have net survival value. The linkage of these cells into a network with their neighbors throughout a lifetime allows for a precisely functioning team of cells expected to compensate for gradual declines in individual cell functionality. Replacement of apoptotic cells with naive cells might decrease brain functionality and might risk upsetting the conduction of cardiac impulses. The evolutionary viewpoint lends itself to new hypotheses, but only the boldest speculator would have predicted a system in which cells are given primary responsibility for deciding whether to kill themselves when they deem it beneficial to the organism.

On fighting versus accepting stressful circumstances: primary and secondary control among HIV-positive men in prison.

The primacy of primary control over secondary control and ethnic differences in control processes were tested in HIV-positive male state prison inmates. They rated their perceptions of control and psychological distress at an initial interview (N = 95) and 3 months later (N = 78). Regression analyses revealed that primary control had primacy as it had greater adaptive value. However, secondary control did not function as a backup to primary control, and temporal differences in control were not found. No mean differences due to ethnicity (African American vs. White) were found, but there was a strong ethnic difference in the effects of primary control. White participants showed the expected negative relationship between distress and primary control, but African American participants did not. The idea that the benefits of primary control would be the same across various subcultures was not supported.

Circadian and lunar gamete release in Fucus vesiculosus in the atidal Baltic Sea

Released eggs from Fucus vesiculosus were counted every 12 or 4 h in the field and every 24 h in laboratory experiments at constant temperature and a 17 h light: 7 h dark cycle, mimiclung natural light conditions. A fortnightly rhythm was confirmed both in the field and in controlled laboratory stu&es, with a main egg release 2 d before full and new moon, but with indication of a minor weekly period of unequal amplitude. The highest daily release of eggs was typically found from 18:OO to 22:OO h. Dehydration was not found to influence the pattern of egg release and in the field no correlation was found with temperature or water level fluctuations. An endogenous clock in F. vesiculosus is suggested and different entraining factors presented and discussed. We further suggest that the observed rhythmicity is of great adaptive value for coordination of gamete release in a dioecious species like F. vesiculosus in the atidal environment of the Baltic Sea, where this species occurs almost always submerged. Ecologically, the cyclic gamete release means that reproduction and recruitment are reduced to a few occasions during the reproductive period, which was earlier assumed to be several months long. This information may be crucial in the successful management of this ecologically important species in the Baltic Sea which has been severely reduced in abundance in recent decades due to pollution.

An ecological theory for the origin ofHomo

The genusHomoevolved its pronounced encephalization through postnatal extension of the high rate of brain growth that characterizes all primatesin utero.Linked to this extension was delayed development, which represented an enormous ecological sacrifice because it produced the longest postnatal interval of physical helplessness in the Mammalia and forced mothers to carry infants.Graphs relating brain growth to body growth indicate a pongid pattern of development for gracile australopithecines, implying that infants could cling to mothers whose forelimbs were occupied with climbing. Also present were several postcranial traits that would have made the adults more adept climbers than modern humans. Habitual use of these inherited traits is suggested by the fact that evolution failed to eliminate certain ones, such as short legs and long pedal phalanges, that impeded terrestrial locomotion. Moreover, the intensity of predation by large, swift, social carnivores must have compelled australopithecines to use trees as refuges, in the manner of chimpanzees and baboons; australopithecines probably also gathered some of their food in trees. Gracile australopithecines failed to expand their brain size, experiencing general evolutionary stasis for more than 1.5 m.y. I propose that this stability resulted from these animals' semiarboreal mode of life: First, their postcranial morphology remained compromised by selection pressures to maintain both terrestrial and arboreal adaptations. Second, by requiring that neonates be mature enough to cling to mothers, obligate arboreal activity precluded encephalization of the kind that characterizesHomo;this evolutionary constraint has previously been overlooked.In contrast to australopithecines, earlyHomoapproachedH. erectusin pelvic configuration and brain size. A new brain-body growth curve for earlyHomoindicates extension of the fetal pattern well into the postnatal interval, implying that neonates were highly immature so that adults had to be fully terrestrial.Homoevolved shortly after the onset of the modern ice age about 2.5 Ma. Fossil pollen and carbon isotopes in paleosols record a contraction of forests in Africa at this time. I propose that this represented a crisis that led to the evolution ofHomoby compelling some australopithecine populations to adopt a fully terrestrial existence. Although ecologically difficult, this behavioral restriction finally made possible encephalization through the evolution of delayed development. During the ecological crisis, a large brain evolved in at least one population of gracile australopithecines. An advanced tool industry and cunning behavior were of such great adaptive value for avoiding predators and expanding food resources on the ground that selection for encephalization soon overrode the problems imposed by helpless infants.The fossil record of antelopes and micromammals provides a test of the idea that environmental forcing opened the way for the evolution ofHomo:both of these groups experienced heavy extinction of forest-adapted species about 2.5–2.4 Ma and a rapid proliferation of species adapted to unforested habitats. The transformation of the hominid clade during Plio-Pleistocene time did not follow a simple pattern.Homomay have arisen either by anagenetic transformation of a “bottlenecked” species or by speciation, and it may not have evolved immediately with the onset of climatic change. Furthermore, just as a few forest-adapted antelope species survived the biotic crisis, a small-brained gracile taxon with arboreal adaptations may have persisted to the start of the Pleistocene. Robust australopithecines survived into the Pleistocene, perhaps because a broad vegetarian diet reduced their need to migrate frequently between home bases. With their extinction in mid-Pleistocene time, about the time that savannahs became widespread, onlyHomoremained.