Mathematical biosociology of beliefs and prejudices

Following a suggestion made previously (Bull. Math. Biophysics,13, 61, 1951), it is assumed that every individual has both a tendency to behavearationally, by accepting everything on faith, and rationally, by subjecting everything to rational analysis. Arational behavior is characterized by various beliefs, prejudices, etc., which are considered to be conditioned reactions, learned by the individual before he completely develops his faculties for rational thinking. The two tendencies are assumed to be due to excitations of two different regions of the central nervous system, and are measured by the intensities ɛ _f and ɛ _r of those excitations. Those intensities are further assumed to increase linearly with time, the increases of the two beginning, in general, at different ages. The rates of increase are considered as normally distributed in the population. The relative frequency of arational and rational behavior is determined by the difference φ=ɛ _f =ɛ _r according to equations 0 developed previously (Bull. Math. Biophysics,11, 255, 1949). It is shown that with the above assumptions the majority of the population, which starts with arational behavior, will, within two or three of generations, either change to rational behavior or continue indefinitely to behave arationally. This will hold as long as imitative factors are present. Expressions for the numbers of individuals who behave rationally and arationally are derived. If the intensity of conditioning toward an arational behavior decreases with increasing size of the rationally behaving minority, or, if the rationally behaving individuals are not influenced by imitation, then a slow secular trend toward rational behavior may be present. An expression is also derived for the fraction of individuals who behave rationally as a function of age. This fraction increases with increase of the age at which the beginning conditioning toward any beliefs or prejudices begins.     

Some remarks on the mathematical bio-sociology of the relativity of injustice

The author's theory of the adoption of certain types of behavior patterns (Rashevsky, N., 1957, “Contributions to the Theory Initiative Behavior”.Bull. Maths. Biophysics,19, 91–119; 1968,Looking at History through Mathematics, Cambridge, Massachusetts: M.I.T. Press) consisting of elementary behaviors for each of which there is an opposite one and the two are mutually exclusive, is applied to describe the changes in the general type of behavior of a society. The elementary acts of which the whole problem consists may be either overt activities or beliefs or opinions. The general behavior patternsadopted by the society are considered as the “proper” or “just” ones. Any deviation from it in either one or more of the component elementary behaviors is considered as “unjust” and is subject to some punitive action. The total number of possible mutually exclusive behavior patterns is very large but finite. Within this very large range of possible patterns, we find that this notion of justice is relative, because changes from any behavior pattern to any other may occur. It is further shown that the amount of punishment for the deviation from the accepted pattern in order to be effective as well as efficient must be applied in different ways to different individuals even for the same transgression.     

Physical contact between soldier and worker is essential in soldier self-regulation of Coptotermes formosanus (Isoptera, Rhinotermitidae)

In a termite society, the soldier proportion is regulated at a species-specific level with a seasonal fluctuation. A feedback mechanism in soldier proportion regulation is well recognized, while the proximate means by which the presence of soldiers inhibits the new soldier formation from workers remains mostly elusive. In the present study, some possible means for this inhibition were tested with the Formosan subterranean termite, Coptotermes formosanus Shiraki. The results showed that neither soldier-originated volatiles nor non-volatile chemicals without physical contact were responsible for the inhibition of new soldier formation. The essentiality of physical contact between workers and soldiers in soldier regulation was established. However, by physical contacts, as the soldier-replacement experiment showed, workers could not individually recognize or “count” soldiers to maintain a set soldier proportion. The possible feedback mechanisms for soldier regulation are discussed.     

The role of the individual in social dynamics

The mathematical theories of social dynamics developed previously are deterministic and leave no room for the effects of single “exceptional” individuals. They all, however, lead to the existence of instability points and threshold phenomena. It is shown that in the neighborhood of such instability points, exceptional individuals, who appear rarely, can appreciablyadvance orretard the moment at which the instability is reached and at which a sudden change in the society occurs. Such individuals, however, do not eitherprevent orcause the instability, or the change, to occur. The indeterminacy introduced by “rare” individuals into the time course of social change is inversely proportional to the rate of social change.     

Behavioral modification in choice process of<Emphasis Type="Italic">Drosophila</Emphasis>

In visual operant conditioning ofDrosophila at the flight simulator, only motor output of flies—yaw torque—is recorded, which is involved in the conditioning process. The current study used a newly-designed data analysis method to study the torque distribution ofDrosophila. Modification of torque distribution represents the effects of operant conditioning on flies’ behavioral mode. Earlier works^[10] showed that, when facing contradictory visual cues, flies could make choices based upon the relative weightiness of different cues, and it was demonstrated that mushroom bodies might play an important role in such choice behavior. The new “torque-position map” method was used to explore the CS-US associative learning and choice behavior inDrosophila from the aspect of its behavioral mode. Finally, this work also discussed various possible neural bases involved in visual associative learning, choice processing and modification processing of the behavioral mode in the visual operant conditioning ofDrosophila.     

Promising Strategies for the Mineralisation of 2,4,6-trinitrotoluene

2,4,6-trinitrotoluene (TNT) is known to be one of the most common military explosives. In spite of its established toxicity and mutagenicity for many organisms, soils and groundwater are still being frequently contaminated at manufacturing, disposal and TNT destruction sites. The inability of natural aquatic and soil biota to use TNT as growth substrate has been recognized as the primary limitation in the application of bioremediation processes to contaminated environments. However, promising degradation pathways have been recently discovered which may lead to the mineralisation of TNT. Significant advances have been made in studying the mechanism of TNT denitration, which can be considered as the major reaction and the driving force towards beneficial biodegradation. The possibilities to favour TNT denitration are discussed based on current knowledge of the enzymology and genetics of denitration in nitroaromatic degrading organisms. The literature survey demonstrates that the only enzymes characterized so far for their denitrase activity towards TNT belong to the class I flavin-dependent β/α barrel oxidoreductases, also known as the “Old Yellow Enzyme” family. In addition, this review provides an overview of strategies and future directions towards a rational search for new catabolic activities, including metagenomic library screening, plus new possibilities to improve the activity of known catabolic enzymes acting on TNT, such as DNA shuffling.     

Mate choice in modern societies

Most research on mate choice in modern societies is based on data that may or may not reflect actual mating behavior (e.g., stated preferences, personal advertisements). In the present study, real-life matings were reported by a large representative sample of men and women (N = 1,133). These data were used to test an evolutionary model in which mate choice is hypothesized to depend on resources potentially contributed to reproduction by each sex. Consistent with the model, it was found that (a) men (but not women) of higher social status acquire more mating partners, suggesting that male status is an important criterion in female choice; (b) women’s (but not men’s) number of partners decreases linearly with age, suggesting that female reproductive potential is an important criterion in male choice; and (c) women (but not men) display a significant relationship between marital dissolution and promiscuity, suggesting that female sexual exclusivity is an important criterion in male choice. These results are discussed in relation to understanding mate choice mechanisms from behavioral data. Daniel Pérusse is an assistant professor in the Department of Anthropology at the Université de Montréal. His research interests include the evolutionary biology of human social and reproductive behavior, sexual selection theory, and biocultural evolution. His current research bears on human socialization processes and psychosocial development from an evolutionary and behavior-genetic perspective. Recent publications include “Cultural and Reproductive Success in Industrial Societies: Testing the Relationship at the Proximate and Ultimate Levels” (Behavioral and Brain Sciences 16(2):267–322, 1993) and “Human Parental Behavior: Evidence for Genetic Influence and Potential Implications for Gene-Culture Theory” with M. C. Neale, A. Heath, and L. J. Eaves (Behavior Genetics, in press).     

A contribution to the mathematical biology of social behavior: Riots by oppressed groups

The author’s theory of imitation or mass behavior (N. Rashevsky:Mathematical Biology of Social Behavior, chapter xii, revised edition. Chicago: The University of Chicago Press, 1959; also Rashevsky:Looking at History through Mathematics, Cambridge, Mass.: The MIT Pres, 1968), when society chooses one of two mutually exclusive behaviors, is applied to the interaction of two social groups, an oppressor group and an oppressed one. Using crude approximations, conditions are derived as to when the oppressed group will revolt or riot, when the revolt will be suppressed, and when the oppressors will completely give in and oppression will end. Even in the simple approximation used, the situation depends on 14 parameters showing that a simplistic view on riots such as mere strong punishments is utterly inadequate. It is also shown that situations may exist in which revolution-like changes from one type of behavior of a society to another cannot be prevented by any measures.     

Induction of Excision Repairable DNA Lesions in Lymphocytes Exposed to Lead and ALA In Vitro

Numbers of studies have been carried out on the potential of lead genotoxicity. The mechanisms of lead genotoxicity are not fully known but partly attributed to the formation of highly reactive oxygen metabolites (ROM). However, lead ions have no ability to generate ROM. In this study, we have investigated the ability of lead and ALA to induce excision repairable DNA lesions by using cytosine arabinoside or cytokinesis block micronucleus (ARA-C/CBMN) assay. N-methyl-N-nitrosourea was used as a positive control which is a mutagen and known to induce excision repair. The results of the ARA-C/CBMN assay show that ALA exposures have significantly (p < 0.01) increased the ratio of excision repairable DNA lesions in peripheral blood lymphocytes; however, lead have not. Accordingly, accumulation of ALA should be considered as an effective partner of lead induced DNA damage in lead exposure.     

Some generalized conjugacy theorems and the concepts of fitness and survival in logistic growth models

Current research into the dynamics of iterative ecological and biological models has lead to a number of theorems concerning the existence of various types of iterative dynamical behavior. In particular, much study has been done on the dynamical behavior of the “simplest dynamical system”f _b(x)=bx(1−x), which is just the canonical discrete form of logistic growth equations found in ecology, sociobiology, and population biology. In this paper, we make use of some of the techniques and concepts of topological dynamics to construct a number of generalized conjugacy theorems. These theorems are then used to demonstrate that the mappingf _b has a number of conjugacy classes in which the dynamics of the iterates is equivalent to within a change of variables. The concepts of fitness and survival in logistic equations are then shown to be independent, if we follow certain intuitive definitions for these concepts. This conclusion follows from a comparison of the conjugacy classes of the functionf _b and the extinction sets off _b.     

Positional Behavior of Delacour’s Langurs (Trachypithecus delacouri) in Northern Vietnam

Information on positional behavior can help elucidate relationships between a species’ morphology, behavior, and environment. Delacour’s langurs (Trachypithecus delacouri) are similar to other colobines in body mass and intermembral index, yet inhabit a limestone karst environment. From August 2007 to July 2008, we collected 372 h of positional behavior and substrate use data from 8 groups of Trachypithecus delacouri in Van Long Nature Reserve, Vietnam to address questions about how the distinct —and potentially dangerous— features of karst influence colobine positional behavior. Results show that Trachypithecus delacouri is predominantly quadrupedal (66%). However, they exhibit differences that set them apart from many other colobines. Nearly 80% of locomotor and postural behaviors were performed on rocks. Leaping was remarkably infrequent, representing only 6% of overall locomotion. They leapt 3 times more frequently on trees (13%) than on rocks (4%) and more frequently used trees as a landing substrate than rocks (38% vs. 23%), both significant differences. We argue that rock (and cliff) travel is altogether different from terrestrial and arboreal travel and propose using the term petrous to indicate the substrate and incorporate the implications of its precise sharpness and verticality that lead to the complexities and risk of locomotion on rock surfaces. Trachypithecus delacouri does not show specific adaptations for limestone karst. Instead they appear to be a behaviorally flexible species and, owing to the generalized locomotor capabilities that characterize cercopithecids, capable of locomoting through and living in the limestone rock environment to which they have relatively recently been restricted.     

Nonadditive Interactions in Protein Folding: The Zipper Model of Cytochrome <Emphasis Type="Italic">c</Emphasis>

Hydrogen exchange experiments (Krishna et al. in J. Mol. Biol. 359:1410, 2006) reveal that folding–unfolding of cytochrome c occurs along a defined pathway in a sequential, stepwise manner. The simplified zipper-like model involving nonadditive coupling is proposed to describe the classical “on pathway” folding–unfolding behavior of cytochrome c. Using free energy factors extracted from HX experiments, the model can predict and explain cytochrome c behavior in spectroscopy studies looking at folding equilibria and kinetics. The implications of the proposed model are discussed for such problems as classical pathway vs. energy landscape conceptions, structure and function of a native fold, and interplay of secondary and tertiary interactions.     

Molecular dynamic simulations of electric microfield distributions in a nonideal electron-positron plasma

A symmetric model of a two-component plasma is considered and the distributions of electric microfields acting on charged and neutral particles are calculated using the method of molecular dynamics at a fixed temperature of T = 30000 K and different values of the coupling parameter 0.2 ≤ Γ ≤ 1.2. Changes in these distributions with varying Γ are discussed. Special attention is paid to the behavior of the distribution tails. The behavior of these tails at a neutral point is shown to agree with the tails of the Holtsmark distribution, whereas the tails of the distribution at a charge are considerably heavier and are characterized by the exponent that varies within the range from −2.2 up to −1.8 as Γ increases.     

Stone handling by Japanese macaques (Macaca fuscata): Implications for tool use of stone

Stone-play, a newly innovated cultural behavior, has been observed among the free-ranging Arashiyama B troop Japanese macaques near Kyoto, Japan since 1979. Conditions in which the non-purposeful handling of stones might possibly give rise to tool behavior are discussed. The progression of this behavior is traced through three phases: transmission, tradition, and transformation. During the first two phases, through social learning, the behavior was established within the group as a regular item of their behavioral repertoire and was most frequently observed after eating provisioned grain. In the third phase, observations suggest a “faddish” shift in the practice of certain behavioral sub-types between 1984 and 1985. During this period young individuals increasingly began to carry stones away from the feeding station, mixing stone manipulation with forage-feeding activities in the forest. Observations suggest under such conditions, stone handling is likely to lead to the occasional use of stone as a tool. This conclusion probably can be applied to species other thanMacaca fuscata. Consideration of the eco-setting and social learning correlates of stone handling suggests how the instrumental use of stone might emerge from a tradition of non-instrumental manipulation.     

Genetic improvement of brewer’s yeast: current state, perspectives and limits

Brewer’s yeast strain optimisation may lead to a more efficient beer production process, better final quality or healthier beer. However, brewer’s yeast genetic improvement is very challenging, especially true when it comes to lager brewer’s yeast (Saccharomyces pastorianus) which contributes to 90% of the total beer market. This yeast is a genetic hybrid and allopolyploid. While early studies applying traditional genetic approaches encountered many problems, the development of rational metabolic engineering strategies successfully introduced many desired properties into brewer’s yeast. Recently, the first genome sequence of a lager brewer’s strain became available. This has opened the door for applying advanced omics technologies and facilitating inverse metabolic engineering strategies. The latter approach takes advantage of natural diversity and aims at identifying and transferring the crucial genetic information for an interesting phenotype. In this way, strains can be optimised by introducing “natural” mutations. However, even when it comes to self-cloned strains, severe concerns about genetically modified organisms used in the food and beverage industry are still a major hurdle for any commercialisation. Therefore, research efforts will aim at developing new sophisticated screening methods for the isolation of natural mutants with the desired properties which are based on the knowledge of genotype–phenotype linkage.     

Mathematical biology of social behavior: III

A society composed of individuals each of whom can perform one of two mutually exclusive activitiesR ₁ andR ₂ is considered. The tendency toward the performance of those activities is measured by the intensities ε₁ and ε₂ of excitation of two corresponding neural centers, which cross-inhibit each other. It follows from the theory developed by H. D. Landahl that an individual with ε₁ − ε₂ = 0, that is one who has no preference for either one of the two activities, will on the average performR ₁ andR ₂ with equal probability. As ε₁ − ε₂ increases, the probabilityP ₁ ofR ₁ increases, tending to 1. As ε₂ − ε₁ increases, the probabilityP ₂ ofR ₂ increases, tending to 1. We haveP ₁+P ₂=1. The effect of imitation is now studied. The total number of individuals in the society which exhibits an activityR ₁ at a given time is considered as constituting a stimulus which increases ε₁. Similarly, the total number of individuals which exhibits activityR ₂ at a given time constitutes a stimulus which increases ε₂. Using the standard equations of the mathematical biophysics of the central nervous system, equations are established which govern the behavior of such a society and the following conclusions are reached. It the quantity ε₁ − ε₂ is distributed in the society in such a way that the distribution function is symmetric with respect to ε₁ − ε₂ = 0, then on the average one-half of the population exhibitsR ₁, the other halfR ₂. This social configuration may, however, be unstable. The slightest accidental excess of individuals exhibiting, for example,R ₁, may bring it into a stable configuration, in which most individuals exhibitR ₁, and only a smaller fraction exhibitR ₂. A slight initial deviation in favor ofR ₂ brings it into a stable configuration, in which most individuals exhibitR ₂. Thus in this case there may be two stable configurations. If the population is in one of those stable configurations, and the distribution function of ε₁ − ε₂ is made asymmetric, favoring the other activity, the population will pass into a stable configuration, in which that other activity is predominant, if the asymmetry of the distribution exceeds a threshold value. By making some drastic simplifications the equations derived here may be reduced to a form which waspostulated by the author previously in his mathematical theory of human relations.     

Recommended Method for Chromosome Exploitation: RMCE-based Cassette-exchange Systems in Animal Cell Biotechnology

The availability of site-specific recombinases has revolutionized the rational construction of cell lines with predictable properties. Early efforts were directed to providing pre-characterized genomic loci with a single recombinase target site that served as an address for the integration of vectors carrying a compatible tag. Efficient procedures of this type had to await recombinases like ΦC31, which recombine attP and attB target sites in a one-way reaction – at least in the cellular environment of the higher eukaryotic cell. Still these procedures lead to the co-introduction of prokaryotic vector sequences that are known to cause epigenetic silencing. This review illuminates the actual status of the more advanced recombinase-mediated cassette exchange (RMCE) techniques that have been developed for the major members of site-specific recombinases (SR), Flp, Cre and ΦC31. In RMCE the genomic address consists of a set of heterospecific recombinase target (RT-) sites permitting the exchange of the intervening sequence for the gene of interest (GOI), as part of a similar cassette. This process locks the GOI in place and it is ‘clean’ in the sense that it does not co-introduce prokaryotic vector parts nor does it leave behind a selection marker.     

Prolegomena to a dynamics of ideologies

The paper outlines a possible further development of the suggestion made by the author in his recent book. Ideology is defined here as a verbalized, or at least verbalizable, behavior pattern which may be adopted by society. After a brief discussion of possible classifications of ideologies, a study is made of those ideologies which refer to the question of social and ethical interrelations. Different kinds of ideologies may be represented bybehavior matrices, introduced in the author's book. A uniparametric representation of all such matrices is suggested and discussed. Next the previous results on social imitation are extended to the case ofn different behaviors, each of which is determined by a particular value of a continuously varying parameter. It is shown that, depending on some other social parameters, changes from one ideology to another may proceed either quasicontinuously or definitely discontinuously. The paper concludes with some general speculations on the possibility of applying the above results to a mathematical interpretation of history.     

Developmental and evolutionary assumptions in a study about the impact of premature birth and low income on mother–infant interaction

In order to study the impact of premature birth and low income on mother–infant interaction, four Portuguese samples were gathered: full-term, middle-class (n = 99); premature, middle-class (n = 63); full-term, low income (n = 22); and premature, low income (n = 21). Infants were filmed in a free play situation with their mothers, and the results were scored using the CARE Index. By means of multinomial regression analysis, social economic status (SES) was found to be the best predictor of maternal sensitivity and infant cooperative behavior within a set of medical and social factors. Contrary to the expectations of the cumulative risk perspective, two factors of risk (premature birth together with low SES) were as negative for mother–infant interaction as low SES solely. In this study, as previous studies have shown, maternal sensitivity and infant cooperative behavior were highly correlated, as was maternal control with infant compliance. Our results further indicate that, when maternal lack of responsiveness is high, the infant displays passive behavior, whereas when the maternal lack of responsiveness is medium, the infant displays difficult behavior. Indeed, our findings suggest that, in these cases, the link between types of maternal and infant interactive behavior is more dependent on the degree of maternal lack of responsiveness than it is on birth status or SES. The results will be discussed under a developmental and evolutionary reasoning.