The Inability of Primary School to Introduce Children to the Theory of Biological Evolution

A great number of research papers in the English literature of science education present difficulties pupils have in understanding natural selection. Studies show that children have essentialist and teleological intuitive ideas when dealing with organisms and that these biases hinder their ability to understand the theory of evolution by natural selection. Consequently, it is interesting to ascertain if and how the school education offered today deals with the problem, i.e., helps the children confront these biases. To that purpose, this study answered the two following research questions: (a) How is biological evolution presented—from the past to the present day—in the official documentation of primary school education, namely the science curricula and the textbooks of Greece? and (b) what are the conceptions held by Greek primary school teachers of the concepts of evolutionary theory and relevant issues that they have to teach? Our research found that not only are the intuitive ideas not “confronted” but they are also “affirmed” in Greek primary education. This phenomenon, as some other international studies have shown, must not be only a Greek one. A drastic change in the content and structure of primary school curricula and the training of educators is necessary in order to improve and facilitate the teaching of biological evolution.     

Psychological essentialism from first principles

Cognitive scientists have documented the existence of “essentialist” intuitions in humans: from a very early age, we assume that things have deep unobserved properties that make them what they are. I provide a sketch of an adaptationist explanation of psychological essentialism, arguing that these intuitions are the unsurprising output of adaptations for inductive inference. Variations on this insight have previously been used mostly as after-the-fact speculations, yet theories of adaptive function should ideally have a primary role in informing psychological research. Here I propose that viewing essentialist intuitions through an adaptationist lens has implications for some widespread assumptions about the phenomenon. Notably, researchers' focus on “higher-level” processes like categorization has led them to assume that essentialism is restricted to a few cognitive processes, but the ubiquity of inductive inference problems in cognition suggests otherwise. Additionally, because essentialist intuitions are the output of mechanisms solving related but distinct inference problems, it is unlikely that a single mechanistic theory can account for them all.     

Essentialism and typological thinking in biological systematics

In biological literature, essentialism and typological thinking are believed to be incompatible with evolutionary ideas. At present, the same considerations underlay the claims to abandon the Linnaean hierarchy, or the fundamental classificatory structure rooted in essentialism. This paper suggests to reconsider the negative views of Plato's typology and Aristotle's essentialism following the narrow interpretations that have nothing to do with the classification of living beings. Plato's theory of 'ideas' (or 'forms') is the basis of classificatory theory; it provided such concepts as 'species', 'genus', 'essence', 'dichotomous division' but the development of this theory in the framework of moral and esthetic values could not be beneficial to biology. Aristotle's essentialism is more complicated and exists in two forms; one of these, or classificatory essentialism, is a modification of Plato's typology; another one, or organismal essentialism, represents the shift of 'essence' from the world of relations between objects to the realm of particular things, where the concept of essence lost its basic meaning. It is senseless to look for unreal 'type of an organism' ('essence of a thing') but precisely this kind of essentialism is attractive for biologists and philosophers. Organismal essentialism is the underlying basis of so-called 'individuality thesis' that is used as a weapon against classificatory essentialism. The same thesis is associated with an extensional vision of taxa that also explains the criticism of Linnaean hierarchy, while the latter is the intentional structure and the first tool suggested for the rank coordination of many unequal taxa.     

Non-essentialist methods in pre-Darwinian taxonomy

The current widespread belief that taxonomic methods used before Darwin were essentialist is ill-founded. The essentialist method developed by followers of Plato and Aristotle required definitions to state properties that are always present. Polythetic groups do not obey that requirement, whatever may have been the ontological beliefs of the taxonomist recognizing such groups. Two distinct methods of forming higher taxa, by chaining and by examplar, were widely used in the period between Linnaeus and Darwin, and both generated polythetic groups. Philosopher William Whewell congratulated pre-Darwinian taxonomists for not adhering to the rigid ideal of definition used in the mathematical sciences. What he called the method of types is here called the method of exemplars because typology has been equated with essentialism, whereas the use of a type species as the reference point or prototype for a higher category was a practice inconsistent with essentialism. The story that the essentialism of philosophers dominated the development of systematics may prove to be a myth.     

The Relationship between Cultural Anxiety and Ethnic Essentialism: The Mediating Role of an Endorsement of Multicultural Ideology

Many studies have explored the social consequences of ethnic essentialism in recent decades. In addition, a few studies have focused on the impact of perceived cultural context on ethnic essentialism. However, it is not clear why perceived cultural context can lead to changes in ethnic essentialism. In the present study, we hypothesized that the cultural anxiety of ethnic minorities may trigger a strong endorsement of and support for a multicultural ideology, thereby affecting beliefs about ethnic groups. To address the issue, 226 Tibetan and 102 Hui college students from Mainland China completed our questionnaires. The results across the two samples showed that (1) cultural anxiety was positively associated with both the endorsement of a multicultural ideology and ethnic essentialism, (2) cultural anxiety and the endorsement of a multicultural ideology positively predicted ethnic essentialism after controlling for demographic variables, and (3) cultural anxiety had both a direct effect on ethnic essentialism and an indirect effect on ethnic essentialism through the endorsement of a multicultural ideology. Our findings suggest that when ethnic minorities experience cultural anxiety, they might endorse a multicultural ideology and adopt essentialism to affirm their ethnic identities.     

Estimating evolutionary parameters when viability selection is operating

Some individuals die before a trait is measured or expressed (the invisible fraction), and some relevant traits are not measured in any individual (missing traits). This paper discusses how these concepts can be cast in terms of missing data problems from statistics. Using missing data theory, I show formally the conditions under which a valid evolutionary inference is possible when the invisible fraction and/or missing traits are ignored. These conditions are restrictive and unlikely to be met in even the most comprehensive long-term studies. When these conditions are not met, many selection and quantitative genetic parameters cannot be estimated accurately unless the missing data process is explicitly modelled. Surprisingly, this does not seem to have been attempted in evolutionary biology. In the case of the invisible fraction, viability selection and the missing data process are often intimately linked. In such cases, models used in survival analysis can be extended to provide a flexible and justified model of the missing data mechanism. Although missing traits pose a more difficult problem, important biological parameters can still be estimated without bias when appropriate techniques are used. This is in contrast to current methods which have large biases and poor precision. Generally, the quantitative genetic approach is shown to be superior to phenotypic studies of selection when invisible fractions or missing traits exist because part of the missing information can be recovered from relatives.     

The history of essentialism vs. Ernst Mayr's “Essentialism Story”: A case study of German idealistic morphology

Idealistic morphology as perhaps the most important historical manifestation of typology is very suitable for a historical analysis of Ernst Mayr's “Essentialism Story”, which postulates an antagonism between “typological thinking” and “population thinking”. We show that German-language idealistic-morphological theories consisted of two clearly distinguishable parts. The cornerstone of these theories was the concept of the type as an abstract pattern representing a certain class of phenomena and embodying the norm of this class. The primary objective of pure typology was to create a non-phylogenetic classification system for living organisms based on structurally explicable characters. Thus, typology, as a non-phylogenetic foundation of idealistic morphology, was conceptually neutral with respect to hypotheses of evolutionary mechanisms. Typology was often accompanied by concepts such as Lamarckism, orthogenesis, creationism, essentialism, etc. These peripheral (with respect to pure typology) concepts were autonomous constructions and did not represent a direct logical consequence of typology. In our view “population thinking”, as part of the Darwinian theory of evolutionary mechanism, could not be directly opposed to “typological thinking”. Rather, it was peripheral concepts such as essentialism or creationism that led to conflicts between the Modern Synthesis and idealistic morphology.     

Pollution and agricultural practices. 2 concepts: acceptable daily dose and chemo-defense

Pollution coming from agricultural practices can exist: pesticides, veterinary drugs, heavy metals but also mycotoxins. However, these contaminants are always at low or trace doses in our environment (foods, water, air, soils). In terms of foods, two concepts have been developed to protect the consumers: acceptable daily intake (ADI) and maximum residue limits (MRL). The impact of this pollution on public health is not evident, in contradiction with the level of fear in the population. Moreover, the distinction made between natural and synthetic substances by the public in terms of toxicity is quite nonsense scientifically. Human beings and all living organisms have a good defence system against chemical xenobiotics which ensures their protection.     

A comparison of methods to estimate cross-environment genetic correlations

Advanced techniques for quantitative genetic parameter estimation may not always be necessary to answer broad genetic questions. However, simpler methods are often biased, and the extent of this determines their usefulness. In this study we compare family mean correlations to least squares and restricted error maximum likelihood (REML) variance component approaches to estimating cross-environment genetic correlations. We analysed empirical data from studies where both types of estimates were made, and from studies in our own laboratories. We found that the agreement between estimates was better when full-sib rather than half-sib estimates of cross-environment genetic correlations were used and when mean family size increased. We also note biases in REML estimation that may be especially important when testing to see if correlations differ from 0 or 1. We conclude that correlations calculated from family means can be used to test for the presence of genetic correlations across environments, which is sufficient for some research questions. Variance component approaches should be used when parameter estimation is the objective, or if the goal is anything other than determining broad patterns.     

Understanding the nutrigenomic definitions and concepts at the food-genome junction

The marked differences in individual response to dietary factors have led to major controversies in nutrition and puzzled nutrition scientists over the last century. The emerging field of nutrigenomics helps us to understand the basis for some of these differences and also promises us the ability to tailor diet based on individual genetic makeup. Great advances in Human Genome Project, documentation of single nucleotide polymorphisms (SNPs) in candidate genes and their association with metabolic imbalances have gradually added new tests to the nutrigenomic panel. Studies based on ethnopharmacology and phytotherapy concepts showed that nutrients and botanicals can interact with the genome causing marked changes in gene expression. This has led to the commercial development of nutraceuticals and functional foods that can modify negative health effects of individual genetic profile bringing the field to the "food/genome" junction. Despite the promise of nutrigenomics to personalize diet, there is skepticism whether it can truly bring about meaningful modification of the risk factors connected to chronic diseases, due to the lack of large scale nutrition intervention studies. Several intervention studies currently underway in the United States and abroad (Israel, Spain, and France) will further help validate nutrigenomic concepts. France has already introduced a National Nutrition and Health Program to assess nutritional status and risk of major metabolic diseases. As the field(s) related to nutritional genomics advance in their scope, it is essential that: (a) strict guidelines be followed in the nomenclature and definition of the subdisciplines; and (b) the state/federal regulatory guidelines be updated for diagnostic laboratories, especially for those offering tests directly to the public (without a physician's request) to help protect the consumer.     

The demographic history of populations experiencing asymmetric gene flow: combining simulated and empirical data

Population structure can significantly affect genetic-based demographic inferences, generating spurious bottleneck-like signals. Previous studies have typically assumed island or stepping-stone models, which are characterized by symmetric gene flow. However, many organisms are characterized by asymmetric gene flow. Here, we combined simulated and empirical data to test whether asymmetric gene flow affects the inference of past demographic changes. Through the analysis of simulated genetic data with three methods (i.e. bottleneck , M-ratio and msvar ), we demonstrated that asymmetric gene flow biases past demographic changes. Most biases were towards spurious signals of expansion, albeit their strength depended on values of effective population size and migration rate. It is noteworthy that the spurious signals of demographic changes also depended on the statistical approach underlying each of the three methods. For one of the three methods, biases induced by asymmetric gene flow were confirmed in an empirical multispecific data set involving four freshwater fish species (Squalius cephalus, Leuciscus burdigalensis, Gobio gobio and Phoxinus phoxinus). However, for the two other methods, strong signals of bottlenecks were detected for all species and across two rivers. This suggests that, although potentially biased by asymmetric gene flow, some of these methods were able to bypass this bias when a bottleneck actually occurred. Our results show that population structure and dispersal patterns have to be considered for proper inference of demographic changes from genetic data.     

Human genetic diversity and the nonexistence of biological races

Sewall Wright's population structure statistic, F(ST), measured among samples of world populations is often 15% or less. This would indicate that 85% of genetic variation occurs within groups while only 15% can be attributed to allele frequency differences among groups. In this paper, we show that this low value reflects strong biases that result from violating hidden assumptions that define F(ST). These limitations on F(ST) are demonstrated algebraically and in the context of analyzing dinucleotide repeat allele frequencies for a set of eight loci genotyped in eight human groups and in chimpanzees. In our analyses, estimates of F(ST) fail to identify important variation. For example, when the analysis includes only humans, F(ST) = 0.119, but adding the chimpanzees increases it only a little, F(ST) = 0.183. By relaxing the underlying statistical assumptions, the results for chimpanzees become consistent with common knowledge, and we see a richer pattern of human genetic diversity. Some human groups are far more diverged than would be implied by standard computations of F(ST), while other groups are much less diverged. We discuss the relevance of these findings to the application of biological race concepts to humans. Four different race concepts are considered: typological, population, taxonomic, and lineage. Surprisingly, a great deal of genetic variation within groups is consistent with each of these concepts. However, none of the race concepts is compatible with the patterns of variation revealed by our analyses.     

Fundamental concepts in statistics: elucidation and illustration

Fundamentalconcepts in statistics form the cornerstone of scientific inquiry. Ifwe fail to understand fully these fundamental concepts, then thescientific conclusions we reach are more likely to be wrong. This ismore than supposition: for 60 years, statisticians have warned that thescientific literature harbors misunderstandings about basic statisticalconcepts. Original articles published in 1996 by the AmericanPhysiological Society's journals fared no better in their handling ofbasic statistical concepts. In this review, we summarize the two mainscientific uses of statistics: hypothesis testing and estimation. Mostscientists use statistics solely for hypothesis testing; often,however, estimation is more useful. We also illustrate the concepts ofvariability and uncertainty, and we demonstrate the essentialdistinction between statistical significance and scientific importance.An understanding of concepts such as variability, uncertainty, andsignificance is necessary, but it is not sufficient; we show also thatthe numerical results of statistical analyses have limitations.

     

Getting a head start: the importance of personal genetics education in high schools

With advances in sequencing technology, widespread and affordable genome sequencing will soon be a reality. However, studies suggest that "genetic literacy" of the general public is inadequate to prepare our society for this unprecedented access to our genetic information. As the current generation of high school students will come of age in an era when personal genetic information is increasingly utilized in health care, it is of vital importance to ensure these students understand the genetic concepts necessary to make informed medical decisions. These concepts include not only basic scientific knowledge, but also considerations of the ethical, legal, and social issues that will arise in the age of personal genomics. In this article, we review the current state of genetics education, highlight issues that we believe need to be addressed in a comprehensive genetics education curriculum, and describe our education efforts at the Harvard Medical School-based Personal Genetics Education Project.     

On the failure of modern species concepts

The modern age of species concepts began in 1942, when Ernst Mayr gave concept names to several different approaches to species identification. A long list of species concepts then followed, as well as a complex literature on their merits, motivations and uses. Some of these complexities arose as a consequence of the semantic shift that Mayr introduced, in which procedures for identifying species were elevated to concepts. Much of the debate in recent decades over concepts, and over pluralism versus monism, can be seen as an unnecessary consequence of treating species identification criteria as if they were more fundamental concepts. Recently, biologists have begun to recognize both the shortcomings of a lexicon of multiple species concepts and a common evolutionary idea that underlies them.     

Use and misuse of correspondence analysis in codon usage studies

Correspondence analysis has frequently been used for codon usage studies but this method is often misused. Because amino acid composition exerts constraints on codon usage, it is common to use tables containing relative codon frequencies (or ratios of frequencies) instead of simple codon counts to get rid of these amino acid biases. The problem is that some important properties of correspondence analysis, such as rows weighting, are lost in the process. Moreover, the use of relative measures sometimes introduces other biases and often diminishes the quantity of information to analyse, occasionally resulting in interpretation errors. For instance, in the case of an organism such as Borrelia burgdorferi, the use of relative measures led to the conclusion that there was no translational selection, while analyses based on codon counts show that there is a possibility of a selective effect at that level. In this paper, we expose these problems and we propose alternative strategies to correspondence analysis for studying codon usage biases when amino acid composition effects must be removed.     

The probability of genetic parallelism and convergence in natural populations

Genomic and genetic methods allow investigation of how frequently the same genes are used by different populations during adaptive evolution, yielding insights into the predictability of evolution at the genetic level. We estimated the probability of gene reuse in parallel and convergent phenotypic evolution in nature using data from published studies. The estimates are surprisingly high, with mean probabilities of 0.32 for genetic mapping studies and 0.55 for candidate gene studies. The probability declines with increasing age of the common ancestor of compared taxa, from about 0.8 for young nodes to 0.1–0.4 for the oldest nodes in our study. Probability of gene reuse is higher when populations begin from the same ancestor (genetic parallelism) than when they begin from divergent ancestors (genetic convergence). Our estimates are broadly consistent with genomic estimates of gene reuse during repeated adaptation to similar environments, but most genomic studies lack data on phenotypic traits affected. Frequent reuse of the same genes during repeated phenotypic evolution suggests that strong biases and constraints affect adaptive evolution, resulting in changes at a relatively small subset of available genes. Declines in the probability of gene reuse with increasing age suggest that these biases diverge with time.     

Limb bone bilateral asymmetry: variability and commonality among modern humans

Humans demonstrate species-wide bilateral asymmetry in long bone dimensions. Previous studies have documented greater right-biases in upper limb bone dimensions--especially in length and diaphyseal breadth--as well as more asymmetry in the upper limb when compared with the lower limb. Some studies have reported left-bias in lower limb bone dimensions, which, combined with the contralateral asymmetry in upper limbs, has been termed "crossed symmetry." The examination of sexual dimorphism and population variation in asymmetry has been limited. This study re-examines these topics in a large, geographically and temporally diverse sample of 780 Holocene adult humans. Fourteen bilateral measures were taken, including maximum lengths, articular and peri-articular breadths, and diaphyseal breadths of the femur, tibia, humerus, and radius. Dimensions were converted into percentage directional (%DA) and absolute (%AA) asymmetries. Results reveal that average diaphyseal breadths in both the upper and lower limbs have the greatest absolute and directional asymmetry among all populations, with lower asymmetry evident in maximum lengths or articular dimensions. Upper limb bones demonstrate a systematic right-bias in all dimensions, while lower limb elements have biases closer to zero %DA, but with slight left-bias in diaphyseal breadths and femoral length. Crossed symmetry exists within individuals between similar dimensions of the upper and lower limbs. Females have more asymmetric and right-biased upper limb maximum lengths, while males have greater humeral diaphyseal and head breadth %DAs. The lower limb demonstrates little sexual dimorphism in asymmetry. Industrial groups exhibit relatively less asymmetry than pre-industrial humans and less dimorphism in asymmetry. A mixture of influences from both genetic and behavioral factors is implicated as the source of these patterns.