In a previous study, using experimental metapopulations of the flour beetle, Tribolium castaneum, we investigated phase III of Wright's shifting balance process (Wade and Griesemer 1998). We experimentally modeled migration of varying amounts from demes of high mean fitness into demes of lower mean fitness (as in Wright's characterization of phase III) as well as the reciprocal (the opposite of phase III). We estimated the meta-populational heritability for this level of selection by regression of offspring deme means on (...) the weighted parental deme means.Here we develop a Punnett Square representation of the inheritance of the group mean to place our empirical findings in a conceptual context similar to Mendelian inheritance of individual traits. The comparison of Punnett Squares for individual and group inheritance shows how the latter concept can be rigorously defined and extended despite the lack of explicitly formulated, simple Mendelian laws of inheritance at the group level. Whereas Wright's phase III combines both interdemic selection and meta-populational inheritance, our formulation separates the issue of meta-populational heritability from that of interdemic selection. We use this conceptual context to discuss the controversies over the levels of selection and the units of inheritance. (shrink)

Suicidal behavior is an interesting blank space in Keller & Miller's (K&M's) population genetical account on explaining the existence and persistence of common, harmful, heritable mental disorders. I argue that suicidal behavior is yet another of these disorders. It may well be consistent with all three evolutionary models considered by K&M. (Published Online November 9 2006).

Can a heritability value tell us something about the weight of genetic versus environmental causes that have acted in the development of a particular individual? Two possible questions arise. Q1: what portion of the phenotype of X is due to its genes and what portion to its environment? Q2: what portion of X’s phenotypic deviation from the mean is a result of its genetic deviation and what portion a result of its environmental deviation? An answer to Q1 provides the (...) full information about X’s development, while an answer to Q2 leaves out a large portion unexplained—that portion which corresponds to the phenotypic mean. Q1 is unanswerable, but I show it is nevertheless legitimate under certain quantitative genetics models. With regard to Q2, opinions in the philosophical and biological literature differ as to its legitimacy. I argue that not only is it legitimate, but in particular, under a few simplifying assumptions, it allows for a quantitative probabilistic answer: for normally distributed quantitative traits with no G-E correlation or statistical G × E interaction, we can assess the probability that X’s genes had a greater effect than its environment on its deviation from the mean population value. This probability is expressed as a function the heritability and the individual’s phenotypic value; we can also provide a quantitative probabilistic answer to Q2 for an arbitrary individual where the probability is a function only of heritability. (shrink)

Many psychometricians and behavioral geneticists believe that high heritability of IQ test scores within racial groups coupled with environmental hypotheses failing to account for the differences between the mean scores for groups lends plausibility to explanations of mean differences in terms of genetic factors. I show that heritability estimates and the statistical analysis of variance on which they are based have limited relevance in exposing genetic and environmental factors operating within any single group or population. I begin with (...) agricultural investigations, where replication of genetic types and control over environmental factors are possible, and highlight the difficulties of moving from AOV of observed traits to investigation of measurable genetic factors. The difficulties can only be exacerbated for human data sets, which are equivalent to a crop trial in which each variety is replicated in only one or two of the locations. (shrink)

We argue that heritability estimates cannot be used to make informed judgments about the populations from which they are drawn. Furthermore, predicting changes in heritability from population changes is likely impossible, and of limited value. We add that the attempt to separate human environments into cultural and non-cultural components does not advance our understanding of the environmental multiplier effect.

Behavioral genetics and cultural evolution have both revolutionized our understanding of human behavior – largely independent of each other. Here, we reconcile these two fields under a dual inheritance framework, offering a more nuanced understanding of the interaction between genes and culture. Going beyond typical analyses of gene–environment interactions, we describe the cultural dynamics that shape these interactions by shaping the environment and population structure. A cultural evolutionary approach can explain, for example, how factors such as rates of innovation and (...) diffusion, density of cultural subgroups, and tolerance for behavioral diversity impact heritability estimates, thus yielding predictions for different social contexts. Moreover, when cumulative culture functionally overlaps with genes, genetic effects become masked, unmasked, or even reversed, and the causal effects of an identified gene become confounded with features of the cultural environment. The manner of confounding is specific to a particular society at a particular time, but a WEIRD (western, educated, industrialized, rich, and democratic) sampling problem obscures this boundedness. Cultural evolutionary dynamics are typically missing from models of gene-to-phenotype causality, hindering generalizability of genetic effects across societies and across time. We lay out a reconciled framework and use it to predict the ways in which heritability should differ between societies, between socioeconomic levels, and other groupings within some societies but not others, and over the life course. An integrated cultural evolutionary behavioral genetic approach cuts through the nature–nurture debate and helps resolve controversies in topics such as IQ. (shrink)

The critics of "hereditarianism" often claim that any attempt to explain human behavior by invoking genes is confronted with insurmountable methodological difficulties. They reject the idea that heritability estimates could lead to genetic explanations by pointing out that these estimates are strictly valid only for a given population and that they are exposed to the irremovable confounding effects of genotype-environment interaction and genotype-environment correlation. I argue that these difficulties are greatly exaggerated, and that we would be wrong to regard (...) them as presenting a fundamental obstacle to the search for genetic explanations. I also show that, to the extent they are cogent, these objections may prove to be even more damaging to the "environmentalist" standpoint. (shrink)

This paper investigates the role of the concept of group heritability in group selection theory, in relation to the well-known distinction between type 1 and type 2 group selection (GS1 and GS2). I argue that group heritability is required for the operation of GS1 but not GS2, despite what a number of authors have claimed. I offer a numerical example of the evolution of altruism in a multi-group population which demonstrates that a group heritability coefficient of zero (...) is perfectly compatible with the successful operation of group selection in the GS2 sense. A diagnosis of why group heritability has wrongly been regarded as necessary for GS2 is suggested. (shrink)

The paper addresses the question of whether heritability can be useful in establishing genetics as an explanation for an individual’s display of some trait or behavior. After reviewing the fundamental philosophical challenge to heritability—that heritability is a population level measure—an argument is presented for rethinking the role heritability occupies in both causal and explanatory claims. It is argued that heritability can be useful for genetically based explanations of individual traits, if the conditions for proper genetic (...) explanation are modestly reconceived, and the measure is seen as an evidential tool which conforms to standard methods for determining causal factors. (shrink)

Gyngell and colleagues consider that the recent Nuffield Council report does not go far enough: heritable genome editing is not just justifiable in a few rare cases; instead, there is a moral imperative to undertake it. We agree that there is a moral argument for this, but in the real world it is mitigated by the fact that it is not usually possible to ensure a better life. We suggest that a moral imperative for HGE can currently only be concluded (...) if one first buys into an overly deterministic view of a genome sequence, and the role of variation within in it, in the aetiology of the disease: most diseases cannot simply be attributed to specific genetic variants that we could edit away. Multiple, poorly understood genetic and environmental factors interact to influence the expression of diseases with a genetic component, even well understood ‘monogenic’ disorders. Population-level genome analyses are now demonstrating that many genetic ’mutations' are much less predictive than previously thought 1. Furthermore, HGE might introduce new risks just as it reduces old ones; or remove protections not yet clearly delineated. (shrink)

ABSTRACT Ethical and political attitudes are not randomly distributed in a population. Attitudes of family members, for example, tend to be more similar than those of a random sample of the same size. In the fields of social psychology and political science, the historically standard explanation for these attitude distribution patterns was that social and political attitudes are a function of environmental factors like parental socialization and prevailing social norms. This received view is, however, complicated by more recent work in (...) behavioral genetics, which consistently and repeatedly demonstrates that certain ethical and political attitudes dealing with issues like censorship, abortion, capital punishment, and immigration policy have a significant heritability coefficient, to wit, a substantial percentage of attitude variance in a population can be attributed to genetic variance, independent of environmental factors. In this paper, I argue that the genetic influence on our ethical and political attitudes is mediated by what we can agree to be irrelevant and distorting factors that can lead moral reasoning astray. Further, I argue that we should significantly lower our credences in ethical and political attitudes that fall within the domains of belief that involve significant genetic influence. (shrink)

Complex‐trait genetics has advanced dramatically through methods to estimate the heritability tagged by SNPs, both genome‐wide and in genomic regions of interest such as those defined by functional annotations. The models underlying many of these analyses are inadequate, and consequently many SNP‐heritability results published to date are inaccurate. Here, we review the modelling issues, both for analyses based on individual genotype data and association test statistics, highlighting the role of a low‐dimensional model for the heritability of each (...) SNP. We use state‐of‐art models to present updated results about how heritability is distributed with respect to functional annotations in the human genome, and how it varies with allele frequency, which can reflect purifying selection. Our results give finer detail to the picture that has emerged in recent years of complex trait heritability widely dispersed across the genome. Confounding due to population structure remains a problem that summary statistic analyses cannot reliably overcome. Also see the video abstract here: https://youtu.be/WC2u03V65MQ. (shrink)

The Continuous Parameter Estimation Model is applied to develop individual genomic-level heritabilities for the latent hierarchical structure and developmental dynamics of Life History (LH) strategy LH strategies relate to the allocations of bioenergetic resources into different domains of fitness. LH has moderate to high population-level heritability in humans, both at the level of the high-order Super-K Factor and the lower-order factors, the K-Factor, Covitality Factor, and General Factor of Personality (GFP). Several important questions remain unexplored. We developed measures of (...) genome-level heritabilities employing an American sample of 316 monozygotic (MZ) and 274 dizygotic (DZ) twin dyads and a Swedish sample of 863 MZ and 475 DZ twin dyads. This novel heritability index measures individual genetic transmissibility, therefore opening new avenues for analyzing complex interactions among heritable traits inaccessible to standard structural equations methods. For these samples: (1) moderate to high heritability of factor loadings of Super-K on its lower-order factors is demonstrated, evidencing biological preparedness, genetic accommodation, and the gene-culture coevolution of biased epigenetic rules of development; (2) moderate to high heritability of the magnitudes of the effect of the higher-order factors upon their loadings on their constituent factors, evidencing genetic constraints upon phenotypic plasticity; and (3) that heritability of the LH factors, of factor loadings, and of the magnitudes of the correlations among factors are weaker among those with slower LH speeds, demonstrating that inter-individual variation in transmissibility is a function of individual socioecological selection pressures. (shrink)

Estimates of a trait’s heritability can be used to predict the advance through selective breeding in agriculture and the laboratory where researchers can replicate varieties and locations. These conditions do not apply to human populations, yet considerable attention is still given to high heritability and to small effects of family members growing up together relative to differences within families. This article shows that the conventional partitioning of a trait’s variation produces components that cannot be associated reliably with average (...) differences among varieties and locations , let alone underwrite hypotheses about measurable genetic and environmental influences. (shrink)

Uchiyama et al. emphasize that culture evolves directionally and differentially as a function of selective pressures in different populations. Extending these principles to the level of families, lineages, and individuals exposes additional challenges to estimating heritability. Cultural traits expressed differentially as a function of the genetics whose influence they mask or unmask render inseparable the influences of culture and genetics.

We contend that social science variables are the product of multiple partly heritable traits. Genetic associations with socioeconomic status (SES) may differ across populations, but this is a consequence of the intermediary traits associated with SES differences also varying. Furthermore, genetic data allow social scientists to make causal statements regarding the aetiology and consequences of SES.

In "The pitfalls of heritability," a review of Edward O. Wilson’s Consilience Times Literary Supplement, Feb 12, 1999, p33], Jerry Hirsch claims to have convicted Wilson of a "confusion about genetic similarity and difference." In his book, Wilson claims that if we assume that "a mere one thousand genes out of the fifty to a hundred thousand genes in the human genome were to exist in two forms in the population," the probability of any two humans--excluding identical siblings--having the (...) same genotype is vanishingly small. Hirsch points out that a single genotype can be produced in more than one way, thus increasing the likelihood of a single genotype recurring in the human population. Hirsch’s point is fair enough as far it goes, but it does not go nearly far enough. Hirsch has failed to carry out all the relevant calculations needed to determine the probability of two humans having the same genotype. In the realm of Vast numbers ("Very much greater than ASTronomical"--Dennett, 1995, p109), increased likelihood in and of itself tells us nothing. Here, then, are some of the relevant calculations. (shrink)

SummaryHuman height is a heritable trait that is known to be influenced by environmental factors and general standard of living. Individual and population stature is correlated with health, education and economic achievement. Strong sexual selection pressures for stature have been observed in multiple diverse populations, however; there is significant global variance in gender equality and prohibitions on female mate selection. This paper explores the contribution of general standard of living and gender inequality to the variance in global female population heights. (...) Female population heights of 96 nations were culled from previously published sources and public access databases. Factor analysis with United Nations international data on education rates, life expectancy, incomes, maternal and childhood mortality rates, ratios of gender participation in education and politics, the Human Development Index and the Gender Inequality Index was run. Results indicate that population heights vary more closely with gender inequality than with population health, income or education. (shrink)

Background With growth of genomics research in Africa, concern has arisen about comprehension and adequacy of informed consent given the highly technical terms used in this field. We therefore decided to study whether there are linguistic and cultural concepts used to communicate heritability of characters, traits and diseases in an indigenous African population. Methods We conducted Focus Group Discussions among 115 participants stratified by sex, age and socio-economic status and Key Informant Interviews among 25 stakeholders and Key Opinion Leaders (...) among Yoruba living in Ibadan, Nigeria. We used Atlas-ti v.8.3.17 software to analyze the data, using thematic approach. Results The study participants identified several linguistic and cultural concepts including words, proverbs, and aphorisms that are used to describe heritable characters, traits and diseases in their local dialect. These included words that can be appropriated to describe dominant and recessive traits, variations in penetrance and dilution of strength of heritable characteristics by time and inter-marriage. They also suggested that these traits are transmitted by “blood”, and specific partner’s blood may be stronger than the other regardless of sex. Conclusions Indigenous Yoruba populations have words and linguistic concepts that describe the heritability of characters, traits and diseases which can be appropriated to improve comprehension and adequacy of informed consent in genomics research. Our methods are openly available and can be used by genomic researchers in other African communities. (shrink)

SummaryAggarwal Baniyas were found to have a high prevalence of high blood pressure. Genetic and environmental influences may be implicated for this risk factor of cardiovascular disease. The aim of this study was to investigate the potential for common genetic and environmental influences on blood pressure measures ). The population-based sample was comprised of 309 Aggarwal Baniya families, including 1214 individuals from New Delhi, India. The prevalence of obesity in this community was found to be high. Correlation and heritability (...) were estimated. Most sibling–sibling correlations were larger than the parent–offspring correlations, and all parent–offspring and sibling–sibling correlations were larger than the corresponding spouse correlation. The maximum heritability was estimated as 44.6% for SBP and 62.8% for DBP. The lack of a significant spouse correlation is consistent with little or no influence of the common familial environment. However, the high heritability estimate for both SBP and DBPs reinforces the importance of the non-shared environmental effect. (shrink)

Evolutionary conceptions of species place special weight on each species having dynamic independence as a unit of evolution. However, the idea that species have their own historical fates, tendencies, or roles has resisted systematic analysis. Growing evidence from population genomics shows that many paradigm species regularly engage in hybridization. How can species be defined in terms of independent evolutionary identities if their genomes are dynamically coupled through lateral exchange? I introduce the concept of a “composite lineage” to distinguish species and (...) subspecies on the basis of the proportion of a group’s heritable traits that are uncoupled from reproductive exchange. (shrink)

Observing adaptive evolution is difficult. In the fossil record, phenotypic evolution happens much more slowly than in artificial selection experiments or in experimental evolution. Yet measures of selection on phenotypic traits, with high heritabilities, suggest that phenotypic evolution should also be rapid in the wild, and this discrepancy often remains even after accounting for correlations between different traits (i.e. making predictions using the multivariate version of the breeder's equation). Are fitness correlations with quantitative traits adequate measures of selection in the (...) wild? We should instead view fitnesses as average properties of genotypes, while acknowledging that they can be environment‐dependent. Populations will tend to remain at fitness equilibria, once these are attained, and phenotypes will then be stable. Thus, studying the causes of adaptive change at a genotypic rather than phenotypic level may reveal that, typically, it is occurring too slowly to be easily observed. (shrink)

Natural selection is an extremely powerful process – so powerful, in fact, that it is often tempting to deploy it in explaining phenomena as wide-ranging as the persistence of blue eyes, the origins or persistence of religious belief, or, the history of science. One long-standing debate among both critics and advocates of Darwin’s concerns the scope of Darwinian explanations, and how we are to draw the line. Peter Godfrey-Smith’s Darwinian Populations and Natural Selection is a detailed examination of this question. (...) The book explores the criteria for what may count as a “Darwinian population,” by which Godfrey-Smith means, which collections of entities have the capacity to undergo evolution via natural selection (p. 6). Drawing upon his answer to this question, Godfrey-Smith examines and provides his own solution to the following long-standing debates in philosophy of biology: (a) the twin problems of reproduction and individuation of biological entities, (b) the persistent “gene’s eye view,” (c) the levels and units of selection problem, and (d) the evolution of cultural artifacts and behaviors. (shrink)

Human beings, like other organisms, are the products of evolution. Like other organisms, we exhibit traits that are the product of natural selection. Our psychological capacities are evolved traits as much as are our gait and posture. This much few would dispute. Evolutionary psychology goes further than this, claiming that our psychological traits -- including a wide variety of traits, from mate preference and jealousy to language and reason -- can be understood as specific adaptations to ancestral Pleistocene conditions. In (...) Evolutionary Psychology as Maladapted Psychology, Robert Richardson takes a critical look at evolutionary psychology by subjecting its ambitious and controversial claims to the same sorts of methodological and evidential constraints that are broadly accepted within evolutionary biology. The claims of evolutionary psychology may pass muster as psychology; but what are their evolutionary credentials? Richardson considers three ways adaptive hypotheses can be evaluated, using examples from the biological literature to illustrate what sorts of evidence and methodology would be necessary to establish specific evolutionary and adaptive explanations of human psychological traits. He shows that existing explanations within evolutionary psychology fall woefully short of accepted biological standards. The theories offered by evolutionary psychologists may identify traits that are, or were, beneficial to humans. But gauged by biological standards, there is inadequate evidence: evolutionary psychologists are largely silent on the evolutionary evidence relevant to assessing their claims, including such matters as variation in ancestral populations, heritability, and the advantage offered to our ancestors. As evolutionary claims they are unsubstantiated. Evolutionary psychology, Richardson concludes, may offer a program of research, but it lacks the kind of evidence that is generally expected within evolutionary biology. It is speculation rather than sound science -- and we should treat its claims with skepticism. (shrink)

In the multidisciplinary field of developmental cognitive neuroscience, statistical associations between levels of description play an increasingly important role. One example of such associations is the observation of correlations between relatively common gene variants and individual differences in behavior. It is perhaps surprising that such associations can be detected despite the remoteness of these levels of description, and the fact that behavior is the outcome of an extended developmental process involving interaction of the whole organism with a variable environment. Given (...) that they have been detected, how do such associations inform cognitive-level theories? To investigate this question, we employed a multiscale computational model of development, using a sample domain drawn from the field of language acquisition. The model comprised an artificial neural network model of past-tense acquisition trained using the backpropagation learning algorithm, extended to incorporate population modeling and genetic algorithms. It included five levels of description—four internal: genetic, network, neurocomputation, behavior; and one external: environment. Since the mechanistic assumptions of the model were known and its operation was relatively transparent, we could evaluate whether cross-level associations gave an accurate picture of causal processes. We established that associations could be detected between artificial genes and behavioral variation, even under polygenic assumptions of a many-to-one relationship between genes and neurocomputational parameters, and when an experience-dependent developmental process interceded between the action of genes and the emergence of behavior. We evaluated these associations with respect to their specificity, to their developmental stability, and to their replicability, as well as considering issues of missing heritability and gene–environment interactions. We argue that gene–behavior associations can inform cognitive theory with respect to effect size, specificity, and timing. The model demonstrates a means by which researchers can undertake multiscale modeling with respect to cognition and develop highly specific and complex hypotheses across multiple levels of description. (shrink)

Behavioral scientists routinely publish broad claims about human psychology and behavior in the world's top journals based on samples drawn entirely from Western, Educated, Industrialized, Rich, and Democratic (WEIRD) societies. Researchers – often implicitly – assume that either there is little variation across human populations, or that these “standard subjects” are as representative of the species as any other population. Are these assumptions justified? Here, our review of the comparative database from across the behavioral sciences suggests both that there is (...) substantial variability in experimental results across populations and that WEIRD subjects are particularly unusual compared with the rest of the species – frequent outliers. The domains reviewed include visual perception, fairness, cooperation, spatial reasoning, categorization and inferential induction, moral reasoning, reasoning styles, self-concepts and related motivations, and the heritability of IQ. The findings suggest that members of WEIRD societies, including young children, are among the least representative populations one could find for generalizing about humans. Many of these findings involve domains that are associated with fundamental aspects of psychology, motivation, and behavior – hence, there are no obviousa priorigrounds for claiming that a particular behavioral phenomenon is universal based on sampling from a single subpopulation. Overall, these empirical patterns suggests that we need to be less cavalier in addressing questions ofhumannature on the basis of data drawn from this particularly thin, and rather unusual, slice of humanity. We close by proposing ways to structurally re-organize the behavioral sciences to best tackle these challenges. (shrink)

The sociogenomics revolution is upon us, we are told. Whether revolutionary or not, sociogenomics is poised to flourish given the ease of incorporating polygenic scores (or PGSs) as “genetic propensities” for complex traits into social science research. Pointing to evidence of ubiquitous heritability and the accessibility of genetic data, scholars have argued that social scientists not only have an opportunity but a duty to add PGSs to social science research. Social science research that ignores genetics is, some proponents argue, (...) at best partial and likely scientifically flawed, misleading, and wasteful. Here, I challenge arguments about the value of genetics for social science and with it the claimed necessity of incorporating PGSs into social science models as measures of genetic influences. In so doing, I discuss the impracticability of distinguishing genetic influences from environmental influences because of non-causal gene–environment correlations, especially population stratification, familial confounding, and downward causation. I explain how environmental effects masquerade as genetic influences in PGSs, which undermines their raison d’être as measures of genetic propensity, especially for complex socially contingent behaviors that are the subject of sociogenomics. Additionally, I draw attention to the partial, unknown biology, while highlighting the persistence of an implicit, unavoidable reductionist genes versus environments approach. Leaving sociopolitical and ethical concerns aside, I argue that the potential scientific rewards of adding PGSs to social science are few and greatly overstated and the scientific costs, which include obscuring structural disadvantages and cultural influences, outweigh these meager benefits for most social science applications. (shrink)

Causation has multiple distinct meanings in genetics. One reason for this is meaning slippage between two concepts of the gene: Mendelian and molecular. Another reason is that a variety of genetic methods address different kinds of causal relationships. Some genetic studies address causes of traits in individuals, which can only be assessed when single genes follow predictable inheritance patterns that reliably cause a trait. A second sense concerns the causes of trait differences within a population. Whereas some single genes can (...) be said to cause population-level differences, most often these claims concern the effects of many genes. Polygenic traits can be understood using heritability estimates, which estimate the relative influences of genetic and environmental differences to trait differences within a population. Attempts to understand the molecular mechanisms underlying polygenic traits have been developed, although causal inference based on these results remains controversial. Genetic variation has also recently been leveraged as a randomizing factor to identify environmental causes of trait differences. This technique—Mendelian randomization—offers some solutions to traditional epidemiological challenges, although it is limited to the study of environments with known genetic influences. (shrink)

We hypothesize that heritable epigenetic changes can affect rates of fitness increase as well as patterns of genotypic and phenotypic change during adaptation. In particular, we suggest that when natural selection acts on pure epigenetic variation in addition to genetic variation, populations adapt faster, and adaptive phenotypes can arise before any genetic changes. This may make it difficult to reconcile the timing of adaptive events detected using conventional population genetics tools based on DNA sequence data with environmental drivers of adaptation, (...) such as changes in climate. Epigenetic modifications are frequently associated with somatic cell differentiation, but recently epigenetic changes have been found that can be transmitted over many generations. Here, we show how the interplay of these heritable epigenetic changes with genetic changes can affect adaptive evolution, and how epigenetic changes affect the signature of selection in the genetic record. (shrink)

Some adaptationist explanations are regarded as maximally solid and others fanciful just-so stories. Just-so stories are explanations based on very little evidence. Lack of evidence leads to circular-sounding reasoning: “this trait was shaped by selection in unseen ancestral populations and this selection must have occurred because the trait is present.” Well-supported adaptationist explanations include evidence that is not only abundant but selected from comparative, populational, and optimality perspectives, the three adaptationist subdisciplines. Each subdiscipline obtains its broad relevance in evolutionary (...) biology via assumptions that can only be tested with the methods of the other subdisciplines. However, even in the best-supported explanations, assumptions regarding variation, heritability, and fitness in unseen ancestral populations are always present. These assumptions are accepted given how well they would explain the data if they were true. This means that some degree of “circularity” is present in all evolutionary explanations. Evolutionary explanation corresponds not to a deductive structure, as biologists usually assert, but instead to ones such as abduction or induction. With these structures in mind, we show the way to a healthier view of “circularity” in evolutionary biology, and why integration across the comparative, populational, and optimality approaches is necessary. (shrink)

Natural selection is an important force that shapes the evolution of all living things by determining which individuals contribute the most descendents to future generations. The biological unit upon which selection acts has been the subject of serious debate, with reasonable arguments made on behalf of populations, individuals, individual phenotypic characters and, finally, individual genes themselves. In this essay, I argue that the usual unit of selection is the gene. There are powerful logical arguments in favor of this conclusion, as (...) well as many real-world examples. I also explore the possibility that epigenetic differences between individuals may be heritable between generations. Although few such examples exist, epigenetic differences provide an exciting source of potentially heritable variation that may allow rapid evolutionary change to occur, perhaps in response to environmental influences. (shrink)

The argument that heritable epigenetic change plays a distinct role in evolution would be strengthened through recognition that it is what bootstrapped the origin and early evolution of life, and that, like behavioral and symbolic change, it is non-Darwinian. The mathematics of natural selection, a population-level process, is limited to replication with negligible individual-level change that uses a self-assembly code.

Evolutionary theory is formulated in terms of individuals that carry heritable information and are subject to selective pressures. However, individuality itself is a trait that had to evolve - an individual is not an indivisible entity, but a result of evolutionary processes that necessarily begin at the lower level of hierarchical organisation. Traditional approaches to biological individuality focus on cooperation and relatedness within a group, division of labour, policing mechanisms and strong selection at the higher level. Nevertheless, despite considerable theoretical (...) progress in these areas, a full dynamical first-principles account of how new types of individuals arise is missing. To the extent that individuality is an emergent trait, the problem can be approached by recognising the importance of individuating mechanisms that are present from the very beginning of the transition, when only lower-level selection is acting. Here we review some of the most influential theoretical work on the role of individuating mechanisms in these transitions, and demonstrate how a lower-level, bottom-up evolutionary framework can be used to understand biological complexity involved in the origin of cellular life, early eukaryotic evolution, sexual life cycles and multicellular development. Some of these mechanisms inevitably stem from environmental constraints, population structure and ancestral life cycles. Others are unique to specific transitions - features of the natural history and biochemistry that are co-opted into conflict mediation. Identifying mechanisms of individuation that provide a coarse-grained description of the system's evolutionary dynamics is an important step towards understanding how biological complexity and hierarchical organisation evolves. In this way, individuality can be reconceptualised as an approximate model that with varying degrees of precision applies to a wide range of biological systems. (shrink)

Homo sapiens is a mammal of the order Primates. What most distinguishes primates from other mammals is their ability to cerebrate. Cerebration developed fastest among the Anthropoidea primates , and subsequently the hominids . The increase in brain mass only by Homo sapiens—and only over the past 10,000 years—possess superior Darwinian fitness: for the preceding 30 million years primates had played a rather marginal role in the world’s biological system.Homo sapiens’ success as the creator of developed civilization was possible only (...) thanks to his special adaptation capabilities, shaped by natural selection at the dawn of his existence.Primates first appeared in the Oligocene about 30 million years ago, and the first two-legged anthropoid, Australopithecus, about 6.5–5.7 million years ago. The transition from Australopithecus to the species we call Homo was in many ways an evolutionary milestone. Australopithecus was exclusively herbivorous and formed neither organized communities nor settlements. His successor, Homo erectus, on the other hand, possessed heretofore unknown skills like hunting and gathering, which considerably influenced both his lifestyle and his diet—he increasingly ate meat from cadavers or animals he had killed himself. Fossil remains of Homo erectus dating back two million years have been unearthed throughout Africa, China, Indonesia, Pakistan, the Middle East, and Europe.Homo sapiens derives from the rather small Homo erectus population in East Africa and has been the earth’s only hominid for a relatively short time about 10,000 years ago before he still shared his world with Neanderthal man and the diminutive Homo floresiensis.Despite racial differences there is surprisingly little variation in the human genome. We are all 99 percent genetically alike, moreover genome variations do not correlate to skin color.Homo sapiens’ hunter-gatherer lifestyle led him to seek solutions which today find application only in human communities. In time his biological capabilities were enriched by the skill of speech, this in turn helping to develop creativity, self-awareness, a sense of dignity, and group, ethnic and national loyalty, eventually leading to the emergence of religion as a path to life’s fundamental truths and an antidote to the everpresent fear of death.The Neolithic Revolution began about 10,000 years ago. Several thousand years later the evolution of farming and breeding led to the emergence of the first civilizations. The transition from hunting and gathering to agriculture changed radically not only economic and social structures but, as speech developed, helped form civilizations and cultures.Over the past 2000 years humanity has changed the global environment but has itself remained unchanged in heritability. The awareness that despite all racial, ethnic, cultural, or linguistic differences we belong to an exceptionally homogeneous species, can be an inspiration for humanity to strive towards a universal civilization in which all these differences could be contained. (shrink)

Our aim in this article is to attempt to discuss propagating organization of process, a poorly articulated union of matter, energy, work, constraints and that vexed concept, “information”, which unite in far from equilibrium living physical systems. Our hope is to stimulate discussions by philosophers of biology and biologists to further clarify the concepts we discuss here. We place our discussion in the broad context of a “general biology”, properties that might well be found in life anywhere in the cosmos, (...) freed from the specific examples of terrestrial life after 3.8 billion years of evolution. By placing the discussion in this wider, if still hypothetical, context, we also try to place in context some of the extant discussion of information as intimately related to DNA, RNA and protein transcription and translation processes. While characteristic of current terrestrial life, there are no compelling grounds to suppose the same mechanisms would be involved in any life form able to evolve by heritable variation and natural selection. In turn, this allows us to discuss at least briefly, the focus of much of the philosophy of biology on population genetics, which, of course, assumes DNA, RNA, proteins, and other features of terrestrial life. Presumably, evolution by natural selection—and perhaps self-organization—could occur on many worlds via different causal mechanisms. Here we seek a non-reductionist explanation for the synthesis, accumulation, and propagation of information, work, and constraint, which we hope will provide some insight into both the biotic and abiotic universe, in terms of both molecular self reproduction and the basic work energy cycle where work is the constrained release of energy into a few degrees of freedom. The typical requirement for work itself is to construct those very constraints on the release of energy that then constitute further work. Information creation, we argue, arises in two ways: first information as natural selection assembling the very constraints on the release of energy that then constitutes work and the propagation of organization. Second, information in a more extended sense is “semiotic”, that is about the world or internal state of the organism and requires appropriate response. The idea is to combine ideas from biology, physics, and computer science, to formulate explanatory hypotheses on how information can be captured and rendered in the expected physical manifestation, which can then participate in the propagation of the organization of process in the expected biological work cycles to create the diversity in our observable biosphere. Our conclusions, to date, of this enquiry suggest a foundation which views information as the construction of constraints, which, in their physical manifestation, partially underlie the processes of evolution to dynamically determine the fitness of organisms within the context of a biotic universe. (shrink)

Terminology within the biological sciences gets its import not just from semantic meaning, but also from the way it functions within the rhetorics of the various disciplinary practices. The ‘sociobiology’ of human behavior inherits three distinct rhetorics from the genetic disciplines. Sociobiologists use population genetic, biometrical genetic, and molecular genetic rhetorics, without acknowledging the conceptual and experimental constraints that are assumed by geneticists. The eclectic blending of these three rhetorics obscures important differences of context and meaning. Sociobiologists use foundational terms (...) in genetics, such as ‘gene’, ‘fitness’, ‘evolution’, ‘heritability’, ‘trait’ and ‘polygenic inheritance’, in starkly different ways from geneticists, while basing their analysis of human behavior on the implied authority of genetics. As a free‐floating ‘gene talk’ moves across different disciplinary contexts, and before different audiences, it takes the form of an over‐simplified and misleading arch‐determinism. The result is widespread application of vague, incomplete, and distorted biological theory. If most sociobiologists, do not deliberately promote biological determinism, still less a political agenda, there is ample evidence that they misconstrue the implications of the genetic language that they borrow. (shrink)

Barely a decade after the discovery of the chromosomal basis of inheritance, and the articulation of the genetical theory of population change, the gene came to be widely regarded as the fundamental unit of biological organization. This is hardly surprising. The gene concept is a powerful one; it plays a unifying role in our understanding of evolution. Darwin told us that evolution by natural selection occurs in a population when organisms survive, die and reproduce differentially on account of their heritable (...) form. This is a very schematic theory. It requires an account of the process of inheritance and also an account of the generation of phenotype. The gene concept plays a prominent role in explaining, and uniting, these phenomena. Genes are the units of inheritance; they are passed from parents to offspring in reproduction. Moreover, they are seen as units of phenotypic control. Evolutionary biologists often speak of the genome as a program for the production of an organism. Genes also became the elements of which populations are composed. Our best theory of population dynamics—inherited from Fisher, Haldane, and Wright—is a theory of changes in the relative frequencies of gene types. Genes are not just the principal causes of evolutionary change, they are also the units over which evolutionary change is defined and measured. So, at least, the orthodox reading of the Modern Synthesis theory of evolution would have us believe... (shrink)

The target article excludes ancestral neutrality as a cause for the inheritance of schizophrenia, with an argument relating to selection against a single allele in the Finnish population. However, drift would predominate over selection within subisolates of the Finnish population. Comparisons of subisolates with heterogeneous populations may provide clues to the endophenotypic structure of complex polygenetic heritable mental disorders. (Published Online November 9 2006).

Evolutionary psychologists attempt to infer our evolved psychology from the selection pressures present in our ancestral environments. Their use of this inference strategy—often called “adaptive thinking”—is thought to be justified by way of appeal to a rather modest form of adaptationism, according to which the mind's adaptive complexity reveals it to be a product of selection. I argue, on the contrary, that the mind's being an adaptation is only a necessary and not a sufficient condition for the validity of adaptive (...) thinking, and that evolutionary psychology's predictive project is in fact committed to an extremely strong and highly implausible form of adaptationism. According to this “strong adaptationism,” the macroevolutionary trajectory of a population is determined by, and therefore predictable on the basis of, the selection pressures acting upon it. Not only is this form of adaptationism prima facie highly implausible, it requires making a number of naïve and likely false assumptions concerning the nature of heritable phenotypic variation in natural populations. In particular, it assumes that phenotypic variation is inevitably small in its extent, unbiased in its direction, and copious in its quantity. Because it is unlikely that these conditions obtain as a general rule, and even more unlikely that they obtained in early human populations, I conclude that there is little reason to believe that adaptive thinking can be used to infer the current structure of our minds from evidence of past selection pressures. (shrink)

Given research and public interest for conditions related to an extended lifespan, we addressed the questions of what matters and what matters most for subsequent survival past age 80. The data was drawn from the population-based and multidisciplinary Swedish OCTO Twin Study, in which a sample consisting of identical and same-sex fraternal twin pairs, followed from age 80 until death, provided detailed data on health, physical functioning, life style, personality, and sociodemographic conditions. Information concerning date of birth and death were (...) obtained from population census register. We estimated heritability using an ACE model and evaluated the role of multiple predictors for the mortality-related hazard rate using Cox regression. Our findings confirmed a low heritability of 12%. As expected, longer survival was associated with being a female, an apolipoprotein E e4 allele non-carrier, and a non-smoker. Several diseases were found to be associated with shorter survival as well as certain health conditions. Stronger grip and better lung function, as well as better vision, and better cognitive function was related to longer survival. Social embeddedness, better self-evaluated health, and life-satisfaction were also significantly associated with longer survival. After controlling for the impact of comorbidity, functional markers, and personality-related predictors, we found that sex, cerebrovascular diseases, compromised cognitive functioning, self-related health, and life-satisfaction remained as strong predictors. Cancer was only associated with the mortality hazard when accounting for other co-morbidities. The survival estimates were mostly in anticipated directions and contained effect sizes within the expected range. Noteworthy, we found that some of the so-called “soft-markers” remained strong predictors, despite a control for other factors. For example, self-evaluation of health and ratings of life-satisfaction provide additional and valuable information. (shrink)

Many aspects of biology, such as population genetics and senescence, are predicated on identifying individuals and generations. Conventional demarcations of individuals and generations, such as physiological autonomy, unicellular bottlenecks, and alternation of generation, are rife with problems. Do physically separated cuttings or plant ramets constitute separate individuals or generations? Are chimaeras one or more individuals? To resolve these problems, Clarke : 321–361, 2012) proposed that individuals are circumscribed by mechanisms that constrain heritable variance in fitness. Simultaneously, Gorelick and Heng : (...) 1088–1098 2011) showed that sex constrains heritable variance Therefore, for eukaryotes, meiosis and karyogamy provide a consistent way to demarcate individuals and generations. Epigenetic reset associated with meiosis and karyogamy rejuvenates the next generation, but not the parent that engaged in the sex act. Wholesale epigenetic resets that probably only occur with meiosis and karyogamy imply that monozygotic twins are two different individuals, but apomictic progeny are diffuse parts of one disaggregated individual. Mitotic heritability circumscribes an individual, whereas meiotic heritability demarcates new individuals and generations. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Normalization and the Welfare StateLadelle McWhorterIn Racism and Sexual Oppression in Anglo-America, I argued that as race was absorbed into biology in the nineteenth century, it was recast from a morphological typology to a function of physiological and evolutionary development (McWhorter 2009b). Racial difference became a sign of developmental difference. Racial groups represented stages of human evolution, and raced individuals were to be disciplined and managed in accordance with (...) developmental norms.Twentieth-century race was therefore a category and tool of normalization; to be raced was to be located at a particular point along a developmental curve. Some races were thought to be more or less arrested in their development, while others were merely retarded, and theorists disagreed at times about which were which. But they all agreed that the most highly developed race was the Nordic or the Anglo-Saxon. Anglo-Saxons were the norm for modern human beings— anatomically, physiologically, intellectually, and morally. There were other white races whose status was debated (Mediterraneans and Ashkenazi Jews, for example), and there were disputes over the evolutionary status of Chinese, Hindus, and Mexicans. But most theorists agreed that at the very bottom of the developmental scale we should place Celts, Negroes, and American Indians. These peoples were savages, primitives. They should be trained to the extent possible to contribute to the society that had already superseded them, but their proper destiny was to pass away into extinction as humanity advanced.These evolutionary stragglers, along with the evolutionary throwbacks that appeared sometimes among whites, were considered dangerous for two main reasons. First, a great many of them were expensive. They were shiftless, often incompetent, and frequently lawless. Because of them, it was necessary to [End Page 39] maintain police forces, prisons, poorhouses, and asylums. They were a drain on the economic advance of society, which affected its educational and technological advance and ultimately its evolutionary advance as well. Second, because they had primitive sexual urges unrestrained by reason as well as heritable defects and diseases, they threatened the bloodlines of more advanced human beings. In short, they posed a risk for the ongoing evolutionary advancement of the entire Human Race. To protect the Race, it was necessary to contain these primitives, savages, and throwbacks and to reduce their numbers through careful management of their sexuality. This, I argued in the book, was racism’s cutting edge in the early twentieth century.Since publishing the book, I have done some work on the changes in practices of racism in the wake of the Biological Synthesis—that is, the unification of biology and genetics that occurred in the 1930s through the efforts of renowned scientists such as Theodosius Dobzhansky and Ernst Mayr (McWhorter 2010a, 2010b, 2010c). As I discussed in that work, by 1950, evolutionary biology was less a study of species development than it was a study of the effects of evolutionary forces acting on and within populations. Correlatively, racial practices shifted toward management of statistically delineated populations or ethnic groups. Theorists and policymakers recognized that not all members of a given population have the same genes, meaning that old-style racism (which assumed, for example, that all Negroes were stupid) was false; some Negroes might be quite brilliant, in fact. It was not The Negro who was stupid but the population of Negroes in the aggregate that was measurably stupider than the population of Anglo-Saxons. Accordingly, normalization now occurred at the level of the population. Disciplinary practices designed for cultivating the capacities of groups of individuals were altered or replaced to focus on groups as groups, as aggregates. The point was to shift the statistical norm of the population rather than to alter the bodies or behavior of each and every individual. I have argued elsewhere (McWhorter 2009a, 5) that this merger of disciplinary normalization and population management constitutes the full flowering of what Foucault calls biopower (Foucault 1978, 140).When Lisa Guenther invited me to speak at the plenary on “Re-thinking Whiteness” that took place at the fifth annual meeting of philoSOPHIA at Vanderbilt University, she explained that although many presenters offer polished papers, it has been a... (shrink)

I argue that the use of heritable modifications for psychology, personality, and behavior should be limited to the reversal or prevention of relatively unambiguous instances of pathology or likely harm (e.g. sociopathy). Most of the likely modifications of psychological personality would not be of this nature, however, and parents therefore should not have the freedom to make such modifications to future children. I argue by examining the viewpoints of both the individual and society. For individuals, modifications would interfere with their (...) capacity for self-determination in a way that undermines the very concept of self-determination. I argue that modification of psychology and personality is unlike present parenting in morally significant ways. For society, modification offers a medium for power to manipulate the makeup of persons and populations, possibly causing biological harm to the species and altering our conceptions of social responsibility. (shrink)

Adaptation by means of natural selection depends on the ability of populations to maintain variation in heritable traits. According to the Modern Synthesis this variation is sustained by mutations and genetic drift. Epigenetics, evodevo, niche construction and cultural factors have more recently been shown to contribute to heritable variation, however, leading an increasing number of biologists to call for an extended view of speciation and evolution. An additional common feature across the animal kingdom is learning, defined as the ability to (...) change behavior according to novel experiences or skills. Learning constitutes an additional source for phenotypic variation, and change in behavior may induce long lasting shifts in fitness, and hence favor evolutionary novelties. Based on published studies, I demonstrate how learning about food, mate choice and habitats has contributed substantially to speciation in the canonical story of Darwin’s finches on the Galapagos Islands. Learning cannot be reduced to genetics, because it demands decisions, which requires a subject. Evolutionary novelties may hence emerge both from shifts in allelic frequencies and from shifts in learned, subject driven behavior. The existence of two principally different sources of variation also prevents the Modern Synthesis from self-referring explanations. (shrink)

Recent examples of rapid evolution under natural selection seem to require that the disciplines of ecology and evolution become better integrated. This inference makes sense only if one’s understanding of these disciplines is based on Hutchinson’s two-speed model of the ecological theater and the evolutionary play. Instead, these disciplines are more accurately viewed as occupying distinct “epistemic niches.” When so understood, we see that rapid evolution under selection, even if it is generally true, does not imply that evolutionary explanations are (...) improved by the inclusion of ecological details. Nor are ecological explanations necessarily improved by the inclusion of information about trait variation, heritability, effective population size, or other standard evolutionary factors. To illustrate, I develop a version of Kitcher’s “gory details” argument to show that, even for some trait that is under strong directional selection, a dynamically sufficient explanation of its ecological relationships should ignore most of the information explaining why that trait is evolving. The wholesale integration of ecology and evolution looks even less appealing when empirical sufficiency, a purely practical requirement, is taken into account. As a way forward, I propose an eco-evo partitioning framework. This strategy enables researchers to estimate the empirical sufficiency of a purely ecological, a purely evolutionary, or a combined eco-evo approach. (shrink)

There is surprisingly little philosophical work on conceptually spelling out the difference between the traits on which natural selection may be said to act (e.g. “having a high running speed”) and mere circumstantial traits (e.g. “happening to be in the path of a forest fire”). I label this issue the “selectable traits problem” and, in this paper, I propose a solution for it. I first show that, contrary to our first intuition, simply equating selectable traits with heritable ones is not (...) an adequate solution. I then go on to argue that two recent philosophical solutions to this problem—due to Peter Godfrey-Smith and Pierrick Bourrat—are unconvincing because they cannot accommodate frequency-dependent selection. The way out of this difficulty is, I argue, to accept that extrinsic properties dependent on relations between intrinsic properties of the population members should also count as selectable traits. I then show that my proposal is legitimized by more than the simple accommodation of frequency-dependent selection. (shrink)

Bernard Norton's friends in the history of science have had many reasons for commemorating, with admiration and affection, not only his research and teaching but no less his conversation and his company. One of his most estimable traits was his refusal to beat about the bush in raising the questions he thought worthwhile pursuing. I still remember discoursing at Pittsburgh on Darwin's route to his theory of natural selection, and being asked at the end by Bernard what were Darwin's views (...) on heredity. I answered with the conventional waffle to the effect that the theory concerned the populational fate rather than the individual production and transmission of heritable variation, so that whatever views Darwin had on heredity had only a subsidiary place in his theorizing. Bernard was not fooled. ‘I would have thought’, he said, ‘that in order to understand anyone's theorising about evolution it would be necessary to look at his views on heredity’. (shrink)

Social institutions are the laws, informal rules, and conventions that give durable structure to social interactions within a population. Such institutions are typically not designed consciously, are heritable at the population level, are frequently but not always group benefi cial, and are often symbolically marked. Conceptualizing social institutions as one of multiple possible stable cultural equilibrium allows a straightforward explanation of their properties. The evolution of institutions is partly driven by both the deliberate and intuitive decisions of individuals and collectivities. (...) The innate components of human psychology coevolved in response to a culturally evolved, institutional environment and refl ect a prosocial tendency of choices we make about institutional forms. (shrink)

Darwinism is defined here as an evolving research tradition based upon the concepts of natural selection acting upon heritable variation articulated via background assumptions about systems dynamics. Darwin’s theory of evolution was developed within a context of the background assumptions of Newtonian systems dynamics. The Modern Evolutionary Synthesis, or neo-Darwinism, successfully joined Darwinian selection and Mendelian genetics by developing population genetics informed by background assumptions of Boltzmannian systems dynamics. Currently the Darwinian Research Tradition is changing as it incorporates new information (...) and ideas from molecular biology, paleontology, developmental biology, and systems ecology. This putative expanded and extended synthesis is most perspicuously deployed using background assumptions from complex systems dynamics. Such attempts seek to not only broaden the range of phenomena encompassed by the Darwinian Research Tradition, such as neutral molecular evolution, punctuated equilibrium, as well as developmental biology, and systems ecology more generally, but to also address issues of the emergence of evolutionary novelties as well as of life itself. (shrink)

The article proposes to further develop the ideas of the Extended Evolutionary Synthesis by including into evolutionary research an analysis of phenomena that occur above the organismal level. We demonstrate that the current Extended Synthesis is focused more on individual traits (genetically or non-genetically inherited) and less on community system traits (synergetic/organizational traits) that characterize transgenerational biological, ecological, social, and cultural systems. In this regard, we will consider various communities that are made up of interacting populations, and for which the (...) individual members can belong to the same or to different species. Examples of communities include biofilms, ant colonies, symbiotic associations resulting in holobiont formation, and human societies. The proposed model of evolution at the level of communities revises classic theorizing on the major transitions in evolution by analyzing the interplay between community/social traits and individual traits, and how this brings forth ideas of top-down regulations of bottom-up evolutionary processes (collaboration of downward and upward causation). The work demonstrates that such interplay also includes reticulate interactions and reticulate causation. In this regard, we exemplify how community systems provide various non-genetic ‘scaffoldings’, ‘constraints’, and ‘affordances’ for individual and sociocultural evolutionary development. Such research complements prevailing models that focus on the vertical transmission of heritable information, from parent to offspring, with research that instead focusses on horizontal, oblique and even reverse information transmission, going from offspring to parent. We call this reversed information transfer the ‘offspring effect’ to contrast it from the ‘parental effect’. We argue that the proposed approach to inheritance is effective for modelling cumulative and distributed developmental process and for explaining the biological origins and evolution of language. (shrink)