Non-genetic Transmission Research Articles

The Double Pedigree: A Method for Studying Culturally and Genetically Inherited Behavior in Tandem

Transgenerational sources of biological variation have been at the center of evolutionary studies ever since Darwin and Wallace identified natural selection. This is because evolution can only operate on traits whose variation is transmitted, i.e. traits that are heritable. The discovery of genetic inheritance has led to a semantic shift, resulting in the tendency to consider that only genes are inherited across generations. Today, however, concepts of heredity are being broadened again to integrate the accruing evidence of non-genetic inheritance, and many evolutionary biologists are calling for the inclusion of non-genetic inheritance into an inclusive evolutionary synthesis. Here, we focus on social heredity and its role in the inheritance of behavioral traits. We discuss quantitative genetics methods that might allow us to disentangle genetic and non-genetic transmission in natural populations with known pedigrees. We then propose an experimental design based on cross-fostering among animal cultures, environments and families that has the potential to partition inherited phenotypic variation into socially (i.e. culturally) and genetically inherited components. This approach builds towards a new conceptual framework based on the use of an extended version of the animal model of quantitative genetics to integrate genetic and cultural components of behavioral inheritance.

Motility, Potentiality, and Infinity—A Semiotic Hypothesis on Nature and Religion

Against any obscurantist stand, denying the interest of natural sciences for the comprehension of human meaning and language, but also against any reductionist hypothesis, frustrating the specificity of the semiotic point of view on nature, the paper argues that the deepest dynamic at the basis of meaning consists in its being a mechanism of ‘potentiality navigation’ within a universe generally characterized by motility. On the one hand, such a hypothesis widens the sphere of meaning to all beings somehow endowed with the capacity of moving and/or perceiving movement. On the other hand, through a new evolutionist interpretation of the concept of generativity, such a hypothesis preserves the peculiarity of human meaning, meant as essentially founded on a certain intuition of infinity. Two corollaries stem from this hypothesis: first, religiosity can be considered as a matrix of grammars of infinity, aiming at regimenting its flight of potentialities. Second, non-genetic transmission of cultural information exerts determinant influence also at the level of that very deep mechanism of the human predicament that is the cognitive navigation of motor potentialities. A re-reading of the structuralist epistemology, scientific literature on the nervous cells of jellyfish, and some recent experiments on the mirror neurons of dancers, as well as certain intuitions of Teilhard de Chardin, are the main arguments of the paper.

Long‐term consequences of stunting in early life

This review summarizes the impact of stunting, highlights recent research findings, discusses policy and programme implications and identifies research priorities. There is growing evidence of the connections between slow growth in height early in life and impaired health and educational and economic performance later in life. Recent research findings, including follow-up of an intervention trial in Guatemala, indicate that stunting can have long-term effects on cognitive development, school achievement, economic productivity in adulthood and maternal reproductive outcomes. This evidence has contributed to the growing scientific consensus that tackling childhood stunting is a high priority for reducing the global burden of disease and for fostering economic development. Follow-up of randomized intervention trials is needed in other regions to add to the findings of the Guatemala trial. Further research is also needed to: understand the pathways by which prevention of stunting can have long-term effects; identify the pathways through which the non-genetic transmission of nutritional effects is mediated in future generations; and determine the impact of interventions focused on linear growth in early life on chronic disease risk in adulthood.

The serotonin 1A receptor gene as a genetic and prenatal maternal environmental factor in anxiety

Low serotonin(1A) receptor (5-HT(1A)R) binding is a risk factor for anxiety and depression, and deletion of the 5-HT(1A)R results in anxiety-like behavior in mice. Here we show that anxiety-like behavior in mice also can be caused, independently of the offspring's own 5-HT(1A)R genotype, by a receptor deficit in the mother: a nongenetic transmission of a genetic defect. Some of the nongenetically transmitted anxiety manifestations were acquired prenatally and linked to a delay in dentate gyrus maturation in the ventral hippocampus of the offspring. Both the developmental delay and the anxiety-like phenotype were phenocopied by the genetic inactivation of p16(ink4a) encoding a cyclin-dependent kinase inhibitor implicated in neuronal precursor differentiation. No maternal 5-HT(1A)R genotype-dependent anxiety developed when the strain background was switched from Swiss Webster to C57BL/6, consistent with the increased resilience of this strain to early adverse environment. Instead, all anxiety manifestations were caused by the offspring's own receptor deficiency, indicating that the genetic and nongenetic effects converge to common anxiety manifestations. We propose that 5-HT(1A)R deficit represents a dual risk for anxiety and that vulnerability to anxiety associated with genetic 5-HT(1A)R deficiency can be transmitted by both genetic and nongenetic mechanisms in a population. Thus, the overall effect of risk alleles can be higher than estimated by traditional genetic assays and may contribute to the relatively high heritability of anxiety and psychiatric disorders in general.

Interspecific Social Learning: Novel Preference Can Be Acquired from a Competing Species

Nongenetic transmission of behavioral traits via social learning allows local traditions in humans, and, controversially, in other animals [1-4]. Social learning is usually studied as an intraspecific phenomenon (but see [5-7]). However, other species with some overlap in ecology can be more than merely potential competitors: prior settlement and longer residence can render them preferable sources of information [8]. Socially induced acquisition of choices or preferences capitalizes upon the knowledge of presumably better-informed individuals [9] and should be adaptive under many natural circumstances [10, 11]. Here we show with a field experiment that females of two migrant flycatcher species can acquire a novel, arbitrary preference of competing resident tits for a symbol attached to the nest sites. The experiment demonstrates that such blind acquisition of heterospecific traits can occur in the wild. Even though genetic variation for habitat preferences exists in many taxa [12] and overlap between bird species likely induces costs [13], this result shows that interspecific social learning can cause increased overlap in nest-site preferences. Conventional, negative species interactions push ecological niches of species apart, but the use of competing species as a source of information counters that force and may lead to convergence.

Human personality traits are associated with individual environmental traits in male adolescents—a pilot study

The human personality seems to be formed by biological (internal) and environmental (external) factors, which function interactively. This pilot study examined the relationship between fundamental personality traits and individual environmental traits in healthy adolescents. A complex relationship between personality traits and candidate environmental traits was found in this sample. Parental smoking, one of the hypothetical environmental traits, was significantly associated with the sociability personality trait of adolescent offspring. Another hypothetical environmental trait-parent/child attachment status-"was related to novelty-seeking personality. Unexpectedly, these associations were observed only in male but not in female adolescents. The present study suggested that (1) parental smoking behavior might directly or indirectly affect offspring social behavior and related personality by nongenetic transmission; (2) past and present data indicated that the triad of a poor parent/child relationship, novelty-seeking personality, and risky/delinquent behavior is closely connected. Investigations of environmental traits at a nonclinical level may lead us to understand the overall human personality, as with research on genes and biological traits that are implicated in the formation of mental activity.

Evidence for a major gene influencing risk of pancreatic cancer.

Family history of pancreatic cancer, the fifth leading cause of cancer death in the United States, confers a 1.5-13-fold higher risk of developing pancreatic cancer. Pancreatic cancer is associated with several genetic syndromes, including hereditary breast cancer (BRCA2), familial atypical multiple mole melanoma (FAMMM) syndrome, Peutz-Jeghers syndrome, hereditary pancreatitis, and hereditary nonpolyposis colorectal cancer (HNPCC). However, these syndromes explain little of the observed familial aggregation of pancreatic cancer. We performed complex segregation analysis on 287 families ascertained through an index case diagnosed with pancreatic cancer at the Johns Hopkins Medical Institutions between January 1, 1994 and December 31, 1999. We tested for the presence of a major gene controlling either the "age-at-onset of pancreatic cancer" of "susceptibility to pancreatic cancer," and incorporated smoking data on kindred members as a covariate. We found evidence for involvement of a major gene in the etiology of pancreatic cancer. Whether inheritance was modeled as "age-at-onset" or "susceptibility," nongenetic transmission models were strongly rejected. However, modeling "age-at-onset" provided a better fit to the observed data than did modeling "susceptibility." The most parsimonious models included autosomal-dominant inheritance of a rare allele. Under the age-at-onset model, approximately 0.7% of the population appears to be at high risk of developing pancreatic cancer due to this putative gene, whereas 0.4% of the population is at high risk under the susceptibility model. Inclusion of smoking as a covariate did not significantly improve the fit of these models. This hospital-based segregation analysis of pancreatic cancer found evidence supporting the role of a rare major gene influencing risk of pancreatic cancer.

Inheritance of cleft palate in Italy. Evidence for a major autosomal recessive locus.

Although several studies have demonstrated familial aggregation of nonsyndromic cleft palate (CP), the mode of inheritance still remains uncertain. We report the results of complex segregation analysis performed in families of 357 consecutive newborns affected with nonsyndromic CP (i.e., CP not a component feature of malformation syndrome, sequence or association), and registered in the North East Italy and Emilia Romagna congenital malformation registries in the period 1981-1993. This sample, based on a large number of consecutive births, in a well-defined geographical area, with quality control to detect associated anomalies and malformation syndromes, is independent of the number of affected subjects in the family and of CP severity, fitness, and survival. We have analyzed, using the mixed model, the whole sample of nonsyndromic CP, including isolated (i.e., without other anomalies) CP (CPI) and CP associated with at least one other anomaly (CPA), for which a diagnosis of malformation syndrome was not possible. When nonsyndromic CP (including CPA) are considered in the analysis, there is no heterogeneity between CPA and CPI nor between CP including hard palate (CPH) and CP of the soft palate only (CPS). POINTER and COMDS programs cannot discriminate between alternative genetic models; only the hypothesis of non-genetic transmission is rejected. The COMDS analysis two-locus model, which indicates that a modifier locus (or loci) operates in addition to a single major locus (SML), does not show evidence of better fit than SML, polygenic, and multifactorial models. When the severity parameter (defined as CPH and CPS) is added, CPI and CPA show heterogeneity. Eventually, when the analysis is limited to CPI and includes information on severity, a recessive SML, with low penetrance and determining CPH, provides a significant best fit. To have defined a genetic model for CPI and provided evidence for SML inheritance suggests that genetic linkage studies could be implemented. This conclusion is in agreement with previous studies which showed a significant association between alleles of transforming growth factor alpha and CP only in humans, and that single recessive genes may play a crucial role during palatogenesis in mice as well as in Brittany spaniels. Application of the candidate genes to human CPH families could reveal whether these genes are involved.

New segregation analysis of panic disorder.

We performed simple segregation analyses of panic disorder using 126 families of probands with DSM-III-R panic disorder who were ascertained for a family study of anxiety disorders at an anxiety disorders research clinic. We present parameter estimates for dominant, recessive, and arbitrary single major locus models without sex effects, as well as for a nongenetic transmission model, and compare these models to each other and to models obtained by other investigators. We rejected the nongenetic transmission model when comparing it to the recessive model. Consistent with some previous reports, we find comparable support for dominant and recessive models, and in both cases estimate nonzero phenocopy rates. The effect of restricting the analysis to families of probands without any lifetime history of comorbid major depression (MDD) was also examined. No notable differences in parameter estimates were found in that subsample, although the power of that analysis was low. Consistency between the findings in our sample and in another independently collected sample suggests the possibility of pooling such samples in the future in order to achieve the necessary power for more complex analyses.

Non-genetic transmission of information: Candidate cognitive processes and the evolution of culture

The evolution of dual-inheritance systems, specifically the evolution of human culture, are considered as evolutionary events of profound significance. In this paper I adopt the view commonly held amongst biologists in recent years that human cultural change can be fruitfully understood as cultural evolution. Such an approach does not deny the possibility of understanding cultural change from other viewpoints. It does, however, have the advantage of having to be couched in explicitly psychological terms. Using the replicator-interactor theory of Dawkins and Hull I explore what cognitive mechanisms might be identified as having the properties of a replicator, and how reconstructions of human evolution may help in identifying such mechanisms.

Secular trends in the familial transmission of alcoholism.

This is a study of the familial transmission of alcoholism in the families of 60 female and 240 male alcoholics ascertained in four psychiatric hospital units and in a local parole office. Eight hundred and thirty-one interviewed first-degree relatives and 125 spouses are included. The lifetime population prevalences of alcoholism in white males and females based on the Epidemiological Catchment Area Study in St. Louis were compared with the family rates. A semistructured comprehensive interview schedule (Home Environment and Lifetime Psychiatric Evaluation Record) was used and diagnoses made according to Feighner criteria for alcoholism. The methods of Survival Analysis established the presence of strong secular trends in the age-of-onset and lifetime prevalence of alcoholism in these families and in the general population. Accordingly, new methods for the analysis of family data that incorporate secular variation were developed. The Multifactorial Model of Disease Transmission was used to estimate familial correlations and these were parameterized by the "Tau" model of Familial Transmission. The model does not assume that all familial resemblance is due to genetic factors, but also includes the possibility of nongenetic transmission. Our analyses confirmed that more recently born cohorts of individuals had increased expected lifetime prevalences of alcoholism and decreased ages of onset, when compared with older cohorts. Separate age-of-onset distributions were required for males and females and the secular trends in age-of-onset were greatest in females. The differences between males and females were least in more recently born cohorts suggesting that sex-specific differences in the family and population distribution of alcoholism are decreasing.(ABSTRACT TRUNCATED AT 250 WORDS)

From icons to symbols: Some speculations on the origins of language

This paper is divided into three sections. In the first section we offer a retooling of some traditional concepts, namely icons and symbols, which allows us to describe an evolutionary continuum of communication systems. The second section consists of an argument from theoretical biology. In it we explore the advantages and disadvantages of phenotypic plasticity. We argue that a range of the conditions that selectively favor phenotypic plasticity also favor a nongenetic transmission system that would allow for the inheritance of acquired characters. The first two sections are independent, the third depends on both of them. In it we offer an argument that human natural languages have just the features required of an ideal transmission mechanism under the conditions described in section 2.

Dual inheritance in haploid organisms: a model of magnetotactic bacteria

Models of the interaction between genetic inheritance and nongenetic information transmission across generations often deal with flexible behavior in complicated organisms, making the underlying hypotheses difficult to test. Magnetotactic bacteria also utilize inheritance of genetic and nongenetic information, in which there is an innately prescribed acquisition of a tendency to swim toward one geomagnetic pole rather than the other. A class of models is formulated in which the evolution of innate factors biasing progeny bacteria to adopt or avoid the pole-seeking behavior of their maternal cell can be studied. Analysis of these models indicates that natural selection in geomagnetic environments with reversing polarity of the terrestrial type will favor bacteria that are innately constrained to adopt the maternal behavior much more often than the alternative pole-seeking behavior. This predicted mode of information transfer is found to be in reasonable accord with the data on pole-seeking tendencies. The models also appear to be amenable to direct test by means of artificial selection protocols in which imposed magnetic fields are changed abruptly.

Social transmission of behavioural traditions in a coral reef fish

Traditional behaviours involve the non-genetic transmission of social information across age classes or generations. French grunts ( Haemulon flavolineatum) exhibit social traditions of daytime schooling sites and twilight migration routes. Individuals transplanted to new schooling sites and allowed to follow residents at the new sites used the new migration routes and returned to the new sites in the absence of resident fish. Control fish with no opportunity to learn showed no such directionality or return. This is the first demonstration of apparent pre-cultural behaviour in free-living fish. Our observations suggest additional classes of behaviour and taxonomic groups in which pre-cultural activities are likely to have evolved.

Pre-mating and pregnancy stress in rats affects behaviour of grandpups.

EXPERIMENTAL manipulations of female rats have significantly influenced the open field behaviour of their grandpups. This phenomenon has been called “non-genetic transmission of information”1. Whereas the experimental manipulations of the grandmothers reported in ref. 1 consisted of pre-weaning infantile “handling”, we have investigated whether stress of the grandmother rat before and during pregnancy affected the open field behaviour of the offspring of the foetuses carried during or immediately after the periods of stress.

A "transmissible entity" in the control of cancer in mice.

AbstractThe paper is divided into three sections. Section 1 consists of an account of the historical development of a biological concept for cancer control in mice by the senior author. Section 2 presents new data on the effect of a liver‐derived inhibitor of spontaneous tumors of mammary gland origin in mice in inducing a ‘transmissible entity’ that has been passed down through nine generations. The entity affects the biological characteristics of spontaneous tumors in mice and increases in potency in controlling cancer in mice of succeeding generations. The possibility of whether a genetic or a nongenetic transmission is involved in the passage of a ‘transmissible entity’ from generation to generation cannot be determined by the existing data. Section 3 lists the conclusions that have been reached concerning the biological and biochemical characteristics of the tumor inhibitor.

Non-genetic adaptation to temperature and salinity

Non-genetic adaptation to temperature and salinity