Heredity of type 2 diabetes confers increased susceptibility to oxidative stress and inflammation

INTRODUCTION AND OBJECTIVE

Heredity of type 2 diabetes mellitus (T2DM) is associated with greater risk for developing T2DM. Thus, individuals who have a first-degree relative with T2DM (FDRT) provide a natural model to study factors of susceptibility towards development of T2DM, which are poorly understood. Emerging key players in T2DM pathophysiology such as adverse oxidative stress and inflammatory responses could be among possible mechanisms that predispose FDRTs to develop T2DM. Here, we aimed to examine the role of oxidative stress and inflammatory responses as mediators of this excess risk by studying dynamic postprandial responses in FDRTs.

RESEARCH DESIGN AND METHODS

In this open-label case-control study, we recruited normoglycemic men with (n=9) or without (n=9) a family history of T2DM. We assessed plasma glucose, insulin, lipid profile, cytokines and F₂-isoprostanes, expression levels of oxidative and inflammatory genes/proteins in circulating mononuclear cells (MNC), myotubes and adipocytes at baseline (fasting state), and after consumption of a carbohydrate-rich liquid meal or insulin stimulation.

RESULTS

Postprandial glucose and insulin responses were not different between groups. Expression of oxidant transcription factor NRF2 protein (p<0.05 for myotubes) and gene (p_group=0.002, p_time×group=0.016), along with its target genes TXNRD1 (p_group=0.004, p_time×group=0.007), GPX3 (p_group=0.011, p_time×group=0.019) and SOD-1 (p_group=0.046 and p_time×group=0.191) was upregulated in FDRT-derived MNC after meal ingestion or insulin stimulation. Synergistically, expression of target genes of inflammatory transcription factor nuclear factor kappa B such as tumor necrosis factor alpha (p_group=0.001, p_time×group=0.007) was greater in FDRT-derived MNC than in non-FDRT-derived MNC after meal ingestion or insulin stimulation.

CONCLUSIONS

Our findings shed light on how heredity of T2DM confers increased susceptibility to oxidative stress and inflammation. This could provide early insights into the underlying mechanisms and future risk of FDRTs for developing T2DM and its associated complications.

Should we ask for more than consistency of Darwinism with Mendelism?

A nonmathematical exposition of the current status of the formal darwinism project is presented, linking it to the fundamental theorem of natural selection, which is regarded as Fisher's own 'formal darwinism project'. The purpose is to found organism-level thinking about design and adaptation, in short Darwinism, on what is known about the mechanics of genetic inheritance, in short Mendelism, and the project is to do so in as general a biological setting as possible. This view also makes sense of the name 'fundamental theorem of natural selection'.

Adipocyte epigenetic alterations and potential therapeutic targets in transgenerationally inherited lean and obese phenotypes following ancestral exposures

The incidence of obesity has increased dramatically over the past two decades with a prevalence of approximately 40% of the adult population within the United States. The current study examines the potential for transgenerational adipocyte (fat cell) epigenetic alterations. Adipocytes were isolated from the gonadal fat pad of the great-grand offspring F3 generation 1-year old rats ancestrally exposed to DDT (dichlorodiphenyltrichloroethane), atrazine, or vehicle control in order to obtain adipocytes for DNA methylation analysis. Observations indicate that there were differential DNA methylated regions (DMRs) in the adipocytes with the lean or obese phenotypes compared to control normal (non-obese or lean) populations. The comparison of epigenetic alterations indicated that there were substantial overlaps between the different treatment lineage groups for both the lean and obese phenotypes. Novel correlated genes and gene pathways associated with DNA methylation were identified, and may aid in the discovery of potential therapeutic targets for metabolic diseases such as obesity. Observations indicate that ancestral exposures during critical windows of development can induce the epigenetic transgenerational inheritance of DNA methylation changes in adipocytes that ultimately may contribute to an altered metabolic phenotype.

Isolated Growth Hormone Deficiency Type 2 due to a novel GH1 Mutation: A Case Report

Isolated growth hormone (GH) deficiency (IGHD) type 2 is a rare autosomal dominant disorder characterized by severe short stature with low GH level. Timely diagnosis is important for optimal results of recombinant human GH (rhGH) treatment and detection of additional pituitary deficiencies in affected relatives. A male child presented at the age of one year with severe, proportionate short stature [-4.9 standard deviation score (SDS)] and with a normal body mass index (-1.1 SDS). Physical examination revealed frontal bossing, midfacial hypoplasia, normal external genitalia and no dysmorphic features. Paternal and maternal heights were -6.1 and -1.9 SDS. Serum insulin-like growth factor-1 (IGF-1) and IGF-binding protein-3 were undetectable and the peak GH concentration by clonidine stimulation test was extremely low (0.18 ng/mL). Brain magnetic resonance imaging showed anterior pituitary hypoplasia. Genetic analysis identified a novel heterozygous mutation (c.291+2T>G) expected to lead to splicing out exon 3 of GH1. rhGH from age 2.4 years led to appropriate catch-up. In conclusion, we identified a novel GH1 gene mutation in an infant with classical IGHD type 2 presentation.

Characterization of permethrin resistance in a Musca domestica strain: resistance development, cross-resistance potential and realized heritability

BACKGROUND

Permethrin (a pyrethroid) has been recommended for the management of a number of insect pests, including Musca domestica. Recently, resistance to permethrin has been reported from the Punjab province, Pakistan, which necessitates the need to manage the resistance problem. For this reason, a field strain of M. domestica was selected with permethrin for ten consecutive generations (G1-G10) to determine the risk assessment, the rapidity with which permethrin resistance can develop, and the presence or absence of the cross-resistance phenomenon.

RESULTS

The results revealed that permethrin resistance increased very quickly in response to selection experiments. The resistance ratio (RR) value increased by 16.04- to 605.92-fold and the LD₅₀ value increased by 100.22 to 3787.08 ng fly^-1 after selection experiments. Moreover, the increase in LD₅₀ value remained stable when the selected strain (Perm-SEL) was cultured in the absence of permethrin for the next five generations (G11-G15). The results revealed the possibility of minor cross-resistance in the Perm-SEL strain with β-cyfluthrin and deltamethrin, and lack of cross-resistance with imidacloprid and spinosad. The realized heritability (h² ) value for the Perm-SEL strain was 0.23. Assuming a mean slope value of 1.27 and an h² value of 0.23, then ten to four generations would be estimated for a 10-fold increase in the LD₅₀ values at 50-90% selection intensity, respectively.

CONCLUSION

The results of present study revealed high risk for permethrin resistance development under continuous selection pressure. Permethrin resistance developed very quickly under laboratory conditions, which might reflect the likelihood of resistance evolution in field conditions if permethrin selection pressure holds for a long time. © 2019 Society of Chemical Industry.

Mutational analysis of the LDLR gene in a cohort of Colombian families with familial hypercholesterolemia

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) is characterized by elevated serum cholesterol levels due to high low-density lipoprotein (LDL) cholesterol levels. FH is an autosomal dominant genetic disorder and one of the most common dominant hereditary diseases in the world. However, the frequency of mutations in Colombia is unknown. The purpose of this preliminary study was to identify mutations in the LDL receptor (LDLR) gene in a Colombian population with FH.

METHODS

The study included 24 families with clinical diagnosis of sure/probable FH. The 18 exons of the LDLR were sequenced by Sanger method.

RESULTS

Among 18 variants identified, 3 were known pathogenic mutations and were identified in nine individuals in five unrelated families. Five affected individuals were heterozygous for one mutation each. They were the p.W4X in two, the p.D139G in two and the p.G396D in one. Two affected individuals were homozygous for p.G396D. The variant c.1187-1G > T, which has uncertain significance in FH pathogenesis, was present in all the individuals with the p.D139G mutation.

CONCLUSIONS

In total, 18 variants were identified, of which 14 correspond to known nonpathogenic variants. Three pathogenic variants were identified in the LDLR. No pathological mutations were identified in the LDLR in 79% of the study population.

Biogenetic ties and parent-child relationships: The misplaced critique

According to an almost axiomatic standard in bioethics, moral commitment should ground parents' relationship with their children, rather than biogenetic relatedness. This standard has been used lately to express skepticism about extending existing assisted reproductive treatments (ARTs) to same-sex couples and to research into novel fertility interventions for those couples, but this skepticism is misplaced on several grounds. As a matter of access and equity, same-sex couples seem presumptively entitled to genetic relatedness to their children as far as possible both in regard to existing ARTs and to novel ARTs under investigation. For those worried about the effects of trying to secure biogenetic relatedness for same-sex couples, it may be noted that same-sex couples will only ever be a fraction of the parents implicated in propping up "biologism," as the expectation of biogenetic relatedness it is sometimes called. The cultural force of biologism would survive almost intact even if no same-sex couples were ever to have genetically related children. It is therefore hard to see why same-sex couples should forfeit aspirations to biogenetic relationships with their children or enjoy less subsidy for ARTs than the subsidy given to different-sex couples. As matter of moral consistency, the full implications of the biologism critique have yet to be evaluated relative to different-sex couples.

Inheritance of pre-emergent metribuzin tolerance and putative gene discovery through high-throughput SNP array in wheat (Triticum aestivum L.)

BACKGROUND

Herbicide tolerance is an important trait that allows effective weed management in wheat crops in dryland farming. Genetic knowledge of metribuzin tolerance in wheat is needed to develop new cultivars for the industry. Here, we investigated gene effects for metribuzin tolerance in nine crosses of wheat by partitioning the means and variances of six basic generations from each cross into their genetic components to assess the gene action governing the inheritance of this trait. Metribuzin tolerance was measured by a visual senescence score 21 days after treatment. The wheat 90 K iSelect SNP genotyping assay was used to identify the distribution of alleles at SNP sites in tolerant and susceptible groups.

RESULTS

The scaling and joint-scaling tests indicated that the inheritance of metribuzin tolerance in wheat was adequately described by the additive-dominance model, with additive gene action the most significant factor for tolerance. The potence ratio for all the crosses ranged between - 1 and + 1 for senescence under metribuzin-treated conditions indicating a semi-dominant gene action in the inheritance of metribuzin tolerance in wheat. The number of segregating genes governing metribuzin tolerance was estimated between 3 and 15. The consistent high heritability range (0.82 to 0.92) in F_5-7 generations of Chuan Mai 25 (tolerant) × Ritchie (susceptible) cross indicated a significant contribution of additive genetic effects to metribuzin tolerance in wheat. Several genes related to photosynthesis (e.g. photosynthesis system II assembly factor YCF48), metabolic detoxification of xenobiotics and cell growth and development (cytochrome P450, glutathione S-transferase, glycosyltransferase, ATP-binding cassette transporters and glutathione peroxidase) were identified on different chromosomes (2A, 2D, 3B, 4A, 4B, 7A, 7B, 7D) governing metribuzin tolerance.

CONCLUSIONS

The simple additive-dominance gene effects for metribuzin tolerance will help breeders to select tolerant lines in early generations and the identified genes may guide the development of functional markers for metribuzin tolerance.

The disequilibrium of double descent: changing inheritance norms among Himba pastoralists

Matrilineal systems in sub-Saharan Africa tend to co-occur with horticulture and are rare among pastoralists, with the causal arrow pointing from the introduction of cattle to the loss of matriliny. However, most work on this topic stems from either phylogenetic analyses or historical data. To better understand the shift from matrilineal to patrilineal inheritance that occurred among Bantu populations after the adoption of pastoralism, data from societies that are currently in transition are needed. Himba pastoralists, who practice 'double descent', may represent one such society. Using multi-generational ethnography and structured survey data, we describe current norms and preferences about inheritance, as well as associated norms related to female autonomy. We find that preferences for patrilineal inheritance are strong, despite the current practice of matrilineal cattle inheritance. We also find that a preference for patriliny predicts greater acceptance of norm violating behaviour favouring sons over nephews. Finally, we show that there are important generational differences in how men view women's autonomy, which are probably attributable to both changing norms about inheritance and exposure to majority-culture views on women's roles. Our data shed light on how systemic change like the shifts in descent reckoning that occurred during the Bantu expansion can occur. This article is part of the theme issue 'The evolution of female-biased kinship in humans and other mammals'.

School tracking and its role in social reproduction: reinforcing educational inheritance and the direct effects of social origin

The degree of social reproduction varies considerably between industrialized countries, raising the question of which institutional regulations promote or restrict this process. Education is considered the main mediator of social reproduction. Because school tracking - the sorting of children according to ability and interest at different ages - is known to affect educational attainment and the degree of tracking varies strongly across countries, it may thus account for differences in social reproduction. However, empirical studies are scarce, and the total impact of tracking on social reproduction remains ambiguous. Using the European Social Survey (ESS) 2012 and 2014 from 24 countries, we demonstrate that school tracking is strongly associated with higher degrees of social reproduction. Decomposing the process of social reproduction into educational inheritance, educational returns and direct effects of social origin, we find that although all channels contribute to social reproduction, the impact of tracking seems to be exerted through educational inheritance and to a similar degree through direct effects of social origin, whereas educational returns do not seem to be affected. Even net of educational attainment, social origin thus has a stronger effect on social status in tracked systems. We ascribe this effect to differences in qualitative choices within educational tracks, such as fields of study.

Differential Influences of Genes and Environment Across the Distribution of Reading Ability

We partitioned early childhood reading into genetic and environmental sources of variance and examined the full distribution of ability levels from low through normal to high as computed by quantile regression. The full sample comprised twin pairs measured at preschool (n = 977), kindergarten (n = 1028), grade 1 (n = 999), and grade 2 (n = 1000). Quantile regression analyses of the full distribution of literacy ability showed genetic influence in all grades from preschool to grade 2. At preschool, the low end of the distribution had higher genetic influence than the high end of the distribution and the shared environment influence was the opposite. These shared environment influences of preschool became insignificant with formal schooling. This suggests that higher scores in pre-literacy skills (preschool) are more influenced by shared environment factors, though these are short-lived. This study discusses the factors that may be influencing the results.

A genome-wide association study identifies genetic loci associated with specific lobar brain volumes

Brain lobar volumes are heritable but genetic studies are limited. We performed genome-wide association studies of frontal, occipital, parietal and temporal lobe volumes in 16,016 individuals, and replicated our findings in 8,789 individuals. We identified six genetic loci associated with specific lobar volumes independent of intracranial volume. Two loci, associated with occipital (6q22.32) and temporal lobe volume (12q14.3), were previously reported to associate with intracranial and hippocampal volume, respectively. We identified four loci previously unknown to affect brain volumes: 3q24 for parietal lobe volume, and 1q22, 4p16.3 and 14q23.1 for occipital lobe volume. The associated variants were located in regions enriched for histone modifications (DAAM1 and THBS3), or close to genes causing Mendelian brain-related diseases (ZIC4 and FGFRL1). No genetic overlap between lobar volumes and neurological or psychiatric diseases was observed. Our findings reveal part of the complex genetics underlying brain development and suggest a role for regulatory regions in determining brain volumes.

Selection for imidacloprid resistance and mode of inheritance in the brown planthopper, Nilaparvata lugens

BACKGROUND

Strong resistance to imidacloprid in Nilaparvata lugens (Stål) has developed in Southeast and East Asia. Although the mode of inheritance for resistance is very useful information for pest control, this information is unknown in N. lugens. Here, we established two resistant strains that were selected from field populations in Vietnam and the Philippines, and conducted crossing experiments to determine the inheritance pattern.

RESULTS

The resistance ratio of 50% lethal dose (LD₅₀ ) values for the two resistance-selected strains, i.e., resistant strains originating from Vietnam (VT-Res) and the Philippines (PH-Res), to their control strains were ∼ 8- and 157-fold, respectively. Reciprocal cross experiments between VT-Res and the susceptible strain (S-strain), and between PH-Res and the S-strain showed that the degree of dominance was 0.81 and 0.82, and 0.95 and 0.96, respectively. Analysis of the F₂ populations and backcrosses to the parental strains indicated that resistance is a major-gene trait following Mendelian inheritance. The strength of the resistance was suppressed by pre-treatment with piperonyl butoxide, an inhibitor of cytochrome P450-monooxygenases.

CONCLUSION

Our results suggest that imidacloprid resistance in N. lugens is autosomal and an almost completely dominant major-gene trait that is likely manifested by high expression levels of a detoxification enzyme. © 2019 Society of Chemical Industry.

A Brief Review of Genetic Approaches to the Study of Food Preferences: Current Knowledge and Future Directions

Genetic variation plays a crucial role in individual differences in food preferences which ultimately influence food selection and health. Our current understanding of this pathway has been informed through twin studies (to assess the heritability of food preferences), candidate gene studies, and genome-wide association studies (GWAS). However, most of this literature is mainly focused on genes previously identified as having taste or smell functions. New data suggests that genes not associated with taste or smell perception may be involved in food preferences and contribute to health outcomes. This review highlights these emerging findings and suggests a polygenic risk assessment approach to explore new relationships between food preferences and health risks.

Prospective Cardiovascular Genetics Evaluation in Spontaneous Coronary Artery Dissection

BACKGROUND

Previous studies describing genetics evaluation in spontaneous coronary artery dissection (SCAD) have been retrospective in nature or presented as single case reports. As part of a dedicated clinical program, we evaluated patients in cardiovascular genetics clinic to determine the role of genetically triggered vascular disease and genetic testing in SCAD.

METHODS AND RESULTS

Patient data were entered prospectively into the Massachusetts General Hospital SCAD registry database from July 2013 to September 2017. Clinically indicated genetic testing was conducted based on patient imaging, family history, physical examination, and patient preference. Of the 107 patients enrolled in the registry, 73 underwent cardiovascular genetics evaluation at our center (average age, 45.3±9.4 years; 85.3% female), and genetic testing was performed for 44 patients. A family history of aneurysm or dissection was not a prevalent feature in the study population, and only 1 patient had a family history of SCAD. Six patients (8.2%) had identifiable genetically triggered vascular disease: 3 with vascular Ehlers-Danlos syndrome (COL3A1), 1 with Nail-patella syndrome (LMX1B), 1 with autosomal dominant polycystic kidney disease (PKD1), and 1 with Loeys-Dietz syndrome (SMAD3). None of these 6 had radiographic evidence of fibromuscular dysplasia.

CONCLUSIONS

In this series, 8.2% of the SCAD patients evaluated had a molecularly identifiable disorder associated with vascular disease. The most common diagnosis was vascular Ehlers-Danlos syndrome. Patients with positive gene testing were significantly younger at the time of their first SCAD event. A low threshold for genetic testing should be considered in patients with SCAD.

Evolutionary transitions in heritability and individuality

With a few exceptions, the literature on evolutionary transitions in individuality (ETIs) has mostly focused on the relationships between lower-level (particle-level) and higher-level (collective-level) selection, leaving aside the question of the relationship between particle-level and collective-level inheritance. Yet, without an account of this relationship, our hope to fully understand the evolutionary mechanisms underlying ETIs is impeded. To that effect, I present a highly idealized model to study the relationship between particle-level and collective-level heritability both when a collective-level trait is a linear function and when it is a nonlinear function of a particle-level trait. I first show that when a collective trait is a linear function of a particle-level trait, collective-level heritability is a by-product of particle-level heritability. It is equal to particle-level heritability, whether the particles interact randomly or not to form collectives. Second, I show that one effect of population structure is the reduction in variance in offspring collective-level character for a given parental collective. I propose that this reduction in variance is one dimension of individuality. Third, I show that even in the simple case of a nonlinear collective-level character, collective-level heritability is not only weak but also highly dependent on the frequency of the different types of particles in the global population. Finally, I show that population structure, because one of its effects is to reduce the variance in offspring collective-level character, allows not only for an increase in collective-level character but renders it less context dependent. This in turn permits a stable collective-level response to selection. The upshot is that population structure is a driver for ETIs. These results are particularly significant in that the relationship between population structure and collective-level heritability has, to my knowledge, not been previously explored in the context of ETIs.

The evolutionary potential of diet-dependent effects on lifespan and fecundity in a multi-parental population of Drosophila melanogaster

The nutritional conditions experienced by a population have a major role in shaping trait evolution in many taxa. Constraints exerted by nutrient limitation or nutrient imbalance can influence the maximal value that fitness components such as reproduction and lifespan attains, and organisms may shift how resources are allocated to different structures and functions in response to changes in nutrition. Whether the phenotypic changes associated with changes in nutrition represent an adaptive response is largely unknown. Further, it is unclear whether the response of fitness components to diet even has the potential to evolve in most systems. In this study, we use an admixed multi-parental population of Drosophila melanogaster reared in three different diet conditions to estimate quantitative genetic parameters for lifespan and fecundity. We find significant genetic variation for both traits in our population and show that lifespan has moderate to high heritabilities within diets. Genetic correlations for lifespan between diets were significantly less than one, demonstrating a strong genotype by diet interaction. These findings demonstrate substantial standing genetic variation in our population that is comparable to natural populations and highlights the potential for adaptation to changing nutritional environments.

Asymmetrical selection maintains heritable phenotypic variation between two subspecies of Monardella villosa

PREMISE

Monardella villosa is an evolutionarily young species complex distributed across a large geographic range. Our goal was to determine whether the phenotypic difference between two subspecies of M. villosa was heritable and whether the alternative phenotypes were adaptive to their respective local habitats.

METHODS

We collected seeds from 25 populations of M. villosa, 14 from subspecies franciscana, which grows closer to the coast, and 11 from subspecies villosa, which has a larger and more inland geographic distribution. We reciprocally transplanted the two subspecies into their respective habitats and compared plant germination, post-emergence survival, and growth. We used linear mixed models to quantify the effects of genotype and environment to determine whether subspecies were locally adapted and whether leaf traits that distinguish these subspecies were genetically based.

RESULTS

Plants of both subspecies grown at the coastal site had significantly lower survival and biomass than the inland site. The subspecies were not locally adapted; however, the coastal subspecies franciscana did have a home site advantage. We also found that distinctive leaf morphological traits were genetically based, with high broad-sense heritability of traits.

CONCLUSIONS

The two subspecies of Monardella villosa were not locally adapted to their respective habitat, but rather we found that selection for local genotypes may be stronger at the coastal site. Despite the lack of evidence for local adaptation in the strict sense, the subspecies had heritable variation in several leaf phenotypes, indicating that heterogeneous selection imposes an adaptive trade-off for leaf trichome production within this species.

Inter-generational consequences for growing Caenorhabditis elegans in liquid

In recent years, studies in Caenorhabditis elegans nematodes have shown that different stresses can generate multigenerational changes. Here, we show that worms that grow in liquid media, and also their plate-grown progeny, are different from worms whose ancestors were grown on plates. It has been suggested that C. elegans might encounter liquid environments in nature, although actual observations in the wild are few and far between. By contrast, in the laboratory, growing worms in liquid is commonplace, and often used as an alternative to growing worms on agar plates, to control the composition of the worms' diet, to starve (and synchronize) worms or to grow large populations for biochemical assays. We found that plate-grown descendants of M9 liquid medium-grown worms were longer than control worms, and the heritable effects were already apparent very early in development. We tested for the involvement of different known epigenetic inheritance mechanisms, but could not find a single mutant in which these inter-generational effects are cancelled. While we found that growing in liquid always leads to inter-generational changes in the worms' size, trans-generational effects were found to be variable, and in some cases, the effects were gone after one to two generations. These results demonstrate that standard cultivation conditions in early life can dramatically change the worms' physiology in adulthood, and can also affect the next generations. This article is part of the theme issue 'Developing differences: early-life effects and evolutionary medicine'.

Early in life effects and heredity: reconciling neo-Darwinism with neo-Lamarckism under the banner of the inclusive evolutionary synthesis

Recent discoveries show that early in life effects often have long-lasting influences, sometimes even spanning several generations. Such intergenerational effects of early life events appear not easily reconcilable with strict genetic inheritance. However, an integrative evolutionary medicine of early life effects needs a sound view of inheritance in development and evolution. Here, we show how to articulate the gene-centred and non-gene-centred visions of inheritance. We first recall the coexistence of two gene concepts in scientific discussions, a statistical one (focused on patterns of parent-offspring resemblance, and implicitly including non-DNA-sequence-based resemblance), and a molecular one (based on the DNA sequence). We then show how all the different mechanisms of inheritance recently discovered can be integrated into an inclusive theory of evolution where different mechanisms would enable adaptation to changing environments at different timescales. One surprising consequence of this integrative vision of inheritance is that early in life effects start much earlier than fertilization. This article is part of the theme issue 'Developing differences: early-life effects and evolutionary medicine'.

The Connection between Charles Darwin's Evolutionary Theory of 'Heredity of Behaviors' and the 19th Century Neuroscience: The Influence of Neuroscience on Darwin's Overcoming of Lamarck's Theory of Evolution

The nineteenth century neuroscience studied the instinct of animal to understand the human mind. In particular, it has been found that the inheritance of unconscious behavior like instinct is mediated through ganglion chains, such as the spinal cord or sympathetic nervous system, which control unconscious reflexes. At the same time, the theory of Inheritance of Acquired Characteristics (hereafter 'IAC') widely known as Lamarck's evolutionary theory provided the theoretical frame on the origin of instinct and the heredity of action that the parental generation's habits were converted into the nature of the offspring generation. Contrary to conventional knowledge, this theory was not originally invented by Lamarck, and Darwin also did not discard this theory even after discovering the theory of natural selection in 1838 and maintained it throughout his intellectual life. Above all, in the field of epigenetics, the theory of 'IAC' has gained attention as a reliable scientific theory today. Darwin discovered crucial errors in the late 1830s that the Lamarck version's theory of 'IAC' did not adequately account for the principle of the inheritance of unconscious behavior like instinct. Lamarck's theory regarded habits as conscious and willful acts and saw that those habits are transmitted through the brain to control conscious actions. Lamarck's theory could not account for the complex and elaborate instincts of invertebrate animals, such as brainless ants. Contrary to Lamarck's view, Darwin established the new theory of 'IAC' that could be combined with contemporary neurological theory, which explains the heredity of unconscious behavior. Based on the knowledge of neurology, Darwin was able to translate the 'principle of habit' into a neurological term called 'principle of reflex'. This article focuses on how Darwin join the theory of 'IAC' with nineteenth century neuroscience and how the neurological knowledge from the nineteenth century contributed to Darwin's overcoming of Lamarck's 'IAC'. The significance of this study is to elucidate Darwin's notion of 'IAC' theory rather than natural selection theory as a principle of heredity of behavior. The theory of 'IAC' was able to account for the rapid variation of instincts in a relatively short period of time, unlike natural selection, which operates slowly in geological time spans of tens of millions of years. The nineteenth century neurological theory also provided neurological principles for 'plasticity of instinct,' empirically supporting the fact that all nervous systems responsible for reflexes respond sensitively to very fine stimuli. However, researchers of neo-Darwinian tendencies, such as Richard Dawkins and evolutionary psychologists advocating the 'selfish gene' hypothesis, which today claim to be Darwin's descendants, are characterized by human nature embedded in biological information, such as the brain and genes, so that it cannot change at all. This study aims to contribute to reconstructing the evolutionary discourse by illuminating Darwin's insights into the "plasticity of nature" that instincts can change relatively easily even at the level of invertebrates such as earthworms.