GENETIC ORIGIN OF SOME SEX DIFFERENCES AMONG HUMAN BEINGS

PEDIATRICS ◽  
1965 ◽  
Vol 35 (5) ◽  
pp. 798-812
Author(s):  
Barton Childs
Keyword(s):  
Sex Differences ◽  
Sex Chromosomes ◽  
New Combinations ◽  
Human Beings ◽  
Genetic Origin ◽  
Control Functions ◽  
Y Chromosomes ◽  
Definition Of ◽  
The Individual ◽  
Heterogametic Sex

Sexual reproduction helps to ensure the survival of species by providing opportunities for new combinations of chromosomes in individuals. Organisms have evolved means to accomplish this end by establishing special sex-determining chromosomes which must contain the genes which decide the reproductive attributes of the individual. This decision sets in motion a train of events determining many characteristics related to and stemming from the reproductive sex of the individual which, taken in the aggregate, formulate much of his or her role in life as a male or female. Differences between the sexes are thus created which sometimes appear to be unrelated to reproductive functions, but which are traceable ultimately to them, and some of these differences might represent a hazard to one or other sex, due either to biological or cultural inequalities. Though there are occasional errors and imperfections of sex determination, the mechanism is on the whole a good one and even unsophisticated people are seldom unsure or imprecise in the diagnosis of sex among human beings. But establishment of the sex chromosomes in the forms they have taken in various organisms has resulted in certain consequences which, though they might be beneficial in some instances, certainly contribute to inequalities between the two sexes in ways not necessarily related to the reproductive aspects of sex. The disparity in size between the X and Y chromosomes, for example, means that the homogametic sex (female) is diploid with regard to many loci, while the heterogametic sex (males) must be always haploid. If these chromosomes contain genes which control functions apart from aspects of reproductive sex, even though these be compensated, the genes will be making contributions to aspects of maleness and femaleness which are not accommodated in the usual, practical definition of sex.

scholarly journals The maintenance of polygenic sex determination depends on the dominance of fitness effects which are predictive of the role of sexual antagonism

2021 ◽  
Author(s):  
Richard P Meisel
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
House Fly ◽  
Sexual Antagonism ◽  
Antagonistic Effects ◽  
Fitness Effects ◽  
Y Chromosomes ◽  
Sexually Antagonistic Selection ◽  
The Individual ◽  
Polygenic Sex Determination

Abstract In species with polygenic sex determination, multiple male- and female-determining loci on different proto-sex chromosomes segregate as polymorphisms within populations. The extent to which these polymorphisms are at stable equilibria is not yet resolved. Previous work demonstrated that polygenic sex determination is most likely to be maintained as a stable polymorphism when the proto-sex chromosomes have opposite (sexually antagonistic) fitness effects in males and females. However, these models usually consider polygenic sex determination systems with only two proto-sex chromosomes, or they do not broadly consider the dominance of the alleles under selection. To address these shortcomings, I used forward population genetic simulations to identify selection pressures that can maintain polygenic sex determination under different dominance scenarios in a system with more than two proto-sex chromosomes (modeled after the house fly). I found that overdominant fitness effects of male-determining proto-Y chromosomes are more likely to maintain polygenic sex determination than dominant, recessive, or additive fitness effects. The overdominant fitness effects that maintain polygenic sex determination tend to have proto-Y chromosomes with sexually antagonistic effects (male-beneficial and female-detrimental). In contrast, dominant fitness effects that maintain polygenic sex determination tend to have sexually antagonistic multi-chromosomal genotypes, but the individual proto-sex chromosomes do not have sexually antagonistic effects. These results demonstrate that sexual antagonism can be an emergent property of the multi-chromosome genotype without individual sexually antagonistic chromosomes. My results further illustrate how the dominance of fitness effects has consequences for both the likelihood that polygenic sex determination will be maintained as well as the role sexually antagonistic selection is expected to play in maintaining the polymorphism.

scholarly journals Genetic sex determination and sex-specific lifespan in tetrapods – evidence of a toxic Y effect

2020 ◽  
Author(s):  
Zahida Sultanova ◽  
Philip A. Downing ◽  
Pau Carazo
Keyword(s):  
Sex Chromosomes ◽  
Alternative Hypothesis ◽  
Z Chromosome ◽  
W Chromosome ◽  
Deleterious Mutations ◽  
Recessive Mutations ◽  
Y Chromosomes ◽  
Heterogametic Sex ◽  
Taxonomic Patterns

ABSTRACTSex-specific lifespans are ubiquitous across the tree of life and exhibit broad taxonomic patterns that remain a puzzle, such as males living longer than females in birds and vice versa in mammals. The prevailing “unguarded-X” hypothesis (UXh) explains this by differential expression of recessive mutations in the X/Z chromosome of the heterogametic sex (e.g., females in birds and males in mammals), but has only received indirect support to date. An alternative hypothesis is that the accumulation of deleterious mutations and repetitive elements on the Y/W chromosome might lower the survival of the heterogametic sex (“toxic Y” hypothesis). Here, we report lower survival of the heterogametic relative to the homogametic sex across 138 species of birds, mammals, reptiles and amphibians, as expected if sex chromosomes shape sex-specific lifespans. We then analysed bird and mammal karyotypes and found that the relative sizes of the X and Z chromosomes are not associated with sex-specific lifespans, contrary to UXh predictions. In contrast, we found that Y size correlates negatively with male survival in mammals, where toxic Y effects are expected to be particularly strong. This suggests that small Y chromosomes benefit male lifespans. Our results confirm the role of sex chromosomes in explaining sex differences in lifespan, but indicate that, at least in mammals, this is better explained by “toxic Y” rather than UXh effects.

scholarly journals Toxic Y chromosome: Increased repeat expression and age-associated heterochromatin loss in male Drosophila with a young Y chromosome

PLoS Genetics ◽  
2021 ◽  
Vol 17 (4) ◽  
pp. e1009438
Author(s):  
Alison H. Nguyen ◽  
Doris Bachtrog
Keyword(s):  
Y Chromosome ◽  
Sex Chromosomes ◽  
Young Male ◽  
Heterochromatin Formation ◽  
Young Males ◽  
Repeat Content ◽  
Y Chromosomes ◽  
Active Transcription ◽  
Heterogametic Sex ◽  
Effects Of Aging

Sex-specific differences in lifespan are prevalent across the tree of life and influenced by heteromorphic sex chromosomes. In species with XY sex chromosomes, females often outlive males. Males and females can differ in their overall repeat content due to the repetitive Y chromosome, and repeats on the Y might lower survival of the heterogametic sex (toxic Y effect). Here, we take advantage of the well-assembled young Y chromosome of Drosophila miranda to study the sex-specific dynamics of chromatin structure and repeat expression during aging in male and female flies. Male D. miranda have about twice as much repetitive DNA compared to females, and live shorter than females. Heterochromatin is crucial for silencing of repetitive elements, yet old D. miranda flies lose H3K9me3 modifications in their pericentromere, with heterochromatin loss being more severe during aging in males than females. Satellite DNA becomes de-repressed more rapidly in old vs. young male flies relative to females. In contrast to what is observed in D. melanogaster, we find that transposable elements (TEs) are expressed at higher levels in male D. miranda throughout their life. We show that epigenetic silencing via heterochromatin formation is ineffective on the TE-rich neo-Y chromosome, presumably due to active transcription of a large number of neo-Y linked genes, resulting in up-regulation of Y-linked TEs already in young males. This is consistent with an interaction between the evolutionary age of the Y chromosome and the genomic effects of aging. Our data support growing evidence that “toxic Y chromosomes” can diminish male fitness and a reduction in heterochromatin can contribute to sex-specific aging.

The Philosophy and Ideals of Islamic Education

2021 ◽  
Author(s):  
Mujadad Zaman
Keyword(s):  
Islamic Education ◽  
Human Beings ◽  
Islamic History ◽  
Moral Exemplar ◽  
Wide Range ◽  
Islamic Thought ◽  
Self Actualization ◽  
Definition Of ◽  
The Individual ◽  
Individual Self

The philosophy of Islamic education covers a wide range of ideas and practices drawn from Islamic scripture, metaphysics, philosophy, and common piety, all of which accumulate to inform discourses of learning, pedagogy, and ethics. This provides a definition of Islamic education and yet also of Islam more generally. In other words, since metaphysics and ontology are related to questions of learning and pedagogy, a compendious and indigenous definition of “education” offers an insight into a wider spectrum of Islamic thought, culture, and weltanschauung. As such, there is no singular historical or contemporary philosophy of Islamic education which avails all of this complexity but rather there exists a number of ideas and practices which inform how education plays a role in the embodiment of knowledge and the self-actualization of the individual self to ultimately come to know God. Such an exposition may come to stand as a superordinate vision of learning framing Islamic educational ideals. Questions of how these ideas are made manifest and practiced are partly answered through scripture as well as the historical, and continuing, importance of Muhammad, the Prophet of Islam; as paragon and moral exemplar in Islamic thought. Having said “I was sent as a teacher,” his life and manner (sunnah) offer a wide-ranging source of pedagogic and intellectual value for his community (ummah) who have regarded the emulation of his character as among the highest of human virtues. In this theocentric cosmology a tripart conception of education emerges, beginning with the sacred nature of knowledge (ʿilm), the imperative for its coupling with action (ʿamal), in reference to the Prophet, and finally, these foundations supporting the flourishing of an etiquette and comportment (adab) defined by an equanimous state of being and wisdom (ḥikma). In this sense, the reason for there being not one identifiable philosophy of Islamic education, whether premodern or in the modern context, is due to the concatenations of thoughts and practices gravitating around superordinate, metaphysical ideals. The absence of a historical discipline, named “philosophy of education” in Islamic history, infers that education, learning, and the nurturing of young minds is an enterprise anchored by a cosmology which serves the common dominators of divine laudation and piety. Education, therefore, whether evolving from within formal institutional arenas (madrasas) or the setting of the craft guilds (futuwwa), help to enunciate a communality and consilience of how human beings may come to know themselves, their world, and ultimately God.

SYMPOSIUM ON CONGENITAL METABOLIC DISEASE

PEDIATRICS ◽  
1958 ◽  
Vol 21 (6) ◽  
pp. 1018-1021
Author(s):  
Charles U. Lowe ◽  
Barton Childs
Keyword(s):  
Gene Action ◽  
Genetic Material ◽  
Basic Mechanism ◽  
Reaction Rates ◽  
Human Beings ◽  
Secondary Effects ◽  
Genetic Origin ◽  
Daughter Cells ◽  
Metabolic Functions ◽  
Definition Of

MOST of the conditions to be considered in this symposium share one feature: their genetic origin. It could be profitable then to outline some of the principles of gene action and of the characteristics of genetic disease which will apply equally to all of the disorders to be reviewed. To begin, a definition of gene action is offered. This must be an empirical one since it is not known, with any precision, what a gene is. However, it is known that the genetic material provides the most basic mechanism for homeostasis, ensuring that offspring will exhibit the characteristics of the parent, whether the offspring be daughter cells or human beings. This is accomplished by means of control over the formation and design of the vital molecules of the organism; those molecules which in their turn control its intricate and interrealted metabolic functions. It is for the most part these metabolic functions which we attempt to measure in the elucidation of gene action in disease, and it will be seen in the ensuing discussions that only rarely is one able to make any direct assessment of the physicochemical properties of these molecules which bear a specific relationship to the gene. Much more commonly, a measurement is made of some form of activity of such substances, and a stepwise elucidation may be accomplished of the secondary effects which are consequent upon alterations in reaction rates or reaction failure. It is, in general, these secondary, tertiary, or consequential effects which are most easily measured, and which are the overt expressions of the disease. The principle illustrated here is, what a gene is said to do, depends upon which function we measure.

scholarly journals Recombination landscape dimorphism contributes to sex chromosome evolution in the dioecious plant Rumex hastatulus

2021 ◽  
Author(s):  
Joanna L Rifkin ◽  
Solomiya Hnatovzka ◽  
Meng Yuan ◽  
Bianca M Sacchi ◽  
Baharul I Choudhury ◽  
...  
Keyword(s):  
Sex Differences ◽  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Pollen Competition ◽  
Sex Chromosome Evolution ◽  
Dioecious Plant ◽  
Male Recombination ◽  
Rumex Hastatulus ◽  
Heterogametic Sex

There is growing evidence across diverse taxa for sex differences in the genomic landscape of recombination, but the causes and consequences of these differences remain poorly understood. Strong recombination landscape dimorphism between the sexes could have important implications for the dynamics of sex chromosome evolution and turnover because low recombination in the heterogametic sex can help favour the spread of sexually antagonistic alleles. Here, we present a sex-specific linkage map and revised genome assembly of Rumex hastatulus, representing the first characterization of sex differences in recombination landscape in a dioecious plant. We provide evidence for strong sex differences in recombination, with pericentromeric regions of highly suppressed recombination in males that cover over half of the genome. These differences are found on autosomes as well as sex chromosomes, suggesting that pre-existing differences in recombination may have contributed to sex chromosome formation and divergence. Analysis of segregation distortion suggests that haploid selection due to pollen competition occurs disproportionately in regions with low male recombination. Our results are consistent with the hypothesis that sex differences in the recombination landscape contributed to the formation of a large heteromorphic pair of sex chromosomes, and that pollen competition is an important determinant of recombination dimorphism.

Criticism of Gehlen’s Theory of Instinct-Reduction and Phenomenological Clarification of the Concept of Instinct as the Genetic Origin of Embodied Consciousness

2017 ◽  
Vol 2017 (2) ◽  
Author(s):  
Lee Nam-In
Keyword(s):  
Evolutionary Psychology ◽  
Evolutionary Biology ◽  
Human Beings ◽  
Genetic Origin ◽  
The Past ◽  
Embodied Consciousness ◽  
Definition Of ◽  
Logical Sense ◽  
Living Being

AbstractIn the past 20 years, the concept of instinct has been discussed in respect to various disciplines such as evolutionary biology, evolutionary psychology, linguistics, ethics, aesthetics, and phenomenology, etc. However, the meaning of instinct still remains unclarified in many respects. In order to overcome this situation, it is necessary to elucidate the genuine meaning of instinct so that the discussion of instinct in these disciplines can be carried out systematically. The objective of this paper is to establish the genuine concept of instinct on the basis of a phenomenological criticism of A. Gehlen’s theory of instinct-reduction. Moreover, it seeks to show that this concept is the genetic origin of the embodied consciousness. According to Gehlen, instinct is defined as Instinkthandlung. However, this definition of instinct is problematic in the formal logical sense, since the definiendum (the instinct) is already included in the definiens (Instinkthandlung). Moreover, it faces different kinds of serious material problems. Criticizing Gehlen’s theory of instinct systematically, I will show that instinct should be redefined as “the innate living force that urges a species of living being to pursue a certain kind of object,” and I will attempt to clarify this definition of instinct in a more detailed manner by offering 11 points. Thereafter, I will argue that Gehlen’s theory of instinct-reduction has to be replaced by the theory of instinct-enlargement in human beings. Finally, I will point out that the genuine concept of instinct is nothing other than the genetic origin of the embodied consciousness.

scholarly journals Toxic Y chromosome: increased repeat expression and age-associated heterochromatin loss in male Drosophila with a young Y chromosome

2020 ◽  
Author(s):  
Alison H. Nguyen ◽  
Doris Bachtrog
Keyword(s):  
Y Chromosome ◽  
Sex Chromosomes ◽  
Young Male ◽  
Heterochromatin Formation ◽  
Young Males ◽  
Repeat Content ◽  
Y Chromosomes ◽  
Heteromorphic Sex Chromosomes ◽  
Heterogametic Sex ◽  
Effects Of Aging

Sex‐specific differences in lifespan are prevalent across the tree of life and influenced by heteromorphic sex chromosomes. In species with XY sex chromosomes, females often outlive males. Males and females can differ in their overall repeat content due to the repetitive Y chromosome, and repeats on the Y might lower survival of the heterogametic sex (toxic Y effect). Here, we take advantage of the well‐assembled young Y chromosome of Drosophila miranda to study the sex‐specific dynamics of chromatin structure and repeat expression during aging in male and female flies. Male D. miranda have about twice as much repetitive DNA compared to females, and live shorter than females. Heterochromatin is crucial for silencing of repetitive elements, yet old D. miranda flies lose H3K9me3 modifications in their pericentromere, with heterochromatin loss being more severe during aging in males than females. Satellite DNA becomes de‐repressed more rapidly in old vs. young male flies relative to females. In contrast to what is observed in D. melanogaster, we find that transposable elements (TEs) are expressed at higher levels in male D. miranda throughout their life. We show that epigenetic silencing via heterochromatin formation is ineffective on the large TE‐ rich neo‐Y chromosome, resulting in up‐regulation of Y‐linked TEs already in young males. This is consistent with an interaction between the age of the Y chromosome and the genomic effects of aging. Our data support growing evidence that “toxic Y chromosomes” can diminish male fitness and a reduction in heterochromatin can contribute to sex‐specific aging.

scholarly journals Islam and Hated Intolerance

2020 ◽  
Vol 7 (5) ◽  
pp. 194-204
Author(s):  
Tonang Lubis
Keyword(s):  
Historical Background ◽  
Human Beings ◽  
The People ◽  
Large Numbers ◽  
Definition Of ◽  
The Individual

Islam does not allow the nervousness and the mutual contempt and hatred that follows it between the tribes, peoples and nations, but rather, on the contrary, heralds the friendship and brotherhood among Muslims, tolerance of religions and dialogue between the human beings. Islam has achieved the compatibility and harmony between a large numbers of people of different races and lineages. So Islam liberated the individual from the narrow tribal framework in a wider and welcoming society that included the tribe members as well as the members of other tribes. When Islam included the tribes in a society, its concern was to fight nerve tendencies and the tribal spirit. It made the original principles not to differentiate between the people on the basis of genealogy or the races or the colors, because the differentiation in Islam is based on the faith, piety and goodness. In this article, we dealt with the definition of nervousness in terms of language and convention, a historical background of the intolerance and its origin, signs of intolerance, causes of intolerance, types of intolerance: Intellectual intolerance, doctrinal intolerance, gradient or class intolerance, intolerance to sanctify the inherited past, partisan intolerance, and tribal intolerance. Tribal intolerance is from the pre-Islamic biography, then we dealt with the issue of treating hateful intolerance mentioned in the Holy Qur’an and the noble Prophet’s Sunnah. At the end of the article, we mentioned a number of results for this research.

scholarly journals Dosage-sensitive functions in embryonic development drove the survival of genes on sex-specific chromosomes in snakes, birds, and mammals

2020 ◽  
Author(s):  
Daniel W. Bellott ◽  
David C. Page
Keyword(s):  
Gene Expression ◽  
Dosage Compensation ◽  
Sex Chromosomes ◽  
Meta Analysis ◽  
Purifying Selection ◽  
Y Chromosomes ◽  
The Face ◽  
Heterogametic Sex ◽  
Additional Constraints ◽  
Insight Into

AbstractDifferent ancestral autosomes independently evolved into sex chromosomes in snakes, birds, and mammals. In snakes and birds, females are ZW, while males are ZZ; in mammals, females are XX and males are XY. While X and Z chromosomes retain nearly all ancestral genes, sex-specific W and Y chromosomes suffered extensive genetic decay. In both birds and mammals, the genes that survived on sex-specific chromosomes are enriched for broadly expressed, dosage sensitive regulators of gene expression, subject to strong purifying selection. To gain deeper insight into the processes that govern survival on sex-specific chromosomes, we carried out a meta-analysis of survival across 41 species — three snakes, 24 birds and 14 mammals — doubling the number of ancestral genes under investigation and increasing our power to detect enrichments among survivors relative to non-survivors. Out of 2573 ancestral genes, representing an eighth of the ancestral amniote genome, only 322 survive on present-day sex-specific chromosomes. Survivors are enriched for dosage sensitive developmental processes, particularly development of the face. However, there was no enrichment for expression in sex-specific tissues, involvement in sex-determination or gonadogenesis pathways, or conserved sex-biased expression. Broad expression and dosage sensitivity contributed independently to gene survival, suggesting that pleiotropy imposes additional constraints on the evolution of dosage compensation. We propose that maintaining the viability of the heterogametic sex drove gene survival on amniote sex-specific chromosomes, and that subtle modulation of the expression of survivor genes and their autosomal orthologs has disproportionately large effects on development and disease.

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