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Telegony is a largely discredited theory of heredity holding that offspring can inherit the characteristics of a previous mate of the female parent; thus the child of a woman might partake of traits of a previous sexual partner. Experiments in the late 19th century on several species failed to provide evidence that offspring would inherit any character from their mother's previous mates. [1] It was superseded by the rediscovery of Mendelian inheritance and the Boveri–Sutton chromosome theory. The Encyclopædia Britannica says telegony "must now be classed as superstitions." [2]
Telegony is the idea that a female will be permanently affected when she is first impregnated, since the fetus will pass back characteristics to her that will affect all future offspring, no matter their progeny. [3]
The term was coined by August Weismann from the Greek words τῆλε (tèle) meaning 'far' and γονος (gonos) meaning 'offspring'. [3]
The idea of telegony goes back to Aristotle. It states that individuals can inherit traits not only from their fathers, but also from other males previously known to their mothers. In other words, it was thought that paternity could be shared. [4]
Of a supposed Parnassos, founder of Delphi, Pausanias observes, "Like the other heroes, as they are called, he had two fathers; one they say was the god Poseidon, the human father being Cleopompus." [5] Sometimes the result could be twins such as Castor and Pollux, one born divine and one mortal.
The more general doctrine of "maternal impressions" was also known in Ancient Israel. The book of Genesis describes Jacob inducing goats and sheep in Laban's herds to bear striped and spotted young by placing dark wooden rods with white stripes in their watering troughs. [6] Telegony influenced early Christianity as well. The Gnostic followers of Valentinius (circa 100–160 CE) characteristically took the concept from the physiological world into the realm of psychology and spirituality by extending the supposed influence even to the thoughts of the woman. It was also implied in the Gospel of Philip, a text among those found at Nag Hammadi. [7]
In the 19th century, the most widely credited example was that of Lord Morton's mare, reported by the distinguished surgeon Sir Everard Home, and cited by Charles Darwin. [8] Lord Morton bred a white mare with a wild quagga stallion, [a] and when he later bred the same mare with a white stallion, the offspring strangely had stripes in the legs, like the quagga. [9]
The Surgeon-General of New York, the physiologist Austin Flint, in his Text-Book of Human Physiology (fourth edition, 1888) described the phenomenon as follows: [10]
A peculiar and, it seems to me, an inexplicable fact is, that previous pregnancies have an influence upon offspring. This is well known to breeders of animals. If pure-blooded mares or bitches have been once covered by an inferior male, in subsequent fecondations the young are likely to partake of the character of the first male, even if they be afterwards bred with males of unimpeachable pedigree. What the mechanism of the influence of the first conception is, it is impossible to say; but the fact is incontestable. The same influence is observed in the human subject. A woman may have, by a second husband, children who resemble a former husband, and this is particularly well marked in certain instances by the colour of the hair and eyes. A white woman who has had children by a negro may subsequently bear children to a white man, these children presenting some of the unmistakable peculiarities of the negro race. [10]
Both Schopenhauer and Herbert Spencer found telegony to be a credible theory; [11] August Weismann, on the other hand, had expressed doubts about the theory earlier and it fell out of scientific favor in the 1890s. A series of experiments by James Cossar Ewart in Scotland and other researchers in Germany and Brazil failed to find any evidence of the phenomenon. Also, the statistician Karl Pearson tried to find an evidence for telegony in humans using family measurement data and the statistical methods he invented, but failed to conclude that the steady telegonic influence really exists. [b] [12]
In mammals, each sperm has the haploid set of chromosomes and each egg has another haploid set. During the process of fertilization a zygote with the diploid set is produced. This set will be inherited by every somatic cell of a mammal, with exactly half the genetic material coming from the producer of the sperm (the father) and another half from the producer of the egg (the mother). Thus, the myth of telegony is fundamentally incompatible with our knowledge of genetics and the reproductive process. Encyclopædia Britannica stated "All these beliefs, from inheritance of acquired traits to telegony, must now be classed as superstitions." [2]
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The theory of telegony has been revisited in the 21st century with new discoveries of non-genetic mechanisms. [13] [14]
A few studies in the 21st century have indicated that an organism can inherit traits that are not mediated by the genetic (DNA) material inherited from parents. The study of such effects is called epigenetics. One study published in 2014 reported the existence of telegony in Telostylinus angusticollis as a non-genetic mechanism of epigenetic inheritance. [15] [16]
Telegony influenced late 19th-century racialist beliefs. A woman who had a child with a non-Aryan man, it was argued, could never have a "pure" Aryan child at a later point in time. This idea was adopted by the German Nazi Party. [11]
Telegony re-emerged within post-Soviet Russian Orthodoxy. Virginity and Telegony: The Orthodox church and modern science of genetic inversions was published in 2004. Pravda.ru gave an overview of the concept and a brief review of the book, saying that the authors invented "scary and incredible stories" to "make women be very careful about their sexual contacts" and that the idea was being used by the Church to scare the faithful. [17] Anna Kuznetsova, who was appointed Children's Rights Commissioner for the Russian Federation in 2016, had said several years earlier that she believes in the concept, amongst other fringe views. The founding editor of the business newspaper Vedomosti , Leonoid Bershidsky, interpreted the appointment of someone with such views as a sign that Russian President Vladimir Putin was becoming more ideological. [18]
The religious practice known as P'ikareum is an unusual variant in that it holds that one can purify one’s own bloodline from sin by having sex with a holy person, such as the founder of one of the religious sects that engages in this practice.
Within popular culture, the belief that an illegitimate child would look like the mother's husband instead of the biological father gave married women some freedom to commit adultery without getting caught. [19]
An allele, or allelomorph, is a variant of the sequence of nucleotides at a particular location, or locus, on a DNA molecule.
Genetics is the study of genes, genetic variation, and heredity in organisms. It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar working in the 19th century in Brno, was the first to study genetics scientifically. Mendel studied "trait inheritance", patterns in the way traits are handed down from parents to offspring over time. He observed that organisms inherit traits by way of discrete "units of inheritance". This term, still used today, is a somewhat ambiguous definition of what is referred to as a gene.
Heredity, also called inheritance or biological inheritance, is the passing on of traits from parents to their offspring; either through asexual reproduction or sexual reproduction, the offspring cells or organisms acquire the genetic information of their parents. Through heredity, variations between individuals can accumulate and cause species to evolve by natural selection. The study of heredity in biology is genetics.
Genomic imprinting is an epigenetic phenomenon that causes genes to be expressed or not, depending on whether they are inherited from the female or male parent. Genes can also be partially imprinted. Partial imprinting occurs when alleles from both parents are differently expressed rather than complete expression and complete suppression of one parent's allele. Forms of genomic imprinting have been demonstrated in fungi, plants and animals. In 2014, there were about 150 imprinted genes known in mice and about half that in humans. As of 2019, 260 imprinted genes have been reported in mice and 228 in humans.
The quagga is an extinct subspecies of the plains zebra that was endemic to South Africa until it was hunted to extinction in the late 19th century. It was long thought to be a distinct species, but MtDNA studies have supported it being a subspecies of plains zebra. A more recent study suggested that it was the southernmost cline or ecotype of the species.
Biological determinism, also known as genetic determinism, is the belief that human behaviour is directly controlled by an individual's genes or some component of their physiology, generally at the expense of the role of the environment, whether in embryonic development or in learning. Genetic reductionism is a similar concept, but it is distinct from genetic determinism in that the former refers to the level of understanding, while the latter refers to the supposed causal role of genes. Biological determinism has been associated with movements in science and society including eugenics, scientific racism, and the debates around the heritability of IQ, the basis of sexual orientation, and evolutionary foundations of cooperation in sociobiology.
Lamarckism, also known as Lamarckian inheritance or neo-Lamarckism, is the notion that an organism can pass on to its offspring physical characteristics that the parent organism acquired through use or disuse during its lifetime. It is also called the inheritance of acquired characteristics or more recently soft inheritance. The idea is named after the French zoologist Jean-Baptiste Lamarck (1744–1829), who incorporated the classical era theory of soft inheritance into his theory of evolution as a supplement to his concept of orthogenesis, a drive towards complexity.
A zebroid is the offspring of any cross between a zebra and any other equine to create a hybrid. In most cases, the sire is a zebra stallion but not every time. The offspring of a donkey sire and zebra dam, called a donkra, and the offspring of a horse sire and a zebra dam, called a hebra, do exist, but are rare and are usually sterile. Zebroids have been bred since the 19th century. Charles Darwin noted several zebra hybrids in his works.
Germ plasm is a biological concept developed in the 19th century by the German biologist August Weismann. It states that heritable information is transmitted only by germ cells in the gonads, not by somatic cells. The related idea that information cannot pass from somatic cells to the germ line, contrary to Lamarckism, is called the Weismann barrier. To some extent this theory anticipated the development of modern genetics.
Human genetics is the study of inheritance as it occurs in human beings. Human genetics encompasses a variety of overlapping fields including: classical genetics, cytogenetics, molecular genetics, biochemical genetics, genomics, population genetics, developmental genetics, clinical genetics, and genetic counseling.
Blending inheritance is an obsolete theory in biology from the 19th century. The theory is that the progeny inherits any characteristic as the average of the parents' values of that characteristic. As an example of this, a crossing of a red flower variety with a white variety of the same species would yield pink-flowered offspring.
Out-crossing or out-breeding is the technique of crossing between different breeds. This is the practice of introducing distantly related genetic material into a breeding line, thereby increasing genetic diversity.
Lord Morton’s mare was an equid hybrid and once an often-noticed example in the history of evolutionary theory.
Mate choice is one of the primary mechanisms under which evolution can occur. It is characterized by a "selective response by animals to particular stimuli" which can be observed as behavior. In other words, before an animal engages with a potential mate, they first evaluate various aspects of that mate which are indicative of quality—such as the resources or phenotypes they have—and evaluate whether or not those particular trait(s) are somehow beneficial to them. The evaluation will then incur a response of some sort.
The Neriidae are a family of true flies (Diptera) closely related to the Micropezidae. Some species are known as cactus flies, while others have been called banana stalk flies and the family was earlier treated as subfamily of the Micropezidae which are often called stilt-legged flies. Neriids differ from micropezids in having no significant reduction of the fore legs. Neriids breed in rotting vegetation, such as decaying tree bark or rotting fruit. About 100 species are placed in 19 genera. Neriidae are found mainly in tropical regions, but two North American genera occur, each with one species, and one species of Telostylinus occurs in temperate regions of eastern Australia.
Sex-limited genes are genes that are present in both sexes of sexually reproducing species but are expressed in only one sex and have no penetrance, or are simply 'turned off' in the other. In other words, sex-limited genes cause the two sexes to show different traits or phenotypes, despite having the same genotype. This term is restricted to autosomal traits, and should not be confused with sex-linked characteristics, which have to do with genetic differences on the sex chromosomes. Sex-limited genes are also distinguished from sex-influenced genes, where the same gene will show differential expression in each sex. Sex-influenced genes commonly show a dominant/recessive relationship, where the same gene will have a dominant effect in one sex and a recessive effect in the other. However, the resulting phenotypes caused by sex-limited genes are present in only one sex and can be seen prominently in various species that typically show high sexual dimorphism.
Transgenerational epigenetic inheritance is the proposed transmission of epigenetic markers and modifications from one generation to multiple subsequent generations without altering the primary structure of DNA. Thus, the regulation of genes via epigenetic mechanisms can be heritable; the amount of transcripts and proteins produced can be altered by inherited epigenetic changes. In order for epigenetic marks to be heritable, however, they must occur in the gametes in animals, but since plants lack a definitive germline and can propagate, epigenetic marks in any tissue can be heritable.
Addiction vulnerability is an individual's risk of developing an addiction during their lifetime. There are a range of genetic and environmental risk factors for developing an addiction that vary across the population. Genetic and environmental risk factors each account for roughly half of an individual's risk for developing an addiction; the contribution from epigenetic risk factors to the total risk is unknown. Even in individuals with a relatively low genetic risk, exposure to sufficiently high doses of an addictive drug for a long period of time can result in an addiction. In other words, anyone can become an individual with a substance use disorder under particular circumstances. Research is working toward establishing a comprehensive picture of the neurobiology of addiction vulnerability, including all factors at work in propensity for addiction.
Derocephalus angusticollis is a fly in the family Neriidae. They are typically found on the east coast of Australia near rotting vegetation. Aggregating on the rotting bark of trees such as Acacia longifolia and other trees in New South Wales and southern Queensland. Derocephalus angusticollis flies found in the wild have accelerated speeds of development and age of mortality when compared to those in captivity. One characteristic of the neriid fly is that it demonstrates sexual dimorphism. Males have a larger build as well as exaggerated physical characteristics such as wider heads and longer limbs. Certain phenotypic characteristics are dependent on the diet of the parents.
Multifactorial diseases are not confined to any specific pattern of single gene inheritance and are likely to be caused when multiple genes come together along with the effects of environmental factors.
In summary, we show that adult body size of offspring can be influenced by the phenotype of a female's previous mate rather than the genetic sire in Telostylinus angusticollis. This novel transgenerational effect (an example of telegony) appears to be driven by the condition-dependent influence of male seminal fluid on the development of immature ovules. The potential for such effects exists in any taxon characterised by internal fertilisation and polyandry, and such effects could influence the evolution of reproductive strategies.