Ontogeny

From Wikipedia, the free encyclopedia

The initial stages of human embryogenesis

Parts of a human embryo

This article concerns ontogeny in biology. Not to be confused with the philosophical concept ontology, or the medical terms oncology or odontology.

Ontogeny (also ontogenesis or morphogenesis) is the origination and development of an organism, usually from the time of fertilization of the egg to the organism's mature form. Yet, the term can be used to refer to the study of the entirety of an organism's lifespan.

Ontogeny pertains to the developmental history of an organism within its own lifetime, as distinct from phylogeny, which refers to the evolutionary history of a species. In practice, writers on evolution often speak of species as "developing" traits or characteristics. This can be misleading. While developmental (i.e., ontogenetic) processes can influence subsequent evolutionary (e.g., phylogenetic) processes^[1] (see evolutionary developmental biology), individual organisms develop (ontogeny), while species evolve (phylogeny).

Ontogeny, embryology and developmental biology are closely related studies and the terms are sometimes used interchangeably. Recently (2003), the term ontogeny has been used in cell biology to describe the development of various cell types within an organism.^[2]

Ontogeny is a useful field of study in many disciplines, including developmental biology, developmental psychology, developmental cognitive neuroscience, and developmental psychobiology.

Ontogeny is also a concept used in anthropology as "the process through which each of us embodies the history of our own making".^[3]

Etymology

The word ontogeny comes from the Greek ὄν, on (gen. ὄντος, ontos), i.e. "being; that which is", which is the present participle of the verb εἰμί, eimi, i.e. "to be, I am", and from the suffix -geny from the Greek -γένεια -geneia, which expresses the concept of "mode of production".^[4]

Nature and nurture

A seminal paper named ontogeny as one of the four primary questions of biology, along with Huxley's three others: causation, survival value and evolution.^[5] Tinbergen emphasized that the change of behavioral machinery during development was distinct from the change in behavior during development. "We can conclude that the thrush itself, i.e. its behavioral machinery, has changed only if the behavior change occurred while the environment was held constant...When we turn from description to causal analysis, and ask in what way the observed change in behavior machinery has been brought about, the natural first step is to try and distinguish between environmental influences and those within the animal...In ontogeny the conclusion that a certain change is internally controlled (is "innate") is reached by elimination. " (p. 424) Tinbergen was concerned that the elimination of environmental factors is difficult to establish, and the use of the word "innate" often misleading.

Ontogenetic allometry

Most organisms undergo dramatic changes in shape as they grow and mature. Even "reptiles" (e.g., crocodilians, turtles, snakes,^[6] lizards^[7]), in which the offspring are often viewed as miniature adults, show a variety of ontogenetic changes in morphology and physiology.^[8]

Anthropological application

Comparing ourselves to others is something humans do all the time. "In doing so we are acknowledging not so much our sameness to others or our difference, but rather the commonality that resides in our difference. In other words, because each one of us is at once remarkably similar to, and remarkably different from, all other humans, it makes little sense to think of comparison in terms of a list of absolute similarities and a list of absolute differences. Rather, in respect of all other humans, we find similarities in the ways we are different from one another and differences in the ways we are the same. That we are able to do this is a function of the genuinely historical process that is human ontogeny".^[3]

Sex

From Wikipedia, the free encyclopedia

The male gamete (sperm) fertilizing the female gamete (ovum)

Organisms of many species are specialized into male and female varieties, each known as a sex.^[1] Sexual reproduction involves the combining and mixing of genetic traits: specialized cells known as gametes combine to form offspring that inherit traits from each parent. Gametes can be identical in form and function (known as isogamy), but in many cases an asymmetry has evolved such that two sex-specific types of gametes (heterogametes) exist (known as anisogamy). By definition, male gametes are small, motile, and optimized to transport their genetic information over a distance, while female gametes are large, non-motile and contain the nutrients necessary for the early development of the young organism. Among humans and other mammals, males typically carry XY chromosomes, whereas females typically carry XX chromosomes, which are a part of the XY sex-determination system.

The gametes produced by an organism determine its sex: males produce male gametes (spermatozoa, or sperm, in animals; pollen in plants) while females produce female gametes (ova, or egg cells); individual organisms which produce both male and female gametes are termed hermaphroditic. Frequently, physical differences are associated with the different sexes of an organism; these sexual dimorphisms can reflect the different reproductive pressures the sexes experience.

Evolution

It is considered that sexual reproduction first appeared about a billion years ago, evolved within ancestral single-celled eukaryotes.^[2] The reason for the initial evolution of sex, and the reason(s) it has survived to the present, are still matters of debate. Some of the many plausible theories include: that sex creates variation among offspring, sex helps in the spread of advantageous traits, and that sex helps in the removal of disadvantageous traits.Sexual reproduction is a process specific to eukaryotes, organisms whose cells contain a nucleus and mitochondria. In addition to animals, plants, and fungi, other eukaryotes (e.g. the malaria parasite) also engage in sexual reproduction. Some bacteria use conjugation to transfer genetic material between cells; while not the same as sexual reproduction, this also results in the mixture of genetic traits.

What is considered defining of sexual reproduction in eukaryotes is the difference between the gametes and the binary nature of fertilization. Multiplicity of gamete types within a species would still be considered a form of sexual reproduction. However, no third gamete is known in multicellular animals.^[3][4][5]

While the evolution of sex itself dates to the prokaryote or early eukaryote stage, the origin of chromosomal sex determination may have been fairly early in eukaryotes. The ZW sex-determination system is shared by birds, some fish and some crustaceans. Most mammals, but also some insects (Drosophila) and plants (Ginkgo) use XY sex-determination. X0 sex-determination is found in certain insects.

No genes are shared between the avian ZW and mammal XY chromosomes,^[6] and from a comparison between chicken and human, the Z chromosome appeared similar to the autosomal chromosome 9 in human, rather than X or Y, suggesting that the ZW and XY sex-determination systems do not share an origin, but that the sex chromosomes are derived from autosomal chromosomes of the common ancestor of birds and mammals. A paper from 2004 compared the chicken Z chromosome with platypus X chromosomes and suggested that the two systems are related.^[7]

Sexual reproduction

The life cycle of sexually reproducing organisms cycles through haploid and diploid stages

Sexual reproduction in eukaryotes is a process whereby organisms form offspring that combine genetic traits from both parents. Chromosomes are passed on from one generation to the next in this process. Each cell in the offspring has half the chromosomes of the mother and half of the father.^[8] Genetic traits are contained within the deoxyribonucleic acid (DNA) of chromosomes—by combining one of each type of chromosomes from each parent, an organism is formed containing a doubled set of chromosomes. This double-chromosome stage is called "diploid", while the single-chromosome stage is "haploid". Diploid organisms can, in turn, form haploid cells (gametes) that randomly contain one of each of the chromosome pairs, via meiosis.^[9] Meiosis also involves a stage of chromosomal crossover, in which regions of DNA are exchanged between matched types of chromosomes, to form a new pair of mixed chromosomes. Crossing over and fertilization (the recombining of single sets of chromosomes to make a new diploid) result in the new organism containing a different set of genetic traits from either parent.

In many organisms, the haploid stage has been reduced to just gametes specialized to recombine and form a new diploid organism; in others, the gametes are capable of undergoing cell division to produce multicellular haploid organisms. In either case, gametes may be externally similar, particularly in size (isogamy), or may have evolved an asymmetry such that the gametes are different in size and other aspects (anisogamy).^[10] By convention, the larger gamete (called an ovum, or egg cell) is considered female, while the smaller gamete (called a spermatozoon, or sperm cell) is considered male. An individual that produces exclusively large gametes is female, and one that produces exclusively small gametes is male. An individual that produces both types of gametes is a hermaphrodite; in some cases hermaphrodites are able to self-fertilize and produce offspring on their own, without a second organism.^[11]

Animals

Hoverflies engaging in sexual intercourse

Most sexually reproducing animals spend their lives as diploid organisms, with the haploid stage reduced to single cell gametes.^[12] The gametes of animals have male and female forms—spermatozoa and egg cells. These gametes combine to form embryos which develop into a new organism.

The male gamete, a spermatozoon (produced within a testicle), is a small cell containing a single long flagellum which propels it.^[13] Spermatozoa are extremely reduced cells, lacking many cellular components that would be necessary for embryonic development. They are specialized for motility, seeking out an egg cell and fusing with it in a process called fertilization.

Female gametes are egg cells (produced within ovaries), large immobile cells that contain the nutrients and cellular components necessary for a developing embryo.^[14] Egg cells are often associated with other cells which support the development of the embryo, forming an egg. In mammals, the fertilized embryo instead develops within the female, receiving nutrition directly from its mother.

Animals are usually mobile and seek out a partner of the opposite sex for mating. Animals which live in the water can mate using external fertilization, where the eggs and sperm are released into and combine within the surrounding water.^[15] Most animals that live outside of water, however, must transfer sperm from male to female to achieve internal fertilization.

In most birds, both excretion and reproduction is done through a single posterior opening, called the cloaca—male and female birds touch cloaca to transfer sperm, a process called "cloacal kissing".^[16] In many other terrestrial animals, males use specialized sex organs to assist the transport of sperm—these male sex organs are called intromittent organs. In humans and other mammals this male organ is the penis, which enters the female reproductive tract (called the vagina) to achieve insemination—a process called sexual intercourse. The penis contains a tube through which semen (a fluid containing sperm) travels. In female mammals the vagina connects with the uterus, an organ which directly supports the development of a fertilized embryo within (a process called gestation).

Because of their motility, animal sexual behavior can involve coercive sex. Traumatic insemination, for example, is used by some insect species to inseminate females through a wound in the abdominal cavity – a process detrimental to the female's health.

Plants

Flowers are the sexual organs of flowering plants, usually containing both male and female parts.

Like animals, plants have developed specialized male and female gametes.^[17] Within most familiar plants, male gametes are contained within hard coats, forming pollen. The female gametes of plants are contained within ovules; once fertilized by pollen these form seeds which, like eggs, contain the nutrients necessary for the development of the embryonic plant.

Female (left) and male (right) cones are the sex organs of pines and other conifers.

Many plants have flowers and these are the sexual organs of those plants. Flowers are usually hermaphroditic, producing both male and female gametes. The female parts, in the center of a flower, are the carpels—one or more of these may be merged to form a single pistil. Within carpels are ovules which develop into seeds after fertilization. The male parts of the flower are the stamens: these long filamentous organs are arranged between the pistil and the petals and produce pollen at their tips. When a pollen grain lands upon the top of a carpel, the tissues of the plant react to transport the grain down into the carpel to merge with an ovule, eventually forming seeds.

In pines and other conifers the sex organs are conifer cones and have male and female forms. The more familiar female cones are typically more durable, containing ovules within them. Male cones are smaller and produce pollen which is transported by wind to land in female cones. As with flowers, seeds form within the female cone after pollination.

Because plants are immobile, they depend upon passive methods for transporting pollen grains to other plants. Many plants, including conifers and grasses, produce lightweight pollen which is carried by wind to neighboring plants. Other plants have heavier, sticky pollen that is specialized for transportation by insects. The plants attract these insects with nectar-containing flowers. Insects transport the pollen as they move to other flowers, which also contain female reproductive organs, resulting in pollination.

Fungi

Mushrooms are produced as part of fungal sexual reproduction

Most fungi reproduce sexually, having both a haploid and diploid stage in their life cycles. These fungi are typically isogamous, lacking male and female specialization: haploid fungi grow into contact with each other and then fuse their cells. In some of these cases the fusion is asymmetric, and the cell which donates only a nucleus (and not accompanying cellular material) could arguably be considered "male".^[18]

Some fungi, including baker's yeast, have mating types that create a duality similar to male and female roles. Yeast with the same mating type will not fuse with each other to form diploid cells, only with yeast carrying the other mating type.^[19]

Fungi produce mushrooms as part of their sexual reproduction. Within the mushroom diploid cells are formed, later dividing into haploid spores—the height of the mushroom aids the dispersal of these sexually produced offspring.

Sex determination

Sex helps the spread of advantageous traits through recombination. The diagrams compare evolution of allele frequency in a sexual population (top) and an asexual population (bottom). The vertical axis shows frequency and the horizontal axis shows time. The alleles a/A and b/B occur at random. The advantageous alleles A and B, arising independently, can be rapidly combined by sexual reproduction into the most advantageous combination AB. Asexual reproduction takes longer to achieve this combination, because it can only produce AB if A arises in an individual which already has B, or vice versa.

The most basic sexual system is one in which all organisms are hermaphrodites, producing both male and female gametes—this is true of some animals (e.g. snails) and the majority of flowering plants.^[20] In many cases, however, specialization of sex has evolved such that some organisms produce only male or only female gametes. The biological cause for an organism developing into one sex or the other is called sex determination.

In the majority of species with sex specialization, organisms are either male (producing only male gametes) or female (producing only female gametes). Exceptions are common—for example, in the roundworm C. elegans the two sexes are hermaphrodite and male (a system called androdioecy).

Sometimes an organism's development is intermediate between male and female, a condition called intersex. Sometimes intersex individuals are called "hermaphrodite"; but, unlike biological hermaphrodites, intersex individuals are unusual cases and are not typically fertile in both male and female aspects.

Genetic

Like humans and other mammals, the common fruit fly has an XY sex-determination system.

In genetic sex-determination systems, an organism's sex is determined by the genome it inherits. Genetic sex-determination usually depends on asymmetrically inherited sex chromosomes which carry genetic features that influence development; sex may be determined either by the presence of a sex chromosome or by how many the organism has. Genetic sex-determination, because it is determined by chromosome assortment, usually results in a 1:1 ratio of male and female offspring.

Humans and other mammals have an XY sex-determination system: the Y chromosome carries factors responsible for triggering male development. The default sex, in the absence of a Y chromosome, is female. Thus, XX mammals are female and XY are male. XY sex determination is found in other organisms, including the common fruit fly and some plants.^[20] In some cases, including in the fruit fly, it is the number of X chromosomes that determines sex rather than the presence of a Y chromosome (see below).

In birds, which have a ZW sex-determination system, the opposite is true: the W chromosome carries factors responsible for female development, and default development is male.^[21] In this case ZZ individuals are male and ZW are female. The majority of butterflies and moths also have a ZW sex-determination system. In both XY and ZW sex determination systems, the sex chromosome carrying the critical factors is often significantly smaller, carrying little more than the genes necessary for triggering the development of a given sex.^[22]

Many insects use a sex determination system based on the number of sex chromosomes. This is called X0 sex-determination—the 0 indicates the absence of the sex chromosome. All other chromosomes in these organisms are diploid, but organisms may inherit one or two X chromosomes. In field crickets, for example, insects with a single X chromosome develop as male, while those with two develop as female.^[23] In the nematode C. elegans most worms are self-fertilizing XX hermaphrodites, but occasionally abnormalities in chromosome inheritance regularly give rise to individuals with only one X chromosome—these X0 individuals are fertile males (and half their offspring are male).^[24]

Other insects, including honey bees and ants, use a haplodiploid sex-determination system.^[25] In this case diploid individuals are generally female, and haploid individuals (which develop from unfertilized eggs) are male. This sex-determination system results in highly biased sex ratios, as the sex of offspring is determined by fertilization rather than the assortment of chromosomes during meiosis.

Nongenetic

Clownfish are initially male; the largest fish in a group becomes female

For many species, sex is not determined by inherited traits, but instead by environmental factors experienced during development or later in life. Many reptiles have temperature-dependent sex determination: the temperature embryos experience during their development determines the sex of the organism. In some turtles, for example, males are produced at lower incubation temperatures than females; this difference in critical temperatures can be as little as 1–2 °C.

Many fish change sex over the course of their lifespan, a phenomenon called sequential hermaphroditism. In clownfish, smaller fish are male, and the dominant and largest fish in a group becomes female. In many wrasses the opposite is true—most fish are initially female and become male when they reach a certain size. Sequential hermaphrodites may produce both types of gametes over the course of their lifetime, but at any given point they are either female or male.

In some ferns the default sex is hermaphrodite, but ferns which grow in soil that has previously supported hermaphrodites are influenced by residual hormones to instead develop as male.^[26]

Sexual dimorphism

Common Pheasants are sexually dimorphic in both size and appearance.

Many animals and some plants have differences between the male and female sexes in size and appearance, a phenomenon called sexual dimorphism. Sex differences in humans include, generally, a larger size and more body hair in men; women have breasts, wider hips, and a higher body fat percentage. In other species, the differences may be more extreme, such as differences in coloration or bodyweight. In humans, biological sex is determined by five factors present at birth: the presence or absence of a Y chromosome, the type of gonads, the sex hormones, the internal reproductive anatomy (such as the uterus in females), and the external genitalia.^[27]

Sexual dimorphisms in animals are often associated with sexual selection – the competition between individuals of one sex to mate with the opposite sex.^[28] Antlers in male deer, for example, are used in combat between males to win reproductive access to female deer. In many cases the male of a species is larger than the female. Mammal species with extreme sexual size dimorphism tend to have highly polygynous mating systems—presumably due to selection for success in competition with other males—such as the elephant seals. Other examples demonstrate that it is the preference of females that drive sexual dimorphism, such as in the case of the stalk-eyed fly.^[29]

Other animals, including most insects and many fish, have larger females. This may be associated with the cost of producing egg cells, which requires more nutrition than producing sperm—larger females are able to produce more eggs.^[30] For example, female southern black widow spiders are typically twice as long as the males.^[31] Occasionally this dimorphism is extreme, with males reduced to living as parasites dependent on the female, such as in the anglerfish. Some plant species also exhibit dimorphism in which the females are significantly larger than the males, such as in the moss Dicranum^[32] and the liverwort Sphaerocarpos.^[33] There is some evidence that, in these genera, the dimorphism may be tied to a sex chromosome,^[33][34] or to chemical signalling from females.^[35]

In birds, males often have a more colourful appearance and may have features (like the long tail of male peacocks) that would seem to put the organism at a disadvantage (e.g. bright colors would seem to make a bird more visible to predators). One proposed explanation for this is the handicap principle.^[36] This hypothesis says that, by demonstrating he can survive with such handicaps, the male is advertising his genetic fitness to females—traits that will benefit daughters as well, who will not be encumbered with such handicaps.

Birth

From Wikipedia, the free encyclopedia

Lambing: the mother licks the first lamb while giving birth to the second

Birth, also known as parturition, is the act or process of bearing or bringing forth offspring.^[1] In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the fetus at a developmental stage when it is ready to feed and breathe. In some species the offspring is precocial and can move around almost immediately after birth but in others it is altricial and completely dependent on parenting. In marsupials, the fetus is born at a very immature stage after a short gestational period and develops further in its mother's pouch.

It is not only mammals that give birth. Some reptiles, amphibians, fish and invertebrates carry their developing young inside them. Some of these are ovoviviparous, with the eggs being hatched inside the mother's body, and others are viviparous, with the embryo developing inside her body, as in mammals.

Birth in mammals

Large mammals, such as primates, cattle, horses, some antelopes, giraffes, hippopotamuses, rhinoceroses, elephants, seals, whales, dolphins, and porpoises, generally are pregnant with one offspring at a time; although, they may have twin or multiple births on occasion. In these large animals, the birth process is similar to that of a human though in most, the offspring is precocial. This means that it is born in a more advanced state than a human baby and is able to stand, walk and run (or swim in the case of an aquatic mammal) shortly after birth.^[2] In the case of whales, dolphins and porpoises, the single calf is normally born tail first which minimises the risk of drowning.^[3] The mother encourages the newborn calf to rise to the surface of the water to breathe.^[4]

Most smaller mammals have multiple births, producing litters of young which may number twelve or more. In these animals, each fetus is surrounded by its own amniotic sac and has a separate placenta. This separates from the wall of the uterus during labor and the fetus works its way towards the birth canal.^{[citation needed]}

Human birth

An illustration of normal head-first presentation by the obstetrician William Smellie from about 1792. The membranes have ruptured and the cervix is fully dilated.

Humans usually produce a single offspring at a time. The mother's body is prepared for birth by hormones produced by the pituitary gland, the ovary and the placenta.^[2] The total gestation period from fertilization to birth is normally about 38 weeks (birth usually occurring 40 weeks after the last menstrual period). The normal process of childbirth takes several hours and has three stages. The first stage starts with a series of involuntary contractions of the muscular walls of the uterus and gradual dilation of the cervix. The active phase of the first stage starts when the cervix is dilated more than about 4 cm in diameter and is when the contractions become stronger and regular. The head (or the buttocks in a breech birth) of the baby is pushed against the cervix, which gradually dilates until is fully dilated at 10 cm diameter. At some time, the amniotic sac bursts and the amniotic fluid escapes (also known as rupture of membranes or breaking the water).^[5] In stage two, starting when the cervix is fully dilated, strong contractions of the uterus and active pushing by the mother expels the baby out through the vagina, which during this stage of labour is called a birth canal as this passage contains a baby, and the baby is born with umbilical cord attached.^[6] In stage three, which begins after the birth of the baby, further contractions expel the placenta, amniotic sac, and the remaining portion of the umbilical cord usually within a few minutes.^[7]

Enormous changes take place in the newborn's circulation to enable breathing in air. In the uterus, the unborn baby is dependent on circulation of blood through the placenta for sustenance including gaseous exchange and the unborn baby's blood bypasses the lungs by flowing though the foramen ovale, which is a hole in the septum dividing the right atrium and left atrium. After birth the umbilical cord is clamped and cut, the baby starts to breathe air, and blood from the right ventricle starts to flow to the lungs for gaseous exchange and oxygenated blood returns to the left atrium, which is pumped into the left ventricle, and then pumped into the main arterial system. As result of these changes, the blood pressure in the left atrium exceeds the pressure in the right atrium, and this pressure difference forces the foramen ovale to close separating the left and right sides of the heart. The umbilical vein, umbilical arteries, ductus venosus and ductus arteriosus are not needed for life in air and in time these vessels become ligaments (embryonic remnants).^[8]

Cattle

Cow and newborn calf

Birthing in cattle is typical of a larger mammal. A cow goes through three stages of labor during normal delivery of a calf. During stage one, the animal seeks a quiet place away from the rest of the herd. Hormone changes cause soft tissues of the birth canal to relax as the mother's body prepares for birth. The contractions of the uterus are not obvious externally, but the cow may be restless. She may appear agitated, alternating between standing and lying down, with her tail slightly raised and her back arched. The fetus is pushed toward the birth canal by each contraction and the cow's cervix gradually begins to dilate. Stage one may last several hours, and ends when the cervix is fully dilated. Stage two can be seen to be underway when there is external protrusion of the amniotic sac through the vulva, closely followed by the appearance of the calf's front hooves and head in a front presentation (or occasionally the calf's tail and rear end in a posterior presentation).^[9] During the second stage, the cow will usually lie down on her side to push and the calf progresses through the birth canal. The complete delivery of the calf (or calves in a multiple birth) signifies the end of stage two. The cow scrambles to her feet (if lying down at this stage), turns round and starts vigorously licking the calf. The calf takes its first few breaths and within minutes is struggling to rise to its feet. The third and final stage of labor is the delivery of the placenta, which is usually expelled within a few hours and is often eaten by the normally herbivorous cow.^[9][10]

Dogs

In the dog, as birth approaches, contractions become more frequent. The amniotic sac looking like a glistening grey balloon, with a puppy inside, is propelled through the vulva. After further contractions, the sac is expelled and the bitch breaks the membranes releasing clear fluid and exposing the puppy. The mother chews at the umbilical cord and licks the puppy vigorously, which stimulates it to breathe. If the puppy has not taken its first breath within about six minutes, it is likely to die. Further puppies follow in a similar way one by one usually with less straining than the first. The mother will then usually eat the afterbirth.^[11]

Marsupials

A kangaroo joey firmly attached to a nipple inside the pouch

An infant marsupial is born in a very immature state. The gestation period is usually shorter than the intervals between oestrus periods. During gestation there is no placenta but the fetus is contained in a little yellow sac and feeds on a yolk. The first sign that a birth is imminent is the mother cleaning out her pouch. When it is born, the infant is pink, blind, furless and a few centimetres long. It has nostrils in order to breathe and forelegs to cling onto its mother's hairs but its hind legs are undeveloped. It crawls through its mother's fur and makes its way into the pouch. Here it fixes onto a teat which swells inside its mouth. It stays attached to the teat for several months until it is sufficiently developed to emerge.^[12]

Birth in other animals

The vast majority of invertebrates, most fish, reptiles and amphibians and all birds are oviparous, that is, they lay eggs with little or no embryonic development taking place within the mother. In aquatic organisms, fertilization is nearly always external with sperm and eggs being liberated into the water (an exception is sharks and rays, which have internal fertilization^[13]). Millions of eggs may be produced with no further parental involvement, in the expectation that a small number may survive to become mature individuals. Terrestrial invertebrates may also produce large numbers of eggs, a few of which may avoid predation and carry on the species. Some fish, reptiles and amphibians have adopted a different strategy and invest their effort in producing a small number of young at a more advanced stage which are more likely to survive to adulthood. Birds care for their young in the nest and provide for their needs after hatching and it is perhaps unsurprising that internal development does not occur in birds, given their need to fly.^[14]

Ovoviviparity is a mode of reproduction in which embryos develop inside eggs that remain in the mother's body until they are ready to hatch. Ovoviviparous animals are similar to viviparous species in that there is internal fertilization and the young are born in an advanced state, but differ in that there is no placental connection and the unborn young are nourished by egg yolk. The mother's body provides gas exchange (respiration), but that is largely necessary for oviparous animals as well.^[14] In many sharks the eggs hatch in the oviduct within the mother's body and the embryos are nourished by the egg's yolk and fluids secreted by glands in the walls of the oviduct. The Lamniforme sharks practice oophagy, where the first embryos to hatch consume the remaining eggs and sand tiger shark pups cannibalistically consume neighbouring embryos. The requiem sharks maintain a placental link to the developing young, this practice is known as viviparity. This is more analogous to mammalian gestation than to that of other fishes. In all these cases, the young are born alive and fully functional.^[15] The majority of caecilians are oviviviparous and give birth to already developed offspring. When the young have finished their yolk sacs they feed on nutrients secreted by cells lining the oviduct and even the cells themselves which they eat with specialist scraping teeth.^[16] The Alpine salamander (Salamandra atra) and several species of Tanzanian toad in the genus Nectophrynoides are oviviviparous, developing through the larval stage inside the mother's oviduct and eventually emerging as fully formed juveniles.^[17]

A more developed form of vivipary called placental viviparity is adopted by some species of scorpions^[18] and cockroaches,^[19] certain genera of sharks, snakes and velvet worms. In these, the developing embryo is nourished by some form of placental structure. The earliest known placenta was found recently in a group of extinct fishes called placoderms, which are ancestral to mammals. A fossil from Australia's Gogo Formation, laid down in the Devonian period, 380 million years ago, was found with an embryo inside it connected by an umbilical cord to a yolk sac. The find confirmed the hypothesis that a sub-group of placoderms, called ptyctodontids, fertilized their eggs internally. Some fishes that fertilize their eggs internally also give birth to live young, as seen here. This discovery moved our knowledge of live birth back 200 million years.^[20] The fossil of another genus was found with three embryos in the same position.^[21] Placoderms are a sister group of the ancestor of all living jawed fishes (Gnathostomata), including both chondrichthyians, the sharks & rays, and Osteichthyes, the bony fishes.

Among lizards, the viviparous lizard Zootoca vivipara, slow worms and many species of skink are viviparous, giving birth to live young. Some are ovoviviparous but others such as members of the genera Tiliqua and Corucia, give birth to live young that develop internally, deriving their nourishment from a mammal-like placenta attached to the inside of the mother's uterus. In a recently described example, an African species, Trachylepis ivensi, has developed a purely reptilian placenta directly comparable in structure and function to a mammalian placenta.^[22] Vivipary is rare in snakes, but boas and vipers are viviparous, giving birth to live young.

Female aphid giving birth

The majority of insects lay eggs but a very few give birth to offspring that are miniature versions of the adult.^[14] The aphid has a complex life cycle and during the summer months is able to multiply with great rapidity. Its reproduction is typically parthenogenetic and viviparous and females produce unfertilized eggs which they retain within their bodies.^[23] The embryos develop within their mothers' ovarioles and the offspring are clones of their mothers. Female nymphs are born which grow rapidly and soon produce more female offspring themselves.^[24] In some instances, the newborn nymphs already have developing embryos inside them.^[14]

The Lord of the Rings

From Wikipedia, the free encyclopedia

 

The Lord of the Rings

Volumes: The Fellowship of the Ring The Two Towers The Return of the King
Author	J. R. R. Tolkien
Country	England
Language	English
Genre	High fantasy Adventure
Publisher	George Allen & Unwin (UK)
Published	29 July 1954 11 November 1954 20 October 1955
Media type	Print (hardback & paperback)
Preceded by	The Hobbit

The Lord of the Rings is an epic high-fantasy novel written by English author J. R. R. Tolkien. The story began as a sequel to Tolkien's 1937 fantasy novel The Hobbit, but eventually developed into a much larger work. Written in stages between 1937 and 1949, much of it during World War II,^[1] The Lord of the Rings is one of the best-selling novels ever written, with over 150 million copies sold.^[2]

The title of the novel refers to the story's main antagonist, the Dark Lord Sauron,^{[note 1]} who had in an earlier age created the One Ring to rule the other Rings of Power as the ultimate weapon in his campaign to conquer and rule all of Middle-earth. From quiet beginnings in the Shire, a hobbit land not unlike the English countryside, the story ranges across northwest Middle-earth, following the course of the War of the Ring through the eyes of its characters, the hobbits Frodo Baggins, Samwise "Sam" Gamgee, Meriadoc "Merry" Brandybuck and Peregrin "Pippin" Took, but also the hobbits' chief allies and travelling companions: the Men Aragorn, a Ranger of the North, and Boromir, a Captain of Gondor; Gimli, a Dwarf warrior; Legolas, an Elven prince; and Gandalf, a Wizard.

The work was initially intended by Tolkien to be one volume of a two-volume set, the other to be The Silmarillion, but this idea was dismissed by his publisher.^[4][5] For economic reasons The Lord of the Rings was published in three volumes over the course of a year from 29 July 1954 to 20 October 1955.^[4][6] The three volumes were titled The Fellowship of the Ring, The Two Towers, and The Return of the King. Structurally, the novel is divided internally into six books, two per volume, with several appendices of background material included at the end of the third volume. Some editions combine the entire work into a single volume. The Lord of the Rings has since been reprinted numerous times and translated into many languages.

Tolkien's work has been the subject of extensive analysis of its themes and origins. Although a major work in itself, the story was only the last movement of a larger epic Tolkien had worked on since 1917,^[7] in a process he described as mythopoeia.^{[citation needed]} Influences on this earlier work, and on the story of The Lord of the Rings, include philology, mythology, religion and the author's distaste for the effects of industrialization, as well as earlier fantasy works and Tolkien's experiences in World War I.^[1] The Lord of the Rings in its turn is considered to have had a great effect on modern fantasy; the impact of Tolkien's works is such that the use of the words "Tolkienian" and "Tolkienesque" has been recorded in the Oxford English Dictionary.^[8]

The enduring popularity of The Lord of the Rings has led to numerous references in popular culture, the founding of many societies by fans of Tolkien's works,^[9] and the publication of many books about Tolkien and his works. The Lord of the Rings has inspired, and continues to inspire, artwork, music, films and television, video games, and subsequent literature. Award-winning adaptations of The Lord of the Rings have been made for radio, theatre, and film.^[10]

Plot summary

Thousands of years before the events of the novel, the Dark Lord Sauron had forged the One Ring to rule the other Rings of Power and corrupt those who wear them: the leaders of Men, Elves and Dwarves. He was later vanquished in battle by an alliance of Elves and Men led by Elendil and Gil-galad. Isildur, a ruler of Men, cut the One Ring from Sauron's finger, claiming it as an heirloom for his line, and Sauron lost his physical form. When Isildur was later ambushed and killed by Orcs, the Ring was lost in the River Anduin at Gladden Fields.
Over two thousand years later, the Ring was found by one of the river-folk called Déagol. His friend^[11] Sméagol immediately fell under the Ring's influence and strangled Déagol to acquire it. Sméagol was banished and hid under the Misty Mountains, where the Ring extended his lifespan and transformed him over the course of hundreds of years into a twisted, corrupted creature called Gollum. He lost the Ring, his "precious", and, as recounted in The Hobbit, Bilbo Baggins found it. Meanwhile, Sauron re-assumed physical form and took back his old realm of Mordor. Gollum set out in search of the Ring, but was captured by Sauron, who learnt from him that "Baggins" in the Shire had taken it. Gollum was set loose, and Sauron, who needed the Ring to regain his full power, sent forth his powerful servants, the Nazgûl, to seize it.

The Fellowship of the Ring

The story begins in the Shire, where the Hobbit Frodo Baggins inherits the Ring from Bilbo Baggins, his cousin^{[note 2]} and guardian. Neither is aware of its origin and nature, but Gandalf the Grey, a wizard and old friend of Bilbo, suspects the Ring's identity. When he becomes certain, he strongly advises Frodo to take it away from the Shire. Frodo leaves, accompanied by his gardener and friend, Samwise ("Sam") Gamgee, and two cousins, Meriadoc ("Merry") Brandybuck and Peregrin ("Pippin") Took. They nearly encounter the Nazgûl while still in the Shire, but shake off pursuit by cutting through the Old Forest, where they are aided by the enigmatic Tom Bombadil, who alone is unaffected by the Ring's corrupting influence. After leaving the forest, they stop in the town of Bree where they meet Strider, who is later revealed to be Aragorn, Isildur's heir. He persuades them to take him on as guide and protector. They flee from Bree after narrowly escaping another assault, but the Nazgûl follow and attack them on the hill of Weathertop, wounding Frodo with a Morgul blade. Aragorn leads the hobbits toward the Elven refuge of Rivendell, while Frodo gradually succumbs to the wound. The Ringwraiths nearly overtake Frodo at the Ford of Bruinen, but flood waters summoned by Elrond, master of Rivendell, rise up and overwhelm them.

Frodo recovers in Rivendell under the care of Elrond. The Council of Elrond reveals much significant history about Sauron and the Ring, as well as the news that Sauron has corrupted Gandalf's fellow wizard, Saruman. The Council decides that the Ring must be destroyed, but that can only be done by returning it to the flames of Mount Doom in Mordor, where it was forged. Frodo volunteers to take on this daunting task, and a "Fellowship of the Ring" is formed to aid him: Sam, Merry, Pippin, Aragorn, Gandalf, Gimli the Dwarf, Legolas the Elf, and the Man Boromir, son of the Ruling Steward Denethor of the realm of Gondor.

After a failed attempt to cross the Misty Mountains via the pass below Caradhras, the company are forced to try a more perilous path through the Mines of Moria, where they are attacked by the Watcher in the Water before the gate. Inside, they discover the fate of Balin and his colony of Dwarves. After repulsing an attack, they are pursued by orcs and an ancient and powerful demonic creature called a Balrog. Gandalf confronts the Balrog, but in their struggle, both fall into a deep chasm. The others escape and take refuge in the Elven forest of Lothlórien, where they are counselled by Galadriel and Celeborn.

With boats and gifts from Galadriel, the company travel down the River Anduin to the hill of Amon Hen. Boromir succumbs to the lure of the Ring and attempts to take it from Frodo. Frodo escapes and determines to continue the quest alone, though Sam guesses his intent and comes along.

The Two Towers

Orcs sent by Saruman and Sauron kill Boromir and kidnap Merry and Pippin. After agonizing over which pair of hobbits to follow, Aragorn, Gimli and Legolas pursue the orcs bearing Merry and Pippin to Saruman. In the kingdom of Rohan, the orcs are slain by a company of the Rohirrim. Merry and Pippin escape into Fangorn Forest, where they are befriended by Treebeard, the oldest of the tree-like Ents. Aragorn, Gimli and Legolas track the hobbits to Fangorn, and encounter Gandalf, resurrected as the significantly more powerful "Gandalf the White" after his mutually fatal duel with the Balrog. Gandalf assures them that Merry and Pippin are safe. They then ride to Edoras, the capital of Rohan, where they free Théoden, King of Rohan, from the influence of Saruman's henchman Gríma Wormtongue. Théoden musters his fighting strength and rides to the ancient fortress of Helm's Deep, but en route Gandalf leaves to seek help from Treebeard.

Meanwhile, the Ents, roused from their customarily peaceful ways by Merry and Pippin, attack Isengard, Saruman's stronghold, and trap the wizard in the tower of Orthanc. Gandalf convinces Treebeard to send an army of Huorns to Théoden's aid. Gandalf and Rohirrim reinforcements arrive at Helm's Deep just in time to defeat and scatter Saruman's army. The Huorns dispose of the fleeing orcs. Gandalf then parleys with Saruman at Orthanc. When Saruman rejects his offer of redemption, Gandalf strips him of his rank and most of his powers. Pippin looks into a palantír, a seeing-stone that Saruman had used to communicate with Sauron and through which he was enslaved. Gandalf rides for Minas Tirith, chief city of Gondor, taking Pippin with him.

Frodo and Sam capture Gollum, who had been following them from Moria, and force him to guide them to Mordor. Finding Mordor's Black Gate too well guarded to attempt, they travel instead to a secret passage Gollum knows. Torn between his loyalty to Frodo and his desire for the Ring, Gollum eventually betrays Frodo by leading him to the great spider Shelob in the tunnels of Cirith Ungol. Frodo is felled by Shelob's sting, but Sam fights her off. Sam takes the Ring and leaves Frodo, believing him to be dead. When orcs find Frodo, Sam overhears them say that Frodo is only unconscious, and chases after them.

The Return of the King

Sauron unleashes a heavy assault upon Gondor. Gandalf arrives at Minas Tirith to alert Denethor of the impending attack. The city is besieged, and Denethor, deceived by Sauron, gives up hope and commits suicide, nearly taking his remaining son Faramir with him. Aragorn feels he has no choice but to take the Paths of the Dead in order to reach Gondor in time, accompanied by Legolas, Gimli and the Dúnedain Rangers from the North. There Aragorn raises an undead army of oath-breakers bound by an ancient curse that said they could not rest until they had fulfilled their vow to the king of Gondor. The ghostly army helps them to defeat the Corsairs of Umbar who are invading southern Gondor. Commandeering the ships of the Corsairs, Aragorn leads reinforcements up the Anduin to relieve the siege of Minas Tirith, and the forces of Gondor and Rohan defeat Sauron's army in the Battle of the Pelennor Fields.

Meanwhile, Sam rescues Frodo from the tower of Cirith Ungol, and they set out across Mordor. In order to distract Sauron from his true danger, Aragorn leads the armies of Gondor and Rohan in a march on the Black Gate of Mordor. His vastly outnumbered troops fight desperately against Sauron's forces. Reaching the edge of the Cracks of Doom, Frodo is unable to resist the Ring any longer, and suddenly and fiercely claims it for himself. But Gollum suddenly reappears, struggles with Frodo and bites off his finger, Ring and all. Celebrating wildly, Gollum accidentally falls into the fire, taking the Ring with him; and so Frodo's mission is completed. With the destruction of the One Ring, Sauron is permanently shorn of his power, the Nazgûl perish, and his armies are thrown into such disarray that Aragorn's forces emerge victorious.

With the end of the War of the Ring, Aragorn is crowned Elessar, King of Arnor and Gondor, and marries his long-time love, Arwen, daughter of Elrond. Saruman escapes from Isengard and, seeking to carve out a new kingdom, enslaves the Shire. The four hobbits, upon returning home, raise a rebellion and overthrow him. Gríma turns on Saruman and kills him in front of Frodo's house, and is slain in turn by hobbit archers. The War of the Ring thus comes to its true end on Frodo's very doorstep.

Merry and Pippin are acclaimed heroes, while Sam marries Rosie Cotton and uses his gifts from Galadriel to help heal the Shire. Frodo, however, remains wounded in body and spirit after having borne the oppressive weight of the One Ring so long.

Several years later, accompanied by Bilbo and Gandalf, he sails from the Grey Havens west over the Sea to the Undying Lands to find peace. After Rosie's death, Sam gives his daughter the Red Book of Westmarch, containing the account of Bilbo's adventures and the War of the Ring as witnessed by the hobbits. Sam is then said to have crossed west over the Sea himself, the last of the Ring-bearers.

Main characters

Protagonists:

• Frodo Baggins, bearer of the One Ring, given to him by Bilbo Baggins
• Samwise Gamgee, gardener and friend of the Bagginses
• Meriadoc Brandybuck (Merry), Frodo's cousin
• Peregrin Took (Pippin or Pip), Frodo's cousin
• Gandalf the Grey, a wizard, leads the Fellowship until his fall in Moria, returns from death to lead the armies of the west against Sauron.
• Aragorn, descendant of Isildur and rightful heir to the thrones of Arnor and Gondor
• Legolas Greenleaf, an Elf prince and son of King Thranduil of Mirkwood
• Gimli, son of Glóin, a dwarf
• Denethor, ruling Steward of Gondor and Lord of Minas Tirith
• Boromir, the eldest son and heir of Denethor
• Faramir, younger brother of Boromir
• Galadriel, Elf co-ruler of Lothlórien, and grandmother of Arwen
• Celeborn, Elf co-ruler of Lothlórien, husband of Galadriel, and grandfather of Arwen
• Elrond Half-Elven, Half-elven Lord of Rivendell and father of Arwen
• Arwen Undómiel, daughter of Elrond, love interest of Aragorn
• Bilbo Baggins, Frodo's cousin^{[note 2]}
• Théoden, King of Rohan, ally of Gondor
• Éomer, the 3rd Marshal of the Mark and Théoden's nephew. Later King of Rohan after Théoden's death.
• Éowyn, sister of Éomer, who disguises herself as a male warrior named Dernhelm to fight beside Théoden
• Treebeard, oldest of the Ents

Antagonists:

• Sauron, the Dark Lord and titular Lord of the Rings, a fallen Maia who helped the Elves forge the Rings of Power long ago
• The Nazgûl or Ringwraiths, men enslaved by Sauron when they accepted his treacherous gifts of Rings of Power
• The Witch-king of Angmar, the Lord of the Nazgûl, and Sauron's most powerful servant, who commands Sauron's army
• Saruman the White, a wizard who seeks the One Ring for himself. Corrupted by Sauron through the palantír. Like Gandalf, he is a Maia.
• Gríma Wormtongue, a secret servant of Saruman and traitor to Rohan, who poisons Théoden's perceptions with well placed "advice"
• Gollum, a river hobbit originally named Sméagol
• Shelob, a giant spider who dwells in the passes above Minas Morgul
• The Balrog, a fire-demon dwelling beneath the Mines of Moria

Concept and creation

Background

The Lord of the Rings started as a sequel to J. R. R. Tolkien's work The Hobbit, published in 1937.^[12] The popularity of The Hobbit had led George Allen & Unwin, the publishers, to request a sequel. Tolkien warned them that he wrote quite slowly, and responded with several stories he had already developed. Having rejected his contemporary drafts for The Silmarillion, putting on hold Roverandom, and accepting Farmer Giles of Ham, Allen & Unwin thought more stories about hobbits would be popular.^[13] So at the age of 45, Tolkien began writing the story that would become The Lord of the Rings. The story would not be finished until 12 years later, in 1949, and would not be fully published until 1955, when Tolkien was 63 years old.

Writing

Persuaded by his publishers, he started "a new Hobbit" in December 1937.^[12] After several false starts, the story of the One Ring emerged. The idea for the first chapter ("A Long-Expected Party") arrived fully formed, although the reasons behind Bilbo's disappearance, the significance of the Ring, and the title The Lord of the Rings did not arrive until the spring of 1938.^[12] Originally, he planned to write a story in which Bilbo had used up all his treasure and was looking for another adventure to gain more; however, he remembered the Ring and its powers and thought that would be a better focus for the new work.^[12] As the story progressed, he also brought in elements from 'The Silmarillion' mythology.^[14]

Writing was slow, because Tolkien had a full-time academic position, and needed to earn further money as a university examiner.^[15] Tolkien abandoned The Lord of the Rings during most of 1943 and only restarted it in April 1944,^[12] as a serial for his son Christopher Tolkien, who was sent chapters as they were written while he was serving in South Africa with the Royal Air Force. Tolkien made another concerted effort in 1946, and showed the manuscript to his publishers in 1947.^[12] The story was effectively finished the next year, but Tolkien did not complete the revision of earlier parts of the work until 1949.^[12] The original manuscripts, which total 9,250 pages, now reside in the J.R.R. Tolkien Collection at Marquette University.^[16]

Influences

Mentioned at the beginning of The Lord of the Rings, the Ivy Bush^[17] is the closest public house to Birmingham Oratory which Tolkien attended while living near Edgbaston Reservoir. Perrott's Folly is nearby.

The influence of the Welsh language, which Tolkien had learnt, is summarised in his essay English and Welsh: "If I may once more refer to my work. The Lord of the Rings, in evidence: the names of persons and places in this story were mainly composed on patterns deliberately modelled on those of Welsh (closely similar but not identical). This element in the tale has given perhaps more pleasure to more readers than anything else in it."^[18]

The Lord of the Rings developed as a personal exploration by Tolkien of his interests in philology, religion (particularly Roman Catholicism^[19]), fairy tales, Norse and general Germanic mythology,^[20][21] and also Celtic,^[22] Slavic,^[23][24][25] Persian,^[26] Greek,^[27] and Finnish mythology.^[28] Tolkien acknowledged, and external critics have verified, the influences of George MacDonald and William Morris^[29] and the Anglo-Saxon poem Beowulf.^[30] The question of a direct influence of Wagner's The Nibelung's Ring on Tolkien's work is debated by critics.

Tolkien included neither any explicit religion nor cult in his work. Rather the themes, moral philosophy, and cosmology of The Lord of the Rings reflect his Catholic worldview. In one of his letters Tolkien states, "The Lord of the Rings is of course a fundamentally religious and Catholic work; unconsciously so at first, but consciously in the revision. That is why I have not put in, or have cut out, practically all references to anything like 'religion', to cults or practices, in the imaginary world. For the religious element is absorbed into the story and the symbolism."^[19]

Some locations and characters were inspired by Tolkien's childhood in Birmingham, where he first lived near Sarehole Mill, and later near Edgbaston Reservoir.^[31] There are also hints of the Black Country, which is within easy reach of north west Edgbaston. This shows in such names as "Underhill", and the description of Saruman's industrialisation of Isengard and The Shire. It has also been suggested that The Shire and its surroundings were based on the countryside around Stonyhurst College in Lancashire where Tolkien frequently stayed during the 1940s.^[32] The work was influenced by the effects of his military service during World War I, to the point that Frodo has been "diagnosed" as suffering from Posttraumatic Stress Disorder, or "shell-shock," which was first diagnosed at the Battle of the Somme, at which Tolkien served.^[33]

Publication history

A dispute with his publisher, George Allen & Unwin, led to the book being offered to Collins in 1950. Tolkien intended The Silmarillion (itself largely unrevised at this point) to be published along with The Lord of the Rings, but A&U were unwilling to do this. After Milton Waldman, his contact at Collins, expressed the belief that The Lord of the Rings itself "urgently wanted cutting", Tolkien eventually demanded that they publish the book in 1952.^[34] Collins did not; and so Tolkien wrote to Allen and Unwin, saying, "I would gladly consider the publication of any part of the stuff."^[12]

For publication, the book was divided into three volumes: The Fellowship of the Ring (Books I, The Ring Sets Out, and II, The Ring Goes South), The Two Towers (Books III, The Treason of Isengard, and IV, The Ring Goes East), and The Return of the King (Books V, The War of the Ring, and VI, The End of the Third Age, plus six appendices). This was due largely to post-war paper shortages, as well as being a way to keep down the price of the book. Delays in producing appendices, maps and especially indices led to the volumes being published later than originally hoped — on 29 July 1954, on 11 November 1954 and on 20 October 1955 respectively in the United Kingdom, and slightly later in the United States. The Return of the King was especially delayed. Tolkien, moreover, did not especially like the title The Return of the King, believing it gave away too much of the storyline. He had originally suggested The War of the Ring, which was dismissed by his publishers.^[35]

The books were published under a profit-sharing arrangement, whereby Tolkien would not receive an advance or royalties until the books had broken even, after which he would take a large share of the profits.^[36] It has ultimately become the second best-selling novel ever written, with over 150 million copies sold.^[2] Only A Tale of Two Cities by Charles Dickens has sold more copies worldwide (over 200 million) while the fourth best-selling novel is Tolkien's The Hobbit.^[37][38][39]

Editions and revisions

In the early 1960s Donald A. Wollheim, science fiction editor of the paperback publisher Ace Books, claimed that The Lord of the Rings was not protected in the United States under American copyright law because Houghton Mifflin, the U.S. hardcover publisher, had neglected to copyright the work in the United States.^[40][41] Ace Books then proceeded to publish an edition, unauthorized by Tolkien and without paying royalties to him. Tolkien took issue with this and quickly notified his fans of this objection.^[42] Grass-roots pressure from these fans became so great that Ace Books withdrew their edition and made a nominal payment to Tolkien.^[43][44] Authorized editions followed from Ballantine Books and Houghton Mifflin to tremendous commercial success. By the mid-1960s the novel had become a cultural phenomenon. Tolkien undertook various textual revisions to produce a version of the book that would be published with his consent and establish an unquestioned US copyright. This text became the Second Edition of The Lord of the Rings, published in 1965.^[43] Houghton Mifflin editions after 1994 consolidate variant revisions by Tolkien, and corrections supervised by Christopher Tolkien, which resulted, after some initial glitches, in a computer-based unified text.^[45]

Posthumous publication of drafts

From 1988 to 1992 Christopher Tolkien published the surviving drafts of The Lord of The Rings, chronicling and illuminating with commentary the stages of the text's development, in volumes 6–9 of his History of Middle-earth series. The four volumes carry the titles The Return of the Shadow, The Treason of Isengard, The War of the Ring, and Sauron Defeated.

Translations

The novel has been translated, with various degrees of success, into at least 38 languages.^[46] Tolkien, an expert in philology, examined many of these translations, and made comments on each that reflect both the translation process and his work. As he was unhappy with some choices made by early translators, such as the Swedish translation by Åke Ohlmarks,^[47] Tolkien wrote a "Guide to the Names in The Lord of the Rings" (1967). Because The Lord of the Rings purports to be a translation of the fictitious Red Book of Westmarch, with the English language representing the Westron of the "original", Tolkien suggested that translators attempt to capture the interplay between English and the invented nomenclature of the English work, and gave several examples along with general guidance.

Reception

While early reviews for The Lord of the Rings were mixed, reviews in various media have been, on the whole, highly positive and acknowledge Tolkien's literary achievement as a significant one. The initial review in the Sunday Telegraph described it as "among the greatest works of imaginative fiction of the twentieth century."^[48] The Sunday Times echoed this sentiment, stating that "the English-speaking world is divided into those who have read The Lord of the Rings and The Hobbit and those who are going to read them."^[48] The New York Herald Tribune also seemed to have an idea of how popular the books would become, writing in its review that they were "destined to outlast our time."^[49] W. H. Auden, an admirer of Tolkien's writings, regarded The Lord of the Rings as a "masterpiece", further stating that in some cases it outdid the achievement of John Milton's Paradise Lost.^[50]
New York Times reviewer Judith Shulevitz criticized the "pedantry" of Tolkien's literary style, saying that he "formulated a high-minded belief in the importance of his mission as a literary preservationist, which turns out to be death to literature itself."^[51] Critic Richard Jenkyns, writing in The New Republic, criticized the work for a lack of psychological depth. Both the characters and the work itself are, according to Jenkyns, "anemic, and lacking in fibre."^[52] Even within Tolkien's literary group, The Inklings, reviews were mixed. Hugo Dyson complained loudly at its readings.^[53][54] However, another Inkling, C. S. Lewis, had very different feelings, writing, "here are beauties which pierce like swords or burn like cold iron. Here is a book which will break your heart." Despite these reviews and its lack of paperback printing until the 1960s, The Lord of the Rings initially sold well in hardback.^[7]

In 1957, The Lord of the Rings was awarded the International Fantasy Award. Despite its numerous detractors, the publication of the Ace Books and Ballantine paperbacks helped The Lord of the Rings become immensely popular in the United States in the 1960s. The book has remained so ever since, ranking as one of the most popular works of fiction of the twentieth century, judged by both sales and reader surveys.^[55] In the 2003 "Big Read" survey conducted in Britain by the BBC, The Lord of the Rings was found to be the "Nation's best-loved book." In similar 2004 polls both Germany^[56] and Australia^[57] also found The Lord of the Rings to be their favourite book. In a 1999 poll of Amazon.com customers, The Lord of the Rings was judged to be their favourite "book of the millennium."^[58] The Lord of the Rings was awarded the Prometheus Hall of Fame Award in 2009.

Themes

Although The Lord of the Rings was published in the 1950s, Tolkien insisted that the One Ring was not an allegory for the Atomic Bomb,^[59] nor were his works a strict allegory of any kind, but were open to interpretation as the reader saw fit.^[60][61]
A few critics have found what they consider to be racial elements in the story, generally based upon their views of how Tolkien's imagery depicts good and evil, characters' race (e.g. Elf, Dwarf, Hobbit, Southron, Númenórean, Orc); and that the character's race is seen as determining their behaviour.^[62][63][64] Counter-arguments note that race-focused critiques often omit relevant textual evidence to the contrary,^[65][66][67] cite imagery from adaptations rather than the work itself;^[68] ignore the absence of evidence of racist attitudes or events in the author's personal life^[65][68][69] and claim that the perception of racism is itself a marginal view.^[69]

Critics have also seen social class rather than race as being the determinant factor for the portrayal of good and evil.^[65] Commentators such as science fiction author David Brin have interpreted the work to hold unquestioning devotion to a traditional elitist social structure.^[70] In his essay "Epic Pooh", science fiction and fantasy author Michael Moorcock critiques the world-view displayed by the book as deeply conservative, in both the 'paternalism' of the narrative voice and the power-structures in the narrative.^[71] Tom Shippey cites the origin of this portrayal of evil as a reflection of the prejudices of European middle-classes during the inter-war years towards the industrial working class.^[72]

Other observers have cited Christian and Catholic themes in The Lord of the Rings.^[73]

The book has been read as fitting the model of Joseph Campbell's "monomyth".^[74]

Adaptations

The book has been adapted for radio four times. In 1955 and 1956, the BBC broadcast The Lord of the Rings, a 12-part radio adaptation of the story. In the 1960s radio station WBAI produced a short radio adaptation. A 1979 dramatization of The Lord of the Rings was broadcast in the United States and subsequently issued on tape and CD. 

In 1981, the BBC broadcast The Lord of the Rings, a new dramatization in 26 half-hour instalments. This dramatization of The Lord of the Rings has subsequently been made available on both tape and CD both by the BBC and other publishers. For this purpose it is generally edited into 13 one hour episodes.
Two film adaptations of the book have been made. The first was J. R. R. Tolkien's The Lord of the Rings (1978), by animator Ralph Bakshi,^[75] the first part of what was originally intended to be a two-part adaptation of the story; it covers The Fellowship of the Ring and part of The Two Towers. A three-issue comic book version of the movie was also published in Europe (but not printed in English), with illustrations by Luis Bermejo. When Bakshi's investors shied away of financing the second film that would complete the story, the remainder of the story was covered in an animated television special by Rankin-Bass. Stylistically, the two segments are very different. The second and more critically and commercially successful adaptation was Peter Jackson's live action The Lord of the Rings film trilogy, produced by New Line Cinema and released in three instalments as The Lord of the Rings: The Fellowship of the Ring (2001), The Lord of the Rings: The Two Towers (2002), and The Lord of the Rings: The Return of the King (2003). All three parts won multiple Academy Awards, including consecutive Best Picture nominations. The final instalment of this trilogy was the second film to break the one-billion-dollar barrier and won a total of 11 Oscars (something only two other films in history, Ben-Hur and Titanic, have accomplished), including Best Picture, Best Director and Best Adapted Screenplay.

The Hunt for Gollum, a fan film based on elements of the appendices to The Lord of the Rings, was released on the internet in May 2009 and has been covered in major media.^[76]

Born of Hope, written by Paula DiSante, directed by Kate Madison, and released in December 2009, is a fan film based upon the appendices of The Lord of the Rings.^[77]

In 1990, Recorded Books published an audio version of The Lord of the Rings,^[78] with British actor Rob Inglis – who had previously starred in his own one-man stage productions of The Hobbit and The Lord of the Rings – reading. A large-scale musical theatre adaptation, The Lord of the Rings was first staged in Toronto, Ontario, Canada in 2006 and opened in London in May 2007.

Legacy

Influences on the fantasy genre

The enormous popularity of Tolkien's epic saga greatly expanded the demand for fantasy fiction. Largely thanks to The Lord of the Rings, the genre flowered throughout the 1960s, and enjoys popularity to the present day. The opus has spawned many imitators, such as The Sword of Shannara, which Lin Carter called "the single most cold-blooded, complete rip-off of another book that I have ever read".^[79] Dungeons & Dragons, which popularized the role-playing game (RPG) genre in the 1970s, features many races found in The Lord of the Rings, most notably halflings (another term for hobbits), elves (who are distinct from dark elves, following Tolkien's example), dwarves, half-elves, orcs, and dragons. However, Gary Gygax, lead designer of the game, maintained that he was influenced very little by The Lord of the Rings, stating that he included these elements as a marketing move to draw on the popularity the work enjoyed at the time he was developing the game.^[80]

Because D&D has gone on to influence many popular role-playing video games, the influence of The Lord of the Rings extends to many of them as well, with titles such as Dragon Warrior,^[81][82] the Ultima series , EverQuest, the Warcraft series, and the Elder Scrolls series of games^[83] as well as video games set in Middle-earth itself.
Research also suggests that some consumers of fantasy games derive their motivation from trying to create an epic fantasy narrative which is influenced by The Lord of the Rings.^[84]

Music

In 1965, songwriter Donald Swann, who was best known for his collaboration with Michael Flanders as Flanders & Swann, set six poems from The Lord of the Rings and one from The Adventures of Tom Bombadil ("Errantry") to music. When Swann met with Tolkien to play the songs for his approval, Tolkien suggested for "Namárië" (Galadriel's lament) a setting reminiscent of plain chant, which Swann accepted.^[85] The songs were published in 1967 as The Road Goes Ever On: A Song Cycle,^[86] and a recording of the songs performed by singer William Elvin with Swann on piano was issued that same year by Caedmon Records as Poems and Songs of Middle Earth.^[87]
In 1988, Dutch composer and trombonist Johan de Meij completed his Symphony No. 1 "The Lord of the Rings", which encompassed 5 movements, titled "Gandalf", "Lothlórien", "Gollum", "Journey in the Dark", and "Hobbits". In 1989 the symphony was awarded the Sudler Composition Award, awarded biennially for best wind band composition. The Danish Tolkien Ensemble have released a number of albums that feature the complete poems and songs of The Lord of the Rings set to music, with some featuring recitation by Christopher Lee.

Rock bands of the 1970s were musically and lyrically inspired by the fantasy embracing counter-culture of the time; British 70s rock band Led Zeppelin recorded several songs that contain explicit references to The Lord of the Rings ("Ramble On", "The Battle of Evermore", "Over the Hills and Far Away", and "Misty Mountain Hop"). In 1970, the Swedish musician Bo Hansson released an instrumental concept album based on the book titled Sagan om ringen (translated as "The Saga of the Ring", which was the title of the Swedish translation of The Lord of the Rings at the time).^[88] The album was subsequently released internationally as Music Inspired by Lord of the Rings in 1972.^[88] The songs "Rivendell" and "The Necromancer" by the progressive rock band Rush were inspired by Tolkien. Styx also paid homage to Tolkien on their "Pieces of Eight" album with the song "Lords of the Ring," while Black Sabbath's song, "The Wizard", which appeared on their debut album, was influenced by Tolkien's hero, Gandalf. The heavy metal band Cirith Ungol took their name from a mountain pass in Middle-earth. Progressive rock group Camel paid homage to the text in their lengthy composition "Nimrodel/The Procession/The White Rider", and Progressive rock band Barclay James Harvest was inspired by the character Galadriel to write a song by that name, and used "Bombadil", the name of another character, as a pseudonym under which their 1972 single "Breathless"/"When the City Sleeps" was released; there are other references scattered through the BJH oeuvre.
Later, from the 1980s to the present day, many heavy metal acts have been influenced by Tolkien. Blind Guardian has written many songs relating to Middle-earth, including the full concept album Nightfall in Middle Earth. Almost all of Summoning's songs and the entire discography of Battlelore are Tolkien-themed. Gorgoroth and Amon 
Amarth take their names from an area of Mordor, and Burzum take their name from the Black Speech of Mordor. The Finnish metal band Nightwish and the Norwegian metal band Tristania have also incorporated many Tolkien references into their music. A Swedish metal band, Sabaton, based their song "Shadows" on the nine ring wraiths.^[89] American heavy metal band Megadeth released two song titled This Day We Fight! and How the Story Ends which were both inspired by the Lord of the Rings series, particularly Aragorn's speech in the third film for the latter song.^[90]

Enya wrote an instrumental piece called "Lothlórien" in 1991, and composed two songs for the film The Lord of the Rings: The Fellowship of the Ring—"May It Be" (sung in English and Quenya) and "Aníron" (sung in Sindarin).

Impact on popular culture

"Welcome to Hobbiton" sign in Matamata, New Zealand, where the film trilogy was shot.

The Lord of the Rings has had a profound and wide-ranging impact on popular culture, beginning with its publication in the 1950s, but especially throughout the 1960s and 1970s, during which time young people embraced it as a countercultural saga.^[91] "Frodo Lives!" and "Gandalf for President" were two phrases popular amongst United States Tolkien fans during this time.^[92]

Parodies like the Harvard Lampoon's Bored of the Rings, the VeggieTales episode "Lord of the Beans", the South Park episode "The Return of the Fellowship of the Ring to the Two Towers", the Futurama film "Bender's Game", The Adventures of Jimmy Neutron: Boy Genius episode "Lights! Camera! Danger!", The Big Bang Theory episode "The Precious Fragmentation", and the American Dad! episode "The Return of the Bling" are testimony to the work's continual presence in popular culture.

In 1969, Tolkien sold the merchandising rights to The Lord of The Rings (and The Hobbit) to United Artists under an agreement stipulating a lump sum payment of £10,000^[93] plus a 7.5% royalty after costs,^[94] payable to Allen & Unwin and the author.^[95] In 1976, three years after the author's death, United Artists sold the rights to Saul Zaentz Company, who now trade as Tolkien Enterprises. Since then all "authorized" merchandise has been signed-off by Tolkien Enterprises, although the intellectual property rights of the specific likenesses of characters and other imagery from various adaptations is generally held by the adaptors.^[96] Outside any commercial exploitation from adaptations, from the late 1960s onwards there has been an increasing variety of original licensed merchandise, from posters and calendars created by illustrators such as Pauline Baynes and the Brothers Hildebrandt, to figurines and miniatures to computer, video, tabletop and role-playing games. Recent examples include the Spiel des Jahres award winning (for best use of literature in a game) board game The Lord of the Rings by Reiner Knizia and the Golden Joystick award-winning massively multiplayer online role-playing game, The Lord of the Rings Online: Shadows of Angmar by Turbine, Inc..

The Lord of the Rings has been mentioned in numerous songs including The Ballad of Bilbo Baggins by Leonard Nimoy, Led Zeppelin's Misty Mountain Hop, Over the Hills and Far Away, Ramble On, and The Battle of Evermore, Genesis' song "Stagnation" (from Trespass, 1970) was about Gollum, and Argent included the song "Lothlorien" on the 1971 album Ring of Hands.

Steve Peregrin Took (born Stephen Ross Porter) of British rock band T. Rex took his name from the hobbit Peregrin Took (better known as Pippin). Took later recorded under the pseudonym 'Shagrat the Vagrant', before forming a band called Shagrat in 1970.