Sexual maturity

Sexual maturity is the capability of an organism to reproduce. It may be considered synonymous with adulthood,[1] but, in humans, puberty encompasses the process of sexual maturation and adulthood is based on cultural definitions.[1][2]

Most multicellular organisms are unable to sexually reproduce at birth (or germination), and depending on the species, it may be days, weeks, or years until their bodies are able to do so. Also, certain cues may cause the organism to become sexually mature. They may be external, such as drought, or internal, such as percentage of body fat (such internal cues are not to be confused with hormones which directly produce sexual maturity).

Sexual maturity is brought about by a maturing of the reproductive organs and the production of gametes. It may also be accompanied by a growth spurt or other physical changes which distinguish the immature organism from its adult form. These are termed secondary sex characteristics, and often represent an increase in sexual dimorphism. For example, before puberty, human children have flat chests, but adult females have generally larger breasts than adult males. However, there are exceptions such as obesity and hormone imbalances such as gynecomastia.

After sexual maturity is achieved, it is possible for some organisms to become infertile, or even to change their sex. Some organisms are hermaphrodites and may or may not be able to produce viable offspring. Also, while in many organisms sexual maturity is strongly linked to age, many other factors are involved, and it is possible for some to display most or all of the characteristics of the adult form without being sexually mature. Conversely it is also possible for the "immature" form of an organism to reproduce. This is called progenesis, in which sexual development occurs faster than other physiological development (in contrast, the term neoteny refers to when non-sexual development is slowed - but the result is the same, the retention of juvenile characteristics into adulthood).

References

  1. ^ a b Thomas Edward McNamara (2004). Evolution, Culture, and Consciousness: The Discovery of the Preconscious Mind. University Press of America. p. 262-263. ISBN 076182765X. Retrieved March 20, 2018.
  2. ^ Joseph S. Sanfilippo, Eduardo Lara-Torre, D. Keith Edmonds, Claire Templeman (2008). Clinical Pediatric and Adolescent Gynecology. CRC Press. p. 34. ISBN 0203091787. Retrieved March 20, 2018. The definition of puberty alone can encompass the process of sexual maturation, but a more expansive approach is to think of puberty in combination with the term adolescence. This differentiation prompts the practitioner to consider the psychological, behavioral, and social changes of the adolescent who is experiencing pubertal development.CS1 maint: Uses authors parameter (link)

See also

Adult

Biologically, an adult is a human or other organism that has reached sexual maturity. In human context, the term adult additionally has meanings associated with social and legal concepts. In contrast to a "minor", a legal adult is a person who has attained the age of majority and is therefore regarded as independent, self-sufficient, and responsible. The typical age of attaining legal adulthood is 18, although definition may vary by legal rights and country.

Human adulthood encompasses psychological adult development. Definitions of adulthood are often inconsistent and contradictory; a person may be biologically an adult, and have adult behavior but still be treated as a child if they are under the legal age of majority. Conversely, one may legally be an adult but possess none of the maturity and responsibility that may define an adult character.

In different cultures there are events that relate passing from being a child to becoming an adult or coming of age. This often encompasses the passing a series of tests to demonstrate that a person is prepared for adulthood, or reaching a specified age, sometimes in conjunction with demonstrating preparation. Most modern societies determine legal adulthood based on reaching a legally specified age without requiring a demonstration of physical maturity or preparation for adulthood.

Alexander's kusimanse

Alexander's kusimanse (Crossarchus alexandri) is a genus of mongoose found in the Democratic Republic of Congo and Uganda.This species has a body length of 30 to 45 centimeters (12 to 18 inches) and weighs between 0.45 and 1.4 kg (0.99 and 3.09 lb). Its tail measures 15 and 25 centimeters (5.9 and 9.8 inches) in length.

It is known to share range with the Angolan kusimanse (Crossarchus ansorgei). It feeds on grubs, small rodents, small reptiles, crabs, and some fruits. It can produce 2 to 3 litters (2 to 4 young per litter) of young each year after a gestation period of 8 weeks. The young wean at 3 weeks old and reach sexual maturity at 9 months old.

Baboon

Baboons are primates comprising the genus Papio, one of the 23 genuses of Old World monkeys. The common names of the five species of baboons are the hamadryas, the Guinea (also called the western and the red), the olive, the yellow, and the chacma baboons. They are each native to one of five specific areas of Africa, and the hamadryas baboon is also native to part of the Arabian Peninsula. They are among the largest non-hominoid primates. Baboons have existed for at least two million years.

Baboons vary in size and weight depending on the species. The smallest, the Guinea baboon, is 50 cm (20 in) in length and weighs only 14 kg (31 lb), while the largest, the chacma baboon, is up to 120 cm (47 in) in length and weighs 40 kg (88 lb). All baboons have long, dog-like muzzles, heavy, powerful jaws with sharp canine teeth, close-set eyes, thick fur except on their muzzles, short tails, and nerveless, hairless pads of skin on their protruding buttocks called ischial callosities that provide for sitting comfort. Male hamadryas baboons have large white manes. Baboons exhibit sexual dimorphism in size, colour and/or canine teeth development.

Baboons have diurnality and are terrestrial, but some sleep in trees at night. They are found in open savannahs and woodlands across Africa. They are omnivorous: common sources of food are insects, fish, shellfish, hares, birds, vervet monkeys, and small antelopes. Their principal predators are Nile crocodiles, large cats, and hyenas. Most baboons live in hierarchical troops containing harems. Baboons can determine from vocal exchanges what the dominance relations are between individuals.

In general, each male can mate with any female: the mating order among the males depends partially on their social ranking. Females typically give birth after a six-month gestation, usually to a single infant. The females tend to be the primary caretaker of the young, although several females may share the duties for all of their offspring. Offspring are weaned after about a year. They reach sexual maturity in five to eight years. Males leave their birth group, usually before they reach sexual maturity, whereas females stay in the same group their entire lives. Baboons in captivity live up to 45 years, while in the wild they live up to 30 years.

Black-headed monitor

The black-headed monitor (Varanus tristis) is a relatively small species of monitor lizards native to Australia. It is placed in the subgenus Odatria. Their average length is between 50 and 80 cm depending on location. V. t. tristis is the larger of two distinct subspecies, found mainly to the west of Australia. The freckled monitor (V. t. orientalis) is a smaller subspecies with a lighter, more distinct colouration confined mainly to eastern Australia. Clutch sizes range between four and 10 eggs. Males can be identified after sexual maturity (usually around two years of age) by a large cluster of spiny scales either size of the animal's vent. Female specimens lack these obvious protrusions and rarely possess more than a small number of spines only slightly larger than the surrounding scales.

Blue ling

The blue ling (Molva dypterygia) is a member of the cod family from the North Atlantic. It is usually 70 to 110 cm long, but the maximum length is 155 cm. Blue ling feed on fish (flatfishes, gobies, rocklings) and crustaceans and benthic invertebrates. The fish reaches sexual maturity at the age of six to 12 years.

Bobak marmot

The bobak marmot (Marmota bobak), also known as the steppe marmot, is a species of marmot that inhabits the steppes of Eastern Europe and Central Asia. It is a social animal and inhabits steppe grassland, including cultivated field borders. It hibernates for more than half the year. Litter sizes average about five offspring and it takes three years for the young marmots to reach sexual maturity. Male offspring leave the home colony after their second winter, and about 60% of mature females give birth in any one year. The fur is used to make hats and coats and a Moscow fur-farm is experimenting with breeding bobak marmots for their pelts.

Calamistrum

In spiders, the calamistrum is a row of specialized leg bristles used to comb out fine bands of silk. It is only found on cribellate spiders, that is, spiders that possess the spinning organ known as the cribellum. The calamistrum and cribellum are used to form the hackled bands of silk which are characteristic of the webs of these spiders. The calamistrum is found on the upper margin of the metatarsus of the hind legs. Each bristle of the calamistrum is serrated on one side and smooth on the other.The length of a spider's calamistrum is always equal to or greater than the width of the cribellum. The ratio between calamistrum length and cribellum width varies greatly, however, even among related species. This is likely due to differences in spinning behavior and as well as differences in the size and shape of the legs and abdomen.When male cribellate spiders reach sexual maturity, they either lose the cribellum and calamistrum or retain them in a vestigial form.

Instar

An instar ( (listen), from the Latin "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (ecdysis), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, changes in the number of body segments or head width. After moulting, i.e. shedding their exoskeleton, the juvenile arthropods continue in their life cycle until they either pupate or moult again. The instar period of growth is fixed; however, in some insects, like the salvinia stem-borer moth, the number of instars depends on early larval nutrition. Some arthropods can continue to moult after sexual maturity, but the stages between these subsequent moults are generally not called instars.

For most insect species, an instar is the developmental stage of the larval forms of holometabolous (complete metamorphism) or nymphal forms of hemimetabolous (incomplete metamorphism) insects, but an instar can be any developmental stage including pupa or imago (the adult, which does not moult in insects).

The number of instars an insect undergoes often depends on the species and the environmental conditions, as described for a number of species of Lepidoptera. However it is believed that the number of instars can be physiologically constant per species in some insect orders, as for example Diptera and Hymenoptera. It should be minded that the number of larval instars is not directly related to speed of development. For instance, environmental conditions may dramatically affect the developmental rates of species and still have no impact on the number of larval instars. As examples, lower temperatures and lower humidity often slow the rate of development- an example is seen in the lepidopteran tobacco budworm and that may have an effect on how many molts will caterpillars undergo. On the other hand, temperature is demonstrated to affect the development rates of a number of hymenopterans without affecting numbers of instars or larval morphology, as observed in the ensign wasp and in the red imported fire ant. In fact the number of larval instars in ants has been the subject of a number of recent investigations, and no instances of temperature-related variation in numbers of instars have yet been recorded.

Juvenile (organism)

A juvenile is an individual organism that has not yet reached its adult form, sexual maturity or size. Juveniles sometimes look very different from the adult form, particularly in colour. In many organisms the juvenile has a different name from the adult (see also List of animal names).

Some organisms reach sexual maturity in a short metamorphosis, such as eclosion in many insects. For others, the transition from juvenile to fully mature is a more prolonged process—puberty, for example. In such cases, juveniles during this transformation are sometimes called subadults.

Many invertebrates, on reaching the adult stage, are fully mature and their development and growth stops. Their juveniles are larvae or nymphs.

In vertebrates and some invertebrates (e.g. spiders), larval forms (e.g. tadpoles) are usually considered a development stage of their own, and "juvenile" refers to a post-larval stage that is not fully grown and not sexually mature. In amniotes and most plants, the embryo represents the larval stage. Here, a "juvenile" is an individual in the time between hatching/birth/germination and reaching maturity.

Maturity

Maturity may refer to:

Adulthood or age of majority

Maturity model

Capability Maturity Model, in software engineering, a model representing the degree of formality and optimization of processes in an organization

Developmental age, the age of an embryo as measured from the point of fertilization

Mature technology, a technology has been in use and development for long enough that most of its initial problems have been overcome

Maturity (finance), indicating the final date for payment of principal and interest

Maturity (geology), rock, source rock, and hydrocarbon generation

Maturity (psychological), responding to the circumstances or environment in an appropriate manner

Maturity (sedimentology), the proximity of a sedimentary deposit from its source

Sexual maturity, the stage when an organism can reproduce, though this is distinct from adulthood

Mosquitofish

The western mosquitofish (Gambusia affinis) and eastern mosquitofish (Gambusia holbrooki) are a species of freshwater fish, also known commonly, if ambiguously, as simply mosquitofish or by its generic name, Gambusia, or by the common name gambezi.

Mosquitofish are small in comparison to many other freshwater fish, with females reaching an overall length of 7 cm (2.8 in) and males at a length of 4 cm (1.6 in). The female can be distinguished from the male by her larger size and a gravid spot at the posterior of her abdomen. The name "mosquitofish" was given because the diet of this fish sometimes consists of large numbers of mosquito larvae, relative to body size. Gambusia typically eat zooplankton, beetles, mayflies, caddisflies, mites, and other invertebrates; mosquito larvae make up only a small portion of their diet.Mosquitofish were introduced directly into ecosystems in many parts of the world as a biocontrol to lower mosquito populations which in turn negatively affected many other species in each distinct bioregion. Mosquitofish in Australia are classified as a noxious pest and may have exacerbated the mosquito problem in many areas by outcompeting native invertebrate predators of mosquito larvae. Several counties in California distribute mosquitofish at no charge to residents with manmade fish ponds and pools as part of their mosquito abatement programs. The fish are made available to residents only and are intended to be used solely on their own property, not introduced into natural habitat. On 24 February 2014, Chennai Corporation in India introduced western mosquitofish in 660 ponds to control the mosquito population in freshwater bodies.Fertilization is internal; the male secretes milt into the genital aperture of the female through his gonopodium. Within 16 to 28 days after mating, the female gives birth to about 60 young. The males reach sexual maturity within 43 to 62 days. The females, if born early in the reproductive season, reach sexual maturity within 21 to 28 days; females born later in the season reach sexual maturity in six to seven months.

Papuan seerfish

The Papuan seerfish (Scomberomorus multiradiatus) also called the Papuan Spanish mackerel, is a species of fish in the Scombridae family. It is endemic to the Gulf of Papua off the mouth of the Fly River. It is the smallest species in the genus Scomberomorus. Sexual maturity is attained at much less than 30 cm fork length.

Reproductive biology

Reproductive biology includes both sexual and asexual reproduction.Reproductive biology includes a wide number of fields:

Reproductive systems

Endocrinology

Sexual development (Puberty)

Sexual maturity

Reproduction

Fertility

Secondary sex characteristic

Secondary sex characteristics are features that appear during puberty in humans, and at sexual maturity in other animals. These are particularly evident in the sexually dimorphic phenotypic traits that distinguish the sexes of a species, but unlike the sex organs, are not directly part of the reproductive system. They are believed to be the product of sexual selection for traits which display fitness, giving an individual an advantage over its rivals in courtship and aggressive interactions. They are distinguished from the primary sex characteristics, the sex organs, which are directly necessary for sexual reproduction to occur.

Secondary sex characteristics include manes of male lions and long feathers of male peafowl, the tusks of male narwhals, enlarged proboscises in male elephant seals and proboscis monkeys, the bright facial and rump coloration of male mandrills, and horns in many goats and antelopes, and these are believed to be produced by a positive feedback loop known as the Fisherian runaway produced by the secondary characteristic in one sex and the desire for that characteristic in the other sex. Male birds and fish of many species have brighter coloration or other external ornaments. Differences in size between sexes are also considered secondary sexual characteristics.

In humans, visible secondary sex characteristics include pubic hair, enlarged breasts and widened hips of females, and facial hair and Adam's apple on males. However, both males and females can develop facial hair.

Selection shadow

The selection shadow is a concept involved with the evolutionary theories of ageing that states that selection pressures on an individual decrease as an individual ages and passes sexual maturity, resulting in a "shadow" of time where selective fitness is not considered. Over generations, this results in maladaptive mutations that accumulate later in life due to aging being non-adaptive toward reproductive fitness. The concept was first worked out by J. B. S. Haldane and Peter Medawar in the 1940s, with Medawar creating the first graphical model.

Spermarche

Spermarche—also known as semenarche—is the beginning of development of sperm in boys' testicles at puberty. It is the counterpart of menarche in girls. Depending on their upbringing, cultural differences, and prior sexual knowledge, boys may have different reactions to spermarche, ranging from fear to excitement. Spermarche is one of the first events in the life of a male leading to sexual maturity. It occurs at the time when the secondary sexual characteristics are just beginning to develop. The age when spermarche occurs is not easy to determine. However, researchers have tried to determine the age in various populations by taking urine samples of boys and determining the presence of spermatozoa. The presence of sperm in urine is referred to as spermaturia. From various sources, it appears that spermarche occurs between 13 and 15 years of age in most cases.

Thelarche

Thelarche is the onset of secondary breast development, which often represents the beginning of pubertal development. The initial growth of breasts occurs during fetal development in both males and females. Thelarche is the stage at which male and female breasts become distinct due to variance in hormone levels; however, some males have a condition in which they develop breasts, a term called Gynecomastia. Thelarche, also known as breast budding, typically occurs between the ages of 8 and 13 years with significant variation between individuals. The cause of this variation is a question central to countless research projects, yet it is generally accepted that race, genetics, exercise, and body mass each influence the age of thelarche. Puberty is considered delayed if breast development does not start before age 13 or if a female has not had her first period (Menarche) within 3 years of thelarche. Ordinarily, females experience menarche about 2 years after thelarche has begun. Complete breast development, from thelarche to adult breasts, takes between 2 and 4 years. If secondary breast development occurs before the age of 7 or 8 years, the individual may be experiencing either premature thelarche or precocious puberty.

Pubertal changes, including breast development, are assessed using the Tanner Scale (Sexual Maturity Rating Scale) where stage 1 represents the lack of breast development, stage 2 is the breast budding or thelarche stage, stages 3 and 4 are continual breast growth and areolar development, and finally, stage 5 signifies completion of development. This system does not use breast size, but instead examines the shape of breasts, nipples, and areolae to determine the progression of growth.The growth and accumulation of adipose tissue in the breasts are induced by estrogen, while the development of mammary glands and areolae are caused by progesterone; both estrogen and progesterone are produced by ovaries. Due to change in hormone levels, young breasts are likely to develop asymmetrically and in many cases, adult breasts will remain unequal in size or shape. For some girls, thelarche will occur, soon followed by the regression of breast development, and then months or years later, normal breast growth will commence again accompanied by normal pubertal changes; this is termed transient thelarche.

Vaginal flora in pregnancy

The vaginal flora in pregnancy, or vaginal microbiota in pregnancy, is different from the vaginal flora (the population of microorganisms that resides in the vagina) before sexual maturity, during reproductive years, and after menopause. A description of the vaginal flora of pregnant women who are immunocompromised is not covered in this article. The composition of the vaginal flora significantly differs in pregnancy. Bacteria or viruses that are infectious most often have no symptoms.

Yearling (horse)

A yearling is a young horse either male or female that is between one and two years old. Yearlings are comparable in development to a very early adolescent and are not fully mature physically. While they may be in the earliest stages of sexual maturity, they are considered too young to be breeding stock.

Yearlings may be further defined by sex, using the term "colt" to describe any male horse under age four, and filly for any female under four.

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