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, 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 inconsistent and contradictory. Conversely, one may 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 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 specified age without requiring a demonstration of physical maturity or preparation for adulthood.
And cross-culturally, adulthood has been determined by the start of puberty. In the past, a person moved from the status of child directly to the status of adult with this shift being marked by some type of coming-of-age test or ceremony. After the social construct of adolescence was created, adulthood split into two forms: biological adulthood and social adulthood. Thus, there are now two primary forms of adults: social adults. Depending on the context, adult can indicate either definition. Although few or no established dictionaries provide a definition for the two word term biological adult, the first definition of adult in multiple dictionaries includes "the stage of the life cycle of an animal after reproductive capacity has been attained". Thus, the base definition of the word adult is the period beginning at physical sexual maturity, which occurs sometime after the onset of puberty. Although this is the primary definition of the base word "adult", the term is frequently used to refer to social adults.
The two-word term biological adult stresses or clarifies that the original definition, based on physical maturity, is being used. The time of puberty varies, but begins around 10 or 11 years old. Girls begin the process of puberty at age 10 or 11, boys at age 11 or 12. Girls complete puberty by 15–17, boys by age 16 or 17. Nutrition and environment usually play a part in the onset of puberty. Adulthood means that one has reached the age of majority – when parents lose parenting rights and responsibilities regarding the person concerned. Depending on one's jurisdiction, the age of majority may or may not be set independently of and should not be confused with the minimum ages applicable to other activities, such as engaging in a contract, voting, having a job, serving in the military, buying/possessing firearms, traveling abroad, involvement with alcoholic beverages, sexual activity, being a model or actor in pornography, running for President, etc. Admission of a young person to a place may be restricted because of danger for that person, concern that the place may lead the person to immoral behavior or because of the risk that the young person causes damage.
One can distinguish the legality of acts of a young person, or of enabling a young person to carry out that act, by selling, renting out, permitting entrance, allowing participation, etc. There may be distinction between commercially and enabling. Sometimes there is the requirement of supervision by a legal guardian, or just by an adult. Sometimes there is no requirement, but rather a recommendation. Using the example of pornography, one can distinguish between: being allowed inside an adult establishment being allowed to purchase pornography being allowed to possess pornography another person being allowed to sell, rent out, or show the young person pornography, see disseminating pornography to a minor being a pornographic actor: rules for the young person, for other people, regarding production, etc. With regard to films with violence, etc.: another person being allowed to sell, rent out, or show the young person a film. Niger, Democratic Republic of Congo and Cameroon define adulthood at age 15, but marriage of girls at an earlier age is common.
In most of the world, including most of the United States and China, the legal adult age is 18 for most purposes, with some notable exceptions: British Columbia, New Brunswick and Labrador, Northwest Territories, Nova Scotia, Yukon Territory in Canada. In contrast to biological perspectives of aging and adulthood, social scientists conc
In anthropology, kinship is the web of social relationships that form an important part of the lives of all humans in all societies, although its exact meanings within this discipline are debated. Anthropologist Robin Fox states that "the study of kinship is the study of what man does with these basic facts of life – mating, parenthood, siblingship etc." Human society is unique, he argues, in that we are "working with the same raw material as exists in the animal world, but can conceptualize and categorize it to serve social ends." These social ends include the socialization of children and the formation of basic economic and religious groups. Kinship can refer both to the patterns of social relationships themselves, or it can refer to the study of the patterns of social relationships in one or more human cultures. Over its history, anthropology has developed a number of related concepts and terms in the study of kinship, such as descent, descent group, affinity/affine, consanguinity/cognate and fictive kinship.
Further within these two broad usages of the term, there are different theoretical approaches. Broadly, kinship patterns may be considered to include people related by both descent – i.e. social relations during development – and by marriage. Human kinship relations through marriage are called "affinity" in contrast to the relationships that arise in one's group of origin, which may be called one's descent group. In some cultures, kinship relationships may be considered to extend out to people an individual has economic or political relationships with, or other forms of social connections. Within a culture, some descent groups may be considered to lead back to gods or animal ancestors; this may be conceived of on a less literal basis. Kinship can refer to a principle by which individuals or groups of individuals are organized into social groups, roles and genealogy by means of kinship terminologies. Family relations can be represented abstractly by degrees of relationship. A relationship may reflect an absolute.
Degrees of relationship are not identical to legal succession. Many codes of ethics consider the bond of kinship as creating obligations between the related persons stronger than those between strangers, as in Confucian filial piety. In a more general sense, kinship may refer to a similarity or affinity between entities on the basis of some or all of their characteristics that are under focus; this may be due to a shared ontological origin, a shared historical or cultural connection, or some other perceived shared features that connect the two entities. For example, a person studying the ontological roots of human languages might ask whether there is kinship between the English word seven and the German word sieben, it can be used in a more diffuse sense as in, for example, the news headline "Madonna feels kinship with vilified Wallis Simpson", to imply a felt similarity or empathy between two or more entities. In biology, "kinship" refers to the degree of genetic relatedness or coefficient of relationship between individual members of a species.
It may be used in this specific sense when applied to human relationships, in which case its meaning is closer to consanguinity or genealogy. Family is a group of people affiliated by consanguinity, affinity, or co-residence/shared consumption. In most societies it is the principal institution for the socialization of children; as the basic unit for raising children, Anthropologists most classify family organization as matrifocal. However, producing children is not the only function of the family. Different societies classify kinship relations differently and therefore use different systems of kinship terminology – for example some languages distinguish between affinal and consanguine uncles, whereas others have only one word to refer to both a father and his brothers. Kinship terminologies include the terms of address used in different languages or communities for different relatives and the terms of reference used to identify the relationship of these relatives to ego or to each other. Kin terminologies can be either classificatory.
When a descriptive terminology is used, a term refers to only one specific type of relationship, while a classificatory terminology groups many different types of relationships under one term. For example, the word brother in English-speaking societies indicates a son of one's same parent. In many other classificatory kinship terminologies, in contrast, a person's male first cousin may be referred to as brothers; the major patterns of kinship systems that are known which Lewis Henry Morgan identified through kinship terminology in his 1871 work Systems of Consanguinity and Affinity of the Human Family are: Iroquois kinship Crow kinship (an expansion of b
In animals, infanticide involves the killing of young offspring by a mature animal of the same species, is studied in zoology in the field of ethology. Ovicide is the analogous destruction of eggs; the practice has been observed in many species throughout the animal kingdom primates. These include microscopic rotifers, fish, amphibians and mammals. Infanticide can be practiced by both females. Infanticide caused by sexual conflict has the general theme of the killer becoming the new sexual partner of the victim's parent, which would otherwise be unavailable; this represents a gain in fitness by the killer, a loss in fitness by the parents of the offspring killed. This is a type of evolutionary struggle between the two sexes, in which the victim sex may have counter-adaptations that reduce the success of this practice, it may occur for other reasons, such as the struggle for food between females. In this case individuals may kill related offspring. Filial infanticide occurs; this sometimes involves consumption of the young themselves, termed filial cannibalism.
The behavior is widespread in fishes, is seen in terrestrial animals as well. Human infanticide has been recorded in every culture. A unique aspect of human infanticide is sex-selective infanticide. Infanticide only came to be seen as a significant occurrence in nature quite recently. At the time it was first treated by Yukimaru Sugiyama, infanticide was attributed to stress causing factors like overcrowding and captivity, was considered pathological and maladaptive. Classical ethology held that conspecifics killed each other. By the 1980s it had gained much greater acceptance. Possible reasons it was not treated as a prevalent natural phenomenon include its abhorrence to people, the popular group and species selectionist notions of the time, the fact that it is difficult to observe in the field; this form of infanticide represents a struggle between the sexes, where one sex exploits the other, much to the latter's disadvantage. It is the male who benefits from this behavior, though in cases where males play similar roles to females in parental care the victim and perpetrator may be reversed.
Hanuman langurs are Old World monkeys found in India. They are a social animal, living in groups that consist of a single dominant male and multiple females; the dominant male has a reproductive monopoly within the group, which causes sub-ordinate males to have a much lower fitness value in comparison. To gain the opportunity to reproduce, sub-ordinate males try to take over the dominant role within a group resulting in an aggressive struggle with the existing dominant male. If successful in overthrowing the previous male, unrelated infants of the females are killed; this infanticidal period is limited to the window. Cannibalism, has not been observed in this species. Infanticide not only reduces intraspecific competition between the incumbent's offspring and those of other males but increases the parental investment afforded to their own young, allows females to become fertile faster; this is because females of this species, as well as many other mammals, do not ovulate during lactation. It becomes easier to understand how infanticide evolved.
If a male kills a female's young, she is able to become pregnant again. Because of this, the newly dominant male is able to reproduce at a faster rate than without the act of infanticide; as males are in a constant struggle to protect their group, those that express infanticidal behavior will contribute a larger portion to future gene pools. Similar behavior is seen in male lions, among other species, who kill young cubs, thereby enabling them to impregnate the females. Unlike langurs, male lions live in small groups, which cooperate to take control of a pride from an existing group, they will attempt to kill any cubs that are nine months old or younger, though as in other species, the female will attempt to defend her cubs viciously. Males have, on average, only a two-year window in which to pass on their genes, lionesses only give birth once every two years, so the selective pressure on them to conform to this behavior is strong. In fact it is estimated that a quarter of cubs dying in the first year of life are victims of infanticide.
Male mice show great variation in behavior over time. After fertilizing a female, they become aggressive towards mouse pups for three weeks, killing any they come across. After this period however, their behavior changes and they become paternal, caring for their own offspring; this lasts for two months, but afterwards they become infanticidal once more. It is no coincidence here that the female gestation period is three weeks as well, or that it takes two months for pups to become weaned and leave their nest; the proximate mechanism that allows for the correct timing of these periods involves circadian rhythms, each day and night cycle affecting the mouse's internal neural physiology, disturbances in the duration of these cycles results in different periods of time between behaviors. The adaptive value of this behavior switching is twofold. Gerbils, on the o
Biology is the natural science that studies life and living organisms, including their physical structure, chemical processes, molecular interactions, physiological mechanisms and evolution. Despite the complexity of the science, there are certain unifying concepts that consolidate it into a single, coherent field. Biology recognizes the cell as the basic unit of life, genes as the basic unit of heredity, evolution as the engine that propels the creation and extinction of species. Living organisms are open systems that survive by transforming energy and decreasing their local entropy to maintain a stable and vital condition defined as homeostasis. Sub-disciplines of biology are defined by the research methods employed and the kind of system studied: theoretical biology uses mathematical methods to formulate quantitative models while experimental biology performs empirical experiments to test the validity of proposed theories and understand the mechanisms underlying life and how it appeared and evolved from non-living matter about 4 billion years ago through a gradual increase in the complexity of the system.
See branches of biology. The term biology is derived from the Greek word βίος, bios, "life" and the suffix -λογία, -logia, "study of." The Latin-language form of the term first appeared in 1736 when Swedish scientist Carl Linnaeus used biologi in his Bibliotheca botanica. It was used again in 1766 in a work entitled Philosophiae naturalis sive physicae: tomus III, continens geologian, phytologian generalis, by Michael Christoph Hanov, a disciple of Christian Wolff; the first German use, was in a 1771 translation of Linnaeus' work. In 1797, Theodor Georg August Roose used the term in the preface of a book, Grundzüge der Lehre van der Lebenskraft. Karl Friedrich Burdach used the term in 1800 in a more restricted sense of the study of human beings from a morphological and psychological perspective; the term came into its modern usage with the six-volume treatise Biologie, oder Philosophie der lebenden Natur by Gottfried Reinhold Treviranus, who announced: The objects of our research will be the different forms and manifestations of life, the conditions and laws under which these phenomena occur, the causes through which they have been effected.
The science that concerns itself with these objects we will indicate by the name biology or the doctrine of life. Although modern biology is a recent development, sciences related to and included within it have been studied since ancient times. Natural philosophy was studied as early as the ancient civilizations of Mesopotamia, the Indian subcontinent, China. However, the origins of modern biology and its approach to the study of nature are most traced back to ancient Greece. While the formal study of medicine dates back to Hippocrates, it was Aristotle who contributed most extensively to the development of biology. Important are his History of Animals and other works where he showed naturalist leanings, more empirical works that focused on biological causation and the diversity of life. Aristotle's successor at the Lyceum, wrote a series of books on botany that survived as the most important contribution of antiquity to the plant sciences into the Middle Ages. Scholars of the medieval Islamic world who wrote on biology included al-Jahiz, Al-Dīnawarī, who wrote on botany, Rhazes who wrote on anatomy and physiology.
Medicine was well studied by Islamic scholars working in Greek philosopher traditions, while natural history drew on Aristotelian thought in upholding a fixed hierarchy of life. Biology began to develop and grow with Anton van Leeuwenhoek's dramatic improvement of the microscope, it was that scholars discovered spermatozoa, bacteria and the diversity of microscopic life. Investigations by Jan Swammerdam led to new interest in entomology and helped to develop the basic techniques of microscopic dissection and staining. Advances in microscopy had a profound impact on biological thinking. In the early 19th century, a number of biologists pointed to the central importance of the cell. In 1838, Schleiden and Schwann began promoting the now universal ideas that the basic unit of organisms is the cell and that individual cells have all the characteristics of life, although they opposed the idea that all cells come from the division of other cells. Thanks to the work of Robert Remak and Rudolf Virchow, however, by the 1860s most biologists accepted all three tenets of what came to be known as cell theory.
Meanwhile and classification became the focus of natural historians. Carl Linnaeus published a basic taxonomy for the natural world in 1735, in the 1750s introduced scientific names for all his species. Georges-Louis Leclerc, Comte de Buffon, treated species as artificial categories and living forms as malleable—even suggesting the possibility of common descent. Although he was opposed to evolution, Buffon is a key figure in the history of evolutionary thought. Serious evolutionary thinking originated with the works of Jean-Baptiste Lamarck, the first to present a coherent theory of evolution, he posited that evolution was the result of environmental stress on properties of animals, meaning that the more and rigorously an organ was used, the more complex and efficient it would become, thus adapting the animal to its environment. Lamarck believed that these acquired traits could be passed on to the animal's offspring, who would
In biology, an organism is any individual entity that exhibits the properties of life. It is a synonym for "life form". Organisms are classified by taxonomy into specified groups such as the multicellular animals and fungi. All types of organisms are capable of reproduction and development, some degree of response to stimuli. Humans are multicellular animals composed of many trillions of cells which differentiate during development into specialized tissues and organs. An organism may be either a eukaryote. Prokaryotes are represented by two separate domains -- archaea. Eukaryotic organisms are characterized by the presence of a membrane-bound cell nucleus and contain additional membrane-bound compartments called organelles. Fungi and plants are examples of kingdoms of organisms within the eukaryotes. Estimates on the number of Earth's current species range from 10 million to 14 million, of which only about 1.2 million have been documented. More than 99% of all species, amounting to over five billion species, that lived are estimated to be extinct.
In 2016, a set of 355 genes from the last universal common ancestor of all organisms was identified. The term "organism" first appeared in the English language in 1703 and took on its current definition by 1834, it is directly related to the term "organization". There is a long tradition of defining organisms as self-organizing beings, going back at least to Immanuel Kant's 1790 Critique of Judgment. An organism may be defined as an assembly of molecules functioning as a more or less stable whole that exhibits the properties of life. Dictionary definitions can be broad, using phrases such as "any living structure, such as a plant, fungus or bacterium, capable of growth and reproduction". Many definitions exclude viruses and possible man-made non-organic life forms, as viruses are dependent on the biochemical machinery of a host cell for reproduction. A superorganism is an organism consisting of many individuals working together as a single functional or social unit. There has been controversy about the best way to define the organism and indeed about whether or not such a definition is necessary.
Several contributions are responses to the suggestion that the category of "organism" may well not be adequate in biology. Viruses are not considered to be organisms because they are incapable of autonomous reproduction, growth or metabolism; this controversy is problematic because some cellular organisms are incapable of independent survival and live as obligatory intracellular parasites. Although viruses have a few enzymes and molecules characteristic of living organisms, they have no metabolism of their own; this rules out autonomous reproduction: they can only be passively replicated by the machinery of the host cell. In this sense, they are similar to inanimate matter. While viruses sustain no independent metabolism and thus are not classified as organisms, they do have their own genes, they do evolve by mechanisms similar to the evolutionary mechanisms of organisms; the most common argument in support of viruses as living organisms is their ability to undergo evolution and replicate through self-assembly.
Some scientists argue. In fact, viruses are evolved by their host cells, meaning that there was co-evolution of viruses and host cells. If host cells did not exist, viral evolution would be impossible; this is not true for cells. If viruses did not exist, the direction of cellular evolution could be different, but cells would be able to evolve; as for the reproduction, viruses rely on hosts' machinery to replicate. The discovery of viral metagenomes with genes coding for energy metabolism and protein synthesis fueled the debate about whether viruses belong in the tree of life; the presence of these genes suggested. However, it was found that the genes coding for energy and protein metabolism have a cellular origin. Most these genes were acquired through horizontal gene transfer from viral hosts. Organisms are complex chemical systems, organized in ways that promote reproduction and some measure of sustainability or survival; the same laws that govern non-living chemistry govern the chemical processes of life.
It is the phenomena of entire organisms that determine their fitness to an environment and therefore the survivability of their DNA-based genes. Organisms owe their origin and many other internal functions to chemical phenomena the chemistry of large organic molecules. Organisms are complex systems of chemical compounds that, through interaction and environment, play a wide variety of roles. Organisms are semi-closed chemical systems. Although they are individual units of life, they are not closed to the environment around them. To operate they take in and release energy. Autotrophs produce usable energy using light from the sun or inorganic compounds while heterotrophs take in organic compounds from the environment; the primary chemical element in these compounds is carbon. The chemical properties of this element such as its grea
Biologically, a child is a human being between the stages of birth and puberty, or between the developmental period of infancy and puberty. The legal definition of child refers to a minor, otherwise known as a person younger than the age of majority. Child may describe a relationship with a parent or, metaphorically, an authority figure, or signify group membership in a clan, tribe, or religion. Biologically, a child is a person between birth and puberty, or the period of human development from infancy to puberty; the term child may refer to anyone below the age of majority or some other age limit. The United Nations Convention on the Rights of the Child defines child as "a human being below the age of 18 years unless under the law applicable to the child, majority is attained earlier"; this is ratified by 192 of 194 member countries. The term child may refer to someone below another defined age limit unconnected to the age of majority. In Singapore, for example, a child is defined as someone under the age of 14 under the "Children and Young Persons Act" whereas the age of majority is 21.
In U. S. Immigration Law, a child refers to anyone, under the age of 21; some English definitions of the word child include the fetus. In many cultures, a child is considered an adult after undergoing a rite of passage, which may or may not correspond to the time of puberty. Children have fewer rights than adults and are classed as unable to make serious decisions, must always be under the care of a responsible adult or child custody, whether their parents divorce or not. Recognition of childhood as a state different from adulthood began to emerge in the 16th and 17th centuries. Society began to relate to the child not as a miniature adult but as a person of a lower level of maturity needing adult protection and nurturing; this change can be traced in paintings: In the Middle Ages, children were portrayed in art as miniature adults with no childlike characteristics. In the 16th century, images of children began to acquire a distinct childlike appearance. From the late 17th century onwards, children were shown playing with toys and literature for children began to develop at this time.
According to Professor Peter Jones of Cambridge university development of the brain continues long past legal definitions of adulthood so "to have a definition of when you move from childhood to adulthood looks absurd. It's a much more nuanced transition that takes place over three decades." Children go through stages of social development. Children learn through play and in most societies through formal schooling; as a child is growing they are learning. They learn how to prioritize their actions, their behavior is transcending. They learn how to learn new behavior. Children with ADHD and learning disabilities may need extra help to develop social skills; the impulsive characteristics of an ADHD child may lead to poor peer relationships. Children with poor attention spans may not tune into social cues in their environment, making it difficult for them to learn social skills through experience. Health issues affecting children are managed separately from those affecting adults, by pediatricians; the age at which children are considered responsible for their society-bound actions has changed over time, this is reflected in the way they are treated in courts of law.
In Roman times, children were regarded as not culpable for crimes, a position adopted by the Church. In the 19th century, children younger than seven years old were believed incapable of crime. Children from the age of seven forward were considered responsible for their actions. Therefore, they could face criminal charges, be sent to adult prison, be punished like adults by whipping, branding or hanging. Minimum employment age and marriage age vary; the age limit of voluntary/involuntary military service is disputed at the international level. During the early 17th century in England, about two-thirds of all children died before the age of four. During the Industrial Revolution, the life expectancy of children increased dramatically, and this has continued. Child mortality rates have fallen across the world. About 12.6 million under-five infants died worldwide in 1990, which declined to 6.6 million in 2012. The infant mortality rate dropped from 90 deaths per 1,000 live births in 1990, to 48 in 2012.
The highest average infant mortality rates are in sub-Saharan Africa, at 98 deaths per 1,000 live births – over double the world's average. Education, in the general sense, refers to the act or process of imparting or acquiring general knowledge, developing the powers of reasoning and judgment, preparing intellectually for mature life. Formal education most takes place through schooling. A right to education has been recognized by some governments. At the global level, Article 13 of the United Nations' 1966 International Covenant on Economic and Cultural Rights recognizes the right of everyone to an education. Education is compulsory in most places up to a certain age, but attendance at school may not be, with alternative options such as home-schooling or e-learning being recognized as valid forms of education in certain jurisdictions. Children in some countries are kept out of school, or attend only for short periods. Data from UNICEF indicate
Parental investment, in evolutionary biology and evolutionary psychology, is any parental expenditure that benefits offspring. Parental investment may be performed by both males and females, females alone or males alone. Care can be provided from pre-natal to post-natal. Parental investment theory, a term coined by Robert Trivers in 1972, predicts that the sex that invests more in its offspring will be more selective when choosing a mate, the less-investing sex will have intra-sexual competition for access to mates; this theory has been influential in explaining sex differences in sexual selection and mate preferences, throughout the animal kingdom and in humans. In 1859, Charles Darwin published On the Origin of Species; this introduced the concept of natural selection to the world, as well as related theories such as sexual selection. For the first time, evolutionary theory was used to explain why females are "coy" and males are "ardent" and compete with each other for females' attention. In 1930, Ronald Fisher wrote The Genetical Theory of Natural Selection, in which he introduced the modern concept of parental investment, introduced the sexy son hypothesis, introduced Fisher's principle.
In 1948, Angus John Bateman published an influential study of fruit flies in which he concluded that because female gametes are more costly to produce than male gametes, the reproductive success of females was limited by the ability to produce ovum, the reproductive success of males was limited by access to females. In 1972, Trivers continued this line of thinking with his proposal of parental investment theory, which describes how parental investment affects sexual behavior, he concludes that the sex that has higher parental investment will be more selective when choosing a mate, the sex with lower investment will compete intra-sexually for mating opportunities. In 1974, Trivers extended parental investment theory to explain parent-offspring conflict, the conflict between investment, optimal from the parent's versus the offspring's perspective. Parental investment theory is a branch of life history theory; the earliest consideration of parental investment is given by Ronald Fisher in his 1930 book The Genetical Theory of Natural Selection, wherein Fisher argued that parental expenditure on both sexes of offspring should be equal.
Clutton-Brock expanded the concept of parental investment to include costs to any other component of parental fitness. Male dunnocks tend to not discriminate between their own young and those of another male in polyandrous or polygynandrous systems, they increase their own reproductive success through feeding the offspring in relation to their own access to the female throughout the mating period, a good predictor of paternity. This indiscriminative parental care by males is observed in redlip blennies. In some insects, male parental investment is given in the form of a nuptial gift. For instance, ornate moth females receive a spermatophore containing nutrients and defensive toxins from the male during copulation; this gift, which can account for up to 10% of the male's body mass, constitutes the total parental investment the male provides. In some species, such as humans and many birds, the offspring are altricial and unable to fend for themselves for an extended period of time after birth. In these species, males invest more in their offspring than do the male parents of precocial species, since reproductive success would otherwise suffer.
The benefits of parental investment to the offspring are large and are associated with the effects on condition, survival, on reproductive success of the offspring. For example, in the cichlid fish Tropheus moorii, a female has high parental investment in her young because she mouthbroods the young and while mouthbrooding, all nourishment she takes in goes to feed the young and she starves herself. In doing this, her young are larger and faster than they would have been without it; these benefits are advantageous since it lowers their risk of being eaten by predators and size is the determining factor in conflicts over resources. However, such benefits can come at the cost of parent's ability to reproduce in the future e.g. through increased risk of injury when defending offspring against predators, loss of mating opportunities whilst rearing offspring, an increase in the time interval until the next reproduction. A special case of parental investment is when young do need nourishment and protection, but the genetic parents do not contribute in the effort to raise their own offspring.
For example, in Bombus terrestris, oftentimes sterile female workers will not reproduce on their own, but will raise their mother's brood instead. This is common in social Hymenoptera due to haplodiploidy, whereby males are haploid and females are diploid; this ensures that sisters are more related to each other than they would be to their own offspring, incentivizing them to help raise their mother's young over their own. Overall, parents are selected to maximize the difference between the benefits and the costs, parental care will be to evolve when the benefits exceed the costs. Reproduction is costly. Individuals are limited in the degree to which they can devote time and resources to producing and raising their young, such expenditure may be detrimental to their future condition and further reproductive output. However, such expenditure is beneficial to the offspring, enhancing their condition and rep