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Infanticide

Infanticide (or infant homicide) is the intentional killing of infants or offspring. Infanticide was a widespread practice throughout human history that was mainly used to dispose of unwanted children, its main purpose being the prevention of resources being spent on weak or disabled offspring. Unwanted infants were usually abandoned to die of exposure, but in some societies they were deliberately killed. Infanticide is generally illegal, but in some places the practice is tolerated, or the prohibition is not strictly enforced.

Most Stone Age human societies routinely practiced infanticide, and estimates of children killed by infanticide in the Mesolithic and Neolithic eras vary from 15 to 50 percent. Infanticide continued to be common in most societies after the historical era began, including ancient Greece, ancient Rome, the Phoenicians, ancient China, ancient Japan, Pre-Islamic Arabia, Aboriginal Australia, Native Americans, and Native Alaskans.

Infanticide became forbidden in Europe and the Near East during the 1st millennium. Christianity forbade infanticide from its earliest times, which led Constantine the Great and Valentinian I to ban infanticide across the Roman Empire in the 4th century. The practice ceased in Arabia in the 7th century after the founding of Islam, since the Quran prohibits infanticide. Infanticide of male babies had become uncommon in China by the Ming dynasty (1368–1644), whereas infanticide of female babies became more common during the One-Child Policy era (1979–2015). During the period of Company rule in India, the East India Company attempted to eliminate infanticide but were only partially successful, and female infanticide in some parts of India still continues. Infanticide is very rare in industrialised countries but may persist elsewhere.

Parental infanticide researchers have found that mothers are more likely to commit infanticide. In the special case of neonaticide (murder in the first 24 hours of life), mothers account for almost all the perpetrators. Fatherly cases of neonaticide are so rare that they are individually recorded.

History
The practice of infanticide has taken many forms over time. Child sacrifice to supernatural figures or forces, such as that believed to have been practiced in ancient Carthage, may be only the most notorious example in the ancient world.

A frequent method of infanticide in ancient Europe and Asia was simply to abandon the infant, leaving it to die by exposure (i.e., hypothermia, hunger, thirst, or animal attack).

On at least one island in Oceania, infanticide was carried out until the 20th century by suffocating the infant, while in pre-Columbian Mesoamerica and in the Inca Empire it was carried out by sacrifice (see below).

Paleolithic and Neolithic
Many Neolithic groups routinely resorted to infanticide in order to control their numbers so that their lands could support them. Joseph Birdsell believed that infanticide rates in prehistoric times were between 15% and 50% of the total number of births, while Laila Williamson estimated a lower rate ranging from 15% to 20%. Both anthropologists believed that these high rates of infanticide persisted until the development of agriculture during the Neolithic Revolution. A book published in 1981 stated that comparative anthropologists estimated that 50% of female newborn babies may have been killed by their parents during the Paleolithic era. The anthropologist Raymond Dart has interpreted fractures on the skulls of hominid infants (e.g. the Taung Child) as due to deliberate killing followed by cannibalism, but such explanations are by now considered uncertain and possibly wrong. Children were not necessarily actively killed, but neglect and intentional malnourishment may also have occurred, as proposed by Vicente Lull as an explanation for an apparent surplus of men and the below average height of women in prehistoric Menorca.

In the New World
Archaeologists have uncovered physical evidence of child sacrifice at several locations. Some of the best attested examples are the diverse rites which were part of the religious practices in Mesoamerica and the Inca Empire.

In the Old World
Three thousand bones of young children, with evidence of sacrificial rituals, have been found in Sardinia. Pelasgians offered a sacrifice of every tenth child during difficult times. Many remains of children have been found in Gezer excavations with signs of sacrifice. Child skeletons with the marks of sacrifice have been found also in Egypt dating 950–720 BCE. In Carthage "[child] sacrifice in the ancient world reached its infamous zenith". Besides the Carthaginians, other Phoenicians, and the Canaanites, Moabites and Sepharvites offered their first-born as a sacrifice to their gods.

Ancient Egypt
In Egyptian households, at all social levels, children of both sexes were valued and there is no evidence of infanticide. The religion of the ancient Egyptians forbade infanticide and during the Greco-Roman period they rescued abandoned babies from manure heaps, a common method of infanticide by Greeks or Romans, and were allowed to either adopt them as foundling or raise them as slaves, often giving them names such as "copro -" to memorialize their rescue. Strabo considered it a peculiarity of the Egyptians that every child must be reared. Diodorus indicates infanticide was a punishable offence. Egypt was heavily dependent on the annual flooding of the Nile to irrigate the land and in years of low inundation, severe famine could occur with breakdowns in social order resulting, notably between and. Instances of cannibalism are recorded during these periods, but it is unknown if this happened during the pharaonic era of ancient Egypt. Beatrix Midant-Reynes describes human sacrifice as having occurred at Abydos in the early dynastic period (c. ), while Jan Assmann asserts there is no clear evidence of human sacrifice ever happening in ancient Egypt.

Carthage
According to Shelby Brown, Carthaginians, descendants of the Phoenicians, sacrificed infants to their gods. Charred bones of hundreds of infants have been found in Carthaginian archaeological sites. One such area harbored as many as 20,000 burial urns. Skeptics suggest that the bodies of children found in Carthaginian and Phoenician cemeteries were merely the cremated remains of children who died naturally.

Plutarch (c. ) mentions the practice, as do Tertullian, Orosius, Diodorus Siculus and Philo. The Hebrew Bible also mentions what appears to be child sacrifice practiced at a place called the Tophet (from the Hebrew taph or toph, to burn) by the Canaanites. Writing in the, Kleitarchos, one of the historians of Alexander the Great, described that the infants rolled into the flaming pit. Diodorus Siculus wrote that babies were roasted to death inside the burning pit of the god Baal Hamon, a bronze statue.

Greece and Rome

The historical Greeks considered the practice of adult and child sacrifice barbarous, however, infant exposure was widely practiced in ancient Greece. It was advocated by Aristotle in the case of congenital deformity: "As to the exposure of children, let there be a law that no deformed child shall live." In Greece, the decision to expose a child was typically the father's, although in Sparta the decision was made by a group of elders. Exposure was the preferred method of disposal, as that act in itself was not considered to be murder; moreover, the exposed child technically had a chance of being rescued by the gods or any passersby. This very situation was a recurring motif in Greek mythology. To notify the neighbors of a birth of a child, a woolen strip was hung over the front door to indicate a female baby and an olive branch to indicate a boy had been born. Families did not always keep their new child. After a woman had a baby, she would show it to her husband. If the husband accepted it, it would live, but if he refused it, it would die. Babies would often be rejected if they were illegitimate, unhealthy or deformed, the wrong sex, or too great a burden on the family. These babies would not be directly killed, but put in a clay pot or jar and deserted outside the front door or on the roadway. In ancient Greek religion, this practice took the responsibility away from the parents because the child would die of natural causes, for example, hunger, asphyxiation or exposure to the elements.

The practice was prevalent in ancient Rome, as well. Philo was the first known philosopher to speak out against it. A letter from a Roman citizen to his sister, or a pregnant wife from her husband, dating from, demonstrates the casual nature with which infanticide was often viewed:
 * "I am still in Alexandria. ... I beg and plead with you to take care of our little child, and as soon as we receive wages, I will send them to you. In the meantime, if (good fortune to you!) you give birth, if it is a boy, let it live; if it is a girl, expose it.", "If you give birth to a boy, keep it. If it is a girl, expose it. Try not to worry. I'll send the money as soon as we get paid."

In some periods of Roman history it was traditional for a newborn to be brought to the pater familias, the family patriarch, who would then decide whether the child was to be kept and raised, or left to die by exposure. The Twelve Tables of Roman law obliged him to put to death a child that was visibly deformed. The concurrent practices of slavery and infanticide contributed to the "background noise" of the crises during the Republic.

Infanticide became a capital offense in Roman law in 374, but offenders were rarely if ever prosecuted.

According to mythology, Romulus and Remus, twin infant sons of the war god Mars, survived near-infanticide after being tossed into the Tiber River. According to the myth, they were raised by wolves, and later founded the city of Rome.

Middle Ages
Whereas theologians and clerics preached sparing their lives, newborn abandonment continued as registered in both the literature record and in legal documents. According to William Lecky, exposure in the early Middle Ages, as distinct from other forms of infanticide, "was practiced on a gigantic scale with absolute impunity, noticed by writers with most frigid indifference and, at least in the case of destitute parents, considered a very venial offence". However the first foundling house in Europe was established in Milan in 787 on account of the high number of infanticides and out-of-wedlock births. The Hospital of the Holy Spirit in Rome was founded by Pope Innocent III because women were throwing their infants into the Tiber river.

Unlike other European regions, in the Middle Ages the German mother had the right to expose the newborn.

In the High Middle Ages, abandoning unwanted children finally eclipsed infanticide. Unwanted children were left at the door of church or abbey, and the clergy was assumed to take care of their upbringing. This practice also gave rise to the first orphanages.

However, very high sex ratios were common in even late medieval Europe, which may indicate sex-selective infanticide. The Waldensians, a pre-Reformation medieval Christian sect deemed heretical by the Catholic Church, were accused of participating in infanticide.

Judaism
Judaism prohibits infanticide, and has for some time, dating back to at least early Common Era. Roman historians wrote about the ideas and customs of other peoples, which often diverged from their own. Tacitus recorded that the Jews "take thought to increase their numbers, for they regard it as a crime to kill any late-born children". Josephus, whose works give an important insight into 1st-century Judaism, wrote that God "forbids women to cause abortion of what is begotten, or to destroy it afterward".

Pagan European tribes
In his book Germania, Tacitus wrote in that the ancient Germanic tribes enforced a similar prohibition. He found such mores remarkable and commented: "To restrain generation and the increase of children, is esteemed [by the Germans] an abominable sin, as also to kill infants newly born." It has become clear over the millennia, though, that Tacitus' description was inaccurate; the consensus of modern scholarship significantly differs. John Boswell believed that in ancient Germanic tribes unwanted children were exposed, usually in the forest. "It was the custom of the [Teutonic] pagans, that if they wanted to kill a son or daughter, they would be killed before they had been given any food." Usually children born out of wedlock were disposed of that way.

In his highly influential Pre-historic Times, John Lubbock described burnt bones indicating the practice of child sacrifice in pagan Britain.

The last canto, Marjatan poika (Son of Marjatta), of Finnish national epic Kalevala describes assumed infanticide. Väinämöinen orders the infant bastard son of Marjatta to be drowned in a marsh.

The Íslendingabók, the main source for the early history of Iceland, recounts that on the Conversion of Iceland to Christianity in 1000 it was provided – in order to make the transition more palatable to Pagans – that "the old laws allowing exposure of newborn children will remain in force". However, this provision – among other concessions made at the time to the Pagans – was abolished some years later.

Christianity
Christianity explicitly rejects infanticide. The Teachings of the Apostles or Didache said "thou shalt not kill a child by abortion, neither shalt thou slay it when born". The Epistle of Barnabas stated an identical command, both thus conflating abortion and infanticide. Apologists Tertullian, Athenagoras, Minucius Felix, Justin Martyr and Lactantius also maintained that exposing a baby to death was a wicked act. In 318, Constantine I considered infanticide a crime, and in 374, Valentinian I mandated the rearing of all children (exposing babies, especially girls, was still common). The Council of Constantinople declared that infanticide was homicide, and in 589, the Third Council of Toledo took measures against the custom of killing their own children.

Arabia
Some Muslim sources allege that pre-Islamic Arabian society practiced infanticide as a form of "post-partum birth control". The word waʾd was used to describe the practice. These sources state that infanticide was practiced either out of destitution (thus practiced on males and females alike), or as "disappointment and fear of social disgrace felt by a father upon the birth of a daughter".

Some authors believe that there is little evidence that infanticide was prevalent in pre-Islamic Arabia or early Muslim history, except for the case of the Tamim tribe, who practiced it during severe famine according to Islamic sources. Others state that "female infanticide was common all over Arabia during this period of time" (pre-Islamic Arabia), especially by burying alive a female newborn. A tablet discovered in Yemen, forbidding the people of a certain town from engaging in the practice, is the only written reference to infanticide within the peninsula in pre-Islamic times.

Islam
Infanticide is explicitly prohibited by the Qur'an. "And do not kill your children for fear of poverty; We give them sustenance and yourselves too; surely to kill them is a great wrong." Together with polytheism and homicide, infanticide is regarded as a grave sin (see and ). Infanticide is also implicitly denounced in the story of Pharaoh's slaughter of the male children of Israelites (see ; ; ; ; ; ).

Ukraine and Russia

Infanticide may have been practiced as human sacrifice, as part of the pagan cult of Perun. Ibn Fadlan describes sacrificial practices at the time of his trip to Kiev Rus (present-day Ukraine) in 921–922, and describes an incident of a woman voluntarily sacrificing her life as part of a funeral rite for a prominent leader, but makes no mention of infanticide. The Primary Chronicle, one of the most important literary sources before the 12th century, indicates that human sacrifice to idols may have been introduced by Vladimir the Great in 980. The same Vladimir the Great formally converted Kiev Rus into Christianity just 8 years later, but pagan cults continued to be practiced clandestinely in remote areas as late as the 13th century.

American explorer George Kennan noted that among the Koryaks, a people of north-eastern Siberia, infanticide was still common in the nineteenth century. One of a pair of twins was always sacrificed.

Great Britain
Infanticide (as a crime) gained both popular and bureaucratic significance in Victorian Britain. By the mid-19th century, in the context of criminal lunacy and the insanity defence, killing one's own child(ren) attracted ferocious debate, as the role of women in society was defined by motherhood, and it was thought that any woman who murdered her own child was by definition insane and could not be held responsible for her actions. Several cases were subsequently highlighted during the Royal Commission on Capital Punishment 1864–66, as a particular felony where an effective avoidance of the death penalty had informally begun.

The New Poor Law Act of 1834 ended parish relief for unmarried mothers and allowed fathers of illegitimate children to avoid paying for "child support". Unmarried mothers then received little assistance, and the poor were left with the option of either entering the workhouse, turning to prostitution, resorting to infanticide, or choosing abortion. By the middle of the century infanticide was common for social reasons, such as illegitimacy, and the introduction of child life insurance additionally encouraged some women to kill their children for gain. Examples include Mary Ann Cotton, who murdered many of her 15 children as well as three husbands; Margaret Waters, the 'Brixton Baby Farmer', a professional baby-farmer who was found guilty of infanticide in 1870; Jessie King, who was hanged in 1889; Amelia Dyer, the 'Angel Maker', who murdered over 400 babies in her care; and Ada Chard-Williams, a baby farmer who was later hanged at Newgate prison.

The Times reported that 67 infants were murdered in London in 1861 and 150 more recorded as "found dead", many of which were found on the streets. Another 250 were suffocated, half of them not recorded as accidental deaths. The report noted that "infancy in London has to creep into life in the midst of foes."

Recording a birth as a still-birth was also another way of concealing infanticide because still-births did not need to be registered until 1926 and they did not need to be buried in public cemeteries. In 1895 The Sun (London) published the article, "Massacre of the Innocents", highlighting the dangers of baby-farming, the recording of stillbirths, and quoting Athelstan Braxton Hicks, the London coroner, on lying-in houses: "I have not the slightest doubt that a large amount of crime is covered by the expression 'still-birth'. There are a large number of cases of what are called newly-born children, which are found all over England, more especially in London and large towns, abandoned in streets, rivers, on commons, and so on... [A] great deal of that crime is due to what are called lying-in houses, which are not registered, or under the supervision of that sort, where the people who act as midwives constantly, as soon as the child is born, either drop it into a pail of water or smother it with a damp cloth. It is a very common thing, also, to find that they bash their heads on the floor and break their skulls."

The last British woman to be executed for infanticide of her own child was Rebecca Smith, who was hanged in Wiltshire in 1849.

The Infant Life Protection Act of 1897 required local authorities to be notified within 48 hours of changes in custody or the death of children under seven years. Under the Children's Act of 1908 "no infant could be kept in a home that was so unfit and so overcrowded as to endanger its health, and no infant could be kept by an unfit nurse who threatened, by neglect or abuse, its proper care, and maintenance."

China

As of the 3rd century BC, short of execution, the harshest penalties were imposed on practitioners of infanticide by the legal codes of the Qin dynasty and Han dynasty of ancient China.

China's society practiced sex selective infanticide. Philosopher Han Fei Tzu, a member of the ruling aristocracy of the, who developed a school of law, wrote: "As to children, a father and mother when they produce a boy congratulate one another, but when they produce a girl they put it to death." Among the Hakka people, and in Yunnan, Anhui, Sichuan, Jiangxi and Fujian a method of killing the baby was to put her into a bucket of cold water, which was called "baby water".

Infanticide was reported as early as the, and, by the Song dynasty , it was widespread in some provinces. Belief in reincarnation allowed poor residents of the country to kill their newborn children if they felt unable to care for them, hoping that they would be reborn in better circumstances. Furthermore, 18th and 19th century Qing reports of villagers in Liaoning show that they did not consider newborn children fully human, instead regarding life as beginning at some point after the sixth month after birth.

The Venetian explorer Marco Polo claimed to have seen newborns exposed in Manzi. Contemporary writers from the Song dynasty note that, in Hubei and Fujian provinces, residents would only keep three sons and two daughters (among poor farmers, two sons, and one daughter), and kill all babies beyond that number at birth. Initially the sex of the child was only one factor to consider. By the time of the Ming dynasty, however (1368–1644), male infanticide was becoming increasingly uncommon. The prevalence of female infanticide remained high much longer. The magnitude of this practice is subject to some dispute; however, one commonly quoted estimate is that, by late Qing, between one fifth and one-quarter of all newborn girls, across the entire social spectrum, were victims of infanticide. If one includes excess mortality among female children under 10 (ascribed to gender-differential neglect), the share of victims rises to one third.

Scottish physician John Dudgeon, who worked in Peking, China, during the early 20th century said that, "Infanticide does not prevail to the extent so generally believed among us, and in the north, it does not exist at all."

Gender-selected abortion or sex identification (without medical uses ), abandonment, and infanticide are illegal in present-day mainland China. Nevertheless, the US State Department, and the human rights organization Amnesty International have all declared that mainland China's family planning programs, called the one child policy (which has since changed to a two-child policy ), contribute to infanticide. The sex gap between males and females aged 0–19 years old was estimated to be 25 million in 2010 by the United Nations Population Fund. But in some cases, in order to avoid mainland China's family planning programs, parents will not report to government when a child is born (in most cases a girl), so she or he will not have an identity in the government and they can keep on giving birth until they are satisfied, without fines or punishment. In 2017, the government announced that all children without an identity can now have an identity legally, known as family register.

Japan
Since feudal Edo era Japan the common slang for infanticide was mabiki (間引き), which means to pull plants from an overcrowded garden. A typical method in Japan was smothering the baby's mouth and nose with wet paper. It became common as a method of population control. Farmers would often kill their second or third sons. Daughters were usually spared, as they could be married off, sold off as servants or prostitutes, or sent off to become geishas. Mabiki persisted in the 19th century and early 20th century. To bear twins was perceived as barbarous and unlucky and efforts were made to hide or kill one or both twins.

South Asia

Female infanticide of newborn girls was systematic in feudatory Rajputs in South Asia for illegitimate female children during the Middle Ages. According to Firishta, as soon as the illegitimate female child was born she was held "in one hand, and a knife in the other, that any person who wanted a wife might take her now, otherwise she was immediately put to death". The practice of female infanticide was also common among the Kutch, Kehtri, Nagar, Bengal, Miazed, Kalowries and Sindh communities.

It was not uncommon that parents threw a child to the sharks in the Ganges River as a sacrificial offering. The East India Company administration were unable to outlaw the custom until the beginning of the 19th century.

According to social activists, female infanticide has remained a problem in India into the 21st century, with both NGOs and the government conducting awareness campaigns to combat it.

Africa
In some African societies some neonates were killed because of beliefs in evil omens or because they were considered unlucky. Twins were usually put to death in Arebo; as well as by the Nama people of South West Africa; in the Lake Victoria Nyanza region; by the Tswana in Portuguese East Africa; in some parts of Igboland, Nigeria twins were sometimes abandoned in a forest at birth (as depicted in Things Fall Apart), oftentimes one twin was killed or hidden by midwives of wealthier mothers; and by the ǃKung people of the Kalahari Desert.

The Kikuyu, Kenya's most populous ethnic group, practiced ritual killing of twins. Infanticide is rooted in the old traditions and beliefs prevailing all over Kenya. A survey conducted by Disability Rights International found that 45% of women interviewed by them in Kenya were pressured to kill their children born with disabilities. The pressure is much higher in the rural areas, with every two mothers being forced out of three.

Australia
Estimations of the prevalence of infanticide among Aboriginal Australians vary widely. Many early European settlers considered it to be extremely common. For example, an 1866 issue of The Australian News for Home Readers informed readers that "the crime of infanticide is so prevalent amongst the natives that it is rare to see an infant". In later times, attitudes shifted and the issue became contested. Author Susanna de Vries said in 2007 that her accounts of Aboriginal violence, including infanticide, were censored by publishers in the 1980s and 1990s. She told reporters that the censorship "stemmed from guilt over the stolen children question". Keith Windschuttle weighed in on the conversation, saying this type of censorship started in the 1970s. In the same article Louis Nowra suggested that infanticide in customary Aboriginal law may have been because it was difficult to keep an abundant number of Aboriginal children alive; there were life-and-death decisions modern-day Australians no longer have to face.

Liz Conor's 2016 work, Skin Deep: Settler Impressions of Aboriginal Women, a culmination of 10 years of research, found that stories about Aboriginal women were told through a colonial lens of racism and misogyny. Vague stories of infanticide and cannibalism were repeated as reliable facts, and sometimes originated in accounts told by members of rival tribes about the other. She also refers to Daisy Bates' now contested accounts of such practices, reproaching some historians for accepting them too uncritically.

The anthropologists Ronald and Catherine Berndt are more balanced in their evaluation, noting that "infanticide does seem to have been practised occasionally almost all over Aboriginal Australia, but it cannot have been so frequent as Taplin ... and Bates ... suggest", while also cautioning that others "underestimated" its prevalence. The flesh of killed infants could be eaten, but this was not always the case.

South Australia and Victoria
According to William D. Rubinstein, "Nineteenth-century European observers of Aboriginal life in South Australia and Victoria reported that about 30% of Aboriginal infants were killed at birth."

In 1881 James Dawson wrote a passage about infanticide among Indigenous people in the western district of Victoria, which stated that "Twins are as common among them as among Europeans; but as food is occasionally very scarce, and a large family troublesome to move about, it is lawful and customary to destroy the weakest twin child, irrespective of sex. It is usual also to destroy those which are malformed."

He also wrote "When a woman has children too rapidly for the convenience and necessities of the parents, she makes up her mind to let one be killed, and consults with her husband which it is to be. As the strength of a tribe depends more on males than females, the girls are generally sacrificed. The child is put to death and buried, or burned without ceremony; not, however, by its father or mother, but by relatives. No one wears mourning for it. Sickly children are never killed on account of their bad health, and are allowed to die naturally."

Western Australia
In 1937, a Christian reverend in the Kimberley offered a "baby bonus" to Aboriginal families as a deterrent against infanticide and to increase the birthrate of the local Indigenous population.

Australian Capital Territory
A Canberran journalist in 1927 wrote of the "cheapness of life" to the Aboriginal people local to the Canberra area 100 years before. "If drought or bush fires had devastated the country and curtailed food supplies, babies got a short shift. Ailing babies, too would not be kept", he wrote.

New South Wales
A bishop wrote in 1928 that it was common for Aboriginal Australians to restrict the size of their tribal groups, including by infanticide, so that the food resources of the tribal area may be sufficient for them.

Northern Territory
Annette Hamilton, a professor of anthropology at Macquarie University, who carried out research in the Aboriginal community of Maningrida in Arnhem Land during the 1960s, wrote that prior to that time part-European babies born to Aboriginal mothers had not been allowed to live, and that "mixed-unions are frowned on by men and women alike as a matter of principle".

Marshall Islands
When Russian explorer Otto von Kotzebue visited the Marshall Islands in Micronesia in 1817, he noted that Marshallese families practiced infanticide after the birth of a third child as a form of population planning due to frequent famines.

Inuit
There is no agreement about the actual estimates of the frequency of newborn female infanticide in the Inuit population. Carmel Schrire mentions diverse studies ranging from 15% to 80%.

Polar Inuit (Inughuit) killed the child by throwing him or her into the sea. There is even a legend in Inuit mythology, "The Unwanted Child", where a mother throws her child into the fjord.

The Yukon and the Mahlemuit tribes of Alaska exposed the female newborns by first stuffing their mouths with grass before leaving them to die. In Arctic Canada the Inuit exposed their babies on the ice and left them to die.

Female Inuit infanticide disappeared in the 1930s and 1940s after contact with the Western cultures from the South.

However, it must be acknowledged these infanticide claims came from non-Inuit observers, whose writings were later used to justify the forced westernization of indigenous peoples. In 2009, Travis Hedwig argued that infanticide runs counter to cultural norms at the time and that researchers were misinterpreting the actions of an unfamiliar culture and people.

Canada
The Handbook of North American Indians reports infanticide among the Dene Natives and those of the Mackenzie Mountains.

Native Americans
In the Eastern Shoshone there was a scarcity of Native American women as a result of female infanticide. For the Maidu Native Americans twins were so dangerous that they not only killed them, but the mother as well. In the region known today as southern Texas, the Mariame Native Americans practiced infanticide of females on a large scale. Wives had to be obtained from neighboring groups.

Mexico
Bernal Díaz recounted that, after landing on the Veracruz coast, they came across a temple dedicated to Tezcatlipoca. "That day they had sacrificed two boys, cutting open their chests and offering their blood and hearts to that accursed idol". In The Conquest of New Spain Díaz describes more child sacrifices in the towns before the Spaniards reached the large Aztec city Tenochtitlan.

South America
Although academic data of infanticides among the indigenous people in South America is not as abundant as that of North America, the estimates seem to be similar.

Brazil
The Tapirapé indigenous people of Brazil allowed no more than three children per woman, and no more than two of the same sex. If the rule was broken infanticide was practiced. The Bororo killed all the newborns that did not appear healthy enough. Infanticide is also documented in the case of the Korubo people in the Amazon.

The Yanomami men killed children while raiding enemy villages. Helena Valero, a Brazilian woman kidnapped by Yanomami warriors in the 1930s, witnessed a Karawetari raid on her tribe:

"They killed so many. I was weeping for fear and for pity but there was nothing I could do. They snatched the children from their mothers to kill them, while the others held the mothers tightly by the arms and wrists as they stood up in a line. All the women wept. ... The men began to kill the children; little ones, bigger ones, they killed many of them."

Peru, Paraguay and Bolivia
While qhapaq hucha was practiced in the Peruvian large cities, child sacrifice in the pre-Columbian tribes of the region is less documented. However, even today studies on the Aymara Indians reveal high incidences of mortality among the newborn, especially female deaths, suggesting infanticide. The Abipones, a small tribe of Guaycuruan stock, of about 5,000 by the end of the 18th century in Paraguay, practiced systematic infanticide; with never more than two children being reared in one family. The Machigenga killed their disabled children. Infanticide among the Chaco in Paraguay was estimated as high as 50% of all newborns in that tribe, who were usually buried. The infanticidal custom had such roots among the Ayoreo in Bolivia and Paraguay that it persisted until the late 20th century.

Modern times
Infanticide has become less common in the Western world. The frequency has been estimated to be 1 in approximately 3000 to 5000 children of all ages and 2.1 per 100,000 newborns per year. It is thought that infanticide today continues at a much higher rate in areas of extremely high poverty and overpopulation, such as parts of India. Female infants, then and even now, are particularly vulnerable, a factor in sex-selective infanticide. Recent estimates suggest that over 100 million girls and women are 'missing' in Asia.

Benin
In spite of the fact that it is illegal, in Benin, West Africa, parents secretly continue with infanticidal customs.

Mainland China
There have been some accusations that infanticide occurs in mainland China due to the one-child policy. In the 1990s, a certain stretch of the Yangtze River was known to be a common site of infanticide by drowning, until government projects made access to it more difficult. A study from 2012 suggests that over 40 million girls and women are missing in mainland China (Klasen and Wink 2002).

India
The practice has continued in some rural areas of India. India has the highest infanticide rate in the world, despite infanticide being illegal.

According to a 2005 report by the United Nations Children's Fund (UNICEF) up to 50 million girls and women are missing in India's population as a result of systematic sex discrimination and sex selective abortions.

Pakistan
Killings of newborn babies have been on the rise in Pakistan, corresponding to an increase in poverty across the country. More than 1,000 infants, mostly girls, were killed or abandoned to die in Pakistan in 2009 according to a Pakistani charity organization.

The Edhi Foundation found 1,210 dead babies in 2010. Many more are abandoned and left at the doorsteps of mosques. As a result, Edhi centers feature signs "Do not murder, lay them here." Though female infanticide is punishable by life in prison, such crimes are rarely prosecuted.

Oceania
On November 28, 2008, The National, one of Papua New Guinea's two largest newspapers at the time, ran a story entitled "Male Babies Killed To Stop Fights" which claimed that in Agibu and Amosa villages of Gimi region of Eastern Highlands province of Papua New Guinea where tribal fighting in the region of Gimi has been going on since 1986 (many of the clashes arising over claims of sorcery) women had agreed that if they stopped producing males, allowing only female babies to survive, their tribe's stock of boys would go down and there would be no men in the future to fight. They had supposedly agreed to have all newborn male babies killed. It is not known how many male babies were supposedly killed by being smothered, but it had reportedly happened to all males over a 10-year period.

However, this claim about male infanticide in Papua New Guinea was probably just the result of inaccurate and sensationalistic news reporting, because Salvation Army workers in the region of Gimi denied that the supposed male infanticide actually happened, and said that the tribal women were merely speaking hypothetically and hyperbolically about male infanticide at a peace and reconciliation workshop in order to make a point. The tribal women had never planned to actually kill their own sons.

England and Wales
In England and Wales there were typically 30 to 50 homicides per million children less than 1 year old between 1982 and 1996. The younger the infant, the higher the risk. The rate for children 1 to 5 years was around 10 per million children. The homicide rate of infants less than 1 year is significantly higher than for the general population.

In English law infanticide is established as a distinct offence by the Infanticide Acts. Defined as the killing of a child under 12 months of age by their mother, the effect of the Acts are to establish a partial defence to charges of murder.

United States
In the United States the infanticide rate during the first hour of life outside the womb dropped from 1.41 per 100,000 during 1963 to 1972 to 0.44 per 100,000 for 1974 to 1983; the rates during the first month after birth also declined, whereas those for older infants rose during this time. The legalization of abortion, which was completed in 1973, was the most important factor in the decline in neonatal mortality during the period from 1964 to 1977, according to a study by economists associated with the National Bureau of Economic Research.

Canada
In Canada, 114 cases of infanticide by a parent were reported during 1964–1968.

Spain
In Spain, far-right political party Vox has claimed that female perpetrators of infanticide outnumber male perpetrators of femicide. However, neither the Spanish National Statistics Institute nor the Ministry of the Interior keep data on the gender of perpetrators, but victims of femicide consistently number higher than victims of infanticide. From 2013 to March 2018, 28 infanticide cases perpetrated by 22 mothers and three stepmothers were reported in Spain.

Intersex children
Intersex infants commonly suffer from infanticide particularly in developing countries, largely caused by stigma surrounding intersex conditions. Often intersex infants are abandoned, while others are actively killed. Many intersex individuals are forced to flee due to persecution and violence. Many intersex individuals commonly seek political asylum due to oppression according to the United Nations Human Rights Council.

Explanations for the practice
There are various reasons for infanticide. Neonaticide typically has different patterns and causes than for the killing of older infants. Traditional neonaticide is often related to economic necessity – the inability to provide for the infant.

In the United Kingdom and the United States, older infants are typically killed for reasons related to child abuse, domestic violence or mental illness. For infants older than one day, younger infants are more at risk, and boys are more at risk than girls. Risk factors for the parent include: Family history of violence, violence in a current relationship, history of abuse or neglect of children, and personality disorder and/or depression.

Religious
In the late 17th and early 18th centuries, "loopholes" were invented by some suicidal members of Lutheran churches who wanted to avoid the damnation that was promised by most Christian doctrine as a penalty of suicide. One famous example of someone who wished to end their life but avoid the eternity in hell was Christina Johansdotter (died 1740). She was a Swedish murderer who killed a child in Stockholm with the sole purpose of being executed. She is an example of those who seek suicide through execution by committing a murder. It was a common act, frequently targeting young children or infants as they were believed to be free from sin, thus believing to go "straight to heaven".

Although mainstream Christian denominations, including Lutherans, view the murder of an innocent as being condemned in the Fifth Commandment, the suicidal members of Lutheran churches who deliberately killed children with the intent of getting executed were usually well aware of Christian doctrine against murder, and planned to repent and seek forgiveness of their sins afterwards. For example, in 18th century Denmark up until the year 1767, murderers were given the opportunity to repent of their sins before they were executed either way. In Denmark on the year of 1767, the religiously motivated suicidal murders finally ceased in that country with the abolishment of the death penalty.

In 1888, Lieut. F. Elton reported that Ugi beach people in the Solomon Islands killed their infants at birth by burying them, and women were also said to practice abortion. They reported that it was too much trouble to raise a child, and instead preferred to buy one from the bush people.

Economic
Many historians believe the reason to be primarily economic, with more children born than the family is prepared to support. In societies that are patrilineal and patrilocal, the family may choose to allow more sons to live and kill some daughters, as the former will support their birth family until they die, whereas the latter will leave economically and geographically to join their husband's family, possibly only after the payment of a burdensome dowry price. Thus the decision to bring up a boy is more economically rewarding to the parents. However, this does not explain why infanticide would occur equally among rich and poor, nor why it would be as frequent during decadent periods of the Roman Empire as during earlier, less affluent, periods.

Before the appearance of effective contraception, infanticide was a common occurrence in ancient brothels. Unlike usual infanticide – where historically girls have been more likely to be killed – prostitutes in certain areas preferred to kill their male offspring.

UK in the 18th and 19th centuries
Instances of infanticide in Britain in 18th and 19th centuries are often attributed to the economic position of the women, with juries committing "pious perjury" in many subsequent murder cases. The knowledge of the difficulties faced in the 18th century by those women who attempted to keep their children can be seen as a reason for juries to show compassion. If the woman chose to keep the child, society was not set up to ease the pressure placed upon the woman, legally, socially or economically.

In mid-18th century Britain there was assistance available for women who were not able to raise their children. The Foundling Hospital opened in 1756 and was able to take in some of the illegitimate children. However, the conditions within the hospital caused Parliament to withdraw funding and the governors to live off of their own incomes. This resulted in a stringent entrance policy, with the committee requiring that the hospital:

 * Will not receive a child that is more than a year old, nor the child of a domestic servant, nor any child whose father can be compelled to maintain it.

Once a mother had admitted her child to the hospital, the hospital did all it could to ensure that the parent and child were not re-united.

MacFarlane argues in Illegitimacy and Illegitimates in Britain (1980) that English society greatly concerned itself with the burden that a bastard child places upon its communities and had gone to some lengths to ensure that the father of the child is identified in order to maintain its well-being. Assistance could be gained through maintenance payments from the father, however, this was capped "at a miserable 2 s and 6 d a week". If the father fell behind with the payments he could only be asked "to pay a maximum of 13 weeks arrears".

Despite the accusations of some that women were getting a free hand-out, there is evidence that many women were far from receiving adequate assistance from their parish. "Within Leeds in 1822 ... relief was limited to 1 s per week". Sheffield required women to enter the workhouse, whereas Halifax gave no relief to the women who required it. The prospect of entering the workhouse was certainly something to be avoided. Lionel Rose quotes Dr Joseph Rogers in Massacre of the Innocents ... (1986). Rogers, who was employed by a London workhouse in 1856 stated that conditions in the nursery were 'wretchedly damp and miserable ... [and] ... overcrowded with young mothers and their infants'.

The loss of social standing for a servant girl was a particular problem in respect of producing a bastard child as they relied upon a good character reference in order to maintain their job and more importantly, to get a new or better job. In a large number of trials for the crime of infanticide, it is the servant girl that stood accused. The disadvantage of being a servant girl is that they had to live to the social standards of their superiors or risk dismissal and no references. Whereas within other professions, such as in the factory, the relationship between employer and employee was much more anonymous and the mother would be better able to make other provisions, such as employing a minder. The result of the lack of basic social care in Britain in the 18th and 19th century is the numerous accounts in court records of women, particularly servant girls, standing trial for the murder of their child.

There may have been no specific offense of infanticide in England before about 1623 because infanticide was a matter for the by ecclesiastical courts, possibly because infant mortality from natural causes was high (about 15% or one in six).

Thereafter the accusation of the suppression of bastard children by lewd mothers was a crime incurring the presumption of guilt.

The Infanticide Acts are several laws. That of 1922 made the killing of an infant child by its mother during the early months of life as a lesser crime than murder. The acts of 1938 and 1939 abolished the earlier act, but introduced the idea that postpartum depression was legally to be regarded as a form of diminished responsibility.

Population control
Marvin Harris estimated that among Paleolithic hunters 23–50% of newborn children were killed. He argued that the goal was to preserve the 0.001% population growth of that time. He also wrote that female infanticide may be a form of population control. Population control is achieved not only by limiting the number of potential mothers; increased fighting among men for access to relatively scarce wives would also lead to a decline in population. For example, on the Melanesian island of Tikopia infanticide was used to keep a stable population in line with its resource base. Research by Marvin Harris and William Divale supports this argument, it has been cited as an example of environmental determinism.

Evolutionary psychology
Evolutionary psychology has proposed several theories for different forms of infanticide. Infanticide by stepfathers, as well as child abuse in general by stepfathers, has been explained by spending resources on not genetically related children reducing reproductive success (See the Cinderella effect and Infanticide (zoology)). Infanticide is one of the few forms of violence more often done by women than men. Cross-cultural research has found that this is more likely to occur when the child has deformities or illnesses as well as when there are lacking resources due to factors such as poverty, other children requiring resources, and no male support. Such a child may have a low chance of reproductive success in which case it would decrease the mother's inclusive fitness, in particular since women generally have a greater parental investment than men, to spend resources on the child.

"Early infanticidal childrearing"
A minority of academics subscribe to an alternate school of thought, considering the practice as "early infanticidal childrearing". They attribute parental infanticidal wishes to massive projection or displacement of the parents' unconscious onto the child, because of intergenerational, ancestral abuse by their own parents. Clearly, an infanticidal parent may have multiple motivations, conflicts, emotions, and thoughts about their baby and their relationship with their baby, which are often colored both by their individual psychology, current relational context and attachment history, and, perhaps most saliently, their psychopathology Almeida, Merminod, and Schechter suggest that parents with fantasies, projections, and delusions involving infanticide need to be taken seriously and assessed carefully, whenever possible, by an interdisciplinary team that includes infant mental health specialists or mental health practitioners who have experience in working with parents, children, and families.

Wider effects
In addition to debates over the morality of infanticide itself, there is some debate over the effects of infanticide on surviving children, and the effects of childrearing in societies that also sanction infanticide. Some argue that the practice of infanticide in any widespread form causes enormous psychological damage in children. Conversely, studying societies that practice infanticide Géza Róheim reported that even infanticidal mothers in New Guinea, who ate a child, did not affect the personality development of the surviving children; that "these are good mothers who eat their own children". Harris and Divale's work on the relationship between female infanticide and warfare suggests that there are, however, extensive negative effects.

Psychiatric
Postpartum psychosis is also a causative factor of infanticide. Stuart S. Asch, MD, a professor of psychiatry at Cornell University established the connections between some cases of infanticide and post-partum depression. , The books, From Cradle to Grave, and The Death of Innocents, describe selected cases of maternal infanticide and the investigative research of Professor Asch working in concert with the New York City Medical Examiner's Office. Stanley Hopwood wrote that childbirth and lactation entail severe stress on the female sex, and that under certain circumstances attempts at infanticide and suicide are common. A study published in the American Journal of Psychiatry revealed that 44% of filicidal fathers had a diagnosis of psychosis. In addition to postpartum psychosis, dissociative psychopathology and sociopathy have also been found to be associated with neonaticide in some cases

In addition, severe postpartum depression can lead to infanticide.

Sex selection
Sex selection may be one of the contributing factors of infanticide. In the absence of sex-selective abortion, sex-selective infanticide can be deduced from very skewed birth statistics. The biologically normal sex ratio for humans at birth is approximately 105 males per 100 females; normal ratios hardly ranging beyond 102–108. When a society has an infant male to female ratio which is significantly higher or lower than the biological norm, and biased data can be ruled out, sex selection can usually be inferred. Intersex infants with ambiguous or atypical genitalia often suffer from infanticide.

Australia
In New South Wales, infanticide is defined in Section 22A(1) of the Crimes Act 1900 (NSW) as follows:

"Where a woman by any willful act or omission causes the death of her child, being a child under the age of twelve months, but at the time of the act or omission the balance of her mind was disturbed by reason of her not having fully recovered from the effect of giving birth to the child or by reason of the effect of lactation consequent upon the birth of the child, then, notwithstanding that the circumstances were such that but for this section the offense would have amounted to murder, she shall be guilty of infanticide, and may for such offense be dealt with and punished as if she had been guilty of the offense of manslaughter of such child."

Because Infanticide is punishable as manslaughter, as per s24, the maximum penalty for this offence is therefore 25 years imprisonment.

In Victoria, infanticide is defined by Section 6 of the Crimes Act of 1958 with a maximum penalty of five years.

New Zealand
In New Zealand, infanticide is provided for by Section 178 of the Crimes Act 1961 which states: "Where a woman causes the death of any child of hers under the age of 10 years in a manner that amounts to culpable homicide, and where at the time of the offence the balance of her mind was disturbed, by reason of her not having fully recovered from the effect of giving birth to that or any other child, or by reason of the effect of lactation, or by reason of any disorder consequent upon childbirth or lactation, to such an extent that she should not be held fully responsible, she is guilty of infanticide, and not of murder or manslaughter, and is liable to imprisonment for a term not exceeding 3 years."

Canada
In Canada, infanticide is a specific offence under section 237 of the Criminal Code. It is defined as a form of culpable homicide which is neither murder nor manslaughter, and occurs when "a female person... by a wilful act or omission... causes the death of her newly-born child [defined as a child under one year of age], if at the time of the act or omission she is not fully recovered from the effects of giving birth to the child and by reason thereof or of the effect of lactation consequent on the birth of the child her mind is then disturbed." Infanticide is also a defence to murder, in that a person accused of murder who successfully presents the defence is entitled to be convicted of infanticide rather than murder. The maximum sentence for infanticide is five years' imprisonment; by contrast, the maximum sentence for manslaughter is life, and the mandatory sentence for murder is life.

The offence derives from an offence created in English law in 1922, which aimed to address the issue of judges and juries who were reluctant to return verdicts of murder against women and girls who killed their newborns out of poverty, depression, the shame of illegitimacy, or otherwise desperate circumstances, since the mandatory sentence was death (even though in those circumstances the death penalty was likely not to be carried out). With infanticide as a separate offence with a lesser penalty, convictions were more likely. The offence of infanticide was created in Canada in 1948.

There is ongoing debate in the Canadian legal and political fields about whether section 237 of the Criminal Code should be amended or abolished altogether.

England and Wales
In England and Wales, the Infanticide Act 1938 describes the offense of infanticide as one which would otherwise amount to murder (by their mother) if the victim was older than 12 months and the mother did not have an "imbalance of mind" due to the effects of childbirth or lactation. Where a mother who has killed such an infant has been charged with murder rather than infanticide s.1(3) of the Act confirms that a jury has the power to find alternative verdicts of Manslaughter in English law or guilty but insane.

The Netherlands
Infanticide is illegal in the Netherlands, although the maximum sentence is lower than for homicide. The Groningen Protocol regulates euthanasia for infants who are believed to "suffer hopelessly and unbearably" under strict conditions.

Poland
Article 149 of the Penal Code of Poland stipulates that a mother who kills her child in labour, while under the influence of the course of the delivery, is punishable by imprisonment of three months to five years.

Romania
Article 200 of the Penal Code of Romania stipulates that the killing of a newborn during the first 24 hours, by the mother who is in a state of mental distress, shall be punished with imprisonment of one to five years. The previous Romanian Penal Code also defined infanticide (pruncucidere) as a distinct criminal offense, providing for punishment of two to seven years imprisonment, recognizing the fact that a mother's judgment may be impaired immediately after birth but did not define the term "infant", and this had led to debates regarding the precise moment when infanticide becomes homicide. This issue was resolved by the new Penal Code, which came into force in 2014.

United States
While legislation regarding infanticide in some countries focuses on rehabilitation, believing that treatment and education will prevent repetitive action, the United States remains focused on delivering punishment. One justification for punishment is the difficulty of implementing rehabilitation services. With an overcrowded prison system, the United States can not provide the necessary treatment and services.

State legislation
In 2009, Texas state representative Jessica Farrar proposed legislation that would define infanticide as a distinct and lesser crime than homicide. Under the terms of the proposed legislation, if jurors concluded that a mother's "judgment was impaired as a result of the effects of giving birth or the effects of lactation following the birth," they would be allowed to convict her of the crime of infanticide, rather than murder. The maximum penalty for infanticide would be two years in prison. Farrar's introduction of this bill prompted liberal bioethics scholar Jacob M. Appel to call her "the bravest politician in America".

Federal legislation
The MOTHERS Act (Moms Opportunity To access Health, Education, Research and Support), precipitated by the death of a Chicago woman with postpartum psychosis was introduced in 2009. The act was ultimately incorporated into the Patient Protection and Affordable Care Act which passed in 2010. The act requires screening for postpartum mood disorders at any time of the adult lifespan as well as expands research on postpartum depression. Provisions of the act also authorize grants to support clinical services for women who have, or are at risk for, postpartum psychosis.

Sex education and birth control
Since infanticide, especially neonaticide, is often a response to an unwanted birth, preventing unwanted pregnancies through improved sex education and increased contraceptive access are advocated as ways of preventing infanticide. Increased use of contraceptives and access to safe legal abortions  have greatly reduced neonaticide in many developed nations. Some say that where abortion is illegal, as in Pakistan, infanticide would decline if safer legal abortions were available.

Psychiatric intervention
Cases of infanticide have also garnered increasing attention and interest from advocates for the mentally ill as well as organizations dedicated to postpartum disorders. Following the trial of Andrea Yates, a mother from the United States who garnered national attention for drowning her 5 children, representatives from organizations such as the Postpartum Support International and the Marcé Society for Treatment and Prevention of Postpartum Disorders began requesting clarification of diagnostic criteria for postpartum disorders and improved guidelines for treatments. While accounts of postpartum psychosis have dated back over 2,000 years ago, perinatal mental illness is still largely under-diagnosed despite postpartum psychosis affecting 1 to 2 per 1000 women. However, with clinical research continuing to demonstrate the large role of rapid neurochemical fluctuation in postpartum psychosis, prevention of infanticide points ever strongly towards psychiatric intervention.

Screening for psychiatric disorders or risk factors, and providing treatment or assistance to those at risk may help prevent infanticide. Current diagnostic considerations include symptoms, psychological history, thoughts of self-harm or harming one's children, physical and neurological examination, laboratory testing, substance abuse, and brain imaging. As psychotic symptoms may fluctuate, it is important that diagnostic assessments cover a wide range of factors.

While studies on the treatment of postpartum psychosis are scarce, a number of case and cohort studies have found evidence describing the effectiveness of lithium monotherapy for both acute and maintenance treatment of postpartum psychosis, with the majority of patients achieving complete remission. Adjunctive treatments include electroconvulsive therapy, antipsychotic medication, or benzodiazepines. Electroconvulsive therapy, in particular, is the primary treatment for patients with catatonia, severe agitation, and difficulties eating or drinking. Antidepressants should be avoided throughout the acute treatment of postpartum psychosis due to risk of worsening mood instability.

Though screening and treatment may help prevent infanticide, in the developed world, significant proportions of neonaticides that are detected occur in young women who deny their pregnancy and avoid outside contacts, many of whom may have limited contact with these health care services.

Safe surrender
In some areas baby hatches or safe surrender sites, safe places for a mother to anonymously leave an infant, are offered, in part to reduce the rate of infanticide. In other places, like the United States, safe-haven laws allow mothers to anonymously give infants to designated officials; they are frequently located at hospitals and police and fire stations. Additionally, some countries in Europe have the laws of anonymous birth and confidential birth that allow mothers to give up an infant after birth. In anonymous birth, the mother does not attach her name to the birth certificate. In confidential birth, the mother registers her name and information, but the document containing her name is sealed until the child comes to age. Typically such babies are put up for adoption, or cared for in orphanages.

Employment
Granting women employment raises their status and autonomy. Having a gainful employment can raise the perceived worth of females. This can lead to an increase in the number of women getting an education and a decrease in the number of female infanticide. As a result, the infant mortality rate will decrease and economic development will increase.

In animals

The practice has been observed in many other species of the animal kingdom since it was first seriously studied by Yukimaru Sugiyama. These include from microscopic rotifers and insects, to fish, amphibians, birds and mammals, including primates such as chacma baboons.

According to studies carried out by Kyoto University in primates, including certain types of gorillas and chimpanzees, several conditions favor the tendency to kill their offspring in some species (to be performed only by males), among them are: Nocturnal life, the absence of nest construction, the marked sexual dimorphism in which the male is much larger than the female, the mating in a specific season and the high period of lactation without resumption of the estrus state in the female.

In art and literature
An instance in which a child born on an inauspicious day is to live or die according to the chance of being trampled by cattle (death being likely) is provided by, painted by Henry Melville and engraved by J Redaway for Fisher's Drawing Room Scrap Book, 1838 with a poetical illustration and notes by Letitia Elizabeth Landon.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Infanticide


text: Talk:Insulator (electricity)

title: Talk:Insulator (electricity)


text:
Internet protocol suite

The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the Internet Protocol (IP). Early versions of this networking model were known as the Department of Defense (DoD) model because the research and development were funded by the United States Department of Defense through DARPA.

The Internet protocol suite provides end-to-end data communication specifying how data should be packetized, addressed, transmitted, routed, and received. This functionality is organized into four abstraction layers, which classify all related protocols according to each protocol's scope of networking. An implementation of the layers for a particular application forms a protocol stack. From lowest to highest, the layers are the link layer, containing communication methods for data that remains within a single network segment (link); the internet layer, providing internetworking between independent networks; the transport layer, handling host-to-host communication; and the application layer, providing process-to-process data exchange for applications.

The technical standards underlying the Internet protocol suite and its constituent protocols are maintained by the Internet Engineering Task Force (IETF). The Internet protocol suite predates the OSI model, a more comprehensive reference framework for general networking systems.

Early research
Initially referred to as the DOD Internet Architecture Model, the Internet protocol suite has its roots in research and development sponsored by the Defense Advanced Research Projects Agency (DARPA) in the late 1960s. After DARPA initiated the pioneering ARPANET in 1969, Steve Crocker established a "Networking Working Group" which developed a host-host protocol, the Network Control Program (NCP). In the early 1970s, DARPA started work on several other data transmission technologies, including mobile packet radio, packet satellite service, local area networks, and other data networks in the public and private domains. In 1972, Bob Kahn joined the DARPA Information Processing Technology Office, where he worked on both satellite packet networks and ground-based radio packet networks, and recognized the value of being able to communicate across both. In the spring of 1973, Vinton Cerf joined Kahn with the goal of designing the next protocol generation for the ARPANET to enable internetworking. They drew on the experience from the ARPANET research community, the International Network Working Group, which Cerf chaired, and researchers at Xerox PARC.

By the summer of 1973, Kahn and Cerf had worked out a fundamental reformulation, in which the differences between local network protocols were hidden by using a common internetwork protocol, and, instead of the network being responsible for reliability, as in the existing ARPANET protocols, this function was delegated to the hosts. Cerf credits Louis Pouzin and Hubert Zimmermann, designers of the CYCLADES network, with important influences on this design. The new protocol was implemented as the Transmission Control Program in 1974 by Cerf, Yogen Dalal and Carl Sunshine.

Initially, the Transmission Control Program (the Internet Protocol did not then exist as a separate protocol) provided only a reliable byte stream service to its users, not datagram. As experience with the protocol grew, collaborators recommended division of functionality into layers of distinct protocols, allowing users direct access to datagram service. Advocates included Danny Cohen, who needed it for his packet voice work; Jonathan Postel of the University of Southern California's Information Sciences Institute, who edited the Request for Comments (RFCs), the technical and strategic document series that has both documented and catalyzed Internet development; and Bob Metcalfe and Yogen Dalal at Xerox PARC. Postel stated, "We are screwing up in our design of Internet protocols by violating the principle of layering." Encapsulation of different mechanisms was intended to create an environment where the upper layers could access only what was needed from the lower layers. A monolithic design would be inflexible and lead to scalability issues. In version 4, written in 1978, Postel split the Transmission Control Program into two distinct protocols, the Internet Protocol as connectionless layer and the Transmission Control Protocol as a reliable connection-oriented service.

The design of the network included the recognition that it should provide only the functions of efficiently transmitting and routing traffic between end nodes and that all other intelligence should be located at the edge of the network, in the end nodes. This design, known as the end-to-end principle, was pioneered by Louis Pouzin in the CYCLADES network. Using this design, it became possible to connect other networks to the ARPANET that used the same principle, irrespective of other local characteristics, thereby solving Kahn's initial internetworking problem. A popular expression is that TCP/IP, the eventual product of Cerf and Kahn's work, can run over "two tin cans and a string." Years later, as a joke, the IP over Avian Carriers formal protocol specification was created and successfully tested.

DARPA contracted with BBN Technologies, Stanford University, and the University College London to develop operational versions of the protocol on several hardware platforms. During development of the protocol the version number of the packet routing layer progressed from version 1 to version 4, the latter of which was installed in the ARPANET in 1983. It became known as Internet Protocol version 4 (IPv4) as the protocol that is still in use in the Internet, alongside its current successor, Internet Protocol version 6 (IPv6).

Early implementation
In 1975, a two-network IP communications test was performed between Stanford and University College London. In November 1977, a three-network IP test was conducted between sites in the US, the UK, and Norway. Several other IP prototypes were developed at multiple research centers between 1978 and 1983.

A computer called a router is provided with an interface to each network. It forwards network packets back and forth between them. Originally a router was called gateway, but the term was changed to avoid confusion with other types of gateways.

Adoption
In March 1982, the US Department of Defense declared TCP/IP as the standard for all military computer networking. In the same year, NORSAR/NDRE and Peter Kirstein's research group at University College London adopted the protocol. The migration of the ARPANET from NCP to TCP/IP was officially completed on flag day January 1, 1983, when the new protocols were permanently activated.

In 1985, the Internet Advisory Board (later Internet Architecture Board) held a three-day TCP/IP workshop for the computer industry, attended by 250 vendor representatives, promoting the protocol and leading to its increasing commercial use. In 1985, the first Interop conference focused on network interoperability by broader adoption of TCP/IP. The conference was founded by Dan Lynch, an early Internet activist. From the beginning, large corporations, such as IBM and DEC, attended the meeting.

IBM, AT&T and DEC were the first major corporations to adopt TCP/IP, this despite having competing proprietary protocols. In IBM, from 1984, Barry Appelman's group did TCP/IP development. They navigated the corporate politics to get a stream of TCP/IP products for various IBM systems, including MVS, VM, and OS/2. At the same time, several smaller companies, such as FTP Software and the Wollongong Group, began offering TCP/IP stacks for DOS and Microsoft Windows. The first VM/CMS TCP/IP stack came from the University of Wisconsin.

Some of the early TCP/IP stacks were written single-handedly by a few programmers. Jay Elinsky and Oleg Vishnepolsky of IBM Research wrote TCP/IP stacks for VM/CMS and OS/2, respectively. In 1984 Donald Gillies at MIT wrote a ntcp multi-connection TCP which runs atop the IP/PacketDriver layer maintained by John Romkey at MIT in 1983–84. Romkey leveraged this TCP in 1986 when FTP Software was founded. Starting in 1985, Phil Karn created a multi-connection TCP application for ham radio systems (KA9Q TCP).

The spread of TCP/IP was fueled further in June 1989, when the University of California, Berkeley agreed to place the TCP/IP code developed for BSD UNIX into the public domain. Various corporate vendors, including IBM, included this code in commercial TCP/IP software releases. Microsoft released a native TCP/IP stack in Windows 95. This event helped cement TCP/IP's dominance over other protocols on Microsoft-based networks, which included IBM's Systems Network Architecture (SNA), and on other platforms such as Digital Equipment Corporation's DECnet, Open Systems Interconnection (OSI), and Xerox Network Systems (XNS).

Nonetheless, for a period in the late 1980s and early 1990s, engineers, organizations and nations were polarized over the issue of which standard, the OSI model or the Internet protocol suite, would result in the best and most robust computer networks.

Formal specification and standards
The technical standards underlying the Internet protocol suite and its constituent protocols have been delegated to the Internet Engineering Task Force (IETF).

The characteristic architecture of the Internet protocol suite is its broad division into operating scopes for the protocols that constitute its core functionality. The defining specification of the suite is RFC 1122, which broadly outlines four abstraction layers. These have stood the test of time, as the IETF has never modified this structure. As such a model of networking, the Internet protocol suite predates the OSI model, a more comprehensive reference framework for general networking systems.

Key architectural principles

The end-to-end principle has evolved over time. Its original expression put the maintenance of state and overall intelligence at the edges, and assumed the Internet that connected the edges retained no state and concentrated on speed and simplicity. Real-world needs for firewalls, network address translators, web content caches and the like have forced changes in this principle.

The robustness principle states: "In general, an implementation must be conservative in its sending behavior, and liberal in its receiving behavior. That is, it must be careful to send well-formed datagrams, but must accept any datagram that it can interpret (e.g., not object to technical errors where the meaning is still clear)." "The second part of the principle is almost as important: software on other hosts may contain deficiencies that make it unwise to exploit legal but obscure protocol features."

Encapsulation is used to provide abstraction of protocols and services. Encapsulation is usually aligned with the division of the protocol suite into layers of general functionality. In general, an application (the highest level of the model) uses a set of protocols to send its data down the layers. The data is further encapsulated at each level.

An early architectural document,, titled Host Requirements, emphasizes architectural principles over layering. RFC 1122 is structured in sections referring to layers, but the document refers to many other architectural principles, and does not emphasize layering. It loosely defines a four-layer model, with the layers having names, not numbers, as follows:
 * The application layer is the scope within which applications, or processes, create user data and communicate this data to other applications on another or the same host. The applications make use of the services provided by the underlying lower layers, especially the transport layer which provides reliable or unreliable pipes to other processes. The communications partners are characterized by the application architecture, such as the client–server model and peer-to-peer networking. This is the layer in which all application protocols, such as SMTP, FTP, SSH, HTTP, operate. Processes are addressed via ports which essentially represent services.
 * The transport layer performs host-to-host communications on either the local network or remote networks separated by routers. It provides a channel for the communication needs of applications. UDP is the basic transport layer protocol, providing an unreliable connectionless datagram service. The Transmission Control Protocol provides flow-control, connection establishment, and reliable transmission of data.
 * The internet layer exchanges datagrams across network boundaries. It provides a uniform networking interface that hides the actual topology (layout) of the underlying network connections. It is therefore also the layer that establishes internetworking. Indeed, it defines and establishes the Internet. This layer defines the addressing and routing structures used for the TCP/IP protocol suite. The primary protocol in this scope is the Internet Protocol, which defines IP addresses.  Its function in routing is to transport datagrams to the next host, functioning as an IP router, that has the connectivity to a network closer to the final data destination.
 * The link layer defines the networking methods within the scope of the local network link on which hosts communicate without intervening routers. This layer includes the protocols used to describe the local network topology and the interfaces needed to effect the transmission of internet layer datagrams to next-neighbor hosts.

Link layer
The protocols of the link layer operate within the scope of the local network connection to which a host is attached. This regime is called the link in TCP/IP parlance and is the lowest component layer of the suite. The link includes all hosts accessible without traversing a router. The size of the link is therefore determined by the networking hardware design. In principle, TCP/IP is designed to be hardware independent and may be implemented on top of virtually any link-layer technology. This includes not only hardware implementations but also virtual link layers such as virtual private networks and networking tunnels.

The link layer is used to move packets between the internet layer interfaces of two different hosts on the same link. The processes of transmitting and receiving packets on the link can be controlled in the device driver for the network card, as well as in firmware or by specialized chipsets. These perform functions, such as framing, to prepare the internet layer packets for transmission, and finally transmit the frames to the physical layer and over a transmission medium. The TCP/IP model includes specifications for translating the network addressing methods used in the Internet Protocol to link-layer addresses, such as media access control (MAC) addresses. All other aspects below that level, however, are implicitly assumed to exist and are not explicitly defined in the TCP/IP model.

The link layer in the TCP/IP model has corresponding functions in Layer 2 of the OSI model.

Internet layer
Internetworking requires sending data from the source network to the destination network. This process is called routing and is supported by host addressing and identification using the hierarchical IP addressing system. The internet layer provides an unreliable datagram transmission facility between hosts located on potentially different IP networks by forwarding datagrams to an appropriate next-hop router for further relaying to its destination. The internet layer has the responsibility of sending packets across potentially multiple networks. With this functionality, the internet layer makes possible internetworking, the interworking of different IP networks, and it essentially establishes the Internet.

The internet layer does not distinguish between the various transport layer protocols. IP carries data for a variety of different upper layer protocols. These protocols are each identified by a unique protocol number: for example, Internet Control Message Protocol (ICMP) and Internet Group Management Protocol (IGMP) are protocols 1 and 2, respectively.

The Internet Protocol is the principal component of the internet layer, and it defines two addressing systems to identify network hosts and to locate them on the network. The original address system of the ARPANET and its successor, the Internet, is Internet Protocol version 4 (IPv4). It uses a 32-bit IP address and is therefore capable of identifying approximately four billion hosts. This limitation was eliminated in 1998 by the standardization of Internet Protocol version 6 (IPv6) which uses 128-bit addresses. IPv6 production implementations emerged in approximately 2006.

Transport layer
The transport layer establishes basic data channels that applications use for task-specific data exchange. The layer establishes host-to-host connectivity in the form of end-to-end message transfer services that are independent of the underlying network and independent of the structure of user data and the logistics of exchanging information. Connectivity at the transport layer can be categorized as either connection-oriented, implemented in TCP, or connectionless, implemented in UDP. The protocols in this layer may provide error control, segmentation, flow control, congestion control, and application addressing (port numbers).

For the purpose of providing process-specific transmission channels for applications, the layer establishes the concept of the network port. This is a numbered logical construct allocated specifically for each of the communication channels an application needs. For many types of services, these port numbers have been standardized so that client computers may address specific services of a server computer without the involvement of service discovery or directory services.

Because IP provides only a best-effort delivery, some transport-layer protocols offer reliability.

TCP is a connection-oriented protocol that addresses numerous reliability issues in providing a reliable byte stream:
 * data arrives in-order
 * data has minimal error (i.e., correctness)
 * duplicate data is discarded
 * lost or discarded packets are resent
 * includes traffic congestion control

The newer Stream Control Transmission Protocol (SCTP) is also a reliable, connection-oriented transport mechanism. It is message-stream-oriented, not byte-stream-oriented like TCP, and provides multiple streams multiplexed over a single connection. It also provides multihoming support, in which a connection end can be represented by multiple IP addresses (representing multiple physical interfaces), such that if one fails, the connection is not interrupted. It was developed initially for telephony applications (to transport SS7 over IP).

Reliability can also be achieved by running IP over a reliable data-link protocol such as the High-Level Data Link Control (HDLC).

The User Datagram Protocol (UDP) is a connectionless datagram protocol. Like IP, it is a best-effort, unreliable protocol. Reliability is addressed through error detection using a checksum algorithm. UDP is typically used for applications such as streaming media (audio, video, Voice over IP, etc.) where on-time arrival is more important than reliability, or for simple query/response applications like DNS lookups, where the overhead of setting up a reliable connection is disproportionately large. Real-time Transport Protocol (RTP) is a datagram protocol that is used over UDP and is designed for real-time data such as streaming media.

The applications at any given network address are distinguished by their TCP or UDP port. By convention, certain  well-known ports are associated with specific applications.

The TCP/IP model's transport or host-to-host layer corresponds roughly to the fourth layer in the OSI model, also called the transport layer.

QUIC is rapidly emerging as an alternative transport protocol. Whilst it is technically carried via UDP packets it seeks to offer enhanced transport connectivity relative to TCP. HTTP/3 works exclusively via QUIC.

Application layer
The application layer includes the protocols used by most applications for providing user services or exchanging application data over the network connections established by the lower-level protocols. This may include some basic network support services such as routing protocols and host configuration. Examples of application layer protocols include the Hypertext Transfer Protocol (HTTP), the File Transfer Protocol (FTP), the Simple Mail Transfer Protocol (SMTP), and the Dynamic Host Configuration Protocol (DHCP). Data coded according to application layer protocols are encapsulated into transport layer protocol units (such as TCP streams or UDP datagrams), which in turn use lower layer protocols to effect actual data transfer.

The TCP/IP model does not consider the specifics of formatting and presenting data and does not define additional layers between the application and transport layers as in the OSI model (presentation and session layers). According to the TCP/IP model, such functions are the realm of libraries and application programming interfaces. The application layer in the TCP/IP model is often compared to a combination of the fifth (session), sixth (presentation), and seventh (application) layers of the OSI model.

Application layer protocols are often associated with particular client–server applications, and common services have well-known port numbers reserved by the Internet Assigned Numbers Authority (IANA). For example, the HyperText Transfer Protocol uses server port 80 and Telnet uses server port 23. Clients connecting to a service usually use ephemeral ports, i.e., port numbers assigned only for the duration of the transaction at random or from a specific range configured in the application.

At the application layer, the TCP/IP model distinguishes between user protocols and support protocols. Support protocols provide services to a system of network infrastructure. User protocols are used for actual user applications. For example, FTP is a user protocol and DNS is a support protocol.

Although the applications are usually aware of key qualities of the transport layer connection such as the endpoint IP addresses and port numbers, application layer protocols generally treat the transport layer (and lower) protocols as black boxes which provide a stable network connection across which to communicate. The transport layer and lower-level layers are unconcerned with the specifics of application layer protocols. Routers and switches do not typically examine the encapsulated traffic, rather they just provide a conduit for it. However, some firewall and bandwidth throttling applications use deep packet inspection to interpret application data. An example is the Resource Reservation Protocol (RSVP). It is also sometimes necessary for Applications affected by NAT to consider the application payload.

Layering evolution and representations in the literature
The Internet protocol suite evolved through research and development funded over a period of time. In this process, the specifics of protocol components and their layering changed. In addition, parallel research and commercial interests from industry associations competed with design features. In particular, efforts in the International Organization for Standardization led to a similar goal, but with a wider scope of networking in general. Efforts to consolidate the two principal schools of layering, which were superficially similar, but diverged sharply in detail, led independent textbook authors to formulate abridging teaching tools.

The following table shows various such networking models. The number of layers varies between three and seven.

Some of the networking models are from textbooks, which are secondary sources that may conflict with the intent of RFC 1122 and other IETF primary sources.

Comparison of TCP/IP and OSI layering
The three top layers in the OSI model, i.e. the application layer, the presentation layer and the session layer, are not distinguished separately in the TCP/IP model which only has an application layer above the transport layer. While some pure OSI protocol applications, such as X.400, also combined them, there is no requirement that a TCP/IP protocol stack must impose monolithic architecture above the transport layer. For example, the NFS application protocol runs over the External Data Representation (XDR) presentation protocol, which, in turn, runs over a protocol called Remote Procedure Call (RPC). RPC provides reliable record transmission, so it can safely use the best-effort UDP transport.

Different authors have interpreted the TCP/IP model differently, and disagree whether the link layer, or any aspect of the TCP/IP model, covers OSI layer 1 (physical layer) issues, or whether TCP/IP assumes a hardware layer exists below the link layer.

Several authors have attempted to incorporate the OSI model's layers 1 and 2 into the TCP/IP model since these are commonly referred to in modern standards (for example, by IEEE and ITU). This often results in a model with five layers, where the link layer or network access layer is split into the OSI model's layers 1 and 2.

The IETF protocol development effort is not concerned with strict layering. Some of its protocols may not fit cleanly into the OSI model, although RFCs sometimes refer to it and often use the old OSI layer numbers. The IETF has repeatedly stated that Internet Protocol and architecture development is not intended to be OSI-compliant. RFC 3439, referring to the internet architecture, contains a section entitled: "Layering Considered Harmful".

For example, the session and presentation layers of the OSI suite are considered to be included in the application layer of the TCP/IP suite. The functionality of the session layer can be found in protocols like HTTP and SMTP and is more evident in protocols like Telnet and the Session Initiation Protocol (SIP). Session-layer functionality is also realized with the port numbering of the TCP and UDP protocols, which are included in the transport layer of the TCP/IP suite. Functions of the presentation layer are realized in the TCP/IP applications with the MIME standard in data exchange.

Another difference is in the treatment of routing protocols. The OSI routing protocol IS-IS belongs to the network layer, and does not depend on CLNS for delivering packets from one router to another, but defines its own layer-3 encapsulation. In contrast, OSPF, RIP, BGP and other routing protocols defined by the IETF are transported over IP, and, for the purpose of sending and receiving routing protocol packets, routers act as hosts. As a consequence, include routing protocols in the application layer. Some authors, such as Tanenbaum in Computer Networks, describe routing protocols in the same layer as IP, reasoning that routing protocols inform decisions made by the forwarding process of routers.

IETF protocols can be encapsulated recursively, as demonstrated by tunnelling protocols such as Generic Routing Encapsulation (GRE). GRE uses the same mechanism that OSI uses for tunnelling at the network layer.

Implementations
The Internet protocol suite does not presume any specific hardware or software environment. It only requires that hardware and a software layer exists that is capable of sending and receiving packets on a computer network. As a result, the suite has been implemented on essentially every computing platform. A minimal implementation of TCP/IP includes the following: Internet Protocol (IP), Address Resolution Protocol (ARP), Internet Control Message Protocol (ICMP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Internet Group Management Protocol (IGMP). In addition to IP, ICMP, TCP, UDP, Internet Protocol version 6 requires Neighbor Discovery Protocol (NDP), ICMPv6, and Multicast Listener Discovery (MLD) and is often accompanied by an integrated IPSec security layer.

title: Internet protocol suite