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Wednesday, May 18, 2022

Phoneme

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Phoneme

In phonology and linguistics, a phoneme (/ˈfnm/) is a unit of sound that can distinguish one word from another in a particular language.

For example, in most dialects of English, with the notable exception of the West Midlands and the north-west of England, the sound patterns /sɪn/ (sin) and /sɪŋ/ (sing) are two separate words that are distinguished by the substitution of one phoneme, /n/, for another phoneme, /ŋ/. Two words like this that differ in meaning through the contrast of a single phoneme form a minimal pair. If, in another language, any two sequences differing only by pronunciation of the final sounds [n] or [ŋ] are perceived as being the same in meaning, then these two sounds are interpreted as phonetic variants of a single phoneme in that language.

Phonemes that are established by the use of minimal pairs, such as tap vs tab or pat vs bat, are written between slashes: /p/, /b/. To show pronunciation, linguists use square brackets: [pʰ] (indicating an aspirated p in pat).

There are differing views as to exactly what phonemes are and how a given language should be analyzed in phonemic (or phonematic) terms. However, a phoneme is generally regarded as an abstraction of a set (or equivalence class) of speech sounds (phones) that are perceived as equivalent to each other in a given language. For example, the English k sounds in the words kill and skill are not identical (as described below), but they are distributional variants of a single phoneme /k/. Speech sounds that differ but do not create a meaningful change in the word are known as allophones of the same phoneme. Allophonic variation may be conditioned, in which case a certain phoneme is realized as a certain allophone in particular phonological environments, or it may otherwise be free, and may vary by speaker or by dialect. Therefore, phonemes are often considered to constitute an abstract underlying representation for segments of words, while speech sounds make up the corresponding phonetic realization, or the surface form.

Notation

Phonemes are conventionally placed between slashes in transcription, whereas speech sounds (phones) are placed between square brackets. Thus, /pʊʃ/ represents a sequence of three phonemes, /p/, /ʊ/, /ʃ/ (the word push in Standard English), and [pʰʊʃ] represents the phonetic sequence of sounds [pʰ] (aspirated p), [ʊ], [ʃ] (the usual pronunciation of push). This should not be confused with the similar convention of the use of angle brackets to enclose the units of orthography, graphemes. For example, ⟨f⟩ represents the written letter (grapheme) f.

The symbols used for particular phonemes are often taken from the International Phonetic Alphabet (IPA), the same set of symbols most commonly used for phones. (For computer-typing purposes, systems such as X-SAMPA exist to represent IPA symbols using only ASCII characters.) However, descriptions of particular languages may use different conventional symbols to represent the phonemes of those languages. For languages whose writing systems employ the phonemic principle, ordinary letters may be used to denote phonemes, although this approach is often hampered by the complexity of the relationship between orthography and pronunciation (see § Correspondence between letters and phonemes below).

Assignment of speech sounds to phonemes

A simplified procedure for determining whether two sounds represent the same or different phonemes

A phoneme is a sound or a group of different sounds perceived to have the same function by speakers of the language or dialect in question. An example is the English phoneme /k/, which occurs in words such as cat, kit, scat, skit. Although most native speakers do not notice this, in most English dialects, the "c/k" sounds in these words are not identical: in kit  [kʰɪt], the sound is aspirated, but in skill  [skɪl], it is unaspirated. The words, therefore, contain different speech sounds, or phones, transcribed [kʰ] for the aspirated form and [k] for the unaspirated one. These different sounds are nonetheless considered to belong to the same phoneme, because if a speaker used one instead of the other, the meaning of the word would not change: using the aspirated form [kʰ] in skill might sound odd, but the word would still be recognized. By contrast, some other sounds would cause a change in meaning if substituted: for example, substitution of the sound [t] would produce the different word still, and that sound must therefore be considered to represent a different phoneme (the phoneme /t/).

The above shows that in English, [k] and [kʰ] are allophones of a single phoneme /k/. In some languages, however, [kʰ] and [k] are perceived by native speakers as different sounds, and substituting one for the other can change the meaning of a word. In those languages, therefore, the two sounds represent different phonemes. For example, in Icelandic, [kʰ] is the first sound of kátur, meaning "cheerful", but [k] is the first sound of gátur, meaning "riddles". Icelandic, therefore, has two separate phonemes /kʰ/ and /k/.

Minimal pairs

A pair of words like kátur and gátur (above) that differ only in one phone is called a minimal pair for the two alternative phones in question (in this case, [kʰ] and [k]). The existence of minimal pairs is a common test to decide whether two phones represent different phonemes or are allophones of the same phoneme.

To take another example, the minimal pair tip and dip illustrates that in English, [t] and [d] belong to separate phonemes, /t/ and /d/; since both words have different meanings, English-speakers must be conscious of the distinction between the two sounds.

Signed languages, such as American Sign Language (ASL), also have minimal pairs, differing only in (exactly) one of the signs' parameters: handshape, movement, location, palm orientation, and nonmanual signal or marker. A minimal pair may exist in the signed language if the basic sign stays the same, but one of the parameters changes.

However, the absence of minimal pairs for a given pair of phones does not always mean that they belong to the same phoneme: they may be so dissimilar phonetically that it is unlikely for speakers to perceive them as the same sound. For example, English has no minimal pair for the sounds [h] (as in hat) and [ŋ] (as in bang), and the fact that they can be shown to be in complementary distribution could be used to argue for their being allophones of the same phoneme. However, they are so dissimilar phonetically that they are considered separate phonemes.

Phonologists have sometimes had recourse to "near minimal pairs" to show that speakers of the language perceive two sounds as significantly different even if no exact minimal pair exists in the lexicon. It is virtually impossible to find a minimal pair to distinguish English /ʃ/ from /ʒ/, yet it seems uncontroversial to claim that the two consonants are distinct phonemes. The two words 'pressure' /ˈprɛʃər/ and 'pleasure' /ˈplɛʒər/ can serve as a near minimal pair.

Suprasegmental phonemes

Besides segmental phonemes such as vowels and consonants, there are also suprasegmental features of pronunciation (such as tone and stress, syllable boundaries and other forms of juncture, nasalization and vowel harmony), which, in many languages, can change the meaning of words and so are phonemic.

Phonemic stress is encountered in languages such as English. For example, the word invite stressed on the second syllable is a verb, but when stressed on the first syllable (without changing any of the individual sounds), it becomes a noun. The position of the stress in the word affects the meaning, so a full phonemic specification (providing enough detail to enable the word to be pronounced unambiguously) would include indication of the position of the stress: /ɪnˈvaɪt/ for the verb, /ˈɪnvaɪt/ for the noun. In other languages, such as French, word stress cannot have this function (its position is generally predictable) and is therefore not phonemic (and is not usually indicated in dictionaries).

Phonemic tones are found in languages such as Mandarin Chinese, in which a given syllable can have five different tonal pronunciations:

Minimal set for phonemic tone in Mandarin Chinese
Tone number 1 2 3 4 5
Hanzi
Pinyin ma
IPA [má] [mǎ] [mà][a] [mâ] [ma]
Gloss mother hemp horse scold question particle

The tone "phonemes" in such languages are sometimes called tonemes. Languages such as English do not have phonemic tone, although they use intonation for functions such as emphasis and attitude.

Distribution of allophones

When a phoneme has more than one allophone, the one actually heard at a given occurrence of that phoneme may be dependent on the phonetic environment (surrounding sounds) – allophones which normally cannot appear in the same environment are said to be in complementary distribution. In other cases the choice of allophone may be dependent on the individual speaker or other unpredictable factors – such allophones are said to be in free variation, but allophones are still selected in a specific phonetic context, not the other way around.

Background and related ideas

The term phonème (from Ancient Greek: φώνημα, romanizedphōnēma, "sound made, utterance, thing spoken, speech, language") was reportedly first used by A. Dufriche-Desgenettes in 1873, but it referred only to a speech sound. The term phoneme as an abstraction was developed by the Polish linguist Jan Niecisław Baudouin de Courtenay and his student Mikołaj Kruszewski during 1875–1895. The term used by these two was fonema, the basic unit of what they called psychophonetics. Daniel Jones became the first linguist in the western world to use the term phoneme in its current sense, employing the word in his article "The phonetic structure of the Sechuana Language". The concept of the phoneme was then elaborated in the works of Nikolai Trubetzkoy and others of the Prague School (during the years 1926–1935), and in those of structuralists like Ferdinand de Saussure, Edward Sapir, and Leonard Bloomfield. Some structuralists (though not Sapir) rejected the idea of a cognitive or psycholinguistic function for the phoneme.

Later, it was used and redefined in generative linguistics, most famously by Noam Chomsky and Morris Halle, and remains central to many accounts of the development of modern phonology. As a theoretical concept or model, though, it has been supplemented and even replaced by others.

Some linguists (such as Roman Jakobson and Morris Halle) proposed that phonemes may be further decomposable into features, such features being the true minimal constituents of language. Features overlap each other in time, as do suprasegmental phonemes in oral language and many phonemes in sign languages. Features could be characterized in different ways: Jakobson and colleagues defined them in acoustic terms, Chomsky and Halle used a predominantly articulatory basis, though retaining some acoustic features, while Ladefoged's system is a purely articulatory system apart from the use of the acoustic term 'sibilant'.

In the description of some languages, the term chroneme has been used to indicate contrastive length or duration of phonemes. In languages in which tones are phonemic, the tone phonemes may be called tonemes. Though not all scholars working on such languages use these terms, they are by no means obsolete.

By analogy with the phoneme, linguists have proposed other sorts of underlying objects, giving them names with the suffix -eme, such as morpheme and grapheme. These are sometimes called emic units. The latter term was first used by Kenneth Pike, who also generalized the concepts of emic and etic description (from phonemic and phonetic respectively) to applications outside linguistics.

Restrictions on occurrence

Languages do not generally allow words or syllables to be built of any arbitrary sequences of phonemes; there are phonotactic restrictions on which sequences of phonemes are possible and in which environments certain phonemes can occur. Phonemes that are significantly limited by such restrictions may be called restricted phonemes.

In English, examples of such restrictions include:

  • /ŋ/, as in sing, occurs only at the end of a syllable, never at the beginning (in many other languages, such as Māori, Swahili, Tagalog, and Thai, /ŋ/ can appear word-initially).
  • /h/ occurs only before vowels and at the beginning of a syllable, never at the end (a few languages, such as Arabic, or Romanian allow /h/ syllable-finally).
  • In non-rhotic dialects, /ɹ/ can only occur immediately before a vowel, never before a consonant.
  • /w/ and /j/ occur only before a vowel, never at the end of a syllable (except in interpretations where a word like boy is analyzed as /bɔj/).

Some phonotactic restrictions can alternatively be analyzed as cases of neutralization. See Neutralization and archiphonemes below, particularly the example of the occurrence of the three English nasals before stops.

Biuniqueness

Biuniqueness is a requirement of classic structuralist phonemics. It means that a given phone, wherever it occurs, must unambiguously be assigned to one and only one phoneme. In other words, the mapping between phones and phonemes is required to be many-to-one rather than many-to-many. The notion of biuniqueness was controversial among some pre-generative linguists and was prominently challenged by Morris Halle and Noam Chomsky in the late 1950s and early 1960s.

An example of the problems arising from the biuniqueness requirement is provided by the phenomenon of flapping in North American English. This may cause either /t/ or /d/ (in the appropriate environments) to be realized with the phone [ɾ] (an alveolar flap). For example, the same flap sound may be heard in the words hitting and bidding, although it is intended to realize the phoneme /t/ in the first word and /d/ in the second. This appears to contradict biuniqueness.

For further discussion of such cases, see the next section.

Neutralization and archiphonemes

Phonemes that are contrastive in certain environments may not be contrastive in all environments. In the environments where they do not contrast, the contrast is said to be neutralized. In these positions it may become less clear which phoneme a given phone represents. Absolute neutralization is a phenomenon in which a segment of the underlying representation is not realized in any of its phonetic representations (surface forms). The term was introduced by Paul Kiparsky (1968), and contrasts with contextual neutralization where some phonemes are not contrastive in certain environments. Some phonologists prefer not to specify a unique phoneme in such cases, since to do so would mean providing redundant or even arbitrary information – instead they use the technique of underspecification. An archiphoneme is an object sometimes used to represent an underspecified phoneme.

An example of neutralization is provided by the Russian vowels /a/ and /o/. These phonemes are contrasting in stressed syllables, but in unstressed syllables the contrast is lost, since both are reduced to the same sound, usually [ə] (for details, see vowel reduction in Russian). In order to assign such an instance of [ə] to one of the phonemes /a/ and /o/, it is necessary to consider morphological factors (such as which of the vowels occurs in other forms of the words, or which inflectional pattern is followed). In some cases even this may not provide an unambiguous answer. A description using the approach of underspecification would not attempt to assign [ə] to a specific phoneme in some or all of these cases, although it might be assigned to an archiphoneme, written something like //A//, which reflects the two neutralized phonemes in this position, or {a}, reflecting its unmerged values.

A somewhat different example is found in English, with the three nasal phonemes /m, n, ŋ/. In word-final position these all contrast, as shown by the minimal triplet sum /sʌm/, sun /sʌn/, sung /sʌŋ/. However, before a stop such as /p, t, k/ (provided there is no morpheme boundary between them), only one of the nasals is possible in any given position: /m/ before /p/, /n/ before /t/ or /d/, and /ŋ/ before /k/, as in limp, lint, link (/lɪmp/, /lɪnt/, /lɪŋk/). The nasals are therefore not contrastive in these environments, and according to some theorists this makes it inappropriate to assign the nasal phones heard here to any one of the phonemes (even though, in this case, the phonetic evidence is unambiguous). Instead they may analyze these phones as belonging to a single archiphoneme, written something like //N//, and state the underlying representations of limp, lint, link to be //lɪNp//, //lɪNt//, //lɪNk//.

This latter type of analysis is often associated with Nikolai Trubetzkoy of the Prague school. Archiphonemes are often notated with a capital letter within double virgules or pipes, as with the examples //A// and //N// given above. Other ways the second of these has been notated include |m-n-ŋ|, {m, n, ŋ} and //n*//.

Another example from English, but this time involving complete phonetic convergence as in the Russian example, is the flapping of /t/ and /d/ in some American English (described above under Biuniqueness). Here the words betting and bedding might both be pronounced [ˈbɛɾɪŋ]. Under the generative grammar theory of linguistics, if a speaker applies such flapping consistently, morphological evidence (the pronunciation of the related forms bet and bed, for example) would reveal which phoneme the flap represents, once it is known which morpheme is being used. However, other theorists would prefer not to make such a determination, and simply assign the flap in both cases to a single archiphoneme, written (for example) //D//.

Further mergers in English are plosives after /s/, where /p, t, k/ conflate with /b, d, ɡ/, as suggested by the alternative spellings sketti and sghetti. That is, there is no particular reason to transcribe spin as /ˈspɪn/ rather than as /ˈsbɪn/, other than its historical development, and it might be less ambiguously transcribed //ˈsBɪn//.

Morphophonemes

A morphophoneme is a theoretical unit at a deeper level of abstraction than traditional phonemes, and is taken to be a unit from which morphemes are built up. A morphophoneme within a morpheme can be expressed in different ways in different allomorphs of that morpheme (according to morphophonological rules). For example, the English plural morpheme -s appearing in words such as cats and dogs can be considered to be a single morphophoneme, which might be transcribed (for example) //z// or |z|, and which is realized as phonemically /s/ after most voiceless consonants (as in cats) and as /z/ in other cases (as in dogs).

Numbers of phonemes in different languages

All known languages use only a small subset of the many possible sounds that the human speech organs can produce, and, because of allophony, the number of distinct phonemes will generally be smaller than the number of identifiably different sounds. Different languages vary considerably in the number of phonemes they have in their systems (although apparent variation may sometimes result from the different approaches taken by the linguists doing the analysis). The total phonemic inventory in languages varies from as few as 11 in Rotokas and Pirahã to as many as 141 in !Xũ.

The number of phonemically distinct vowels can be as low as two, as in Ubykh and Arrernte. At the other extreme, the Bantu language Ngwe has 14 vowel qualities, 12 of which may occur long or short, making 26 oral vowels, plus six nasalized vowels, long and short, making a total of 38 vowels; while !Xóõ achieves 31 pure vowels, not counting its additional variation by vowel length, by varying the phonation. As regards consonant phonemes, Puinave and the Papuan language Tauade each have just seven, and Rotokas has only six. !Xóõ, on the other hand, has somewhere around 77, and Ubykh 81. The English language uses a rather large set of 13 to 21 vowel phonemes, including diphthongs, although its 22 to 26 consonants are close to average. Across all languages, the average number of consonant phonemes per language is about 22, while the average number of vowel phonemes is about 8.

Some languages, such as French, have no phonemic tone or stress, while Cantonese and several of the Kam–Sui languages have nine tones, and one of the Kru languages, Wobé, has been claimed to have 14, though this is disputed.

The most common vowel system consists of the five vowels /i/, /e/, /a/, /o/, /u/. The most common consonants are /p/, /t/, /k/, /m/, /n/. Relatively few languages lack any of these consonants, although it does happen: for example, Arabic lacks /p/, standard Hawaiian lacks /t/, Mohawk and Tlingit lack /p/ and /m/, Hupa lacks both /p/ and a simple /k/, colloquial Samoan lacks /t/ and /n/, while Rotokas and Quileute lack /m/ and /n/.

The non-uniqueness of phonemic solutions

During the development of phoneme theory in the mid-20th century phonologists were concerned not only with the procedures and principles involved in producing a phonemic analysis of the sounds of a given language, but also with the reality or uniqueness of the phonemic solution. These were central concerns of phonology. Some writers took the position expressed by Kenneth Pike: "There is only one accurate phonemic analysis for a given set of data", while others believed that different analyses, equally valid, could be made for the same data. Yuen Ren Chao (1934), in his article "The non-uniqueness of phonemic solutions of phonetic systems" stated "given the sounds of a language, there are usually more than one possible way of reducing them to a set of phonemes, and these different systems or solutions are not simply correct or incorrect, but may be regarded only as being good or bad for various purposes". The linguist F. W. Householder referred to this argument within linguistics as "God's Truth" (i.e. the stance that a given language has an intrinsic structure to be discovered) vs. "hocus-pocus" (i.e. the stance that any proposed, coherent structure is as good as any other).

Different analyses of the English vowel system may be used to illustrate this. The article English phonology states that "English has a particularly large number of vowel phonemes" and that "there are 20 vowel phonemes in Received Pronunciation, 14–16 in General American and 20–21 in Australian English". Although these figures are often quoted as fact, they actually reflect just one of many possible analyses, and later in the English Phonology article an alternative analysis is suggested in which some diphthongs and long vowels may be interpreted as comprising a short vowel linked to either /j/ or /w/. The fullest exposition of this approach is found in Trager and Smith (1951), where all long vowels and diphthongs ("complex nuclei") are made up of a short vowel combined with either /j/, /w/ or /h/ (plus /r/ for rhotic accents), each comprising two phonemes. The transcription for the vowel normally transcribed /aɪ/ would instead be /aj/, /aʊ/ would be /aw/ and /ɑː/ would be /ah/, or /ar/ in a rhotic accent if there is an ⟨r⟩ in the spelling. It is also possible to treat English long vowels and diphthongs as combinations of two vowel phonemes, with long vowels treated as a sequence of two short vowels, so that 'palm' would be represented as /paam/. English can thus be said to have around seven vowel phonemes, or even six if schwa were treated as an allophone of /ʌ/ or of other short vowels.

In the same period there was disagreement about the correct basis for a phonemic analysis. The structuralist position was that the analysis should be made purely on the basis of the sound elements and their distribution, with no reference to extraneous factors such as grammar, morphology or the intuitions of the native speaker; this position is strongly associated with Leonard Bloomfield. Zellig Harris claimed that it is possible to discover the phonemes of a language purely by examining the distribution of phonetic segments. Referring to mentalistic definitions of the phoneme, Twaddell (1935) stated "Such a definition is invalid because (1) we have no right to guess about the linguistic workings of an inaccessible 'mind', and (2) we can secure no advantage from such guesses. The linguistic processes of the 'mind' as such are quite simply unobservable; and introspection about linguistic processes is notoriously a fire in a wooden stove." This approach was opposed to that of Edward Sapir, who gave an important role to native speakers' intuitions about where a particular sound or group of sounds fitted into a pattern. Using English [ŋ] as an example, Sapir argued that, despite the superficial appearance that this sound belongs to a group of three nasal consonant phonemes (/m/, /n/ and /ŋ/), native speakers feel that the velar nasal is really the sequence [ŋɡ]/. The theory of generative phonology which emerged in the 1960s explicitly rejected the Structuralist approach to phonology and favoured the mentalistic or cognitive view of Sapir.

These topics are discussed further in English phonology#Controversial issues.

Correspondence between letters and phonemes

Phonemes are considered to be the basis for alphabetic writing systems. In such systems the written symbols (graphemes) represent, in principle, the phonemes of the language being written. This is most obviously the case when the alphabet was invented with a particular language in mind; for example, the Latin alphabet was devised for Classical Latin, and therefore the Latin of that period enjoyed a near one-to-one correspondence between phonemes and graphemes in most cases, though the devisers of the alphabet chose not to represent the phonemic effect of vowel length. However, because changes in the spoken language are often not accompanied by changes in the established orthography (as well as other reasons, including dialect differences, the effects of morphophonology on orthography, and the use of foreign spellings for some loanwords), the correspondence between spelling and pronunciation in a given language may be highly distorted; this is the case with English, for example.

The correspondence between symbols and phonemes in alphabetic writing systems is not necessarily a one-to-one correspondence. A phoneme might be represented by a combination of two or more letters (digraph, trigraph, etc.), like ⟨sh⟩ in English or ⟨sch⟩ in German (both representing phonemes /ʃ/). Also a single letter may represent two phonemes, as in English ⟨x⟩ representing /gz/ or /ks/. There may also exist spelling/pronunciation rules (such as those for the pronunciation of ⟨c⟩ in Italian) that further complicate the correspondence of letters to phonemes, although they need not affect the ability to predict the pronunciation from the spelling and vice versa, provided the rules are known.

In sign languages

Sign language phonemes are bundles of articulation features. Stokoe was the first scholar to describe the phonemic system of ASL. He identified the bundles tab (elements of location, from Latin tabula), dez (the handshape, from designator), sig (the motion, from signation). Some researchers also discern ori (orientation), facial expression or mouthing. Just as with spoken languages, when features are combined, they create phonemes. As in spoken languages, sign languages have minimal pairs which differ in only one phoneme. For instance, the ASL signs for father and mother differ minimally with respect to location while handshape and movement are identical; location is thus contrastive.

Stokoe's terminology and notation system are no longer used by researchers to describe the phonemes of sign languages; William Stokoe's research, while still considered seminal, has been found not to characterize American Sign Language or other sign languages sufficiently. For instance, non-manual features are not included in Stokoe's classification. More sophisticated models of sign language phonology have since been proposed by Brentari, Sandler, and Van der Kooij.

Chereme

Cherology and chereme (from Ancient Greek: χείρ "hand") are synonyms of phonology and phoneme previously used in the study of sign languages. A chereme, as the basic unit of signed communication, is functionally and psychologically equivalent to the phonemes of oral languages, and has been replaced by that term in the academic literature. Cherology, as the study of cheremes in language, is thus equivalent to phonology. The terms are not in use anymore. Instead, the terms phonology and phoneme (or distinctive feature) are used to stress the linguistic similarities between signed and spoken languages.

The terms were coined in 1960 by William Stokoe at Gallaudet University to describe sign languages as true and full languages. Once a controversial idea, the position is now universally accepted in linguistics. Stokoe's terminology, however, has been largely abandoned.

Heart development

From Wikipedia, the free encyclopedia

Heart development
2037 Embryonic Development of Heart.jpg
Development of the human heart during the first eight weeks (top), and the formation of the heart chambers (bottom). In this figure, the blue and red colors represent blood inflow and outflow (not venous and arterial blood). Initially, all venous blood flows from the tail/atria to the ventricles/head, a very different pattern from that of an adult.

Heart development
, also known as cardiogenesis, refers to the prenatal development of the heart. This begins with the formation of two endocardial tubes which merge to form the tubular heart, also called the primitive heart tube. The heart is the first functional organ in vertebrate embryos.

The tubular heart quickly differentiates into the truncus arteriosus, bulbus cordis, primitive ventricle, primitive atrium, and the sinus venosus. The truncus arteriosus splits into the ascending aorta and the pulmonary trunk. The bulbus cordis forms part of the ventricles. The sinus venosus connects to the fetal circulation.

The heart tube elongates on the right side, looping and becoming the first visual sign of left-right asymmetry of the body. Septa form within the atria and ventricles to separate the left and right sides of the heart.

Early development

The heart derives from embryonic mesodermal germ layer cells that differentiate after gastrulation into mesothelium, endothelium, and myocardium. Mesothelial pericardium forms the outer lining of the heart. The inner lining of the heart – the endocardium, lymphatic and blood vessels, develop from endothelium.

Endocardial tubes

In the splanchnopleuric mesenchyme on either side of the neural plate, a horseshoe-shaped area develops as the cardiogenic region. This has formed from cardiac myoblasts and blood islands as forerunners of blood cells and vessels. By day 19, an endocardial tube begins to develop in each side of this region. These two tubes grow and by the third week have converged towards each other to merge, using programmed cell death to form a single tube, the tubular heart.

From splanchnopleuric mesenchyme, the cardiogenic region develops cranially and laterally to the neural plate. In this area, two separate angiogenic cell clusters form on either side and coalesce to form the endocardial tubes. As embryonic folding starts, the two endocardial tubes are pushed into the thoracic cavity, where they begin to fuse together, and this is completed at about 22 days.

At around 18 to 19 days after fertilisation, the heart begins to form. Early in the fourth week, around day 22 the developing heart starts to beat and to pump circulating blood. The heart begins to develop near the head of the embryo in the cardiogenic area. Following cell signalling, two strands or cords begin to form in the cardiogenic region As these form, a lumen develops within them, at which point, they are referred to as endocardial tubes. At the same time that the tubes are forming other major heart components are also being formed. The two tubes migrate together and fuse to form a single primitive heart tube which quickly forms five distinct regions. From head to tail, these are the truncus arteriosus, bulbus cordis, primitive ventricle, primitive atrium, and the sinus venosus. Initially, all venous blood flows into the sinus venosus, and contractions propel the blood from tail to head, or from the sinus venosus to the truncus arteriosus. The truncus arteriosus will divide to form the aorta and pulmonary artery; the bulbus cordis will develop into the right ventricle; the primitive ventricle will form the left ventricle; the primitive atrium will become the front parts of the left and right atria and their appendages, and the sinus venosus will develop into the posterior part of the right atrium, the sinoatrial node and the coronary sinus.

Heart tube position

The central part of cardiogenic area is in front of the oropharyngeal membrane and the neural plate. The growth of the brain and the cephalic folds push the oropharyngeal membrane forward, while the heart and the pericardial cavity move first to the cervical region and then into the chest. The curved portion of the horseshoe-shaped area expands to form the future ventricular infundibulum and the ventricular regions, as the heart tube continues to expand. The tube starts receiving venous drainage in its caudal pole and will pump blood out of the first aortic arch and into the dorsal aorta through its polar head. Initially the tube remains attached to the dorsal part of the pericardial cavity by a mesodermal tissue fold called the dorsal mesoderm. This mesoderm disappears to form the two pericardial sinuses the transverse and the oblique pericardial sinuses, which connect both sides of the pericardial cavity.

The myocardium thickens and secretes a thick layer of rich extracellular matrix containing hyaluronic acid which separates the endothelium. Then mesothelial cells form the pericardium and migrate to form most of the epicardium. Then the heart tube is formed by the endocardium, which is the inner endothelial lining of the heart, and the myocardial muscle wall which is the epicardium that covers the outside of the tube.

Heart folding

The heart tube continues stretching and by day 23, in a process called morphogenesis, cardiac looping begins. The cephalic portion curves in a frontal clockwise direction. The atrial portion starts moving in a cephalically and then moves to the left from its original position. This curved shape approaches the heart and finishes its growth on day 28. The conduit forms the atrial and ventricular junctions which connect the common atrium and the common ventricle in the early embryo. The arterial bulb forms the trabecular portion of the right ventricle. A cone will form the infundibula blood of both ventricles. The arterial trunk and the roots will form the proximal portion of the aorta and the pulmonary artery. The junction between the ventricle and the arterial bulb will be called the primary intra-ventricular hole. The tube is divided into cardiac regions along its craniocaudal axis: the primitive ventricle, called primitive left ventricle, and the trabecular proximal arterial bulb, called the primitive right ventricle. This time no septum is present in heart.

Heart chambers

Sinus venosus

In the middle of the fourth week, the sinus venosus receives venous blood from the poles of right and left sinus. Each pole receives blood from three major veins: the vitelline vein, the umbilical vein and the common cardinal vein. The sinus opening moves clockwise. This movement is caused mainly by the left to right shunt of blood, which occurs in the venous system during the fourth and fifth week of development.

When the left common cardinal vein disappears in the tenth week only the oblique vein of the left atrium and the coronary sinus remain. The right pole joins the right atrium to form the wall portion of the right atrium. The right and left venous valves fuse and form a peak known as the septum spurium. At the beginning, these valves are large, but over time the left venous valve and the septum spurium fuse with the developing atrial septum. The upper right venous valve disappears, while the bottom venous valve evolves into the inferior valve of the vena cava and the coronary sinus valve.

Heart wall

The main walls of the heart are formed between day 27 and 37 of the development of the early embryo. The growth consists of two tissue masses actively growing that approach one another until they merge and split light into two separate conduits. Tissue masses called endocardial cushions develop into atrioventricular and conotroncal regions. In these places, the cushions will help in the formation of auricular septum, ventricular conduits, atrio-ventricular valves and aortic and pulmonary channels.

Atria

The developing heart at day 30. The septum primum (top, middle) develops downwards to separate the initially joined primitive atrium into left and right atria.

At the end of the fourth week, a crest grows that leaves the cephalic part. This crest is the first part of the septum primum. The two ends of the septum extend into the interior of the endocardial cushions in the atrioventricular canal. The opening between the bottom edge of the septum primum and endocardial cushions is the ostium primum (first opening). The extensions of the upper and lower endocardial pads grow along the margin of the septum primum and close the ostium primum. Coalescence of these perforations will form the ostium secundum (second opening), which allows blood to flow freely from the right atrium to the left.

When the right of the atrium expands due to the incorporation of the pole of the sinus, a new fold appears, called the septum secundum. At its right side it is fused with the left venous valve and the septum spurium. A free opening will then appear, called the foramen ovale. The remains of the upper septum primum, will become the valves of the foramen ovale. The passage between the two atrial chambers consists of a long oblique slit through which blood flows from the right atrium to the left.

Ventricles

Initially, a single pulmonary vein develops in the form of a bulge in the back wall of the left atrium. This vein will connect with the veins of the developing lung buds. As development proceeds, the pulmonary vein and its branches are incorporated into the left atrium and they both form the smooth wall of the atrium. The embryonic left atrium remains as the trabecular left atrial appendage, and the embryonic right atrium remains as the right atrial appendage.

Septum formation of the atrioventricular canal

At the end of the fourth week, two atrioventricular endocardial cushions appear. Initially the atrioventricular canal gives access to the primitive left ventricle, and is separated from arterial bulb by the edge of the ventricular bulb. In the fifth week, the posterior end terminates in the center part of the upper endocardial cushion. Because of this, blood can access both the left primitive ventricle and the right primitive ventricle. As the anterior and posterior pads project inwardly, they merge to form a right and left atrioventricular orifice.

Atrioventricular valves

When forming intra-atrial septa, atrio-ventricular valves will begin to grow. A muscular interventricular septum begins to grow from the common ventricle to the atrio-ventricular endocardial cushions. The division begins in the common ventricle where a furrow in the outer surface of the heart will appear the interventricular foramen eventually disappears. This closure is achieved by further growth of the muscular interventricular septum, a contribution of trunk crest-conal tissue and a membranous component.

Valves and outflow tracts

Truncus septum formation and arterial cone

The arterial cone is closed by the infundibular cushions. The trunk cones are closed by the forming of an infundibulotroncal septum, which is made from a straight proximal portion and distal spiral portion. Then, the narrowest portion of the aorta is in the left and dorsal portion. The distal portion of the aorta is pushed forward to the right. The proximal pulmonary artery is right and ventral, and the distal portion of the pulmonary artery is in the left dorsal portion.

Pacemaker and conduction system

The rhythmic electrical depolarization waves that trigger myocardial contraction is myogenic, which means that they begin in the heart muscle spontaneously and are then responsible for transmitting signals from cell to cell. Myocytes that were obtained in the primitive heart tube, start beating as they connect together by their walls in a syncytium. Myocytes initiate rhythmic electrical activity, before the fusion of the endocardial tubes. The heartbeat begins in the region of the pacemaker which has a spontaneous depolarization time faster than the rest of myocardium.

The primitive ventricle acts as initial pacemaker. But this pacemaker activity is actually made by a group of cells that derive from the sinoatrial right venous sinus. These cells form an ovoid sinoatrial node (SAN), on the left venous valve. After the development of the SAN, the superior endocardial cushions begin to form a pacemaker also known as the atrioventricular node. With the development of the SAN, a band of specialized conducting cells start to form creating the bundle of His that sends a branch to the right ventricle and one to the left ventricle. Most conduction pathways originate from the cardiogenic mesoderm but the sinus node may be derived from the neural crest.

The human embryonic heart begins beating approximately 21 days after fertilization, or five weeks after the last normal menstrual period (LMP), which is the date normally used to date pregnancy in the medical community. The electrical depolarizations that trigger cardiac myocytes to contract arise spontaneously within the myocyte itself. The heartbeat is initiated in the pacemaker regions and spreads to the rest of the heart through a conduction pathway. Pacemaker cells develop in the primitive atrium and the sinus venosus to form the sinoatrial node and the atrioventricular node respectively. Conductive cells develop the bundle of His and carry the depolarization into the lower heart. Cardiac activity is visible beginning at approximately 5 weeks of pregnancy.

The human heart begins beating at a rate near the mother’s, about 75-80 beats per minute (BPM). The embryonic heart rate (EHR) then accelerates linearly for the first month of beating, peaking at 165-185 BPM during the early 7th week, (early 9th week after the LMP). This acceleration is approximately 3.3 BPM per day, or about 10 BPM every three days, an increase of 100 BPM in the first month.

After peaking at about 9.2 weeks after the LMP, it decelerates to about 150 BPM (+/-25 BPM) during the 15th week after the LMP. After the 15th week the deceleration slows reaching an average rate of about 145 (+/-25 BPM) BPM at term.

Imaging

Device for obstetric ultrasonography including usage in 1st trimester.
 
Transvaginal ultrasonography of an embryo at 5 weeks and 5 days of gestational age, with discernible cardiac activity (arrow).

In the first trimester, the heartbeat can be visualized, and the heart rate quantified by obstetric ultrasonography. A study of 32 normal pregnancies showed that a fetal heartbeat was visible at a mean human chorionic gonadotropin (hCG) level of 10,000 UI/l (range 8650-12,200). Obstetric ultrasonography can also use Doppler technique on key vessels such as the umbilical artery to detect abnormal flow.

In later stages of pregnancy, a simple Doppler fetal monitor can be used to quantify the fetal heart rate.

During childbirth, the parameter is part of cardiotocography, which is where the fetal heartbeat and uterine contractions are continuously recorded.

Heart rates

Starting at week 5 the embryonic heart rate accelerates by 3.3 bpm per day for the next month. Before this, the embryo possesses a tubular heart.

The embryonic heart begins to beat at approximately the same rate as the mother's, which is typically 80 to 85 bpm. The approximate fetal heart rate for weeks 5 to 9 (assuming a starting rate of 80):

  • Week 5 starts at 80 and ends at 103 bpm
  • Week 6 starts at 103 and ends at 126 bpm
  • Week 7 starts at 126 and ends at 149 bpm
  • Week 8 starts at 149 and ends at 172 bpm
  • At week 9 the embryonic heart tends to beat within a range of 155 to 195 bpm.

By the end of week 9, the embryonic heart has developed septa and valves, and has all four chambers.

At this point, the fetal heart rate begins to decrease, and generally falls within the range of 120 to 160 bpm by week 12.

Obstetric ultrasonography of an embryo of 8 weeks with visible heartbeat.

Additional images

Irreligion in India

From Wikipedia, the free encyclopedia
 

Atheism and agnosticism have a long history in India and flourished within the Śramaṇa movement. Indian religions like Jainism, Hinduism and Buddhism consider atheism to be acceptable. India has produced some notable atheist politicians and social reformers. According to the 2011 Census of India, 99.76% of Indians identified with a religion while 0.24% did not state their religious identity. According to the 2012 WIN-Gallup Global Index of Religion and Atheism report, 81% of Indians were religious, 13% were non-religious, 3% were convinced atheists, and 3% were unsure or did not respond.

History

Ancient India

Several śramaṇa movements are known to have existed in India before the 6th century BCE (pre-Buddha, pre-Mahavira), and these influenced both the āstika and nāstika traditions of Indian philosophy. Martin Wiltshire states that the Śramaṇa tradition evolved in India over two phases, namely Paccekabuddha and Savaka phases, the former being the tradition of individual ascetic and latter of disciples, and that Buddhism and Jainism ultimately emerged from these as sectarian manifestations. These traditions drew upon already established Brahmanical concepts, states Wiltshire, to formulate their own doctrines. Reginald Ray concurs that Śramaṇa movements already existed and were established traditions in pre-6th century BCE India, but disagrees with Wiltshire that they were nonsectarian before the arrival of Buddha.

Schools of Philosophy

In Indian philosophy, there are six major orthodox (astika) schools of Hindu philosophyNyaya, Vaisheshika, Samkhya, Yoga, Mīmāṃsā and Vedanta, and five major heterodox (nāstika) schools of ŚramaṇaJain, Buddhist, Ajivika, Ajñana, and Cārvāka. The four most studied Nāstika schools, those rejecting the doctrine of Vedas, are Jainism, Buddhism, Cārvāka, and Ājīvika.

Charvaka

There is no heaven, no final liberation, nor any soul in another world, Nor do the actions of the four castes, orders, etc., produce any real effect.

— from the Sarvadarśanasaṅ̇graha, attributed to Brhaspati

The Cārvāka school originated in India around the 6th century BCE. It is classified as a nāstika school. It is noteworthy as evidence of a materialistic movement in ancient India. Followers of this school only accepted pratyakşa (perception) as a valid pramāna (evidence). They considered other pramāna like sabda (testimony), upamāna (analogy), and anumāna (inference) as unreliable. Thus, the existence of a soul (ātman) and God were rejected, because they could not be proved by perception. They also considered everything to be made of four elements: earth, water, air and fire. The Cārvāka pursued enjoyment of life and elimination of physical pain. So, they can be considered hedonistic. All of the original Cārvāka texts are considered lost. A much quoted sūtra (Barhaspatya sutras) by Brhaspati, who is considered the founder of the school, is thought to be lost. The Tattvopaplavasimha by Jayarāśi Bhaṭṭa (8th century CE) and the Sarvadarśanasaṅ̇graha by Madhavacarya (13th century) are considered important secondary Cārvāka texts.

Samkhya

Sāṃkhya is an āstika school, but has some atheistic elements. Sāṃkhya is a radically dualist philosophy. They believed that the two ontological principles, puruṣa (consciousness) and prakriti (matter), to be the underlying foundation of the universe. The objective of life is considered the achievement of separation of pure consciousness from matter (kaivalya). The reasoning within this system led to the Nir-isvara Sāṃkhya (Sāṃkhya without God) philosophy, which deemed the existence of God as unnecessary. There is the opposing reasoning which accepts God, called Sesvara Sankhya (Sāṃkhya with God). Samkhya Karika (c. 350 CE) is the earliest known systematic text of this philosophy.

Mīmāṃsā

Mīmāṃsā (meaning exegesis) is also an astika school. They believed the Vedas to be author-less and self-authenticating. They did not accept the Vedas as being composed by any ṛishi (saint), they considered them to not be authored by anyone (apauruṣeya). They accepted the minor deities of the Vedas but resisted any notion of a Supreme Creator. They only concentrated on upholding the ṛta (order) by following the duties of the Vedas. The foundational text of this school is the Mīmāṃsā Sutra by Jaimini (c. 200 BCE - 200 CE).

Ājīvika

Ājīvika is yet another nastika school with an atheistic outlook. None of their scriptures survive and there is some question as to whether or not the accounts of them in secondary sources (often hostile) are accurate. They believed in a naturalistic atomic theory and held that the consequence of natural laws led to a deterministic universe. They denied karma, but upheld the atman. They lived in ascetic communities and existed in southern India until at least the 14th century.

Buddhism and Jainism

Jainism rejects the idea of a creator deity responsible for the manifestation, creation, or maintenance of this universe. According to Jain doctrine, the universe and its constituents (soul, matter, space, time, and principles of motion) have always existed. All the constituents and actions are governed by universal natural laws and an immaterial entity like God cannot create a material entity like the universe. Jainism offers an elaborate cosmology, including heavenly beings (devas), but these beings are not viewed as creators; they are subject to suffering and change like all other living beings, and must eventually die. Jains define godliness as the inherent quality of any soul characterising infinite bliss, infinite power, Kevala Jnana (pure infinite knowledge) and Perfect peace. However, these qualities of a soul are subdued due to karmas of the soul. One who achieves this state of soul through right belief, right knowledge and right conduct can be termed a god. This perfection of soul is called kevalin. A soul thus becomes a liberated soul – liberated of miseries, cycles of rebirth, world, karmas and finally liberated of body as well. This is called moksha.

Gautama Buddha rejected the existence of a creator deity, refused to endorse many views on creation and stated that questions on the origin of the world are not ultimately useful for ending suffering. Buddhism instead emphasises the system of causal relationships underlying the universe, pratītyasamutpāda, which constitute the dhamma and source of enlightenment. No dependence of phenomena on a supernatural reality is asserted in order to explain the behaviour of matter.

Philosophers and ancient texts

Ajita Kesakambali was a materialist philosopher. He is mentioned in the Samaññaphala Sutta. He rejected gods, an afterlife and karma. Payasi is a character, referred to as a prince, who appears in the Buddhist text Digha Nikaya in the Payasi Sutta. He didn't believe in rebirth or karma. He debated Kassapa, a disciple of Buddha, and lost according to Buddhist sources.

Jabali's speech from the Ramayana

In the Hindu epic Ramayana (Ayodhya Khanda), when Bharata goes to the forest to convince Rama to return home, he was accompanied by a sophist called Jabali ("जाबालिः"). Jabali uses nihilistic reasoning to convince Rama. He also says that rituals are a waste of food and scriptures were written by smart men so that people will give alms. But Rama calls him a deviant from the path of dharma ("धरमपथात"), refuses to accept his "nastika" views and blame his own father for taking Jabali into service. He also equates the Buddha to a thief. On hearing Rama's retort, Jabali retracts his statements, saying that he was merely arguing like a nihilist. However, these verses referring to the Buddha are considered a later interpolation, as those verses use a different metre.

The Carvaka incident in the Mahabharata

A character described as a Carvaka briefly appears in the Mahabharata (in the Shanti Parva). As Yudhishthira enters the city of Hastinapur, a brahmin, referred to as Carvaka, accuses him of killing his own kinsmen and says that he would suffer for it. The accuser is revealed to a rakshasa in disguise, who was a friend of Duryodhana. He had existed since the Satya Yuga by virtue of a boon from the god Brahma, that he could only be killed when he is showing contempt towards brahmins. He was killed by other brahmins by the chanting of sacred hymns and Yudhishthira was assured that his actions were within the kshatriya code. This event may be a possible denigration of the Carvaka philosophy.

Medieval India

In the 9th century CE, Jain philosopher Jinasena wrote the Mahapurana. The book contains the following often quoted words,

Some foolish men declare that a creator made the world. The doctrine that the world was created is ill-advised, and should be rejected. If God created the world, where was he before creation? If you say he was transcendent then, and needed no support, where is he now?

This quote was also featured later in Carl Sagan's book, Cosmos. In the 14th century, philosopher Madhavacarya wrote the Sarvadarśanasaṅ̇graha, which is a compilation of all Indian philosophies, including Carvaka, which is described in the first chapter.

Modern India

19th century

Between 1882 and 1888, the Madras Secular Society published a magazine called The Thinker (Tattuvavivesini in Tamil) from Madras. The magazine carried articles written by anonymous writers and republished articles from the journal of the London Secular Society, which the Madras Secular Society considered itself affiliated to.

20th century

The Yukthivadi in 1929 was the first atheist/rationalist magazine published in Malayalam.

Periyar E. V. Ramasamy (1879 - 1973) was an atheist and rationalist leader of Self-Respect Movement and Dravidar Kazhagam. His views on the irreligion are based on the eradication of the caste system, religion must be denied to achieve the obliteration of caste system.

Vinayak Damodar Savarkar (1883 –1966) was an eminent Hindu nationalist leader of the Indian independence movement. He was also an atheist and a staunch rationalist who disapproved of orthodox Hindu belief, dismissing cow worship as superstitious. Being Hindu, for him, was a cultural and political identity.

Meghnad Saha (1893 – 1956) was an atheist astrophysicist best known for his development of the Saha equation, used to describe chemical and physical conditions in stars.

Jawaharlal Nehru (1889–1964), India's first Prime Minister was a self-described scientific humanist. He wrote in his autobiography, Toward Freedom (1936), about his views on religion and superstition.

Bhagat Singh (1907-1931), an Indian revolutionary and socialist nationalist who was hanged for using violence against British government officials, was a staunch atheist. He laid out his views in the essay Why I Am an Atheist, written in jail shortly before his execution.

Goparaju Ramachandra Rao (1902-1975), better known by his nom de guerre "Gora," was a social reformer, anti-caste activist, atheist and desciple of Mahatma Gandhi. He and his wife, Saraswathi Gora (1912-2007) who was also an atheist and social reformer, founded the Atheist Centre in 1940. The Atheist Centre is an institute working for social change. Gora expounded his philosophy of positive atheism as a way of life. He later wrote more about positive atheism in his 1972 book, Positive Atheism. Gora also organised the first World Atheist Conference in 1972. Subsequently, the Atheist Centre has organised several World Atheist Conferences in Vijayawada and other locations.

Khushwant Singh (1915-2014), a prominent and prolific writer, of Sikh extraction, was avowedly non-religious.

In 1997, the Federation of Indian Rationalist Associations was founded.

21st century

E.A.Jabbar and M. M. Akbar during the debate, Adv Anil Kumar,President Kerala Yukthivadi Sangham in middle
 
Declaration of Ex-Muslims day by Ex-Muslims of Kerala, From left 1.Jazla Madassery,2.Mini,3.Liyakkathali CM,4.Arif Hussain,5.Shafeeq
 
Askar Ali (Hudavi),a 24 year old Muslim maulvi from Kerala who was also an imam at a mosque, who left Islam and become a rationalist and freethinker.He faced murder attempts from Muslims and goondas of Islamic ummah of his native place Malappuram.His video has got one million views on YouTube in a week it has published

Amartya Sen (1933-), an Indian economist, philosopher and Nobel laureate, is an atheist and he holds that this can be associated with one of the atheist schools in Hinduism, the Lokayata.

Sunday Sapiens, the successor of Maharashtra Rationalist Association, is actively involved in developing scientific temper and eradicating superstition.

In 2008, the website Nirmukta was founded. It later became an organisation aiming to promote free thought and secular humanism in India.

In 2009, historian Meera Nanda published a book entitled "The God Market". It examines how Hindu religiosity is gaining more popularity among the rising middle class, as India is liberalising the economy and adopting globalisation.

In March 2009, in Kerala, a pastoral letter addressing the laity was issued by the Kerala Catholic Bishops' Council urging the members to not vote for political parties which advocate atheism. In July 2010, another similar letter was issued.

On 10 March 2012, Sanal Edamaruku investigated a so-called miracle in Vile Parle, where a Jesus statue had started weeping and concluded that the problem was caused by faulty drainage. Later that day, during a TV discussion with some church members, Edamaruku accused the Catholic Church of miracle-mongering. On 10 April, Angelo Fernandes, President of the Maharashtra Christian Youth Forum, filed a police complaint against Edamaruku under the Indian Penal Code Section 295A. In July while on a tour in Finland, Edamaruku was informed by a friend that his house was visited by the police. Since the offence is not bailable, Edamaruku stayed in Finland.

On Friday 7 July 2013, the first "Hug an Atheist Day" was organised in India by Nirmukta. The event aimed to spread awareness and reduce the stigma associated with being an atheist.

On 20 August 2013, Narendra Dabholkar, a rationalist and anti-superstition campaigner, was shot dead by two unknown assailants, while he was out on a morning walk.

On 9th Jan 2021, E.A.Jabbar, freethinker, atheist, and rationalist from Kerala and Islamic preacher M.M. Akbar were engaged in a debate on Quran. Both sides claimed to have defeated the other debater even as there was no clear verdict. Manoj John, an internationally reputed atheist activist, was dragged into a controversy after Liyakhathali CM alleged that the former took money from M.M. Akbar to tilt the debate in Akbar's favour. International atheist organisations immediately conducted a four-month long investigation and absolved Manoj John of having any link with Islamic organisations or having accepted money from them. It later turned out to be a false allegation to tarnish Manoj John's rising reputation and recognition in the global freethought movement, showing at the same time the dissaray among the irreligion camp in Kerala state of India.

In August 2021, Abdul Khader Puthiyangadi, an Indian citizen, a rationalist from Kerala, He was arrested by UAE police in 2021 without bail and sentenced to prison in UAE for 3 years for criticizing Islam on social media in his native language Malayalam. Liyakhathali CM, who was working towards the release of Puthiyangadi without authorisation by the latter's family, has been accused of unauthorised and intransparent fund collection for this purpose by many secular activists but the allegations have not yet been proven.

On 10 January 2022, ex-Muslim rationalist Aneesh Jasy from Tamil Nadu was arrested without bail over his Facebook posts against Islam. 

Rise of ex-Muslims of Kerala

In 2021 in Kerala, several ex-Muslims formed an organisation called Ex-Muslims of Kerala. It is an organisation founded in 2021 by E. A. Jabbar, Liyakkathali CM, Arif Hussain, and a few others who left Islam in Kerala. The organisation gives support to those who left Islam, a minority that is facing persecution from the Islamic community, just because they left the religion. The organisation conducts debates with Islamic scholars and fundamentalists on various topics. Ex-Muslim of Kerala observes 9 January as ex-Muslim day, by conducting seminars on atheism and Islam.

Legal status, rights and laws

Atheism and irreligion are not officially recognised in India. Apostasy is allowed under the right to freedom of religion in the Constitution, and the Special Marriage Act, 1954 allows the marriage of people with no religious beliefs, as well as non-religious and non-ritualistic marriages. However, there are no specific laws catering to atheists and they are considered as belonging to the religion of their birth for administrative purposes. In forms, the box in which you need to fill in 'caste' and 'religion' is still present in a lot of forms. Some of these boxes on forms are also compulsory, and you do not always have the option of leaving them empty. The closest option you get is 'Choose not to say' or 'Other' as an answer to these boxes.

Ravi Kumar, an atheist from Haryana is another person who is struggling and fighting to be officially and legally irreligious and caste-less in India. He went to court to declare him officially atheist and he got one certificate in which it was mentioned that he had "No Caste, No Religion, & No God". Later, Justice Tejinder Singh Dhindsa of the Punjab and Haryana High Court said they had exceeded their authority and asked heim to return the certificate; he refused to do so. The Fatehabad district authorities who issued the cewrtificate wthdrew it in April 2019. Kumar plans to continue his quest to be officially declared an atheist.

Sneha Parthibaraja, a lawyer from Vellore was the first citizen in India to get an official 'no religion, no caste' certificate. She won this right on February 5, 2019, after a 9-year court battle. Indian actor Kamal Haasan, who is known for his atheism, congratulated her on Twitter for this achievement.

Hate speech laws and irreligion

Notable verdicts

On 29 October 2013, the Bombay High Court judged in favour of an atheist school teacher from Nashik. Sanjay Salve had been employed by the state-funded Savitribai Phule Secondary School since 1996. In June 2007, during a prayer session, Salve didn't fold his hands during the pledge or prayer. The school management called this indiscipline and refused him a higher pay grade in 2008 when Salve became eligible for it. Salve sought legal recourse citing the article 28 (a) of the Constitution which states "no person attending any educational institution recognised by the State or receiving aid out of State funds shall be required to take part in any religious instruction that may be imparted in such institution or to attend any religious worship that may be conducted in such institution". The court ruled in Salve's favour and directed the school to release his dues by 31 January 2014.

On 23 September 2014, the Bombay High Court declared that the government cannot force a person to state a religion on any document or form. The court also stated any citizen has the right to declare that he/she doesn't belong to any religion. The decision came in response to a Public Interest Litigation (PIL) filed by Ranjit Mohite, Kishore Nazare and Subhash Ranware, representing an organisation called Full Gospel Church of God, after the Maharashtra state printing press refused to issue them a gazette notification stating that they belonged to no religion. The petitioners stated that the organisation had 4000 members, and that they believe in Jesus Christ but they do not follow Christianity or any religion. Responding to the petition, the Maharashtra and the central governments had stated that "no religion" cannot be treated as a religion on official forms. The court cited the Article 25 of the Constitution, which guarantees right to freedom of conscience, while passing the verdict.

Persecution and attacks

Narendra Nayak, an advocate of atheism, has claimed to have been attacked three times and had his scooter damaged twice, with one of the attacks leaving him with head injuries. This compelled him to take self-defence lessons and carry a nunchaku. Megh Raj Mitter's house was surrounded by a mob after he debunked the Hindu milk miracle, forcing him to call the police.

On 15 March 2007, a bounty of 700,000 (equivalent to 1.8 million or US$24,000 in 2020) was announced on atheist Bangladeshi author Taslima Nasrin, while living in India, by a Muslim cleric named Maulana Tauqeer Raza Khan for allegedly writing derogatory statements about Prophet Mohammad in her work. In December 2013, an FIR was filed against Nasrin in Bareilly by a cleric named Hasan Raza Khan, for hurting religious sentiments. Nasrin had allegedly tweeted on Twitter that "In India, criminals who issue fatwas against women don't get punished." Raza Khan said that by accusing clerics of being criminals, Nasrin had hurt religious sentiments.

On 2 July 2011, the house of U. Kalanathan, secretary of the Kerala Yukthivadi Sangham, was attacked in Vallikunnu after he suggested on television that the temple treasures of Padmanabhaswamy Temple should be used for public welfare. On 20 August 2013, Narendra Dabholkar, a rationalist and anti-superstition campaigner, was assassinated.

On 16 February 2015, rationalist Govind Pansare and his wife were attacked by unknown gunmen. He later died from the wounds on 20 February. On 30 August 2015, M. M. Kalburgi, a scholar and rationalist, was shot dead at his home. He was known for his criticism of superstition and idol worship. Soon afterwards, another rationalist and author, K. S. Bhagwan, received a threatening letter. He had offended religious groups by criticizing the Gita.

In March 2017, 31-year-old A Farooq, an Indian Muslim youth from Coimbatore who became an atheist, was killed by members of a Muslim radical group.

Demographics

Indian government census

The Indian census does not explicitly count atheists. In the 2011 Census of India, the response form required the respondent to choose from six options under religion. The "Others" option was meant for minor or tribal religions as well as atheists and agnostics.

The religion data from 2011 Census of India was released in August 2015. It revealed that about 2,870,000 people had stated no religion in their response, about 0.27% of the nation's population. However, the number included atheists, rationalists and also those who believed in a higher power. K. Veeramani, a Dravidar Kazhagam leader, said that it was the first time the number of non-religious people was recorded in the census. However, he added that he believed that the number of atheists in India was actually higher as many people don't reveal their atheism out of fear.

Different surveys

World Values Survey (2006)

According to the 2006 World Values Survey, conducted by the Dentsu Communication Institute Inc, Japan Research Center (2006), 6.6% of Indians stated that they had no religion.

WIN-Gallup Global Index of Religion and Atheism

According to the 2005 Global Index of Religion and Atheism report from WIN-Gallup, 87% of Indians were religious and 4% called themselves atheists. According to the 2012 report by the same organisation, 81% of Indians were religious, 13% were non-religious, 3% were convinced atheists and 3% were unsure or did not respond.

Worldviews and Opinions of Scientists in India (2007)

In 2007, a survey was conducted by the Institute for the Study of Secularism in Society and Culture of the Trinity College with the help of Center for Inquiry (India) called Worldviews and Opinions of Scientists in India. 1100 scientists surveyed from 130 institutes. Most of them identified themselves as secular (59%) or somewhat secular (16%) but refused to be labelled irreligious. 83% defined secularism, as it appears in the Indian constitutions, as the separation of state and religion. But, 93% also defined it as tolerance of other religious philosophies. 20% equated secularism to atheism. Only 11% called themselves completely not spiritual. However, 8% reportedly said they would refuse to do stem cell research based on religious or moral convictions. Y. S. Rajan commented on this saying that most Indians don't feel there is a conflict between science and religion. Other the hand, Innaiah Narisetti, chairman of Centre for Inquiry (India) and Pushpa Bhargava, the former director of the Centre for Cellular and Molecular Biology, pointed out the lack of scientific temper among Indian scientists.

Religion Among Scientists in an International Context (2014)

In a survey conducted by Elaine Howard Ecklund of Rice University, it was found that:


India United Kingdom
Scientists who identified as nonreligious 6% 65%
Scientists who attend religious services on a regular basis (once a month or more) 32% 12%
Scientists who never attend religious services 19% 68%
Scientists who believe that there are basic truths in many religions 73% 49%
Scientists who believe in God 27% 11%
Scientists who believe in a higher power of some kind 38% 8%

The ongoing study has surveyed 1,581 scientists from UK and 1,763 from India.

Operator (computer programming)

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