Historical Linguistics: Sound Laws, Grammaticalization, Reconstruction and Contact

This chapter answers Section XH3.3 of XH3 Linguistics, "Historical Linguistics (Language Change)", one of the six optional sections of the Humanities and Social Sciences (XH) paper, chosen at application. The heading names sound changes and sound laws (Grimm's Law, Verner's Law), grammar and meaning change (grammaticalization and semantic change), comparative reconstruction of ancestral languages, and language contact including borrowing. The chapter builds from the regularity of sound change to the two classic Germanic sound laws, then to how grammars and word meanings drift, how the comparative method rebuilds an unattested proto-language from its daughters, and how contact plants loanwords that the regular laws help us detect.

1. Sound change and the regularity principle

Languages change at every level, but sound change is the engine historical linguistics leans on, because it is the most regular. The Neogrammarian school in late nineteenth-century Leipzig proposed that sound laws admit no exceptions: a sound change applies to every word in the language that meets its phonetic conditions, mechanically, without regard to meaning. A change may be unconditioned (every instance of a sound changes everywhere) or conditioned (it changes only in a stated environment, for example only between vowels or only before a front vowel). The apparent exceptions are not random; they are the work of other regular laws, of analogy, or of borrowing.

  • Assimilation: a sound becomes more like a neighbour (Latin in- + possibilis > impossibilis). Dissimilation: two similar sounds become less alike. Lenition (weakening, e.g. a stop to a fricative) and its opposite fortition.
  • Metathesis: two sounds swap order (Old English brid > bird). Epenthesis: a sound is inserted. Deletion: a sound is lost, as apocope (word-final loss) or syncope (internal loss).
  • Vowels change too: umlaut (a vowel fronted by a following front vowel, giving mouse/mice), ablaut (grammatical vowel gradation, sing/sang/sung), and large chain shifts such as the English Great Vowel Shift.

Analogy is the other great force of change, and it often repairs what sound change disturbs. Speakers reshape an irregular form on the model of a regular pattern: analogical levelling replaced the older past tense holp with helped, and a child's goed for went shows the same pull. Where sound change is blind to meaning, analogy is sensitive to it, extending a pattern across a whole paradigm, so the two forces constantly pull against each other.

🎯 Why regularity matters
Regularity is the foundation of the whole discipline. If sound change were sporadic, correspondences between languages would be coincidence; because it is regular, a correspondence repeated across many words is evidence of shared descent, and that is exactly what the comparative method exploits.

2. Grimm's Law: the First Germanic Consonant Shift

Grimm's Law, set out by Jacob Grimm in 1822 (and foreshadowed by Rasmus Rask), describes how the Proto-Indo-European (PIE) stop consonants shifted as Proto-Germanic broke away from the rest of Indo-European. It is a chain shift in three series, so each class of stops moved into the slot the next had vacated. This is why Germanic words look so different from their Latin, Greek or Sanskrit cousins while still being regular correspondents of them.

The three series of Grimm's Law (PIE to Proto-Germanic)
PIE soundBecomes in GermanicExample (Latin — English)
Voiceless stops p, t, kVoiceless fricatives f, th, hpater — father, tres — three, cornu — horn
Voiced stops b, d, gVoiceless stops p, t, kdecem — ten, genu — knee
Voiced aspirates bh, dh, ghVoiced stops b, d, gfrater (bh) — brother, foris (dh) — door

Latin preserves the older PIE stops, so a Latin word is a convenient stand-in for the PIE form. In pater > father both p and t shift (p to f, t to th). In decem > ten the d becomes t, and the k becomes h (which English later lost in ten). Crucially, Grimm's Law touches only stops: nasals (m, n), liquids (l, r) and vowels pass through unchanged, which is why mater keeps its m in mother and the n of noct- survives in night.

📖 A chain, not a collision
Jacob Grimm, of the fairy-tale Brothers Grimm, set the law out in his 1822 grammar, a few years after Rasmus Rask had noticed the correspondences. On the usual account, the three series moved as a chain: as the voiced stops shifted into the voiceless slot, the old voiceless stops had already left it by becoming fricatives, so no two series ever collapsed into one and the system stayed fully distinct.

3. Verner's Law and other refinements

Grimm's Law had a stubborn set of exceptions: sometimes a PIE voiceless stop ended up as a Germanic voiced fricative instead of the voiceless one Grimm predicts. In 1875 Karl Verner showed these were not exceptions at all but a second regular law. Verner's Law: the voiceless fricatives produced by Grimm's Law (and inherited s) became voiced (typically between vowels) when the PIE word accent did not fall on the immediately preceding syllable. Once the Germanic accent later shifted uniformly to the first syllable, the original conditioning vanished from view, which is why the pattern looked chaotic until Verner restored the old accent placement.

💡 Father versus brother
PIE *bhréh2tēr 'brother' carried its accent on the first syllable, so the medial t became a voiceless th (Proto-Germanic *brōþēr). PIE *ph2tḗr 'father' carried its accent on the second syllable, leaving the syllable before the t unaccented, so Verner's Law voiced it (Proto-Germanic *fadēr). The same PIE t gives different Germanic consonants purely because the accent sat in different places.

The voiced z created by Verner's Law later became r in North and West Germanic (rhotacism), the source of the s/r alternation in was/were. Two more named laws are worth knowing. Grassmann's Law (dissimilation of aspirates) in Sanskrit and Greek deaspirates the first of two aspirated consonants in successive syllables. Rhotacism also operated in Latin (honos > honor). Each shows the same moral: an apparent irregularity usually dissolves into a further regular rule.

4. Grammaticalization and semantic change

Grammaticalization (a term from Antoine Meillet, 1912) is the process by which a lexical word becomes a grammatical marker, or a grammatical item becomes still more grammatical, along the cline content word > function word > clitic > affix. It is accompanied by semantic bleaching (loss of concrete meaning), phonetic erosion (shortening) and decategorialization. English will (once a verb meaning 'want') became a future auxiliary; the motion phrase going to became the future marker gonna; the Romance adverb suffix -ment(e) comes from Latin mente 'with the mind'. The process is held to be largely unidirectional, the reverse (degrammaticalization) being rare.

Semantic change reshapes word meanings. The main patterns are broadening (meaning widens: holiday from 'holy day' to any day off), narrowing (meaning shrinks: meat once meant food in general, deer once meant any animal, hound any dog), amelioration (meaning improves: knight from 'servant/boy', nice from Latin nescius 'ignorant'), and pejoration (meaning worsens: silly from Old English sǣlig 'blessed, happy', villain from 'farm worker'). The usual mechanisms are metaphor (grasp an idea) and metonymy (the crown for the monarchy).

ℹ️ Layering: old and new side by side
A single function can be grammaticalized more than once, leaving layering — older and newer markers of the same meaning in use together. English marks the future with shall, will and going to at the same time, each caught at a different point on the one journey from lexical verb to pure tense marker.

5. The comparative method and reconstruction

The comparative method reconstructs an unrecorded parent language from its descendants. Sir William Jones's 1786 observation that Sanskrit, Greek and Latin seemed to spring from a common source is commonly taken as its starting point. The method runs in steps:
(1) assemble cognate sets — words of similar form and meaning across the daughter languages;
(2) establish the regular sound correspondences they display;
(3) reconstruct the proto-sound for each correspondence, writing the reconstructed form with an asterisk (*);
(4) check that the reconstructed system is phonetically natural and internally consistent.

  • Majority and directionality criteria: where daughters disagree, the reconstruction prefers the sound most of them show, but naturalness overrides a bare majority — a change attested as common and one-way (such as k > ch before a front vowel) is reconstructed in that direction even against the count.
  • Internal reconstruction uses alternations within one language (such as Verner-type pairs) to recover an earlier stage without comparing other languages.
  • Pitfalls: chance resemblances, onomatopoeia and borrowings can mimic cognates. Only a correspondence that recurs regularly across many sets counts as evidence of common descent.
ℹ️ Family tree and wave model
Relationships are usually drawn as a family tree (the Stammbaum of August Schleicher), in which every split is clean. But shared features often spread across branches after they have separated, which the wave model (Johannes Schmidt) captures better. The two are complementary: the tree shows descent, the wave shows later diffusion by contact.

6. Language contact and borrowing

When speakers of different languages are in contact, features pass between the languages. The commonest is lexical borrowing — a loanword adopted and reshaped to the recipient's sound system (nativization). A calque (loan translation) copies the structure rather than the sounds, translating each part (English skyscraper reappears as a part-by-part translation in many languages; loanword itself calques German Lehnwort). Borrowing is ranked by a rough borrowability hierarchy: nouns and other content words are borrowed most readily, function words and bound morphology least.

Directions of contact influence
TermMeaning
SubstratumInfluence of a displaced or shifted-from language on the dominant one
SuperstratumInfluence of an incoming dominant language on a retained local one
AdstratumMutual influence between neighbouring languages of comparable status
⚠️ Sound laws unmask loanwords
A word that failed to undergo a sound change it should have is a clue that it entered the language after the change had stopped operating — that is, it was borrowed. English paternal keeps its p and t because it came from Latin long after Grimm's Law; the inherited cognate is father. So the regular laws are the very tool that separates native words from loans.

Prolonged, intense contact can make even unrelated languages converge in structure, producing a linguistic area (Sprachbund) in which neighbours come to share features by diffusion rather than by descent. South Asia is the classic case: retroflex consonants and verb-final order recur across the Indo-Aryan, Dravidian and Munda families, a convergence taken up further in the typology chapter.

Key takeaways

  • Sound change is regular (the Neogrammarian principle): a sound law applies to every eligible word, conditioned or unconditioned. Apparent exceptions come from other laws, analogy or borrowing. Types include assimilation, dissimilation, lenition, metathesis, deletion, umlaut and ablaut.
  • Grimm's Law shifts PIE stops in three series: voiceless stops to fricatives (p,t,k > f,th,h), voiced stops to voiceless (b,d,g > p,t,k), voiced aspirates to voiced stops (bh,dh,gh > b,d,g). It affects only stops, not nasals, liquids or vowels.
  • Verner's Law explains Grimm's exceptions: Grimm's voiceless fricatives (and s) became voiced when the PIE accent was not on the immediately preceding syllable; z later became r (rhotacism). Father versus brother shows the same PIE t giving different Germanic consonants by accent placement.
  • Grammaticalization moves a word down the cline content word > function word > clitic > affix with bleaching and erosion, largely unidirectionally (will, gonna, -mente). Semantic change takes four main paths: broadening, narrowing, amelioration and pejoration, via metaphor and metonymy.
  • The comparative method reconstructs a proto-language from cognate sets and their regular sound correspondences, writing proto-forms with an asterisk and using majority with naturalness and directionality. Internal reconstruction uses one language's alternations; chance, onomatopoeia and borrowing are pitfalls.
  • Contact spreads features: loanwords (nativized) and calques (loan translations), ranked by a borrowability hierarchy with content words most borrowable. Influence is substratum, superstratum or adstratum. A word that skipped an expected sound change is probably a loan.

Practice questions (16)

Attempt each one before opening the answer. Every explanation names the tempting wrong option as well as the right one, because that is where marks are lost.

  1. The Neogrammarian hypothesis about sound change is best summarised by which statement?

    1. Sound change spreads gradually from one word to the next, reaching only those particular words that a speech community happens to find socially salient
    2. Sound laws are exceptionless, applying mechanically to every word that meets their phonetic conditions
    3. Sound change is driven mainly by the meanings of words rather than by their phonetic shape
    4. Sound change happens only through contact with a neighbouring language, never from within
    Show answer

    Answer: B — Sound laws are exceptionless, applying mechanically to every word that meets their phonetic conditions

    The Neogrammarians held that a sound law is exceptionless and phonetically conditioned: it applies to every word meeting its conditions, regardless of meaning. Word-by-word spread describes the later idea of lexical diffusion, not the Neogrammarian position; meaning-driven change and contact-only change both contradict the regularity claim.

  2. Old English 'brid' became Modern English 'bird', with the vowel and the r swapping order. This kind of sound change is called:

    1. Assimilation, in which a sound takes on a feature of a neighbouring sound
    2. Epenthesis, in which an extra sound is inserted into a word
    3. Metathesis, in which two sounds exchange their positions
    4. Apocope, in which a sound at the end of a word is lost
    Show answer

    Answer: C — Metathesis, in which two sounds exchange their positions

    A reordering of two sounds is metathesis, exactly what 'brid' to 'bird' shows. Assimilation changes a sound's features without moving it; epenthesis adds a sound; apocope deletes a final sound. Nothing is added or deleted here, only reordered, which rules the others out.

  3. Under Grimm's Law, the Proto-Indo-European voiceless stops p, t, k developed in Proto-Germanic into which class of sounds?

    1. Voiceless fricatives such as f, th and h
    2. Voiced aspirated stops such as bh, dh and gh
    3. Nasal consonants such as m, n and the velar nasal
    4. Voiced stops such as b, d and g
    Show answer

    Answer: A — Voiceless fricatives such as f, th and h

    The first series of Grimm's Law turns PIE voiceless stops into voiceless fricatives (p>f, t>th, k>h), as in pater>father. The voiced-stop answer describes what the voiced aspirates become, not the voiceless stops; nasals are untouched by Grimm's Law; and voiced aspirates are an input to the law, not an output of this series.

  4. Which Latin–English pair has an initial consonant that was changed by Grimm's Law?

    1. Latin 'mater' and English 'mother', where initial m corresponds to initial m
    2. Latin 'regula' and English 'rule', where initial r corresponds to initial r
    3. Latin 'persona' and English 'person', where initial p corresponds to initial p
    4. Latin 'decem' and English 'ten', where initial d corresponds to initial t
    Show answer

    Answer: D — Latin 'decem' and English 'ten', where initial d corresponds to initial t

    PIE/Latin voiced d becomes voiceless t in Germanic (decem>ten), a textbook Grimm correspondence. The m–m pair is unchanged because nasals are outside the law; r–r likewise. 'Person' keeps its p because it is a later Latin loanword that entered English long after Grimm's Law had ceased to operate, so it is not an inherited correspondence at all.

  5. Grimm's Law shifts PIE stops only; it does not affect nasals, liquids or vowels. Consider the word-initial consonants, as pronounced in early Germanic (the k of knee was still sounded), in these five PIE/Latin–English pairs: pater–father, mater–mother, tres–three, genu–knee, nokwt-–night. How many of the five initial consonants are shifted by Grimm's Law? Give the number only.

    Numerical answer — type the value.

    Show answer

    Answer: 3

    Shifted: p>f (father), t>th (three), g>k (knee) — three stops. Not shifted: m in mother and n in night are nasals, which Grimm's Law leaves alone. So three of the five initial consonants shift. Counting the nasals as shifts is the usual slip.

  6. In the words 'father' and 'brother' the medial consonant goes back to the same PIE *t, yet it was voiced in one and stayed voiceless in the other at the Proto-Germanic stage. What conditioned this difference?

    1. The total number of syllables contained in each of the two words, with the longer of the two words resisting the voicing process
    2. The placement of the PIE word accent relative to the consonant, through Verner's Law
    3. The gender of the noun, masculine kin terms keeping the voiceless sound
    4. Borrowing of one word from Latin and inheritance of the other from PIE
    Show answer

    Answer: B — The placement of the PIE word accent relative to the consonant, through Verner's Law

    Verner's Law voiced the Grimm fricative when the PIE accent did not fall on the syllable immediately before it. 'Father' (PIE accent on the second syllable) was voiced; 'brother' (accent on the first syllable) was not. Syllable count and gender are irrelevant to Verner's Law, and both words are inherited, not borrowed, so the Latin-loan explanation fails.

  7. Which of the following statements about Grimm's Law and Verner's Law are correct?

    1. Grimm's Law is a chain shift affecting the Proto-Indo-European stop consonants
    2. Verner's Law accounts for cases where Grimm's Law alone predicts the wrong consonant
    3. The voiced z produced by Verner's Law later became r in North and West Germanic
    4. Both laws apply equally to stops, nasals, liquids and vowels without restriction
    Show answer

    Answer: A — Grimm's Law is a chain shift affecting the Proto-Indo-European stop consonants; B — Verner's Law accounts for cases where Grimm's Law alone predicts the wrong consonant; C — The voiced z produced by Verner's Law later became r in North and West Germanic

    Grimm's Law is a three-series chain shift of PIE stops; Verner's Law resolves its apparent exceptions by reference to accent; and Verner's z rhotacised to r (the s/r of was/were). The claim that both laws apply to all classes of sounds is false: Grimm's Law affects only stops, and Verner's Law operates on the fricatives Grimm produced, not on nasals, liquids or vowels.

  8. Grammaticalization is best defined as the process by which:

    1. A lexical word gradually turns into a grammatical marker such as an auxiliary or an affix
    2. A grammatical affix is borrowed wholesale from a more prestigious language into another, taking the place of a native one
    3. Two sounds in successive syllables dissimilate so that one of them loses a feature
    4. A word meaning becomes more favourable over time, improving its social connotation
    Show answer

    Answer: A — A lexical word gradually turns into a grammatical marker such as an auxiliary or an affix

    Grammaticalization is the shift of a content word to a grammatical function (content word > function word > clitic > affix), with semantic bleaching and phonetic erosion. Wholesale borrowing of an affix is contact, not grammaticalization; dissimilation is a sound change; and a meaning becoming more favourable is amelioration, a type of semantic change.

  9. The English future marker 'gonna', from the motion phrase 'going to', is a classic example of:

    1. A calque, because the phrase was translated part by part from another language
    2. Metathesis, because the sounds of the original phrase have swapped their order
    3. Grammaticalization, with semantic bleaching of the motion sense and phonetic erosion
    4. Narrowing, because the word now refers to a much smaller set of things than before
    Show answer

    Answer: C — Grammaticalization, with semantic bleaching of the motion sense and phonetic erosion

    'Going to' loses its literal 'movement' sense (bleaching) and shortens to 'gonna' (erosion) as it becomes a tense marker — the signature of grammaticalization. It is not translated from another language, so it is not a calque; its sounds are reduced, not reordered, so not metathesis; and it is a grammatical shift, not a narrowing of reference.

  10. The word 'meat' once meant food of any kind, but now means animal flesh only. This is an instance of:

    1. Broadening, because the word now covers a wider range of referents than before
    2. Amelioration, because the word has acquired a more positive connotation
    3. Pejoration, because the word has acquired a more negative connotation
    4. Narrowing, because the word now covers a smaller range of referents than before
    Show answer

    Answer: D — Narrowing, because the word now covers a smaller range of referents than before

    Going from 'food in general' to 'animal flesh' shrinks the set of referents, which is narrowing (compare 'deer' from 'any animal', 'hound' from 'any dog'). Broadening is the opposite. Amelioration and pejoration concern the positive or negative value of a word, not the breadth of its reference, which did not shift in value here.

  11. Consider these histories: P = 'silly' from Old English 'saelig' meaning blessed or happy, to its present sense; Q = 'knight' from a sense of servant or boy to its present sense; R = 'holiday' from 'holy day' to any day off work. Which of the labelled changes involve a shift in the positive-or-negative value of the word (amelioration or pejoration)?

    1. P, which moved from a favourable sense to an unfavourable one (pejoration)
    2. Q, which moved from a lowly sense to an elevated one (amelioration)
    3. R, which widened from a specific day to any day off (broadening)
    4. None of the three involves any change of meaning at all, only of pronunciation
    Show answer

    Answer: A — P, which moved from a favourable sense to an unfavourable one (pejoration); B — Q, which moved from a lowly sense to an elevated one (amelioration)

    'Silly' worsened in value (blessed to foolish) — pejoration; 'knight' improved in value (servant to noble warrior) — amelioration. Both are value shifts. 'Holiday' is a case of broadening, which is a change in breadth of reference, not in positive-or-negative value. The claim that none of the three involves any change of meaning is plainly false.

  12. In the comparative method, a reconstructed proto-form that is not directly attested in any text is conventionally written:

    1. In capital letters, to mark it as a protolanguage form
    2. With a preceding asterisk, as in *pater
    3. Inside square brackets, as a narrow phonetic transcription
    4. With a following question mark, to show it is a guess
    Show answer

    Answer: B — With a preceding asterisk, as in *pater

    An asterisk before the form (for example *pater) marks a reconstructed, unattested shape. Square brackets denote phonetic transcription of real utterances; capitals and a trailing question mark are not the standard convention for reconstructions.

  13. A cognate set gives the word-initial consonant in six related languages as: L1 k, L2 k, L3 ch, L4 ch, L5 ch, L6 ch. The change k > ch (palatalization) is common and one-way, while ch > k is not attested as a natural change. Using the directionality criterion, the proto-sound is reconstructed as *k. In how many of the six daughter languages has this proto-sound been preserved unchanged? Give the number only.

    Numerical answer — type the value.

    Show answer

    Answer: 2

    Although four of the six languages show ch, the naturalness and one-way direction of k > ch mean *k is reconstructed, not *ch. The proto-sound *k is preserved only in L1 and L2 (two languages); L3 to L6 underwent the palatalization. The trap is to pick the majority sound ch and answer 4, but directionality overrides a bare majority.

  14. A linguist recovers an earlier stage of a single language by studying the alternation between s and r within its own paradigms (as in was/were), without comparing it to any sister language. This technique is:

    1. The comparative method, because it reconstructs a proto-form from correspondences
    2. Lexical borrowing, because the alternating forms came from another language
    3. Internal reconstruction, because it uses alternations within one language
    4. Grammaticalization, because a lexical item is becoming a grammatical marker
    Show answer

    Answer: C — Internal reconstruction, because it uses alternations within one language

    Reconstructing an earlier stage from alternations inside a single language, with no sister language used, is internal reconstruction. The comparative method requires comparison across related languages, which is exactly what is excluded here. No borrowing or grammaticalization is involved; the s/r alternation is the residue of Verner's Law plus rhotacism.

  15. Which of the following are correctly described?

    1. A calque (loan translation) copies the structure of a foreign expression by translating it part by part
    2. On the borrowability hierarchy, bound inflectional morphology is borrowed more readily than nouns
    3. A loanword is typically nativized, reshaped to fit the recipient language's sound system
    4. Substratum influence is the effect of a displaced or shifted-from language on the dominant one
    Show answer

    Answer: A — A calque (loan translation) copies the structure of a foreign expression by translating it part by part; C — A loanword is typically nativized, reshaped to fit the recipient language's sound system; D — Substratum influence is the effect of a displaced or shifted-from language on the dominant one

    Calques translate structure part by part; loanwords are nativized to the recipient's phonology; substratum is the influence of the underlying, shifted-from language. The borrowability claim is reversed: content words such as nouns are borrowed most readily, while bound inflectional morphology is among the hardest to borrow.

  16. The English pair 'father' (inherited) and 'paternal' (from Latin) both go back to the same PIE root, yet 'paternal' keeps its p and t while 'father' shows f and th. Which inferences are sound?

    1. 'Paternal' did not undergo Grimm's Law, which is evidence that it entered English after the law had ceased to operate
    2. The regular sound laws can be used as a diagnostic to separate inherited words from loanwords
    3. Because the two words differ, they cannot share any common ancestor and the resemblance is pure chance
    4. 'Father' shows the effects of Grimm's Law because it was inherited through Proto-Germanic, where the law operated
    Show answer

    Answer: A — 'Paternal' did not undergo Grimm's Law, which is evidence that it entered English after the law had ceased to operate; B — The regular sound laws can be used as a diagnostic to separate inherited words from loanwords; D — 'Father' shows the effects of Grimm's Law because it was inherited through Proto-Germanic, where the law operated

    A word that escaped a sound change it should have undergone is a loan that arrived after the change stopped, so 'paternal' is a Latin borrowing; this makes the sound laws a diagnostic for loans; and 'father', being inherited, duly shows Grimm's Law. The chance-resemblance claim is false: the two words are a textbook doublet from one root, one inherited and one borrowed.