• Welcome to the new Internet Infidels Discussion Board, formerly Talk Freethought.

Language as a Clue to Prehistory

The rest of North America has a complicated pattern.

 Na-Dene languages -- speakers arrived in N America around 6,000 - 8,000 ya. Discontinuous: W Canada, SW US

 Proto-Algic language -- likely in the Columbian Plateau in NW US, around 7,000 ya. -- Algonquian, Ritwan

Ritwan is Wiyot, Yurok on the N California Coast

 Proto-Algonquian language - around 2,500 - 3,000 ya. E Canada, Colorado, Illinois-Michigan, East Coast from Virginia to Canada

Algonquian is split up by speakers of  Siouan languages and  Proto-Iroquoian language -- northern and southern branches (Cherokee) split around 3,500 - 3,800 ya.

The farthest south they got was the Köppen Dfa - Cfa boundary, roughly Virginia - Colorado.

 Prehistoric agriculture on the Great Plains and  Eastern Agricultural Complex and Initial formation of an indigenous crop complex in eastern North America at 3800 B.P | PNAS and Origins of Agriculture in Eastern North America on JSTOR

Did Iroquoian and Siouan speakers spread north with agriculture? Did they run into Algonquian speakers who got there first?
 
The tundra biome
The arctic is known for its cold, desert-like conditions. The growing season ranges from 50 to 60 days. The average winter temperature is -34° C (-30° F), but the average summer temperature is 3-12° C (37-54° F) which enables this biome to sustain life.

...
All of the plants are adapted to sweeping winds and disturbances of the soil. Plants are short and group together to resist the cold temperatures and are protected by the snow during the winter. They can carry out photosynthesis at low temperatures and low light intensities. The growing seasons are short and most plants reproduce by budding and division rather than sexually by flowering.

...
Animals are adapted to handle long, cold winters and to breed and raise young quickly in the summer. Animals such as mammals and birds also have additional insulation from fat. Many animals hibernate during the winter because food is not abundant. Another alternative is to migrate south in the winter, like birds do. Reptiles and amphibians are few or absent because of the extremely cold temperatures. Because of constant immigration and emigration, the population continually oscillates.
The Inuit people got around this low productivity of land by catching lots of fish and seals and the like.

It's an impressive feat, living in such a hostile climate with Paleolithic technology -- Old Stone Age technology. Neolithic technology is New Stone Age, with agriculture.
What kind of a fool would try to farm in Inuit territory? Your Victorian system of asessing technological "advancement" aside, most people who live up North now likewise depend on foraged resources to survive, more or less. The global market has just made different resources - lumber, petroleum, coal - more valuable in trade.
 
The Numbers List - I looked for patterns in number-name sets. Complete? (1 - 10) or incomplete?

There was a problem, however. One can be more confident that some protoform existed than that it did not exist. That is in part because lack of reconstruction may indicate instability rather than absence. Let us consider Indo-European, which is very well-studied.

"Foot" -- from *ped- -- preserved in Germanic, Italic, Celtic, Baltic, Greek, Armenian, Indo-Iranian, Tocharian, Anatolian, but not Slavic: Proto-Slavic has *stopa and *noga

"Hand" is much more difficult. Proto-Germanic *handuz, Proto-Italic *manus, Proto-Celtic *phlâmâ, Proto-Balto-Slavic *rankâ, Greek kheir, Armenian jerk', Proto-Indo-Iranian *jhastas, Tocharian A tsar, Tocharian B sar, (Anatolian) Hittite kessar, Luwian Issaris, Lycian izredi

From Greek, Armenian, Indo-Iranian, Tocharian, and Anatolian, one infers *ghesor- but it's been replaced like crazy in the other dialects.

Turning to numbers, '2' to '10' and '100' are well-preserved across Indo-Europeandom, but '1' and '1000' are less well-preserved

1
*oinos -- Germanic, Italic, Celtic, Balto-Slavic, Anatolian?
*oikos -- Indo-Iranian -- likely derived from *oinos
*sem -- Greek, Armenian, Tocharian, Anatolian?

1000
Proto-Germanic *thûsundî, Latin mille, (Irish, Welsh < Latin), Proto-Balto-Slavic *tûsantis, Greek khilioi, (Armenian < Iranian), Proto-Indo-Iranian *sajhasram, Tocharian A wälts, Tocharian B yaltse

*tuHsont- -- Germanic, Balto-Slavic
*smgheslom -- Indo-Iranian
*smih2gheslih2 -- Italic
*gheslom -- Greek

The II form can be interpreted as *sm-gheslom and the Italic one as *smih2-gheslih2 with a -ih2 (>î) suffix, with the *sm- meaning "one, single", giving

*gheslom -- Italic, Greek, Indo-Iranian
 
On the subject of numbers, most Slavic languages have an odd kind of agreement.

2 to 4: genitive singular: of X
5 to 10 and greater: genitive plural: of X's

Slovenian uses its dual (two-things plural) for 2, and Bulgarian, lacking noun cases, does what English does: use its plural for numbers greater than 1.

Some higher numbers are exceptions. If 21 is "twenty and one", then it is with X, and if it is "one and twenty", then it is with "of X's".

English does:
1: singular: X
2 and greater: plural: X's

Some languages have plural markers but neverthless use singular forms with numbers, like Hungarian and Turkic languages.
 
Indo-European:
  • Germanic:
    • West: Afrikaans, Dutch, English, Frisian, German (Luxembourgish, Yiddish)
    • North: Danish, Faroese, Icelandic, Norwegian, Swedish
  • Celtic: Irish, Scots Gaelic, Welsh
  • Latin/Romance: Latin, (Romance) Catalan, Corsican, French, Galician, Italian, Portuguese, Romanian, Spanish
  • Slavic:
    • South: Bulgarian, Macedonian, Serbo-Croatian (Bosnian, Croatian, Serbian), Slovenian
    • West: Czech, Polish, Slovak, Sorbian
    • East: Belarusian, Russian, Ukrainian
  • Baltic: Lithuanian, Latvian
  • Albanian
  • Greek
  • Armenian
  • Indo-Iranian:
    • Indic: Sanskrit, (present-day) Assamese, Bengali, Bhojpuri, Dogri, Gujarati, Hindi, Konkani, Maithili, Maldivian (Dhivehi), Marathi, Nepali, Odia (Oriya), Punjabi, Sindhi, Sinhala, Urdu
    • Iranian: Dari, Kurdish, Pashto, Persian, Tajik

Other Eurasian:
  • Basque
  • Georgian
  • Uralic: Estonian, Finnish, Hungarian
  • Turkic: Azerbaijani, Bashkir, Kazakh, Kyrgyz, Tatar, Turkish, Turkmen, Uyghur, Uzbek
  • Mongolian
  • Korean
  • Japanese
  • Dravidian: Kannada, Malayalam, Tamil, Telugu
  • Sino-Tibetan:
    • Sinitic: Cantonese, Chinese
    • Tibeto-Burman: Meitei, Myanmar (Burmese), Mizo, Tibetan
  • Kra-Dai: Lao, Thai
  • Hmong-Mien: Hmong
  • Austroasiatic: Khmer, Vietnamese

Malayo-Polynesian (Austronesian):
  • Philippine: Cebuano, Ilocano, Tagalog (Filipino)
  • Javanese
  • Sundanese
  • Malagasy
  • Malayic: Malay, Indonesian
  • Oceanic:
    • Fijian
    • Polynesian: Hawaiian, Maori, Samoan, Tahitian, Tongan

Afro-Asiatic:
  • Semitic: Amharic, Arabic, Hebrew, Maltese, Tigrinya
  • Chadic: Hausa
  • Cushitic: Oromo, Somali

Niger-Congo:
  • Mande: Bambara
  • Atlantic-Congo:
    • Twi
    • Volta-Congo:
      • Ewe
      • Volta-Niger: Igbo, Yoruba
      • Bantu: Chichewa (Nyanja), Ganda (Luganda), Kinyarwanda, Lingala, Luganda, Rundi (Kirundi), Shona, Sotho (Sesotho), Swahili, Tsonga, Tswana (Setswana), Xhosa, Zulu

The Americas:
  • Eskimo-Aleut: Inuit: Inuinnaqtun, Inuktitut
  • Mayan: Yucatec Maya
  • Oto-Manguean: Queretaro Otomi
  • Tupian: Guarani
  • Quechua
  • Aymara

Creoles: Haitian Creole, Krio

Constructed languages: Esperanto, Klingon
 
 Classification of Pygmy languages
The term Congo Pygmies (African Pygmies) refers to "forest people" who have, or recently had, a hunter-gatherer economy and a simple, non-hierarchical societal structure based on bands, are of short stature,[note 1] have a deep cultural and religious affinity with the Congo forest[note 2] and live in a generally subservient relationship with agricultural "patrons", with which they trade forest products such as meat and honey for agricultural and iron products.

Though lumped together as "Pygmies" by outsiders, including their patrons, these peoples are not related to each other either ethnically or linguistically. Different Pygmy peoples may have distinct genetic mechanisms for their short stature, demonstrating diverse origins.
Are they some relic populations? Or some offshoot populations? Or did different Pygmies have different origins, with their shortness being convergent? Origins and Genetic Diversity of Pygmy Hunter-Gatherers from Western Central Africa - ScienceDirect

They all speak languages recognizably related to languages of outside populations: Ubangian, Bantu (both Volta-Congo in Atlantic-Congo in Niger-Congo), and Central Sudanic (Nilo-Saharan). But some Pygmy languages share some forest-related vocabulary like botanical vocabulary and vocabulary related to collection of honey.
... genetic studies have shown that Pygmy populations possess ancient divergent Y-DNA lineages (especially haplogroups A and B) in high frequencies in contrast to their neighbours (who possess mostly haplogroup E).[5]

...
Roger Blench (1999)[8] argues that the Pygmies are not descended from residual hunter-gatherer groups, but rather are offshoots of larger neighboring ethnolinguistic groups that had adopted forest subsistence strategies. None of the Pygmy peoples live in the deep forest without trade with agricultural 'patrons'. Blench argues that Pygmies are a deeply established caste, like blacksmiths, and that there was no original Pygmy race or language.
 
Genetic perspectives on the origin of clicks in Bantu languages from southwestern Zambia | European Journal of Human Genetics
Some Bantu languages spoken in southwestern Zambia and neighboring regions of Botswana, Namibia, and Angola are characterized by the presence of click consonants, whereas their closest linguistic relatives lack such clicks. As clicks are a typical feature not of the Bantu language family, but of Khoisan languages, it is highly probable that the Bantu languages in question borrowed the clicks from Khoisan languages. In this paper, we combine complete mitochondrial genome sequences from a representative sample of populations from the Western Province of Zambia speaking Bantu languages with and without clicks, with fine-scaled analyses of Y-chromosomal single nucleotide polymorphisms and short tandem repeats to investigate the prehistoric contact that led to this borrowing of click consonants. Our results reveal complex population-specific histories, with female-biased admixture from Khoisan-speaking groups associated with the incorporation of click sounds in one Bantu-speaking population, while concomitant levels of potential Khoisan admixture did not result in sound change in another. Furthermore, the lack of sequence sharing between the Bantu-speaking groups from southwestern Zambia investigated here and extant Khoisan populations provides an indication that there must have been genetic substructure in the Khoisan-speaking indigenous groups of southern Africa that did not survive until the present or has been substantially reduced.
So some arriving Bantu speakers borrowed clicks from Khoisan speakers, but some didn't.
 
genomic prehistory of peoples speaking Khoisan languages | Human Molecular Genetics | Oxford Academic
Peoples speaking so-called Khoisan languages—that is, indigenous languages of southern Africa that do not belong to the Bantu family—are culturally and linguistically diverse. They comprise herders, hunter-gatherers as well as groups of mixed modes of subsistence, and their languages are classified into three distinct language families. This cultural and linguistic variation is mirrored by extensive genetic diversity. We here review the recent genomics literature and discuss the genetic evidence for a formerly wider geographic spread of peoples with Khoisan-related ancestry, for the deep divergence among populations speaking Khoisan languages overlaid by more recent gene flow among these groups and for the impact of admixture with immigrant food-producers in their prehistory.
About the langs themselves,
Although an initial broad classification of the languages of Africa identified a single Khoisan phylum comprising three branches in southern Africa plus two languages—Sandawe and Hadza—spoken in East Africa (6), nowadays specialists of these languages agree that there are three distinct language families in southern Africa, namely Kx’a, Tuu and Khoe–Kwadi (1). Of these, Kx’a and Tuu might ultimately descend from a shared ancestor, but that has not yet been conclusively demonstrated (7). The Khoe–Kwadi languages are not related to either the Kx’a or the Tuu languages (1,8). As for the East African languages, although there is no demonstrable relationship between Hadza and any of the southern African Khoisan languages, there is some indication that Sandawe might be related to the Khoe–Kwadi family; however, this, too, needs further corroboration (7).
This means 3 to 5 recognizable groupings:

(Kx'a, Tuu), (Khoe–Kwadi, Sandawe), Hadza
 
On the subgrouping of Afroasiatic "or: How to use an unrooted phylogenetic tree in historical linguistics" -- Carsten Peust, Konstanz -- 2012

Lists 27 proposed family trees for the subfamilies of the Afro-Asiatic family, and adds another one. Some of them were proposed by multiple authors, so I weighted them by number of authors.

I then found an average tree by finding a distance matrix from each family tree and then finding an overall average distance matrix. I then did neighbor joining to find the overall tree.

My method: the root node has depth 0, and each branch node has a depth one more than its parent node. All the leaf nodes then got their parent's depth. I then inverted the depths so that the most recent branching has depth 1, and for each pair of leaf nodes, I used the maximum of the inverted depths. I then divided by the maximum of these inverted depths to get the final result for each tree. For incomplete trees, I created a root node that has child nodes the missing language families and that incomplete tree.

I found:

(((((Semitic, Berber), Cushitic), Egyptian), Chadic), Omotic)

However, there was a lot of variation in the trees, which I could capture by randomly varying the distance matrix. When I did so, I found a lot of different trees, with only (Omotic, all the others) being very common. (Semitic, Berber) was moderately common, however.
 
Researchers reconstruct major branches in the tree of language | Santa Fe Institute
"We have to get to the deepest layer of language to identify its ancestry because the outer layers, they are contaminated. They get easily corrupted by replacements and borrowings,” he says.

To tap into the core layers of language, Starostin’s team starts with an established list of core, universal concepts from the human experience. It includes meanings like “rock,” “fire,” “cloud,” "two,” “hand,” and “human,” amongst 110 total concepts. Working from this list, the researchers then use classic methods of linguistic reconstruction to come up with a number of word shapes which they then match with specific meanings from the list. The approach, dubbed “onomasiological reconstruction,” notably differs from traditional approaches to comparative linguistics because it focuses on finding which words were used to express a given meaning in the proto-language, rather than on reconstructing phonetic shapes of those words and associating them with a vague cloud of meanings.
noting
Using ancestral state reconstruction methods for onomasiological reconstruction in multilingual word lists in: Language Dynamics and Change Volume 8 Issue 1 (2018)

Rapid radiation of the inner Indo-European languages: an advanced approach to Indo-European lexicostatistics

Hittite (3700 BCE) split off first, then Tocharian (3000 BCE), then a split into four groups:
  • Albanian - difficult because of its numerous borrowings
  • Greek, Armenian (2000 BCE)
  • Italic, Germanic, Celtic (2100 BCE) -- Insular Celtic (200 BCE)
  • Balto-Slavic, Indo-Iranian (2300 BCE) -- Baltic, Slavic (1300 BCE), Indic, Iranian (1700 BCE)
 
Permutation test applied to lexical reconstructions partially supports the Altaic linguistic macrofamily | Evolutionary Human Sciences | Cambridge Core

Considering Turkic, Mongolic, Tungusic, Korean, Japonic, and using a 110-word Swadesh list. Comparison was automated with the help of consonant classes:

P: labials (p, b, f, v), T: dentals (t, d, th, dh), S: sibiliants (s, z, sh, zh), C: affricates (ts, dz, tsh, dzh), Y: palatal glide, W: labial glide, M: labial nasal, N: non-labial nasal (n, ng), Q: lateral affricate (tl), R; trill, similar, L: lateral, K: velars, uvulars (k, g, kh, gh, q, ...), H: pharyngeal (low-down) (h, (glottal stop), ..., vowels)

This system lumps together different voicings and distinguishes different points of articulation.

The paper uses a symbol for zh rather than C, because C is a general abbreviation for consonant. If one uses such a system, then one might use X for a generic consonant.

Turkic, Mongolic and Tungusic matched very well, with Mongolic and Tungusic the closest, while Japonic had a very good match with Turkic and a good match with Tungusic. Korean had only poor matches with the others, though matching Japonic the best.

Martine Robbeets, however, finds ((Turkic, (Mongolic, Tungusic), (Korean, Japonic)), in agreement with the first three, but not in the other two.

As an example of this method, consider the 1s and 2s pronouns. Turkic: be PH se SH, Mongolic: bi PH, chi CH, Tungusic bi PH, si SH.
 
94255-OA.pdf -- Automated Dating of the World’s Language Families Based on Lexical Similarity

Using the Automated Similarity Judgment Program (ASJP) on vocabulary lists with normalized transcription.

The paper has a big list of calibration points, with each one having a source: historical (H), epigraphic (inscriptions: E), and archeological (A). Dates are in BP (Before Present, standardized as 1950 CE). I also give the ASJP similarity score and the ASJP calculated date. Here is a partial list of their calibration points:

English-Frisian: 1550 H - 30.57 - 1677
Scandinavian (North Germanic): 1100 E - 32.83 - 1569
Germanic: 2100 H - 29.24 - 1745 - emergence of Cimbri, Teutones: beginning of Germanic-breakup migrations

Italo-Western Romance: 1524 H - 32.15 - 1600 - fall of the Western Roman Empire
Romance: 1729 H - 28.96 - 1759 - withdrawal of Roman troops to the south of the Danube; north of that river, Latin became Romanian

Goidelic: 1050 E - 27.52 - 1837 - Irish, Scottish Gaelic, Manx
Brythonic: 1450 H - 42.60 - 1172 - Welsh, Breton

Czech-Slovak: 1050 E - 67.18 - 479
East Slavic: 760 H - 39.47 - 1288 - sack of Kyiv by the Tatars
Slavic: 1450 H - 43.01 - descriptions of Slavs expanding out of their homeland

Iranian: 3900 A - 14.09 - 2856
Indic (Indo-Aryan): 3900 A - 24.79 - 1996
Indo-Iranian: 4400 A - 8.28 - 3665

Indo-European minus Anatolian, Tocharian: 5500 A - 5.29 - 4348

Common Turkic (Turkic minus Chuvash): 1419 H - 37.94 - 1348
Turkic (with Chuvash): 2500 A,H - 9.83 - 3404

Mongolic: 750 H - 20.75 - 2267

Inuit: 800 A - 60.40 - 640

Maltese-Maghreb Arabic: 910 H - 33.57 - 1534
Ethiopian Semitic: 2450 E - 18.90 - 2408

Hmong-Mien: 2500 E - 5.66 - 4243

Eastern Polynesian: 1050 A - 48.34 - 979
Eastern Malayo-Polynesian: 3350 A - 7.56 - 3803 - Oceanic, closest relatives
Ma'anyan-Malagasy: 1350 A - 30.30 - 1690 - settling of Madagascar
Malayo-Poynesian: 4250 A - 12.62 - 3024

Pama-Nyungan: 4500 A - 5.47 - 4295 - “new stone and food staple technologies and intensification in the archaeological record”

Benue-Congo: 6500 A - 3.58 - 4940 - Bantoid separation (macrolithic tools & pottery in Grassfields region)

Central Southern African Khoisan: 2000 A - 11.67 - 3143 - introduction of domestic ungulates

It must be noted that the ASJP calculated dates and the actual ones often have sizable discrepancies. The ASJP ones were obtained by fitting the actual ones to some function of the similarity score. I tried to reverse-engineer that function, and it is almost, but not quite, an exponential function.
 
There are some odd discrepancies, likely from how the similarity scores were calculated. For the Semitic languages,
  • (all) -10.51 - 3301
  • Central - 16.26 - 2638
  • South - 7.56 3804
But the South Semitic languages cannot have split before the Semitic languages as a whole. Here is a family tree:
  • East Semitic: Akkadian
  • West Semitic:
    • Central Semitic:
      • Northwest Semitic: Canaanite (Hebrew, Phoenician), Aramaic
      • Arabic
    • South Semitic:
      • Western: Ethiopian Semitic and Old South Arabian
      • Eastern: Modern South Arabian

Another discrepancy is Niger-Congo 1.54 6227 after a subgroup of it, Atlantic-Congo 1.26 6525
 
Looking at those calibration points, the non-archeological ones are not very old, at most about 2,500 years old. Archeology can reach back further, however, with the oldest ones being Benue-Congo at 6500 BP (4500 BCE) and Indo-European minus Anatolian & Tocharian at 5500 BP (3500 BCE).

Then next one in sequence is Pama-Nyungan of Australia, at about 4500 BP. (2500 BCE). There is an interesting curiosity about Australian Aboriginal languages. Nearly all of them are recognizably related, as the Pama-Nyungan family, except for some in the western half of the north end of the continent. The paper gives this reference:
Evans, Nicholas, and Rhys Jones. 1997. The cradle of the Pama-Nyungans: archaeological and linguistic speculations. In Aboriginal Australia in global perspective: archaeology and linguistics. Patrick McConvell and Nicholas Evans, eds. Pp. 385–417. Melbourne: Oxford University Press.
So these Native Australians spread over the continent with the help of superior technology, even if Paleolithic technology. Much like Algonquian and Inuit-language speakers in North America.

There is something that may or may not be a coincidence, the arrival of the dingo in Australia around then. The dingo is a feral dog, a domestic dog that returned to a wild state, and it arrived very recently, some 4,000 years ago.


The first one links to Who let the dogs in? A review of the recent genetic evidence for the introduction of the dingo to Australia and implications for the movement of people - ScienceDirect - "We then evaluate a list of potential groups who could have been responsible for their introduction, and suggest that Toalean or other hunter-gatherers from south Sulawesi were the likely suspects."
 
This paper contains numerous comments from other linguists, and they point out some details, like using 40 words from the Swadesh 100-word list, and using the ASJP's normalized spelling. The distances between word forms were calculated using the Levenshtein edit distance, often used for text strings.

Johanna Nichols points out that some of the dates are off: Indo-Iranian and Indic ought to be close to the presence. The Indo-Iranian homeland is Sintashta: 2100 - 1800 BCE, the Indic one is the southern edge of Petrovka: 1800 - 1600 BCE. Closer to the ASJP dates than this paper's dates.

The older language families are too young. For instance, Afro-Asiatic is calculated to date at 6,016 BP, much less than other estimates. Egyptian is attested at 5400 BP, and Egyptian is distant from the others (no prefix conjugation, like what Semitic, Berber, and Cushitic have). Semitic is calculated to date as 3,301 BP, when about 2,500 BP, East Semitic langs Akkadian and Eblaite were already distinct, and Amorite even more distinct. So Semitic must be even older.

ASJP's age for Uralic is 3178 BP, but Finno-Ugric speakers were in contact with Indo-Iranian ones at around 4000 BP.

So most of the ASJP's estimates for older language families are underestimates.
 
The ASJP Database - its home page

The ASJP Database - Meanings - usually 40 from the Swadesh 100 list, and sometimes all 100.

The documentation of ASJP's phonetic coding (ASJPcode) is at  Automated Similarity Judgment Program - the Wikipedia article on ASJP.

The ASJP software compares word forms without trying to determine if they are cognates, because non-cognates usually have greater distances between them than cognates, and because sound changes make distance between cognates.

But while it's undoubtedly good for quick comparisons, going further requires detailed historical-linguistics work.

This paper used the  Levenshtein distance - a kind of  Edit distance - a count of how editing is necessary to get one string from another. This seems like it is very difficult to calculate, but for lengths n1, n2, the space needed is O(max(n1,n2)) and the number of calculations O(n1*n2). In fact, there are several related sequence-difference algorithms:
The Hamming distance is easy to calculate. For size n, space O(1) time O(n). All the others require space O(n) time O(n^2).

More generally, edit distances are some of  String metric
 
The quick algorithm: the  Wagner–Fischer algorithm independently discovered numerous times. One makes a table of the distances between the first m1 entries of the first string and the first m2 entries of the second string. Entry (m1,m2) can be calculated incrementally from (m1-1,m2-1) for substitutions, (m1-1,m2) and (m1,m2-1) for indels, and (m1-2,m2-2) for transpositions.

Those edit distances can be adjusted to produce different scores for indels, substitutions, and/or transpositions, like a higher score for an indel than for a sub. The calculation can also be made to track all the previous changes for each change, and also assign collective rather than individual scores for runs of indels.

Edit-distance algorithms are used a lot in bioinformatics, for comparing gene and protein sequences.
 
Back
Top Bottom