Hi!

New to the Forum, new to the thread, introduced by ToMach from Society & Humanities > History & Traditions "Origin of Japanese Language" post #34
Japanese and other languages (mere coincidence) | Japan Forum
If I may add, this line of investigation started by AX is an unexplored territory from the linguistic point of view. I'd like to offer two points for you to consider.
1. The fact that for any two languages selected at random, there will be a small number of word pairs from each language that will show striking similarity in both sound and meaning.
Needless to say, the number of "similar" word pairs one finds will depend on how you define "similar." If you employ a set of strict rules of closeness when filtering out non-matches, then the correspondence figure will be small. If you loosen the rules, the number will increase.
For example, when Prof. 服部四郞 did his comparative study of Japanese and non-Japanese languages, he discovered the random correspondence rate somewhere between 5% and 10%. Apparently his "filter" was not very strictly defined, and also the range of figures 5% to 10% is only a rough range (requoting from 李男德, 韓國語語源硏究II, pp.18-19, III; supplemented with 江實's reconstruction, 日本語の系統, 1980, requoted from 李男德, 韓國語語源硏究IV, pp.250-254)
服部四郞's five "stray" matches between Old Japanese and Modern English
SN OJ江實 OJ服部 : English
27 tane(實,種) sane : seed
31 Fone(骨) pone : bone
36 Fane(羽) pane : feather
37 kE (毛) k(e)i : hair
49 Fara(腹) para : belly
58 kiku (聞) kiku : to hear
62 kOrOsu(殺) korosu : to kill
66 ku (來) kuru : to come
82 FI (火) pIi : fire
100 na (名) na : name
服部四郞's fourteen "stray" matches between O. Japanese and Archaic Chinese
SN OJ江實 OJ服部 : AC董同龢(?)
2 nare (汝) na : njag (thou)
20 tōri (鳥) tOri : tŏg (bird)
40 mE (目) m(e)i : mŏg (eye)
41 Fana (鼻) pana : bjed (nose)
42 kuti (口) kuti : k'ug (mouth)
44 sIta (舌) sita : djat (tongue)
45 *** (爪) tum(e)i : cŏg (claw, fingernail)
48 tE (手) t(e)i : t'jog (hand)
56 kamu (咬) kamu : kŏg (to bite)
61 sinu (死) sinu : sjer (to die)
76 kaFa (河) kapa : har (river)
82 FU (火) pUi~po : hwěr (fire)
83 FaFi (灰) papi : hw(e)r (ashes)
91 kurosi(黑) kuro : hwek (black)
Capital vowels E, O, and I stand for e diacritic, o diacritic, and i diacritic resp.
(e): schwa, for lack of fonts
SN: Swadesh numbering
OJ江實: Old Japanese reconstructed by 江實
OJ服部: Old Japanese reconstructed by 服部四郞
AC董同龢: Archaic Chinese, broad transcription from Tung T'ung-ho董同龢's(?)
Since such matches are considered "stray, random matches," few linguists trained in the tradition of modern linguistics would take such matches seriously, but the Professor reported on it anyway. Good for him!

(I am working on a short paper regarding how to define "similarity" and how the range of correspondence ratio is mathematically related to this similarity. When it is done, I will make it available upon request.)
2. The recent trend in one sector of the linguistics community to experiment with long-distance, mass comparison among huge vocabularies of multiple languages.
Such studies conducted by Joseph Greenberg, Merritt Ruhlen, and others have shown successes in many cases where narrow comparisons have either failed or given inconsistent results. Merritt Ruhlen goes even further by postulating a Proto-Language, the precursor and ancestor to all modern languages of the world. Ruhlen initially offered 27 Global Roots, which he claims to be traces of a common origin. Here is a summary by M.Ahaya
AIM where you can go over the 27 roots for yourselves.
To the comparative linguist who is looking for two, genetically related languages, this is both good news and bad news. If Ruhlen's list turns out to be correct, any "correspondence" that should have supported the genetic relationship between two languages prior to the common origin hypothesis must now NOT include any words springing from a globally common root. This means one has to work harder to establish genetic relationship. On the other hand, given that the global roots list is well studied and close to perfection (which should be fairly larger than 27), one need not concern oneself with words in the list to begin with.
Concluding remark:
Since there will be coincidences resulting from random matching and regular correspondences originating from a globally common origin, anyone doing a comparison of two distinct languages will discover a fairly LARGE number of word pairs if one looks hard enough.

This is an exciting field that you have touched upon, AX.
Live long and prosper!
