The Japanese and Korean are nothing like the different Germanic people. All evidence points to the fact that early Japanese spoke a different language than the Koreans and that they were not mutually comprehensible. The claim that early Japanese mixed with early Koreans more than with the Han Chinese is also quite baseless.
Early as in what?
We don't have records of what Yayoi Japanese sound like, even 2,000 years ago.
That's like me saying...well Romanian and French are incomprehensible 500 years ago.
The claim that Early Japanese mixed with Koreans more than Han means what?
Mixed with in what way? Biologically? Culturally? biologically, Japanese are more related to Koreans than Han Chinese...by far, they group very close.

Article
Origin of the Koreans: A population genetic study
N. Saha, J. S. H. Tay
Department of Paediatrics, Division of Human Genetics, National University of Singapore, Singapore 0511
Keywords
Population genetics • Blood genetic markers • Genetic distance • Genetic origin • Linguistics • Average heterozygosity
Abstract
A population genetic study was undertaken to investigate the origin of Koreans. Thirteen polymorphic and 7 monomorphic blood genetic markers (serum proteins and red cell enzymes) were studied in a group of 437 Koreans. Genetic distance analyses by both cluster and principal components models were performed between Koreans and eight other populations (Koreans in China, Japanese, Han Chinese, Mongolians, Zhuangs, Malays, Javanese, and Soviet Asians) on the basis of 47 alleles controlled by 15 polymorphic loci. A more detailed analysis using 65 alleles at 19 polymorphic loci was performed on six populations. Both analyses demonstrated genetic evidence of the origin of Koreans from the central Asian Mongolians. Further, the Koreans are more closely related to the Japanese and quite distant from the Chinese. The above evidence of the origin of Koreans fits well with the ethnohistoric account of the origin of Koreans and the Korean language. The minority Koreans in China also maintained their genetic identity. © 1992 Wiley-Liss, Inc.
Received: 29 January 1990; Accepted: 4 November 1991
http://www3.intersci...486445/abstract
In Fig. 1 B, two clusters for the northern populations are discernible. Altaic language-speaking Buryat, Yakut, Uyghur, and Manchu clustered with the Korean and Japanese, two language isolates but closely related to Altaic. Two Han populations, one from north China and the other from Yunnan, also contributed to this cluster (cluster N1). Another Altaic language-speaking population, Ewenki, formed a cluster (cluster N2) with Tibetan, Tujia, and Hui, all of which were originally derived from the northern populations though currently living in the western part of China (21).
http://www.pnas.org/...5/20/11763.full
This shows that Northern Chinese, Japanese, and Koreans do group with Japanese...but the article above shows that between Koreans, Japanese, and Chinese...Japanese and Koreans are much more related.
It also shows that genetically Koreans and Japanese were closely related to other Altaic Speaking groups and if you read further in the article, quite distant from Southern Chinese, Taiwanese Aborigines, etc.
On this site, a book by the foremost population genetic researcher, Dr. Luigi Luca Cavalli-Sforza he states that:
He says that although Koreans are quite distant from Ryukuans and Ainu they are very similar to Japanese on the main Islands. You can find that at the bottom of the first column.
Pg 231 (above the page I just mentioned) it shows quite clearly...are more related to the majority of Japanese, than Northern Chinese or anyone else in the region. The people in Southern Honshu around Kinki and people in Kyushu (he says in the text, Southern Kyushu) are outliers for some reason but the majority of Japanese in Hokkaido and Honshu are very close to Koreans.
Even some people in Bhutan seem to be more closely related to the Japanese than Northern Chinese, which I find quite interesting, but I'm not sure the population size measured, that seems odd. If you look at the chart at the top of pg. 231, you can see that Southern Chinese are very divergent (once again) from Japanese and Korean.
. Population-based comparisons confirmed that present-day Japanese have their closest genetic affinity to northern Asian populations, especially to Koreans, which finding is congruent with the proposed Continental gene flow to Japan after the Yayoi period. This phylogeographic approach unraveled a high degree of differentiation in Paleolithic Japanese. Ancient southern and northern migrations were detected based on the existence of basic M and N lineages in Ryukyuans and Ainu. Direct connections with Tibet, parallel to those found for the Y-chromosome, were also apparent.
this is on the female side only though.
http://genome.cshlp....act/14/10a/1832
The phylogeny revealed a closer genetic relationship between Japanese and Koreans than to the other surveyed Asian populations. Based on the result of the dual patterns of the haplotype distribution, it is more likely that the population structure of Koreans may not have evolved from a single ancient population derived from Northeast Asians, but through dual infusions of Y chromosomes entering Korea from two different waves of East Asians.
http://www.springerl...1jacqer4f19jlf/
What evidence do you have to refute this?
So let me repeat, Japanese and more closely related to Koreans linguistically and genetically than any other people presently alive in East Asia. I see nothing that refutes that.
I don't think I need to post more studies, it is kind of obvious where this is going.
As far as linguistics
Who in Asia is more related to the Japanese than Koreans?
Please show some genetic evidence from a study.
As far as Korean and Japanese language similarities...
When people compare languages they don't just look at vocab, the more important thing is grammar, that changes the least, vocab is relatively easy to change overtime, sentence structure is not.
As far as language, there is some argument about if Japanese is related to any of their neighbors, and some argument if Japanese is related to the Koguryo language, which is quite divergent from Modern Korean. The argument is that Japanese is closer to Koguryo than modern Korean, because after Koguryo was broken up their language did not become standard Korean, but Silla did and they were likely not mutually intelligible.
http://www.pliink.co...o-japanese.html
Indiana University-Bloomington linguistics professor Christopher Beckwith's relatively new tome Koguryo: The Language of Japan's Continental Relatives offers a fascinating and plausible solution to the enduring origin puzzle. From around 100 B.C. to the 7th century A.D., modern day Korea was divided into three kingdoms: Koguryo, Shilla, and Paekche. The three states were eventually unified under Shilla in 668, and the modern Korean language originates from the language spoken in Shilla. Koguryo and Paekche, however, had different languages which are posited to be related to each other. Scholars thus make two groupings of Korean peninsula languages: the Han2 languages - spoken in Shilla and among the subjugated class in Paekche - and the Puyo-Koguryoic languages of Koguryo, Puyo (another Northern Korea state), and Paekche's ruling class. The latter family is now totally extinct and probably made a minor impact on modern Korean. The lack of written records and remaining vocabulary items from these languages make it difficult to learn much about the nature of the "Koguryoic" family.
SNIP
There are, however, two sets of Chinese records that list words from the Koguryo language. Beckwith identifies thirteen words ("Archaic Koguryo") contained in a 3rd century Chinese record about the language of the Koguryo people. The second record is the Samsuk Sagi, the "Three Kingdoms of Korea" work that includes a record of a king in 755 changing all the place names in Korea into Chinese. The older toponyms in the Koguryoic areas do not resemble modern day Korean, and despite some controversy of whether the names were given by the Koguryo people or by other peoples populating the area before their arrival, Beckwith shows that a match between these and the Archaic Koguryo lexical items strongly suggest that the toponyms are from the "Old Koguryo" language. For many of these Koguryo place names, the record shows a Chinese transcription of the word's pronunciation as well as a meaning for the word. Beckwith identifies around 130 distinct Old Koguryo words from this document.
Scholars have known about these Koguryo lexical items for almost a century now, but the main problem has been reconstructing the proper Chinese pronunciation of the era in which the words were transcribed. There have been many improvements upon this knowledge in recent years, and Beckwith employs this new understanding of old Chinese to reconstructing many of these Koguryo words with more accuracy than before.
For examples of the close relation of some Koguryo words and Old Japanese, download this 2-page PDF. Almost all scholars agree that the language contained in this "Koguryo" set looks much like Old Japanese. Roy Andrew Miller - who is famously convinced that Japanese is an Altaic language - believed these words to be Proto-Japanese from Wa people who were living on the peninsula. There, however, is no evidence of a Proto-Japanese/Wa conquest in Korea that could have caused a change in place names. An important side note, which Beckwith emphasizes in the paper, Korean words look absolutely nothing like the Koguryo vocabulary, and the weakness of this connection puts the Japanese-Korean relation theory in doubt.
If the Japanese (Wa/Yayoi) and Koguryo/Paekche peoples are truly related, how in the world did they get all the way through the Korean peninsula and down to Japan which there is no record of happening? They didn't. Based on the work of Gisaburo N. Kiyose, Beckwith proposes a somewhat radical immigration narrative for the Wa. He puts the original Koguryoic homeland in Liao-Hsi (present day Liaoning) on the coast of Northeast China. Once the Chinese put pressure on this racial group, the more nomadic and warlike Puyo-Koguryo peoples (who had already split from the Wa at this point) made their way up to Korea and Manchuria. The Wa - who were mostly fishermen and farmers - left by boat to Korea, Kyushu, and the Ryukyuan islands at the same time. Archaeologists have artifacts that show a connection between the Yayoi culture and the culture of that period on the peninsula, and Beckwith suggests that this does not necessarily mean a voyage from settlements in Korea to Japan but a simultaneous settlement of both areas. He also re-emphasizes that no traces of this farming culture can be found in Manchuria or North Korea - which would be critical to proving Japanese came from Northeast Asia as the Altaic family theory would suggest.
Look at this comparison:
http://www.msu.edu/~...bs.Beckwith.pdf
If you have some other proof, please present it.



















