[Mediterraneo10]

They didn't evolve from Old Church Slavonic. OCS was an artificial South Slavic literary standard based on the language from around Thessaloniki, as spoken by Cyrill and Methodius's mission. Russian, Ukrainian, and Belarusian are East Slavic languages, a different branch of the family. Indeed, they all have a common ancestor in Proto-Slavic, but the relationship of Russian etc. and OCS is one of cousins, not parent-child.

[osacial]

1. Russians do not have common ancestry in Proto-Slavic, because ancestors of Rus people in majority did not even speak Slavic languages, but Baltic, and Finnic languages - Rus themselves initially spoke Scandinavian. Poland and NW area of Ukraine is place where Proto-Slavioc originated. Do your math.

Бере-менна can not even be explained by Slavic language, or Proto... Baltic, but it can be explained by Swedish language, where bear-men was clear purpose of Rus women.

2. All the survived early written texts of Rus are in Old Church Slavonic - very similar to Russian(and possibly others that were known as Ruthenian, but I have no knowledge of Ukrainian, Belorussian or Rusyn to judge that).

3. You and me are not going to decide the classification of languages, that are based purely on geographic distribution or in case of Rus languages(or as they are known to others - East Slavic) - common history being part of one nation and not based on similar ancestry.

[Mediterraneo10]

Please pick up a basic introductory textbook to the history of the Slavic languages. Your understanding of the relationship between them is very mistaken. If you want to read in Russian, I can recommend К. А. Войлова’s Старославянский язык, which describes not only what Old Church Slavonic is, but also the family tree of the Slavic languages in general and how Russian, Belarusian and Ukrainian are not a direct descendant of Old Church Slavonic. If you want to read in English, Alexander Schenker’s The Dawn of Slavic covers much of the same ground in an accessible fashion.

> Russians do not have common ancestry in Proto-Slavic, because ancestors of Rus people in majority did not even speak Slavic languages

When historical-comparative linguists say "common ancestry", they mean common linguistic ancestry, not the genetic ancestry of the Slavic languages' speakers.

> All the survived early written texts of Rus are in Old Church Slavonic

This is not the case. The Novgorod birchbark letters that were excavated over the 20th century attest some early East Slavic, noticeably different from the Old Church Slavonic language that was borrowed into Russia/Belarus/Ukraine around the same time as a literary standard after the christianization of the region.

> You and me are not going to decide the classification of languages, that are based purely on geographic distribution

The distinctions "West Slavic", "East Slavic" and "South Slavic" aren't actually based on the geographic distribution. Rather, they are based on the isoglosses that set the Slavic languages apart from one another. The terms "East/West/South" for the basic post-Proto-Slavic isoglosses are used only because those isoglosses map roughly with those cardinal directions. Again, this is something covered in any basic textbook.

> Бере-менна can not even be explained by Slavic language, or Proto... Baltic, but it can be explained by Swedish language, where bear-men was clear purpose of Rus women.

No, беременна is a native Slavic word and not a Swedish borrowing; it goes back to the same root as беру. If it looks similar to a Swedish word, this is only because the Slavic languages and the Germanic languages both inherited the same Proto-Indo-European word. A detailed etymology for the Russian word can be found in Vasmer under the headword *беремя*.

[osacial]

After taking a quick glance on the book of К. А. Войлова "Старославянский язык" nothing really contradicts what I posted before about Old Church Slavonic place in creation of Russian. Also, if you are presenting your source it is up to you to quote where Russian is not descendant from Old Church Slavonic, to disprove me - I have no obligation whatsoever to comb whole book and make something up that proves your point. I had a different - more recent source that I read from Russian linguist(my memory is bad on names), where he discussed Old Church Slavonic and how it replaced most of local languages as a base to Russian and other modern East Slavic languages.

Also I think you are confused about these terms in English, where Old Church Slavonic == Старославянский язык Church Slavonic == Церковнославя́нский язы́к

>The Novgorod birchbark letters that were excavated over the 20th century attest some early East Slavic, noticeably different from the Old Church Slavonic language

That is correct, however what I wrote was completelly different: "All the survived early written texts of Rus are in Old Church Slavonic."

Besides, they were neither early East Slavonic or even classified as modern East Slavic and they are not directly related to Russian as well. Many of those Slavic can be classified as early Western Slavic at best.

>No, беременна is a native Slavic word and not a Swedish borrowing It seems, that I was wrong in this one(as pregnancy in most of Slavic languages use different word, but I did not search further, where Bulgarians use similar word for pregnancy). Sadly, that also means that Old Church Slavonic replaced everything else.