Question: Where is the hypothetical center from which the Indo-European languages radiated?
About the article "Turkey", section "Prehistory of Anatolia and Eastern Thrace".

Candidate passages:
Indo-European studies is a field of linguistics and an interdisciplinary field of study dealing with Indo-European languages, both current and extinct.
Its goal is to amass information about the hypothetical proto-language from which all of these languages are descended, a language dubbed Proto-Indo-European (PIE), and its speakers, the Proto-Indo-Europeans, including their society and religion.
The studies cover where the language originated and how it spread.
This article also lists Indo-European scholars, centres, journals and book series. 
The Proto-Indo-European language (PIE) is the common ancestor of the Indo-European languages, spoken by the Proto-Indo-Europeans.
From the 1960s, knowledge of Anatolian became certain enough to establish its relationship to PIE.
Using the method of internal reconstruction an earlier stage, called Pre-Proto-Indo-European, has been proposed.PIE was an inflected language, in which the grammatical relationships between words were signaled through inflectional morphemes (usually endings).
The roots of PIE are basic morphemes carrying a lexical meaning.
By addition of suffixes, they form stems, and by addition of desinences (usually endings), these form grammatically inflected words (nouns or verbs).
The hypothetical Indo-European verb system is complex and, like the noun, exhibits a system of ablaut. 
Proto-Indo-Iranian is the reconstructed proto-language of the Indo-Iranian branch of Indo-European.
Its speakers, the hypothetical Proto-Indo-Iranians, are assumed to have lived in the late 3rd millennium BC, and are often connected with the early Andronovo archaeological horizon.
Proto-Indo-Iranian was a Satem language, likely removed less than a millennium from the late Proto-Indo-European language, and in turn removed less than a millennium from the Vedic Sanskrit of the Rigveda.
It is the ancestor of the Indo-Aryan languages, the Iranian languages, the Dardic languages and the Nuristani languages. 
Graeco-Armenian (also Helleno-Armenian) is the hypothetical common ancestor of the Greek and Armenian languages which postdates the Proto-Indo-European language (PIE).
Its status is comparable to that of the Italo-Celtic grouping: each is widely considered plausible without being accepted as established "communis opinio".
The hypothetical Proto-Graeco-Armenian stage would need to date to the 3rd millennium BC, only barely differentiated from either late PIE or Graeco-Armeno-Aryan.  
Proto-Iranian, is the reconstructed proto-language of the Iranian languages branch of Indo-European language family, and as such, the ancestor of the Iranian languages such as Persian, Sogdian, Zazaki, Mazandarani, Kurdish and others.
Its speakers, the hypothetical Proto-Iranians, are assumed to have lived in the early 2nd millennium BC, and are usually connected with the Proto-Indo-Iranians and early Andronovo archaeological horizon.
Proto-Iranian was a Satem language descended from the Proto-Indo-Iranian language, which in turn came from the Proto-Indo-European language.
It was likely removed less than a millennium from the Avestan language, and less than two millennia from PIE.