Avichal said:
Most of the words I see originate from Latin and Greek. I suppose that is because they are the oldest languages and everything was derived from those two.
But how did Latin and Greek come up. How did we form the language in the very beginning? Who decided the words, the grammar, the spelling etc?
I have been curious about this question. Sorry if this is a very common question in linguistic, I thought this would be the quickest place to get the answers compared to any other resources.
Thank You!
I think most people know

that Latin and Greek as well as the Germanic languages from which English is descended are branches of a single language family, 'Indo-European' which includes most European languages, Persian, most languages of India and even Hittite. Thought to originate from peoples of Central Asia/ Caucasus who spread or at least their culture did. Something supposed to resemble the original ('proto-Indo-European') has been reconstructed.* Something like a dozen or so such large language groups have been identified. For instance the 'native' languages of America fall into 3 groups, Inuit, Na-dene, and the most widespread 'Amerindian'.
According to some, all languages have a single ancestor. (That would be my expectation. like life, first comer takes all). I have heard it claimed that a handful of words of this ancestor can be identified. That the original 'one' and 'two' were 'tik' and 'pal'.
These ideas and studies go back a long way and you can imagine there has been much disagreement. I think the field has been renewed by the same kind of methods that are used in trying to reconstruct the Tree of Life from DNA sequences. Relations between DNA sequences have been reconstructed that are absolutely not evident by just looking at a few sequences side by side. I am equally not up-to-date on this field

but remember a couple of conferences I attended a dozen or so years ago that would have been a corrective lesson to the people who say scientists make up stories and believe what they want to believe.
But I would appreciate hearing of an appropriate digestible book or site that deals with this language evolution, the wiki site quoted is rather broad biological and philosophical background, and not a little speculation, rather than history. I would like to know not just what they think but what is their criterion or measure of truth or reliability of their conclusions.
Avichal said:
. Latin and Greek must have some rules too.
And how!

Any secondary schoolchild for several centuries till recently would know it, spending years on the rules, something considered as dry and difficult as math.
*a trifle I remember is that our word 'fish' was thought to be related to 'flat', 'foot', and even 'spear' (the family must surely include 'plate', 'blade' and 'Blatt' =leaf, German) whereas the original Indo-European word for fish is the ancestor of our 'salmon'.
Edit: other plausible relatives keep coming to mind, like fold, field, felt, pelt, ply, develop etc...