Natural science first appeared with the Greeks?
(laugh up sleeve) oh, sorry ...don't mean to be rude
Maybe you are referring to the wonderful Greek contributions to science. But to say it first appeared with the Greeks... lol

And who were these "Greeks, Muslims and Europeans"
-- were they the ancestors of today's persons of those regions? Can you prove it?

On a related note,
I don't know if you are aware that people have been on the move a LOT. A good library near you might have an atlas which shows some of the travels of very large groups.

Did you know, for example, that the Sahara was once much wetter (ie. 2500 BC) and that North Africans moved north into Europe as the oases disappeared? That's just a start.