world. (Socrates, Plato, Aristotle, etc.) It combined what we'd now
call 'science' with other aspects of reality, and asked all those questions. (So philosophers asked about the origin of the universe, what it was made of, what it was all for, what was ethical, etc., all in one package.)
As that knowledge grew and people started specializing, and as philosophers started to realize better the role of controlled observation in gaining certain types of knowledge, and as they learned more about the world to start to impose stable categories on phenomena, the sciences split off from philosophy. So, for example, Aristotle is called the father of biology: he catalogued a great many species, speculated (in a very sexist manner) on biology and reproduction. He also philosophized about what made humans different from other animals. But, it was only some time after him that biology turned into a science with a shared set of standards, research problems, etc. - one could say that before Darwin, biology wasn't distinct from a whole host of other inquiries into life-related subjects.
The word "scientists" is a recent invention, formally distinguishing experimental investigators of nature from other modes of inquiry. (Newton called himself a "natural philosopher" because 'scientist' wasn't created yet. And, he probably would have objected even so: he did an awful lot of philosophy (epistemology, especially) in his Principia Mathematica.)
Philosophy as the Mother of Science