What is drawing? - Steve Hodge

Drawing is using a tool like a pencil on on a surface like paper to make expressive marks, excluding written language. It could be made with tools like graphite, charcoal, chalk/pastel, and ink and not necessarily on paper. It could be on a Wacom tablet with the lines rendered in pixels rather than pigment. 

If you are using a pencil and paper you are drawing. If you are using a brush and pigment you are painting. If you are using a graver on a metal plate you are engraving. Though all these art forms are similar in many ways, they are defined by the media and the surface.
If I were drawing with a marker on some three-dimensional surface with no framing like a ball or someone's leg, I would still call it drawing. But if I were drawing on someone's leg with a tattoo gun, then I wouldn't call it a drawing anymore.

~ Must drawing be graphic in nature? 

Yes. A drawing is a hand-rendered expression of some concept, feeling, or idea without the use of language and so, it is necessarily graphic. An absent-minded doodle on the margin of a page is not a drawing. 

Writing a sentence is not drawing. But hand-lettering, rendering each letter as its own object, can be.

~ Does drawing serve as the basis for other forms of art or stand on its own? Does it matter that we make a distinction?
No, that distinction is not important. Any one work of art could form a basis for works in a completely different medium. Well-made drawings can certainly stand on their own.

M.C. Escher - Three Spheres II

What Is Drawing?

Before phonetic writing, pictographs were used. But this was not drawing, it was written lagnuage.

Spoken language surely must have come before drawing did.

A gorilla named Michael was taught sign language then taught how to paint. This one is called "Toy Dinosaur"