Bow is an enculturated chimpanzee. He is literate. He can read and write. But most of his writing in the past consisted of pointing at letters in order to form words and sentences.
Recently, Bow has taken an interest in handwriting. He tries to form letters on paper. As his strongest language is Hebrew, the letters he tries to form are the Assyrian square letters currently used for Hebrew.
While it is still hard to make out what Bow is writing, there is a real contrast between how he handles a pen or marker when doodling and when he is trying to form letters. The video embedded above is of Bow writing. The video below is Bow doodling or drawing.
Chimpanzees are famous for their tool use. Bow knows the use of each tool. For instance, he knows scissors are for cutting — including cutting his nails. He knows a pen or marker can be used to draw or write. He also recognizes the difference between drawing and writing.