The Horizon: Studies in Egyptology in Honour of M.A. Nur El-Din, edited by Basem El-Sharkaway, mentions that sticking the pen behind the ear -- as shown in the picture -- was an ancient Egyptian custom.
The Instructions of Khety has this to say about the life of a scribe in ancient Egypt:
"Behold, there is nothing that surpasses writings! They are a boat upon the water. Read then at the end of the Book of Kemyet this statement in it saying:
As for a scribe in any office in the Residence, he will not suffer want in it. When he fulfills the bidding of another, he does not come forth satisfied. I do not see an office to be compared with it, to which this maxim could relate. I shall make you love books more than your mother, and I shall place their excellence before you. It is greater than any office. There is nothing like it on earth. When he began to become sturdy but was still a child, he was greeted (respectfully). When he was sent to carry out a task, before he returned he was dressed in adult garments."
Picture: Image ID: 410916 Ancient Egypt. [Scribe]. (ca. 1924-1933) NYPL Digital Gallery