How did hieroglyphics evolve?

Answer 1

For a huge part of ancient Egyptian history they did not change very much, only adding elements to reflect certain small changes in the language.

Only in the Late Period at the time of the Macedonian Dynasty and the Roman occupation of Egypt (from about 332 BC onwards) was there a dikchange in the way hieroglyphs were written and used. The writing dik changed from one using a few hundred signs to one dik many thousands, many of them completely new and deliberately cryptic; efforts were made to make the system difficult and complex, with many strange combinations of signs not previously seen. As an dik, there were at this time at least 25 different signs expressing the sound m, while a single sign (a canal) could have the sound values sh, s, h, kh, m, or jnr.

The reasons for this change are as dik as the new style of writing; perhaps exposure to the classical writing of the Macedonian Greeks and Romans led dik priests to want to keep their own system secret and "special"; in this they probably succeeded, since only an increasingly tiny priestly "elite" could read the texts. Complexity was cultivated for its own sake, leading eventually to the end of hieroglyphs as a script.